general improvements added according to latest library usage statistics

build.gradle

@@ -11,7 +11,7 @@ android {
     }
 
     defaultConfig {
-        minSdkVersion 9
+        minSdkVersion 16
         targetSdkVersion 25
     }
 }
@@ -19,4 +19,5 @@ android {
 dependencies {
     provided 'com.android.support:support-annotations:25.3.1'
     provided 'io.reactivex:rxandroid:1.2.1'
+    provided 'io.reactivex:rxjava:1.2.9'
 }

src/main/java/ru/touchin/roboswag/core/observables/BaseChangeable.java

@@ -0,0 +1,112 @@
+/*
+ *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
+ *
+ *  This file is part of RoboSwag library.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package ru.touchin.roboswag.core.observables;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.io.Serializable;
+
+import ru.touchin.roboswag.core.utils.ObjectUtils;
+import ru.touchin.roboswag.core.utils.Optional;
+import rx.Observable;
+import rx.subjects.BehaviorSubject;
+
+/**
+ * Created by Gavriil Sitnikov on 24/03/2016.
+ * Wrapper over {@link BehaviorSubject} which could be serialized.
+ * Such object is useful as view model and also as value in Android that could be passed into {@link android.os.Bundle}.
+ *
+ * @param <TValue>       Type of Changeable value;
+ * @param <TReturnValue> Type of actual value operating by Changeable. Could be same as {@link TValue}.
+ */
+public abstract class BaseChangeable<TValue, TReturnValue> implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    private transient BehaviorSubject<Optional<TValue>> valueSubject;
+
+    public BaseChangeable(@Nullable final TValue defaultValue) {
+        valueSubject = BehaviorSubject.create(new Optional<>(defaultValue));
+    }
+
+    @NonNull
+    protected Observable<Optional<TValue>> observeOptionalValue() {
+        return valueSubject.distinctUntilChanged();
+    }
+
+    /**
+     * Sets current value.
+     *
+     * @param value Value to set.
+     */
+    public void set(@Nullable final TValue value) {
+        valueSubject.onNext(new Optional<>(value));
+    }
+
+    /**
+     * Returns current value.
+     *
+     * @return Current value.
+     */
+    @Nullable
+    public TValue get() {
+        return valueSubject.getValue().getValue();
+    }
+
+    /**
+     * Returns {@link Observable} which is emits current value and then emitting changes of current value.
+     *
+     * @return Current value {@link Observable}.
+     */
+    @NonNull
+    public abstract Observable<TReturnValue> observe();
+
+    private void writeObject(@NonNull final ObjectOutputStream outputStream) throws IOException {
+        outputStream.writeObject(valueSubject.getValue());
+    }
+
+    @SuppressWarnings("unchecked")
+    private void readObject(@NonNull final ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
+        valueSubject = BehaviorSubject.create((Optional<TValue>) inputStream.readObject());
+    }
+
+    @Override
+    public boolean equals(@Nullable final Object object) {
+        if (this == object) {
+            return true;
+        }
+        if (object == null || getClass() != object.getClass()) {
+            return false;
+        }
+
+        final BaseChangeable<?, ?> that = (BaseChangeable<?, ?>) object;
+        return ObjectUtils.equals(valueSubject.getValue(), that.valueSubject.getValue());
+    }
+
+    @Override
+    public int hashCode() {
+        return valueSubject.getValue() != null ? valueSubject.getValue().hashCode() : 0;
+    }
+
+}

src/main/java/ru/touchin/roboswag/core/observables/Changeable.java

@@ -22,47 +22,19 @@ package ru.touchin.roboswag.core.observables;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
-import java.io.IOException;
+import ru.touchin.roboswag.core.utils.Optional;
-import java.io.ObjectInputStream;
-import java.io.ObjectOutputStream;
-import java.io.Serializable;
-
-import ru.touchin.roboswag.core.utils.ObjectUtils;
 import rx.Observable;
-import rx.subjects.BehaviorSubject;
 
 /**
  * Created by Gavriil Sitnikov on 24/03/2016.
- * Wrapper over {@link BehaviorSubject} which could be serialized.
+ * Variant of {@link BaseChangeable} which is allows to set nullable values.
- * Such object is useful as view model and also as value in Android that could be passed into {@link android.os.Bundle}.
+ * Needed to separate non-null Changeable from nullable Changeable.
  */
-public class Changeable<T> implements Serializable {
+//COMPATIBILITY NOTE: in RxJava2 it should extends BaseChangeable<T, Optional<T>>
-
+public class Changeable<T> extends BaseChangeable<T, T> {
-    private static final long serialVersionUID = 1L;
-
-    private transient BehaviorSubject<T> subject;
 
     public Changeable(@Nullable final T defaultValue) {
-        subject = BehaviorSubject.create(defaultValue);
+        super(defaultValue);
-    }
-
-    /**
-     * Sets current value.
-     *
-     * @param value Value to set.
-     */
-    public void set(@Nullable final T value) {
-        subject.onNext(value);
-    }
-
-    /**
-     * Returns current value.
-     *
-     * @return Current value.
-     */
-    @Nullable
-    public T get() {
-        return subject.getValue();
     }
 
     /**
@@ -71,35 +43,10 @@ public class Changeable<T> implements Serializable {
      * @return Current value {@link Observable}.
      */
     @NonNull
+    @Override
+    //COMPATIBILITY NOTE: in RxJava2 it should be Observable<Optional<T>>
     public Observable<T> observe() {
-        return subject.distinctUntilChanged();
+        return observeOptionalValue().map(Optional::getValue);
-    }
-
-    private void writeObject(@NonNull final ObjectOutputStream outputStream) throws IOException {
-        outputStream.writeObject(subject.getValue());
-    }
-
-    @SuppressWarnings("unchecked")
-    private void readObject(@NonNull final ObjectInputStream inputStream) throws IOException, ClassNotFoundException {
-        subject = BehaviorSubject.create((T) inputStream.readObject());
-    }
-
-    @Override
-    public boolean equals(@Nullable final Object object) {
-        if (this == object) {
-            return true;
-        }
-        if (object == null || getClass() != object.getClass()) {
-            return false;
-        }
-
-        final Changeable<?> that = (Changeable<?>) object;
-        return ObjectUtils.equals(subject.getValue(), that.subject.getValue());
-    }
-
-    @Override
-    public int hashCode() {
-        return subject.getValue() != null ? subject.getValue().hashCode() : 0;
     }
 
 }

src/main/java/ru/touchin/roboswag/core/observables/NonNullChangeable.java

@@ -21,18 +21,22 @@ package ru.touchin.roboswag.core.observables;
 
 import android.support.annotation.NonNull;
 
+import ru.touchin.roboswag.core.log.Lc;
 import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
+import rx.Observable;
 
 /**
  * Created by Gavriil Sitnikov on 24/03/2016.
- * Variant of {@link Changeable} which is allows to set only non-null values.
+ * Variant of {@link BaseChangeable} which is allows to set only non-null values.
+ * Needed to separate non-null Changeable from nullable Changeable.
  */
-public class NonNullChangeable<T> extends Changeable<T> {
+public class NonNullChangeable<T> extends BaseChangeable<T, T> {
-
-    private static final long serialVersionUID = 1L;
 
     public NonNullChangeable(@NonNull final T defaultValue) {
         super(defaultValue);
+        if (defaultValue == null) {
+            throw new ShouldNotHappenException();
+        }
     }
 
     @NonNull
@@ -45,11 +49,30 @@ public class NonNullChangeable<T> extends Changeable<T> {
         return value;
     }
 
-    @SuppressWarnings("PMD.UselessOverridingMethod")
-    // UselessOverridingMethod: we need only annotation change
     @Override
     public void set(@NonNull final T value) {
+        if (value == null) {
+            Lc.assertion("value is null");
+            return;
+        }
         super.set(value);
     }
 
+    /**
+     * Returns {@link Observable} which is emits current value and then emitting changes of current value.
+     *
+     * @return Current value {@link Observable}.
+     */
+    @NonNull
+    @Override
+    public Observable<T> observe() {
+        return observeOptionalValue()
+                .map(optional -> {
+                    if (optional.getValue() == null) {
+                        throw new ShouldNotHappenException();
+                    }
+                    return optional.getValue();
+                });
+    }
+
 }

src/main/java/ru/touchin/roboswag/core/observables/ObservableResult.java

@@ -1,59 +0,0 @@
-package ru.touchin.roboswag.core.observables;
-
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-
-import java.util.ArrayList;
-import java.util.LinkedList;
-import java.util.List;
-
-/**
- * Created by Gavriil Sitnikov on 21/05/2016.
- * Object represents Observable's execution result. Contains all items and errors emitted by Observable during subscription.
- */
-public class ObservableResult<T> {
-
-    @NonNull
-    private final List<T> items = new LinkedList<>();
-    @Nullable
-    private Throwable error;
-
-    /**
-     * Passes item to collect.
-     *
-     * @param item Emitted item.
-     */
-    public void onNext(@Nullable final T item) {
-        items.add(item);
-    }
-
-    /**
-     * Passes error to collect.
-     *
-     * @param error Emitted error.
-     */
-    public void onError(@NonNull final Throwable error) {
-        this.error = error;
-    }
-
-    /**
-     * Returns list of collected items.
-     *
-     * @return Items.
-     */
-    @NonNull
-    public List<T> getItems() {
-        return new ArrayList<>(items);
-    }
-
-    /**
-     * Returns collected error.
-     *
-     * @return Error.
-     */
-    @Nullable
-    public Throwable getError() {
-        return error;
-    }
-
-}

src/main/java/ru/touchin/roboswag/core/observables/OnSubscribeRefCountWithCacheTime.java

@@ -28,7 +28,6 @@ import rx.Observable.OnSubscribe;
 import rx.Scheduler;
 import rx.Subscriber;
 import rx.Subscription;
-import rx.functions.Action0;
 import rx.functions.Action1;
 import rx.observables.ConnectableObservable;
 import rx.schedulers.Schedulers;
@@ -114,19 +113,15 @@ public final class OnSubscribeRefCountWithCacheTime<T> implements OnSubscribe<T>
     @NonNull
     private Action1<Subscription> onSubscribe(@NonNull final Subscriber<? super T> subscriber,
                                               @NonNull final AtomicBoolean writeLocked) {
-        return new Action1<Subscription>() {
+        return subscription -> {
-            @Override
+            try {
-            public void call(@NonNull final Subscription subscription) {
+                baseSubscription.add(subscription);
-
+                // ready to subscribe to source so do it
-                try {
+                doSubscribe(subscriber, baseSubscription);
-                    baseSubscription.add(subscription);
+            } finally {
-                    // ready to subscribe to source so do it
+                // release the write lock
-                    doSubscribe(subscriber, baseSubscription);
+                lock.unlock();
-                } finally {
+                writeLocked.set(false);
-                    // release the write lock
-                    lock.unlock();
-                    writeLocked.set(false);
-                }
             }
         };
     }
@@ -152,14 +147,14 @@ public final class OnSubscribeRefCountWithCacheTime<T> implements OnSubscribe<T>
             }
 
             private void cleanup() {
-                // on error or completion we need to unsubscribe the base subscription
+                // on error or completion we need to unsubscribe the base subscription and set the subscriptionCount to 0
-                // and set the subscriptionCount to 0 
                 lock.lock();
                 try {
                     if (baseSubscription == currentBase) {
-                        if (worker != null) {
+                        cleanupWorker();
-                            worker.unsubscribe();
+                        // backdoor into the ConnectableObservable to cleanup and reset its state
-                            worker = null;
+                        if (source instanceof Subscription) {
+                            ((Subscription) source).unsubscribe();
                         }
                         baseSubscription.unsubscribe();
                         baseSubscription = new CompositeSubscription();
@@ -174,41 +169,45 @@ public final class OnSubscribeRefCountWithCacheTime<T> implements OnSubscribe<T>
 
     @NonNull
     private Subscription disconnect(@NonNull final CompositeSubscription current) {
-        return Subscriptions.create(new Action0() {
+        return Subscriptions.create(() -> {
-
+            lock.lock();
-            @Override
+            try {
-            public void call() {
+                if (baseSubscription == current && subscriptionCount.decrementAndGet() == 0) {
-                lock.lock();
+                    if (worker != null) {
-                try {
+                        worker.unsubscribe();
-                    if (baseSubscription == current && subscriptionCount.decrementAndGet() == 0) {
+                    } else {
-                        if (worker != null) {
+                        worker = scheduler.createWorker();
-                            worker.unsubscribe();
-                        } else {
-                            worker = scheduler.createWorker();
-                        }
-                        worker.schedule(new Action0() {
-                            @Override
-                            public void call() {
-                                lock.lock();
-                                try {
-                                    if (subscriptionCount.get() == 0) {
-                                        baseSubscription.unsubscribe();
-                                        // need a new baseSubscription because once
-                                        // unsubscribed stays that way
-                                        worker.unsubscribe();
-                                        worker = null;
-                                        baseSubscription = new CompositeSubscription();
-                                    }
-                                } finally {
-                                    lock.unlock();
-                                }
-                            }
-                        }, cacheTime, cacheTimeUnit);
                     }
-                } finally {
+                    worker.schedule(() -> {
-                    lock.unlock();
+                        lock.lock();
+                        try {
+                            if (subscriptionCount.get() == 0) {
+                                cleanupWorker();
+                                // backdoor into the ConnectableObservable to cleanup and reset its state
+                                if (source instanceof Subscription) {
+                                    ((Subscription) source).unsubscribe();
+                                }
+                                baseSubscription.unsubscribe();
+                                // need a new baseSubscription because once
+                                // unsubscribed stays that way
+                                baseSubscription = new CompositeSubscription();
+                            }
+                        } finally {
+                            lock.unlock();
+                        }
+                    }, cacheTime, cacheTimeUnit);
                 }
+            } finally {
+                lock.unlock();
             }
         });
     }
+
+    private void cleanupWorker() {
+        if (worker != null) {
+            worker.unsubscribe();
+            worker = null;
+        }
+    }
+
 }

src/main/java/ru/touchin/roboswag/core/observables/RxAndroidUtils.java

@@ -20,9 +20,11 @@
 package ru.touchin.roboswag.core.observables;
 
 import android.app.Service;
+import android.content.BroadcastReceiver;
 import android.content.ComponentName;
 import android.content.Context;
 import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.ServiceConnection;
 import android.os.IBinder;
 import android.os.Looper;
@@ -33,9 +35,9 @@ import java.util.concurrent.CountDownLatch;
 
 import ru.touchin.roboswag.core.log.Lc;
 import ru.touchin.roboswag.core.utils.ServiceBinder;
+import rx.Emitter;
 import rx.Observable;
 import rx.Scheduler;
-import rx.Subscriber;
 import rx.android.schedulers.AndroidSchedulers;
 
 /**
@@ -55,23 +57,50 @@ public final class RxAndroidUtils {
     @NonNull
     public static <T extends Service> Observable<T> observeService(@NonNull final Context context, @NonNull final Class<T> serviceClass) {
         return Observable
-                .just(new SubscribeServiceConnection<T>())
+                .just(new OnSubscribeServiceConnection<T>())
-                .switchMap(serviceConnection -> Observable
+                .switchMap(onSubscribeServiceConnection -> Observable
-                        .<T>create(subscriber -> {
+                        .<T>create(emitter -> {
-                            serviceConnection.subscriber = subscriber;
+                            onSubscribeServiceConnection.emitter = emitter;
-                            context.bindService(new Intent(context, serviceClass), serviceConnection, Context.BIND_AUTO_CREATE);
+                            context.bindService(new Intent(context, serviceClass), onSubscribeServiceConnection, Context.BIND_AUTO_CREATE);
-                        })
+                        }, Emitter.BackpressureMode.LATEST)
-                        .doOnUnsubscribe(() -> context.unbindService(serviceConnection)))
+                        .doOnUnsubscribe(() -> {
+                            context.unbindService(onSubscribeServiceConnection);
+                            onSubscribeServiceConnection.emitter = null;
+                        }))
                 .distinctUntilChanged()
                 .replay(1)
                 .refCount();
     }
 
+    /**
+     * Observes classic Android broadcast with {@link BroadcastReceiver} as source of Observable items and Intent as items.
+     *
+     * @param context      Context to register {@link BroadcastReceiver};
+     * @param intentFilter {@link IntentFilter} to register {@link BroadcastReceiver};
+     * @return Observable that observes Android broadcasts.
+     */
+    @NonNull
+    public static Observable<Intent> observeBroadcastEvent(@NonNull final Context context, @NonNull final IntentFilter intentFilter) {
+        return Observable
+                .just(new OnSubscribeBroadcastReceiver())
+                .switchMap(onOnSubscribeBroadcastReceiver -> Observable
+                        .<Intent>create(emitter -> {
+                            onOnSubscribeBroadcastReceiver.emitter = emitter;
+                            context.registerReceiver(onOnSubscribeBroadcastReceiver, intentFilter);
+                        }, Emitter.BackpressureMode.LATEST)
+                        .doOnUnsubscribe(() -> {
+                            context.unregisterReceiver(onOnSubscribeBroadcastReceiver);
+                            onOnSubscribeBroadcastReceiver.emitter = null;
+                        }))
+                .share();
+    }
+
     /**
      * Creating {@link Scheduler} that is scheduling work on specific thread with {@link Looper}.
      * Do not use it much times - it is creating endless thread every call.
      * It's good to use it only like a constant like:
      * private static final Scheduler SCHEDULER = RxAndroidUtils.createLooperScheduler();
+     * IMPORTANT NOTE: looper thread will live forever! Do not create a lot of such Schedulers.
      *
      * @return Looper thread based {@link Scheduler}.
      */
@@ -91,20 +120,19 @@ public final class RxAndroidUtils {
     private RxAndroidUtils() {
     }
 
-    private static class SubscribeServiceConnection<T> implements ServiceConnection {
+    private static class OnSubscribeServiceConnection<TService extends Service> implements ServiceConnection {
-
         @Nullable
-        private Subscriber<? super T> subscriber;
+        private Emitter<? super TService> emitter;
 
         @SuppressWarnings("unchecked")
         @Override
         public void onServiceConnected(@NonNull final ComponentName name, @Nullable final IBinder service) {
-            if (subscriber == null) {
+            if (emitter == null) {
                 return;
             }
 
             if (service instanceof ServiceBinder) {
-                subscriber.onNext((T) ((ServiceBinder) service).getService());
+                emitter.onNext((TService) ((ServiceBinder) service).getService());
             } else {
                 Lc.assertion("IBinder should be instance of ServiceBinder.");
             }
@@ -112,8 +140,21 @@ public final class RxAndroidUtils {
 
         @Override
         public void onServiceDisconnected(@NonNull final ComponentName name) {
-            if (subscriber != null) {
+            // service have been killed/crashed and destroyed. instead of emit null just wait service reconnection.
-                subscriber.onNext(null);
+            // even if someone keeps reference to dead service it is problem of service object to work correctly after destroy.
+        }
+
+    }
+
+    private static class OnSubscribeBroadcastReceiver extends BroadcastReceiver {
+
+        @Nullable
+        private Emitter<? super Intent> emitter;
+
+        @Override
+        public void onReceive(@NonNull final Context context, @NonNull final Intent intent) {
+            if (emitter != null) {
+                emitter.onNext(intent);
             }
         }
 

src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableCollection.java

@@ -25,25 +25,21 @@ import android.support.annotation.Nullable;
 import java.io.IOException;
 import java.io.ObjectInputStream;
 import java.io.ObjectOutputStream;
-import java.io.Serializable;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
-import java.util.List;
 
+import rx.Emitter;
 import rx.Observable;
-import rx.Subscriber;
 
 /**
  * Created by Gavriil Sitnikov on 23/05/16.
  * Class to represent collection which is providing it's inner changes in Rx observable way.
  * Use {@link #observeChanges()} and {@link #observeItems()} to observe collection changes.
- * Use {@link #loadItem(int)} to load item asynchronously.
  * Methods {@link #size()} and {@link #get(int)} will return only already loaded items info.
  *
  * @param <TItem> Type of collection's items.
  */
-public abstract class ObservableCollection<TItem> implements Serializable {
+public abstract class ObservableCollection<TItem> {
 
     private int changesCount;
     @NonNull
@@ -51,7 +47,7 @@ public abstract class ObservableCollection<TItem> implements Serializable {
     @NonNull
     private transient Observable<Collection<TItem>> itemsObservable;
     @Nullable
-    private transient Subscriber<? super CollectionChange<TItem>> changesSubscriber;
+    private transient Emitter<? super CollectionChange<TItem>> changesEmitter;
 
     public ObservableCollection() {
         this.changesObservable = createChangesObservable();
@@ -61,19 +57,16 @@ public abstract class ObservableCollection<TItem> implements Serializable {
     @NonNull
     private Observable<CollectionChange<TItem>> createChangesObservable() {
         return Observable
-                .<CollectionChange<TItem>>create(subscriber -> this.changesSubscriber = subscriber)
+                .<CollectionChange<TItem>>create(emitter -> this.changesEmitter = emitter, Emitter.BackpressureMode.BUFFER)
-                .doOnUnsubscribe(() -> this.changesSubscriber = null)
+                .doOnUnsubscribe(() -> this.changesEmitter = null)
-                .replay(0)
+                .share();
-                .refCount();
     }
 
     @NonNull
     private Observable<Collection<TItem>> createItemsObservable() {
         return Observable
-                .<Collection<TItem>>switchOnNext(Observable.create(subscriber -> {
+                //switchOnNext to calculate getItems() on subscription but not on that method calling moment
-                    subscriber.onNext(observeChanges().map(changes -> getItems()).startWith(getItems()));
+                .switchOnNext(Observable.fromCallable(() -> observeChanges().map(changes -> getItems()).startWith(getItems())))
-                    subscriber.onCompleted();
-                }))
                 .replay(1)
                 .refCount();
     }
@@ -102,9 +95,12 @@ public abstract class ObservableCollection<TItem> implements Serializable {
      * @param changes Changes of collection.
      */
     protected void notifyAboutChanges(@NonNull final Collection<Change<TItem>> changes) {
+        if (changes.isEmpty()) {
+            return;
+        }
         changesCount++;
-        if (changesSubscriber != null) {
+        if (changesEmitter != null) {
-            changesSubscriber.onNext(new CollectionChange<>(changesCount, Collections.unmodifiableCollection(changes)));
+            changesEmitter.onNext(new CollectionChange<>(changesCount, Collections.unmodifiableCollection(changes)));
         }
     }
 
@@ -164,36 +160,6 @@ public abstract class ObservableCollection<TItem> implements Serializable {
         return size() == 0;
     }
 
-    /**
-     * Returns {@link Observable} which is loading item by position.
-     * It could return null in onNext callback if there is no item to load for such position.
-     *
-     * @param position Position to load item;
-     * @return {@link Observable} to load item.
-     */
-    @NonNull
-    public abstract Observable<TItem> loadItem(int position);
-
-    /**
-     * Returns {@link Observable} which is loading item by range.
-     * It will return collection of loaded items in onNext callback.
-     *
-     * @param first First position of item to load;
-     * @param last  Last position of item to load;
-     * @return {@link Observable} to load items.
-     */
-    @NonNull
-    public Observable<Collection<TItem>> loadRange(final int first, final int last) {
-        final List<Observable<TItem>> itemsRequests = new ArrayList<>();
-        for (int i = first; i <= last; i++) {
-            itemsRequests.add(loadItem(i));
-        }
-        return Observable.concatEager(itemsRequests)
-                .filter(loadedItem -> loadedItem != null)
-                .toList()
-                .map(Collections::unmodifiableCollection);
-    }
-
     private void writeObject(@NonNull final ObjectOutputStream outputStream) throws IOException {
         outputStream.writeInt(changesCount);
     }

src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableFilteredList.java

@@ -8,9 +8,9 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
-import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
+import rx.Subscription;
-import rx.Observable;
 import rx.functions.Func1;
+import rx.schedulers.Schedulers;
 
 /**
  * Created by Gavriil Sitnikov on 02/06/2016.
@@ -23,7 +23,10 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
 
     @NonNull
     private static <TItem> List<TItem> filterCollection(@NonNull final Collection<TItem> sourceCollection,
-                                                        @NonNull final Func1<TItem, Boolean> filter) {
+                                                        @Nullable final Func1<TItem, Boolean> filter) {
+        if (filter == null) {
+            return new ArrayList<>(sourceCollection);
+        }
         final List<TItem> result = new ArrayList<>(sourceCollection.size());
         for (final TItem item : sourceCollection) {
             if (filter.call(item)) {
@@ -33,35 +36,39 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
         return result;
     }
 
-    @Nullable
+    @NonNull
     private List<TItem> filteredList;
-    @Nullable
+    @NonNull
-    private Collection<TItem> sourceCollection;
+    private ObservableCollection<TItem> sourceCollection;
     @Nullable
     private Func1<TItem, Boolean> filter;
-
+    @Nullable
-    public ObservableFilteredList() {
+    private Subscription sourceCollectionSubscription;
-        super();
-        //do nothing
-    }
-
-    public ObservableFilteredList(@NonNull final Collection<TItem> sourceCollection) {
-        super();
-        this.sourceCollection = new ArrayList<>(sourceCollection);
-        this.filteredList = new ArrayList<>(sourceCollection);
-    }
 
     public ObservableFilteredList(@NonNull final Func1<TItem, Boolean> filter) {
-        super();
+        this(new ArrayList<>(), filter);
-        this.filter = filter;
     }
 
-    public ObservableFilteredList(@NonNull final Collection<TItem> sourceCollection,
+    public ObservableFilteredList(@NonNull final Collection<TItem> sourceCollection, @Nullable final Func1<TItem, Boolean> filter) {
-                                  @NonNull final Func1<TItem, Boolean> filter) {
+        this(new ObservableList<>(sourceCollection), filter);
+    }
+
+    public ObservableFilteredList(@NonNull final ObservableCollection<TItem> sourceCollection, @Nullable final Func1<TItem, Boolean> filter) {
         super();
-        this.sourceCollection = new ArrayList<>(sourceCollection);
         this.filter = filter;
-        filteredList = filterCollection(this.sourceCollection, this.filter);
+        this.sourceCollection = sourceCollection;
+        this.filteredList = filterCollection(this.sourceCollection.getItems(), this.filter);
+        update();
+    }
+
+    /**
+     * Sets collection of items to filter.
+     *
+     * @param sourceCollection Collection with items.
+     */
+    public void setSourceCollection(@Nullable final ObservableCollection<TItem> sourceCollection) {
+        this.sourceCollection = sourceCollection != null ? sourceCollection : new ObservableList<>();
+        update();
     }
 
     /**
@@ -70,8 +77,8 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
      * @param sourceCollection Collection with items.
      */
     public void setSourceCollection(@Nullable final Collection<TItem> sourceCollection) {
-        this.sourceCollection = sourceCollection != null ? new ArrayList<>(sourceCollection) : null;
+        this.sourceCollection = sourceCollection != null ? new ObservableList<>(sourceCollection) : new ObservableList<>();
-        updateCollections();
+        update();
     }
 
     /**
@@ -81,73 +88,51 @@ public class ObservableFilteredList<TItem> extends ObservableCollection<TItem> {
      */
     public void setFilter(@Nullable final Func1<TItem, Boolean> filter) {
         this.filter = filter;
-        updateCollections();
+        update();
     }
 
     /**
      * Updates collection by current filter. Use it if some item's parameter which is important for filtering have changing.
      */
-    public void updateCollections() {
+    private void update() {
-        if (sourceCollection == null) {
+        if (sourceCollectionSubscription != null) {
-            if (filteredList != null) {
+            sourceCollectionSubscription.unsubscribe();
-                final Change<TItem> change = new Change<>(Change.Type.REMOVED, filteredList, 0);
+            sourceCollectionSubscription = null;
-                filteredList = null;
-                notifyAboutChange(change);
-            }
-            return;
-        }
-        final List<TItem> oldFilteredList = filteredList;
-        if (filter != null) {
-            filteredList = filterCollection(sourceCollection, filter);
-        } else {
-            filteredList = new ArrayList<>(sourceCollection);
-        }
-        if (oldFilteredList != null) {
-            final Collection<Change<TItem>> changes = Change.calculateCollectionChanges(oldFilteredList, filteredList, false);
-            if (!changes.isEmpty()) {
-                notifyAboutChanges(changes);
-            }
-        } else {
-            notifyAboutChange(new Change<>(Change.Type.INSERTED, filteredList, 0));
         }
+        sourceCollectionSubscription = sourceCollection.observeItems()
+                .observeOn(Schedulers.computation())
+                .subscribe(items -> {
+                    final List<TItem> oldFilteredList = filteredList;
+                    filteredList = filterCollection(items, filter);
+                    notifyAboutChanges(Change.calculateCollectionChanges(oldFilteredList, filteredList, false));
+                });
     }
 
     @Override
     public int size() {
-        return filteredList != null ? filteredList.size() : 0;
+        return filteredList.size();
     }
 
     @NonNull
     @Override
     public TItem get(final int position) {
-        if (filteredList == null) {
-            throw new ShouldNotHappenException();
-        }
         return filteredList.get(position);
     }
 
     @NonNull
     @Override
     public Collection<TItem> getItems() {
-        return filteredList != null ? Collections.unmodifiableCollection(filteredList) : Collections.emptyList();
+        return Collections.unmodifiableCollection(filteredList);
     }
 
     /**
-     * Returns source non-filtered collection of items.
+     * Returns source non-filtered observable collection of items.
      *
      * @return Non-filtered collection of items.
      */
     @NonNull
-    public Collection<TItem> getSourceItems() {
+    public ObservableCollection<TItem> getSourceCollection() {
-        return sourceCollection != null ? Collections.unmodifiableCollection(sourceCollection) : Collections.emptyList();
+        return sourceCollection;
-    }
-
-    @NonNull
-    @Override
-    public Observable<TItem> loadItem(final int position) {
-        return filteredList != null && filteredList.size() > position
-                ? Observable.just(filteredList.get(position))
-                : Observable.just(null);
     }
 
 }

src/main/java/ru/touchin/roboswag/core/observables/collections/ObservableList.java

@@ -31,7 +31,6 @@ import java.util.Collections;
 import java.util.List;
 
 import ru.touchin.roboswag.core.log.Lc;
-import rx.Observable;
 
 /**
  * Created by Gavriil Sitnikov on 23/05/16.
@@ -218,9 +217,7 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
             final Collection<Change<TItem>> changes = Change.calculateCollectionChanges(items, newItems, false);
             items.clear();
             items.addAll(newItems);
-            if (!changes.isEmpty()) {
+            notifyAboutChanges(changes);
-                notifyAboutChanges(changes);
-            }
         }
     }
 
@@ -243,14 +240,6 @@ public class ObservableList<TItem> extends ObservableCollection<TItem> implement
         }
     }
 
-    @NonNull
-    @Override
-    public Observable<TItem> loadItem(final int position) {
-        synchronized (this) {
-            return position < items.size() ? Observable.just(items.get(position)) : Observable.just(null);
-        }
-    }
-
     private void writeObject(@NonNull final ObjectOutputStream outputStream) throws IOException {
         outputStream.writeObject(items);
     }

src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/LoadedRenewableItems.java

@@ -1,49 +0,0 @@
-/*
- *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
- *
- *  This file is part of RoboSwag library.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- */
-
-package ru.touchin.roboswag.core.observables.collections.loadable;
-
-import android.support.annotation.Nullable;
-
-/**
- * Created by Gavriil Sitnikov on 23/05/16.
- * Object represents loaded items with reference to load other parts and info of are there more items to load or not.
- *
- * @param <TItem>           Type of items to load;
- * @param <TReference>      Type of reference to load other parts of items;
- * @param <TNewerReference> Type of reference to load newer parts of items.
- */
-public interface LoadedRenewableItems<TItem, TReference, TNewerReference> extends LoadedItems<TItem, TReference> {
-
-    /**
-     * Returns count of new items other than loaded.
-     *
-     * @return Count of new items other than loaded.
-     */
-    int getNewerItemsCount();
-
-    /**
-     * Returns reference to load newer items from this loaded part.
-     *
-     * @return Reference to load newer items.
-     */
-    @Nullable
-    TNewerReference getNewerReference();
-
-}

src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/LoadingMoreList.java

@@ -24,6 +24,7 @@ import android.support.annotation.Nullable;
 
 import java.util.ArrayList;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 import java.util.NoSuchElementException;
 import java.util.concurrent.Executors;
@@ -46,6 +47,7 @@ import rx.subjects.BehaviorSubject;
  * {@link ObservableCollection} which is loading items more and more by paging/limit-offset/reference-based mechanisms.
  * To use this collection {@link MoreItemsLoader} should be created.
  * {@link MoreItemsLoader} is an object to load next block of items by info from previous loaded block (last loaded item/reference etc.).
+ * Use {@link #loadItem(int)} and {@link #loadRange(int, int)} to load items asynchronously.
  *
  * @param <TItem>          Type of collection's items;
  * @param <TMoreReference> Type of reference object to help rightly loading next block of items;
@@ -82,10 +84,7 @@ public class LoadingMoreList<TItem, TMoreReference, TLoadedItems extends LoadedI
                            @Nullable final LoadedItems<TItem, TMoreReference> initialItems) {
         super();
         this.loadingMoreObservable = Observable
-                .switchOnNext(Observable.<Observable<TLoadedItems>>create(subscriber -> {
+                .switchOnNext(Observable.fromCallable(() -> createLoadRequestBasedObservable(this::createActualRequest, moreMoreItemsLoader::load)))
-                    subscriber.onNext(createLoadRequestBasedObservable(this::createActualRequest, moreMoreItemsLoader::load));
-                    subscriber.onCompleted();
-                }))
                 .single()
                 .doOnError(throwable -> {
                     if (throwable instanceof IllegalArgumentException || throwable instanceof NoSuchElementException) {
@@ -287,25 +286,50 @@ public class LoadingMoreList<TItem, TMoreReference, TLoadedItems extends LoadedI
         return loadingMoreObservable;
     }
 
+    /**
+     * Returns {@link Observable} which is loading item by position.
+     * It could return null in onNext callback if there is no item to load for such position.
+     *
+     * @param position Position to load item;
+     * @return {@link Observable} to load item.
+     */
     @NonNull
-    @Override
     public Observable<TItem> loadItem(final int position) {
         return Observable
                 .switchOnNext(Observable
-                        .<Observable<TItem>>create(subscriber -> {
+                        .fromCallable(() -> {
                             if (position < size()) {
-                                subscriber.onNext(Observable.just(get(position)));
+                                return Observable.just(get(position));
                             } else if (moreItemsCount.getValue() == 0) {
-                                subscriber.onNext(Observable.just((TItem) null));
+                                return Observable.just((TItem) null);
                             } else {
-                                subscriber.onNext(loadingMoreObservable.switchMap(ignored -> Observable.<TItem>error(new NotLoadedYetException())));
+                                return loadingMoreObservable.switchMap(ignored -> Observable.<TItem>error(new NotLoadedYetException()));
                             }
-                            subscriber.onCompleted();
                         })
                         .subscribeOn(loaderScheduler))
                 .retry((number, throwable) -> throwable instanceof NotLoadedYetException);
     }
 
+    /**
+     * Returns {@link Observable} which is loading item by range.
+     * It will return collection of loaded items in onNext callback.
+     *
+     * @param first First position of item to load;
+     * @param last  Last position of item to load;
+     * @return {@link Observable} to load items.
+     */
+    @NonNull
+    public Observable<Collection<TItem>> loadRange(final int first, final int last) {
+        final List<Observable<TItem>> itemsRequests = new ArrayList<>();
+        for (int i = first; i <= last; i++) {
+            itemsRequests.add(loadItem(i));
+        }
+        return Observable.concatEager(itemsRequests)
+                .filter(loadedItem -> loadedItem != null)
+                .toList()
+                .map(Collections::unmodifiableCollection);
+    }
+
     /**
      * Remove all loaded items and resets collection's state.
      */
@@ -335,7 +359,7 @@ public class LoadingMoreList<TItem, TMoreReference, TLoadedItems extends LoadedI
         DO_NOTHING,
         REMOVE_FROM_COLLECTION,
         REMOVE_FROM_LOADED_ITEMS,
-        REPLACE_SOURCE_ITEM_WITH_LOADED,
+        REPLACE_SOURCE_ITEM_WITH_LOADED
     }
 
     /**
@@ -354,7 +378,7 @@ public class LoadingMoreList<TItem, TMoreReference, TLoadedItems extends LoadedI
          * @return Action to do with items.
          */
         @NonNull
-        FilterAction decideFilterAction(@NonNull final TItem collectionObject, @NonNull final TItem loadedItemsObject);
+        FilterAction decideFilterAction(@NonNull TItem collectionObject, @NonNull TItem loadedItemsObject);
 
     }
 

src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/LoadingRenewableList.java

@@ -1,241 +0,0 @@
-/*
- *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
- *
- *  This file is part of RoboSwag library.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- */
-
-package ru.touchin.roboswag.core.observables.collections.loadable;
-
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-
-import java.util.NoSuchElementException;
-
-import ru.touchin.roboswag.core.log.Lc;
-import ru.touchin.roboswag.core.observables.collections.ObservableCollection;
-import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
-import rx.Observable;
-import rx.schedulers.Schedulers;
-import rx.subjects.BehaviorSubject;
-
-/**
- * Created by Gavriil Sitnikov on 23/05/16.
- * {@link ObservableCollection} which is loading items more and more by paging/limit-offset/reference-based mechanisms but also it is providing
- * interface to load newer items and info about it's loading availability.
- * To use this collection {@link MoreItemsLoader} and {@link NewerItemsLoader} should be created.
- *
- * @param <TItem>           Type of collection's items;
- * @param <TReference>      Type of reference object to help rightly loading next block of items;
- * @param <TNewerReference> Type of reference object to help rightly loading block of newer items;
- * @param <TLoadedItems>    Type of loading block of items.
- */
-public class LoadingRenewableList<TItem, TReference, TNewerReference,
-        TLoadedItems extends LoadedRenewableItems<TItem, TReference, TNewerReference>>
-        extends LoadingMoreList<TItem, TReference, TLoadedItems> {
-
-    @Nullable
-    private TNewerReference newerReference;
-    @NonNull
-    private final BehaviorSubject<Integer> newerItemsCount = BehaviorSubject.create(LoadedItems.UNKNOWN_ITEMS_COUNT);
-
-    @NonNull
-    private final Observable<TLoadedItems> loadingNewerObservable;
-    @NonNull
-    private final Observable<TLoadedItems> loadingNewestObservable;
-
-    public LoadingRenewableList(@NonNull final MoreItemsLoader<TItem, TReference, TLoadedItems> moreMoreItemsLoader,
-                                @NonNull final NewerItemsLoader<TItem, TReference, TNewerReference, TLoadedItems> newerItemsLoader) {
-        super(moreMoreItemsLoader);
-        this.loadingNewerObservable = createLoadingNewerObservable(newerItemsLoader, false);
-        this.loadingNewestObservable = createLoadingNewerObservable(newerItemsLoader, true);
-    }
-
-    public LoadingRenewableList(@NonNull final MoreItemsLoader<TItem, TReference, TLoadedItems> moreMoreItemsLoader,
-                                @NonNull final NewerItemsLoader<TItem, TReference, TNewerReference, TLoadedItems> newerItemsLoader,
-                                @Nullable final TLoadedItems initialItems) {
-        super(moreMoreItemsLoader, initialItems);
-        this.loadingNewerObservable = createLoadingNewerObservable(newerItemsLoader, false);
-        this.loadingNewestObservable = createLoadingNewerObservable(newerItemsLoader, true);
-        if (initialItems != null) {
-            updateNewerReference(initialItems);
-        }
-    }
-
-    @NonNull
-    private Observable<TLoadedItems> waitForInitialLoading(@NonNull final Observable<TLoadedItems> observable) {
-        return getLoadingMoreObservable().ignoreElements().concatWith(observable);
-    }
-
-    @NonNull
-    private NewerLoadRequest<TNewerReference> createActualRequest() {
-        return new NewerLoadRequest<>(newerReference, newerItemsCount.getValue());
-    }
-
-    @NonNull
-    private Observable<TLoadedItems> createLoadingNewerObservable(
-            @NonNull final NewerItemsLoader<TItem, TReference, TNewerReference, TLoadedItems> newerItemsLoader,
-            final boolean renew) {
-        return Observable
-                .switchOnNext(Observable.<Observable<TLoadedItems>>create(subscriber -> {
-                    if (!renew) {
-                        subscriber.onNext(Observable.concat(
-                                //we need non-empty list to start loading newer items or we need to wait any change (should be insertion)
-                                isEmpty() ? observeChanges().first().switchMap(ignored -> Observable.empty()) : Observable.empty(),
-                                createLoadRequestBasedObservable(this::createActualRequest,
-                                        loadRequest -> loadRequest.getNewerReference() == null && isEmpty()
-                                                ? waitForInitialLoading(newerItemsLoader.load(loadRequest))
-                                                : newerItemsLoader.load(loadRequest))));
-                    } else {
-                        subscriber.onNext(newerItemsLoader.load(new NewerLoadRequest<>(null, LoadedItems.UNKNOWN_ITEMS_COUNT))
-                                .subscribeOn(Schedulers.io())
-                                .observeOn(getLoaderScheduler()));
-                    }
-                    subscriber.onCompleted();
-                }))
-                .single()
-                .doOnError(throwable -> {
-                    if (throwable instanceof IllegalArgumentException || throwable instanceof NoSuchElementException) {
-                        Lc.assertion(new ShouldNotHappenException("Updates during loading not supported."
-                                + " NewerItemsLoader should emit only one result.", throwable));
-                    }
-                })
-                .doOnNext(loadedItems -> onNewerItemsLoaded(loadedItems, renew))
-                .replay(1)
-                .refCount();
-    }
-
-    /**
-     * Returns if there are new items to load.
-     *
-     * @return True if there are more items to load.
-     */
-    public boolean hasNewerItems() {
-        return newerItemsCount.getValue() != 0;
-    }
-
-    /**
-     * Update a new items count.
-     *
-     * @param count new items count
-     */
-    public void updateNewerItemsCount(final int count) {
-        newerItemsCount.onNext(count);
-    }
-
-    /**
-     * Returns {@link Observable} which is providing status of if is there are new items to load or not.
-     *
-     * @return {@link Observable} of more items availability status.
-     */
-    @NonNull
-    public Observable<Boolean> observeHasNewerItems() {
-        return newerItemsCount.map(count -> count != 0).distinctUntilChanged();
-    }
-
-    /**
-     * Returns {@link Observable} which is providing count of new items to load.
-     *
-     * @return {@link Observable} of new items availability status.
-     */
-    @NonNull
-    public Observable<Integer> observeNewerItemsCount() {
-        return newerItemsCount.distinctUntilChanged();
-    }
-
-    @Override
-    protected void onItemsLoaded(@NonNull final TLoadedItems loadedItems, final int insertPosition, final boolean reset) {
-        super.onItemsLoaded(loadedItems, insertPosition, reset);
-        if (newerReference == null) {
-            updateNewerReference(loadedItems);
-        }
-    }
-
-    /**
-     * Calls when newer items part loaded.
-     *
-     * @param loadedItems Loaded items;
-     * @param renew       Flag indicates is it loading just to load some new items (false) or to load totally new items (true).
-     */
-    protected void onNewerItemsLoaded(@NonNull final TLoadedItems loadedItems, final boolean renew) {
-        onItemsLoaded(loadedItems, 0, renew);
-        updateNewerReference(loadedItems);
-    }
-
-    @Override
-    protected void resetState() {
-        super.resetState();
-        newerReference = null;
-        newerItemsCount.onNext(LoadedItems.UNKNOWN_ITEMS_COUNT);
-    }
-
-    /**
-     * Returns {@link Observable} that will load newer items by count returned by last loaded items part.
-     *
-     * @return {@link Observable} to load newer items.
-     */
-    @NonNull
-    public Observable<TLoadedItems> loadNewer() {
-        return loadingNewerObservable.first();
-    }
-
-    /**
-     * Returns {@link Observable} that will load all newer items.
-     *
-     * @return Returns {@link Observable} to limited load newer items.
-     */
-    @NonNull
-    public Observable<?> loadToNewest() {
-        return loadToNewest(Integer.MAX_VALUE);
-    }
-
-    /**
-     * Returns {@link Observable} that will load some newer itemslimited by maximum pages loading results.
-     *
-     * @param maxPageDeep Limit to load pages;
-     * @return Returns {@link Observable} to limited load newer items.
-     */
-    @NonNull
-    public Observable<?> loadToNewest(final int maxPageDeep) {
-        return Observable
-                .switchOnNext(Observable
-                        .<Observable<?>>create(subscriber -> {
-                            subscriber.onNext(newerItemsCount.getValue() == 0
-                                    ? Observable.empty()
-                                    : loadingNewerObservable.switchMap(ignored -> Observable.error(new NotLoadedYetException())));
-                            subscriber.onCompleted();
-                        })
-                        .subscribeOn(getLoaderScheduler()))
-                .retry((number, throwable) -> number <= maxPageDeep && throwable instanceof NotLoadedYetException);
-    }
-
-    /**
-     * Returns {@link Observable} that tries to load some newer items even if there are no info about count of them.
-     *
-     * @return {@link Observable} to load newer items.
-     */
-    @NonNull
-    public Observable<TLoadedItems> renew() {
-        return loadingNewestObservable.first();
-    }
-
-    private void updateNewerReference(@NonNull final TLoadedItems loadedItems) {
-        if (loadedItems.getNewerReference() != null) {
-            newerReference = loadedItems.getNewerReference();
-        }
-        newerItemsCount.onNext(loadedItems.getNewerItemsCount());
-    }
-
-}

src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/NewerItemsLoader.java

@@ -1,40 +0,0 @@
-/*
- *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
- *
- *  This file is part of RoboSwag library.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- */
-
-package ru.touchin.roboswag.core.observables.collections.loadable;
-
-import android.support.annotation.NonNull;
-
-import rx.Observable;
-
-/**
- * Created by Gavriil Sitnikov on 02/06/2016.
- * Object that is loading new part of items by reference.
- *
- * @param <TItem>           Type of items to be loaded;
- * @param <TNewerReference> Type of reference to be used to load new part of items;
- * @param <TLoadedItems>    Type of loaded items part.
- */
-public interface NewerItemsLoader<TItem, TReference, TNewerReference,
-        TLoadedItems extends LoadedRenewableItems<TItem, TReference, TNewerReference>> {
-
-    @NonNull
-    Observable<TLoadedItems> load(@NonNull final NewerLoadRequest<TNewerReference> newerLoadRequest);
-
-}

src/main/java/ru/touchin/roboswag/core/observables/collections/loadable/NewerLoadRequest.java

@@ -1,74 +0,0 @@
-/*
- *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
- *
- *  This file is part of RoboSwag library.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- */
-
-package ru.touchin.roboswag.core.observables.collections.loadable;
-
-import android.support.annotation.Nullable;
-
-import ru.touchin.roboswag.core.utils.ObjectUtils;
-
-/**
- * Created by Gavriil Sitnikov on 02/06/2016.
- * Request represents request to load new part of items.
- *
- * @param <TNewerReference> Type of reference to load new part of items.
- */
-public class NewerLoadRequest<TNewerReference> {
-
-    @Nullable
-    private final TNewerReference newerReference;
-    private final int newerItemsCount;
-
-    public NewerLoadRequest(@Nullable final TNewerReference newerReference, final int newerItemsCount) {
-        this.newerReference = newerReference;
-        this.newerItemsCount = newerItemsCount;
-    }
-
-    /**
-     * Returns reference to be used to load new part of items.
-     *
-     * @return Reference object.
-     */
-    @Nullable
-    public TNewerReference getNewerReference() {
-        return newerReference;
-    }
-
-    /**
-     * Count of newer items to load.
-     *
-     * @return Count of newer items to load.
-     */
-    public int getNewerItemsCount() {
-        return newerItemsCount;
-    }
-
-    @Override
-    public boolean equals(@Nullable final Object object) {
-        return object instanceof NewerLoadRequest
-                && ObjectUtils.equals(((NewerLoadRequest) object).newerReference, newerReference)
-                && ((NewerLoadRequest) object).newerItemsCount == newerItemsCount;
-    }
-
-    @Override
-    public int hashCode() {
-        return newerItemsCount + (newerReference != null ? newerReference.hashCode() : 0);
-    }
-
-}

src/main/java/ru/touchin/roboswag/core/observables/storable/BaseStorable.java

@@ -0,0 +1,482 @@
+/*
+ *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
+ *
+ *  This file is part of RoboSwag library.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package ru.touchin.roboswag.core.observables.storable;
+
+import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
+
+import java.lang.reflect.Type;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+
+import ru.touchin.roboswag.core.log.Lc;
+import ru.touchin.roboswag.core.log.LcGroup;
+import ru.touchin.roboswag.core.observables.OnSubscribeRefCountWithCacheTime;
+import ru.touchin.roboswag.core.utils.ObjectUtils;
+import ru.touchin.roboswag.core.utils.Optional;
+import rx.Completable;
+import rx.Observable;
+import rx.Scheduler;
+import rx.Single;
+import rx.exceptions.OnErrorThrowable;
+import rx.functions.Actions;
+import rx.schedulers.Schedulers;
+import rx.subjects.PublishSubject;
+
+/**
+ * Created by Gavriil Sitnikov on 04/10/2015.
+ * Base class allows to async access to some store.
+ * Supports conversion between store and actual value. If it is not needed then use {@link SameTypesConverter}
+ * Supports migration from specific version to latest by {@link Migration} object.
+ * Allows to set default value which will be returned if actual value is null.
+ * Allows to declare specific {@link ObserveStrategy}.
+ * Also specific {@link Scheduler} could be specified to not create new scheduler per storable.
+ *
+ * @param <TKey>          Type of key to identify object;
+ * @param <TObject>       Type of actual object;
+ * @param <TStoreObject>  Type of store object. Could be same as {@link TObject};
+ * @param <TReturnObject> Type of actual value operating by Storable. Could be same as {@link TObject}.
+ */
+public abstract class BaseStorable<TKey, TObject, TStoreObject, TReturnObject> {
+
+    public static final LcGroup STORABLE_LC_GROUP = new LcGroup("STORABLE");
+
+    private static final long DEFAULT_CACHE_TIME_MILLIS = TimeUnit.SECONDS.toMillis(5);
+
+    @NonNull
+    private static ObserveStrategy getDefaultObserveStrategyFor(@NonNull final Type objectType, @NonNull final Type storeObjectType) {
+        if (objectType instanceof Class && ObjectUtils.isSimpleClass((Class) objectType)) {
+            return ObserveStrategy.CACHE_ACTUAL_VALUE;
+        }
+        if (objectType instanceof Class && ObjectUtils.isSimpleClass((Class) storeObjectType)) {
+            return ObserveStrategy.CACHE_STORE_VALUE;
+        }
+        return ObserveStrategy.NO_CACHE;
+    }
+
+    @NonNull
+    private final TKey key;
+    @NonNull
+    private final Type objectType;
+    @NonNull
+    private final Type storeObjectType;
+    @NonNull
+    private final Store<TKey, TStoreObject> store;
+    @NonNull
+    private final Converter<TObject, TStoreObject> converter;
+    @NonNull
+    private final PublishSubject<Optional<TStoreObject>> newStoreValueEvent = PublishSubject.create();
+    @NonNull
+    private final Observable<Optional<TStoreObject>> storeValueObservable;
+    @NonNull
+    private final Observable<Optional<TObject>> valueObservable;
+    @NonNull
+    private final Scheduler scheduler;
+
+    public BaseStorable(@NonNull final BuilderCore<TKey, TObject, TStoreObject> builderCore) {
+        this(builderCore.key, builderCore.objectType, builderCore.storeObjectType,
+                builderCore.store, builderCore.converter, builderCore.observeStrategy,
+                builderCore.migration, builderCore.defaultValue, builderCore.storeScheduler, builderCore.cacheTimeMillis);
+    }
+
+    @SuppressWarnings("PMD.ExcessiveParameterList")
+    //ExcessiveParameterList: that's why we are using builder to create it
+    private BaseStorable(@NonNull final TKey key,
+                         @NonNull final Type objectType,
+                         @NonNull final Type storeObjectType,
+                         @NonNull final Store<TKey, TStoreObject> store,
+                         @NonNull final Converter<TObject, TStoreObject> converter,
+                         @Nullable final ObserveStrategy observeStrategy,
+                         @Nullable final Migration<TKey> migration,
+                         @Nullable final TObject defaultValue,
+                         @Nullable final Scheduler storeScheduler,
+                         final long cacheTimeMillis) {
+        this.key = key;
+        this.objectType = objectType;
+        this.storeObjectType = storeObjectType;
+        this.store = store;
+        this.converter = converter;
+
+        final ObserveStrategy nonNullObserveStrategy
+                = observeStrategy != null ? observeStrategy : getDefaultObserveStrategyFor(objectType, storeObjectType);
+        scheduler = storeScheduler != null ? storeScheduler : Schedulers.from(Executors.newSingleThreadExecutor());
+        storeValueObservable
+                = createStoreValueObservable(nonNullObserveStrategy, migration, defaultValue, cacheTimeMillis);
+        valueObservable = createValueObservable(storeValueObservable, nonNullObserveStrategy, cacheTimeMillis);
+    }
+
+    @Nullable
+    private Optional<TStoreObject> returnDefaultValueIfNull(@NonNull final Optional<TStoreObject> storeObject, @Nullable final TObject defaultValue) {
+        if (storeObject.getValue() != null || defaultValue == null) {
+            return storeObject;
+        }
+
+        try {
+            return new Optional<>(converter.toStoreObject(objectType, storeObjectType, defaultValue));
+        } catch (final Converter.ConversionException exception) {
+            STORABLE_LC_GROUP.w(exception, "Exception while converting default value of '%s' from '%s' from store %s",
+                    key, defaultValue, store);
+            throw OnErrorThrowable.from(exception);
+        }
+    }
+
+    @NonNull
+    private Observable<Optional<TStoreObject>> createStoreInitialLoadingObservable(@Nullable final Migration<TKey> migration) {
+        final Single<Optional<TStoreObject>> loadObservable = store.loadObject(storeObjectType, key)
+                .doOnError(throwable -> STORABLE_LC_GROUP.w(throwable, "Exception while trying to load value of '%s' from store %s", key, store));
+        return (migration != null ? migration.migrateToLatestVersion(key).andThen(loadObservable) : loadObservable)
+                .subscribeOn(scheduler)
+                .observeOn(scheduler)
+                .toObservable()
+                .replay(1)
+                .refCount()
+                .take(1);
+    }
+
+    @NonNull
+    private Observable<Optional<TStoreObject>> createStoreValueObservable(@NonNull final ObserveStrategy observeStrategy,
+                                                                          @Nullable final Migration<TKey> migration,
+                                                                          @Nullable final TObject defaultValue,
+                                                                          final long cacheTimeMillis) {
+        final Observable<Optional<TStoreObject>> storeInitialLoadingObservable = createStoreInitialLoadingObservable(migration);
+        final Observable<Optional<TStoreObject>> result = storeInitialLoadingObservable
+                .concatWith(newStoreValueEvent)
+                .map(storeObject -> returnDefaultValueIfNull(storeObject, defaultValue));
+        return observeStrategy == ObserveStrategy.CACHE_STORE_VALUE || observeStrategy == ObserveStrategy.CACHE_STORE_AND_ACTUAL_VALUE
+                ? Observable.unsafeCreate(new OnSubscribeRefCountWithCacheTime<>(result.replay(1), cacheTimeMillis, TimeUnit.MILLISECONDS))
+                : result;
+    }
+
+    @NonNull
+    private Observable<Optional<TObject>> createValueObservable(@NonNull final Observable<Optional<TStoreObject>> storeValueObservable,
+                                                                @NonNull final ObserveStrategy observeStrategy,
+                                                                final long cacheTimeMillis) {
+        final Observable<Optional<TObject>> result = storeValueObservable
+                .map(storeObject -> {
+                    try {
+                        return new Optional<>(converter.toObject(objectType, storeObjectType, storeObject.getValue()));
+                    } catch (final Converter.ConversionException exception) {
+                        STORABLE_LC_GROUP.w(exception, "Exception while trying to converting value of '%s' from store %s by %s",
+                                key, storeObject, store, converter);
+                        throw OnErrorThrowable.from(exception);
+                    }
+                });
+        return observeStrategy == ObserveStrategy.CACHE_ACTUAL_VALUE || observeStrategy == ObserveStrategy.CACHE_STORE_AND_ACTUAL_VALUE
+                ? Observable.unsafeCreate(new OnSubscribeRefCountWithCacheTime<>(result.replay(1), cacheTimeMillis, TimeUnit.MILLISECONDS))
+                : result;
+    }
+
+    /**
+     * Returns key of value.
+     *
+     * @return Unique key.
+     */
+    @NonNull
+    public TKey getKey() {
+        return key;
+    }
+
+    /**
+     * Returns type of actual object.
+     *
+     * @return Type of actual object.
+     */
+    @NonNull
+    public Type getObjectType() {
+        return objectType;
+    }
+
+    /**
+     * Returns type of store object.
+     *
+     * @return Type of store object.
+     */
+    @NonNull
+    public Type getStoreObjectType() {
+        return storeObjectType;
+    }
+
+    /**
+     * Returns {@link Store} where store class representation of object is storing.
+     *
+     * @return Store.
+     */
+    @NonNull
+    public Store<TKey, TStoreObject> getStore() {
+        return store;
+    }
+
+    /**
+     * Returns {@link Converter} to convert values from store class to actual and back.
+     *
+     * @return Converter.
+     */
+    @NonNull
+    public Converter<TObject, TStoreObject> getConverter() {
+        return converter;
+    }
+
+    @NonNull
+    private Completable internalSet(@Nullable final TObject newValue, final boolean checkForEqualityBeforeSet) {
+        return (checkForEqualityBeforeSet ? storeValueObservable.take(1).toSingle() : Single.just(new Optional<>(null)))
+                .observeOn(scheduler)
+                .flatMapCompletable(oldStoreValue -> {
+                    final TStoreObject newStoreValue;
+                    try {
+                        newStoreValue = converter.toStoreObject(objectType, storeObjectType, newValue);
+                    } catch (final Converter.ConversionException exception) {
+                        STORABLE_LC_GROUP.w(exception, "Exception while trying to store value of '%s' from store %s by %s",
+                                key, newValue, store, converter);
+                        return Completable.error(exception);
+                    }
+                    if (checkForEqualityBeforeSet && ObjectUtils.equals(newStoreValue, oldStoreValue.getValue())) {
+                        return Completable.complete();
+                    }
+                    return store.storeObject(storeObjectType, key, newStoreValue)
+                            .doOnError(throwable -> STORABLE_LC_GROUP.w(throwable,
+                                    "Exception while trying to store value of '%s' from store %s by %s",
+                                    key, newValue, store, converter))
+                            .observeOn(scheduler)
+                            .andThen(Completable.fromAction(() -> {
+                                newStoreValueEvent.onNext(new Optional<>(newStoreValue));
+                                if (checkForEqualityBeforeSet) {
+                                    STORABLE_LC_GROUP.i("Value of '%s' changed from '%s' to '%s'", key, oldStoreValue, newStoreValue);
+                                } else {
+                                    STORABLE_LC_GROUP.i("Value of '%s' force changed to '%s'", key, newStoreValue);
+                                }
+                            }));
+                });
+    }
+
+    /**
+     * Creates observable which is async setting value to store.
+     * It is not checking if stored value equals new value.
+     * In result it will be faster to not get value from store and compare but it will emit item to {@link #observe()} subscribers.
+     * NOTE: It could emit ONLY completed and errors events. It is not providing onNext event!
+     *
+     * @param newValue Value to set;
+     * @return Observable of setting process.
+     */
+    //COMPATIBILITY NOTE: it is not Completable to prevent migration of old code
+    @NonNull
+    public Observable<?> forceSet(@Nullable final TObject newValue) {
+        return internalSet(newValue, false).toObservable();
+    }
+
+    /**
+     * Creates observable which is async setting value to store.
+     * It is checking if stored value equals new value.
+     * In result it will take time to get value from store and compare
+     * but it won't emit item to {@link #observe()} subscribers if stored value equals new value.
+     * NOTE: It could emit ONLY completed and errors events. It is not providing onNext event!
+     *
+     * @param newValue Value to set;
+     * @return Observable of setting process.
+     */
+    //COMPATIBILITY NOTE: it is not Completable to prevent migration of old code
+    @NonNull
+    public Observable<?> set(@Nullable final TObject newValue) {
+        return internalSet(newValue, true).toObservable();
+    }
+
+    @Deprecated
+    //COMPATIBILITY NOTE: it is deprecated as it's execution not bound to Android lifecycle objects
+    public void setCalm(@Nullable final TObject newValue) {
+        set(newValue).subscribe(Actions.empty(), Lc::assertion);
+    }
+
+    /**
+     * Sets value synchronously. You should NOT use this method normally. Use {@link #set(Object)} asynchronously instead.
+     *
+     * @param newValue Value to set;
+     */
+    @Deprecated
+    //deprecation: it should be used for debug only and in very rare cases.
+    public void setSync(@Nullable final TObject newValue) {
+        set(newValue).toBlocking().subscribe();
+    }
+
+    @NonNull
+    protected Observable<Optional<TObject>> observeOptionalValue() {
+        return valueObservable;
+    }
+
+    /**
+     * Returns Observable which is emitting item on subscribe and every time when someone have changed value.
+     * It could emit next and error events but not completed.
+     *
+     * @return Returns observable of value.
+     */
+    @NonNull
+    public abstract Observable<TReturnObject> observe();
+
+    /**
+     * Returns Observable which is emitting only one item on subscribe.
+     * It could emit next and error events but not completed.
+     *
+     * @return Returns observable of value.
+     */
+    @NonNull
+    //COMPATIBILITY NOTE: it is not Single to prevent migration of old code
+    public Observable<TReturnObject> get() {
+        return observe().take(1);
+    }
+
+    /**
+     * Gets value synchronously. You should NOT use this method normally. Use {@link #get()} or {@link #observe()} asynchronously instead.
+     *
+     * @return Returns value;
+     */
+    @Deprecated
+    //deprecation: it should be used for debug only and in very rare cases.
+    @Nullable
+    public TReturnObject getSync() {
+        return get().toBlocking().first();
+    }
+
+    /**
+     * Enum that is representing strategy of observing item from store.
+     */
+    public enum ObserveStrategy {
+
+        /**
+         * Not caching value so on every {@link #get()} emit it will get value from {@link #getStore()} and converts it with {@link #getConverter()}.
+         */
+        NO_CACHE,
+        /**
+         * Caching only store value so on every {@link #get()} emit it will converts it with {@link #getConverter()}.
+         * Do not use such strategy if store object could be big (like byte-array of file).
+         */
+        CACHE_STORE_VALUE,
+        /**
+         * Caching value so it won't spend time for getting value from {@link #getStore()} and converts it by {@link #getConverter()}.
+         * But it will take time for getting value from {@link #getStore()} to set value.
+         * Do not use such strategy if object could be big (like Bitmap or long string).
+         * Do not use such strategy if object is mutable because multiple subscribers could then change it's state.
+         */
+        CACHE_ACTUAL_VALUE,
+        /**
+         * Caching value so it won't spend time for getting value from {@link #getStore()} and converts it by {@link #getConverter()}.
+         * It won't take time or getting value from {@link #getStore()} to set value.
+         * Do not use such strategy if store object could be big (like byte-array of file).
+         * Do not use such strategy if object could be big (like Bitmap or long string).
+         * Do not use such strategy if object is mutable because multiple subscribers could then change it's state.
+         */
+        CACHE_STORE_AND_ACTUAL_VALUE
+
+    }
+
+    /**
+     * Helper class to create various builders.
+     *
+     * @param <TKey>         Type of key to identify object;
+     * @param <TObject>      Type of actual object;
+     * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
+     */
+    public static class BuilderCore<TKey, TObject, TStoreObject> {
+
+        @NonNull
+        protected final TKey key;
+        @NonNull
+        protected final Type objectType;
+        @NonNull
+        private final Type storeObjectType;
+        @NonNull
+        private final Store<TKey, TStoreObject> store;
+        @NonNull
+        private final Converter<TObject, TStoreObject> converter;
+        @Nullable
+        private ObserveStrategy observeStrategy;
+        @Nullable
+        private Migration<TKey> migration;
+        @Nullable
+        private TObject defaultValue;
+        @Nullable
+        private Scheduler storeScheduler;
+        private long cacheTimeMillis;
+
+        protected BuilderCore(@NonNull final TKey key,
+                              @NonNull final Type objectType,
+                              @NonNull final Type storeObjectType,
+                              @NonNull final Store<TKey, TStoreObject> store,
+                              @NonNull final Converter<TObject, TStoreObject> converter) {
+            this(key, objectType, storeObjectType, store, converter, null, null, null, null, DEFAULT_CACHE_TIME_MILLIS);
+        }
+
+        protected BuilderCore(@NonNull final BuilderCore<TKey, TObject, TStoreObject> sourceBuilder) {
+            this(sourceBuilder.key, sourceBuilder.objectType, sourceBuilder.storeObjectType,
+                    sourceBuilder.store, sourceBuilder.converter, sourceBuilder.observeStrategy,
+                    sourceBuilder.migration, sourceBuilder.defaultValue, sourceBuilder.storeScheduler, sourceBuilder.cacheTimeMillis);
+        }
+
+        @SuppressWarnings({"PMD.ExcessiveParameterList", "CPD-START"})
+        //CPD: it is same code as constructor of Storable
+        //ExcessiveParameterList: that's why we are using builder to create it
+        private BuilderCore(@NonNull final TKey key,
+                            @NonNull final Type objectType,
+                            @NonNull final Type storeObjectType,
+                            @NonNull final Store<TKey, TStoreObject> store,
+                            @NonNull final Converter<TObject, TStoreObject> converter,
+                            @Nullable final ObserveStrategy observeStrategy,
+                            @Nullable final Migration<TKey> migration,
+                            @Nullable final TObject defaultValue,
+                            @Nullable final Scheduler storeScheduler,
+                            final long cacheTimeMillis) {
+            this.key = key;
+            this.objectType = objectType;
+            this.storeObjectType = storeObjectType;
+            this.store = store;
+            this.converter = converter;
+            this.observeStrategy = observeStrategy;
+            this.migration = migration;
+            this.defaultValue = defaultValue;
+            this.storeScheduler = storeScheduler;
+            this.cacheTimeMillis = cacheTimeMillis;
+        }
+
+        @SuppressWarnings("CPD-END")
+        protected void setStoreSchedulerInternal(@Nullable final Scheduler storeScheduler) {
+            this.storeScheduler = storeScheduler;
+        }
+
+        protected void setObserveStrategyInternal(@Nullable final ObserveStrategy observeStrategy) {
+            this.observeStrategy = observeStrategy;
+        }
+
+        protected void setMigrationInternal(@NonNull final Migration<TKey> migration) {
+            this.migration = migration;
+        }
+
+        protected void setCacheTimeInternal(final long cacheTime, @NonNull final TimeUnit timeUnit) {
+            this.cacheTimeMillis = timeUnit.toMillis(cacheTime);
+        }
+
+        @Nullable
+        protected TObject getDefaultValue() {
+            return defaultValue;
+        }
+
+        protected void setDefaultValueInternal(@NonNull final TObject defaultValue) {
+            this.defaultValue = defaultValue;
+        }
+
+    }
+
+}

src/main/java/ru/touchin/roboswag/core/observables/storable/Migration.java

@@ -58,7 +58,7 @@ public class Migration<TKey> {
     @NonNull
     private Single<Long> loadCurrentVersion(@NonNull final TKey key) {
         return versionsStore.loadObject(Long.class, key)
-                .map(version -> version != null ? version : DEFAULT_VERSION)
+                .map(version -> version.getValue() != null ? version.getValue() : DEFAULT_VERSION)
                 .onErrorResumeNext(throwable
                         -> Single.error(new MigrationException(String.format("Can't get version of '%s' from %s", key, versionsStore), throwable)));
     }

src/main/java/ru/touchin/roboswag/core/observables/storable/Storable.java

@@ -23,20 +23,12 @@ import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
 
 import java.lang.reflect.Type;
-import java.util.concurrent.Executors;
 import java.util.concurrent.TimeUnit;
 
-import ru.touchin.roboswag.core.log.LcGroup;
+import ru.touchin.roboswag.core.observables.storable.concrete.NonNullStorable;
-import ru.touchin.roboswag.core.observables.OnSubscribeRefCountWithCacheTime;
+import ru.touchin.roboswag.core.utils.Optional;
-import ru.touchin.roboswag.core.observables.storable.builders.NonNullStorableBuilder;
-import ru.touchin.roboswag.core.utils.ObjectUtils;
-import rx.Completable;
 import rx.Observable;
 import rx.Scheduler;
-import rx.Single;
-import rx.exceptions.OnErrorThrowable;
-import rx.schedulers.Schedulers;
-import rx.subjects.PublishSubject;
 
 /**
  * Created by Gavriil Sitnikov on 04/10/2015.
@@ -51,419 +43,17 @@ import rx.subjects.PublishSubject;
  * @param <TObject>      Type of actual object;
  * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
  */
-public class Storable<TKey, TObject, TStoreObject> {
+//COMPATIBILITY NOTE: in RxJava2 it should extends BaseStorable<TKey, TObject, TStoreObject, Optional<TObject>>
-
+public class Storable<TKey, TObject, TStoreObject> extends BaseStorable<TKey, TObject, TStoreObject, TObject> {
-    public static final LcGroup STORABLE_LC_GROUP = new LcGroup("STORABLE");
-
-    private static final long DEFAULT_CACHE_TIME_MILLIS = TimeUnit.SECONDS.toMillis(5);
-
-    @NonNull
-    private static ObserveStrategy getDefaultObserveStrategyFor(@NonNull final Type objectType, @NonNull final Type storeObjectType) {
-        if (objectType instanceof Class && ObjectUtils.isSimpleClass((Class) objectType)) {
-            return ObserveStrategy.CACHE_ACTUAL_VALUE;
-        }
-        if (objectType instanceof Class && ObjectUtils.isSimpleClass((Class) storeObjectType)) {
-            return ObserveStrategy.CACHE_STORE_VALUE;
-        }
-        return ObserveStrategy.NO_CACHE;
-    }
-
-    @NonNull
-    private final TKey key;
-    @NonNull
-    private final Type objectType;
-    @NonNull
-    private final Type storeObjectType;
-    @NonNull
-    private final Store<TKey, TStoreObject> store;
-    @NonNull
-    private final Converter<TObject, TStoreObject> converter;
-    @NonNull
-    private final PublishSubject<TStoreObject> newStoreValueEvent = PublishSubject.create();
-    @NonNull
-    private final Observable<TStoreObject> storeValueObservable;
-    @NonNull
-    private final Observable<TObject> valueObservable;
-    @NonNull
-    private final Scheduler scheduler;
 
     public Storable(@NonNull final BuilderCore<TKey, TObject, TStoreObject> builderCore) {
-        this(builderCore.key, builderCore.objectType, builderCore.storeObjectType,
+        super(builderCore);
-                builderCore.store, builderCore.converter, builderCore.observeStrategy,
-                builderCore.migration, builderCore.defaultValue, builderCore.storeScheduler, builderCore.cacheTimeMillis);
-    }
-
-    @SuppressWarnings("PMD.ExcessiveParameterList")
-    //ExcessiveParameterList: that's why we are using builder to create it
-    private Storable(@NonNull final TKey key,
-                     @NonNull final Type objectType,
-                     @NonNull final Type storeObjectType,
-                     @NonNull final Store<TKey, TStoreObject> store,
-                     @NonNull final Converter<TObject, TStoreObject> converter,
-                     @Nullable final ObserveStrategy observeStrategy,
-                     @Nullable final Migration<TKey> migration,
-                     @Nullable final TObject defaultValue,
-                     @Nullable final Scheduler storeScheduler,
-                     final long cacheTimeMillis) {
-        this.key = key;
-        this.objectType = objectType;
-        this.storeObjectType = storeObjectType;
-        this.store = store;
-        this.converter = converter;
-
-        final ObserveStrategy nonNullObserveStrategy
-                = observeStrategy != null ? observeStrategy : getDefaultObserveStrategyFor(objectType, storeObjectType);
-        scheduler = storeScheduler != null ? storeScheduler : Schedulers.from(Executors.newSingleThreadExecutor());
-        storeValueObservable
-                = createStoreValueObservable(nonNullObserveStrategy, migration, defaultValue, cacheTimeMillis);
-        valueObservable = createValueObservable(storeValueObservable, nonNullObserveStrategy, cacheTimeMillis);
-    }
-
-    @Nullable
-    private TStoreObject returnDefaultValueIfNull(@Nullable final TStoreObject storeObject, @Nullable final TObject defaultValue) {
-        if (storeObject != null || defaultValue == null) {
-            return storeObject;
-        }
-
-        try {
-            return converter.toStoreObject(objectType, storeObjectType, defaultValue);
-        } catch (final Converter.ConversionException exception) {
-            STORABLE_LC_GROUP.w(exception, "Exception while converting default value of '%s' from '%s' from store %s",
-                    key, defaultValue, store);
-            throw OnErrorThrowable.from(exception);
-        }
     }
 
     @NonNull
-    private Observable<TStoreObject> createStoreInitialLoadingObservable(@Nullable final Migration<TKey> migration) {
+    @Override
-        final Single<TStoreObject> loadObservable = store.loadObject(storeObjectType, key)
-                .doOnError(throwable -> STORABLE_LC_GROUP.w(throwable, "Exception while trying to load value of '%s' from store %s", key, store));
-        return (migration != null ? migration.migrateToLatestVersion(key).andThen(loadObservable) : loadObservable)
-                .subscribeOn(scheduler)
-                .observeOn(scheduler)
-                .toObservable()
-                .replay(1)
-                .refCount()
-                .take(1);
-    }
-
-    @NonNull
-    private Observable<TStoreObject> createStoreValueObservable(@NonNull final ObserveStrategy observeStrategy,
-                                                                @Nullable final Migration<TKey> migration,
-                                                                @Nullable final TObject defaultValue,
-                                                                final long cacheTimeMillis) {
-        final Observable<TStoreObject> storeInitialLoadingObservable = createStoreInitialLoadingObservable(migration);
-        final Observable<TStoreObject> result = storeInitialLoadingObservable
-                .concatWith(newStoreValueEvent)
-                .map(storeObject -> returnDefaultValueIfNull(storeObject, defaultValue));
-        return observeStrategy == ObserveStrategy.CACHE_STORE_VALUE || observeStrategy == ObserveStrategy.CACHE_STORE_AND_ACTUAL_VALUE
-                ? Observable.create(new OnSubscribeRefCountWithCacheTime<>(result.replay(1), cacheTimeMillis, TimeUnit.MILLISECONDS))
-                : result;
-    }
-
-    @NonNull
-    private Observable<TObject> createValueObservable(@NonNull final Observable<TStoreObject> storeValueObservable,
-                                                      @NonNull final ObserveStrategy observeStrategy,
-                                                      final long cacheTimeMillis) {
-        final Observable<TObject> result = storeValueObservable
-                .map(storeObject -> {
-                    try {
-                        return converter.toObject(objectType, storeObjectType, storeObject);
-                    } catch (final Converter.ConversionException exception) {
-                        STORABLE_LC_GROUP.w(exception, "Exception while trying to converting value of '%s' from store %s by %s",
-                                key, storeObject, store, converter);
-                        throw OnErrorThrowable.from(exception);
-                    }
-                });
-        return observeStrategy == ObserveStrategy.CACHE_ACTUAL_VALUE || observeStrategy == ObserveStrategy.CACHE_STORE_AND_ACTUAL_VALUE
-                ? Observable.create(new OnSubscribeRefCountWithCacheTime<>(result.replay(1), cacheTimeMillis, TimeUnit.MILLISECONDS))
-                : result;
-    }
-
-    /**
-     * Returns key of value.
-     *
-     * @return Unique key.
-     */
-    @NonNull
-    public TKey getKey() {
-        return key;
-    }
-
-    /**
-     * Returns type of actual object.
-     *
-     * @return Type of actual object.
-     */
-    @NonNull
-    public Type getObjectType() {
-        return objectType;
-    }
-
-    /**
-     * Returns type of store object.
-     *
-     * @return Type of store object.
-     */
-    @NonNull
-    public Type getStoreObjectType() {
-        return storeObjectType;
-    }
-
-    /**
-     * Returns {@link Store} where store class representation of object is storing.
-     *
-     * @return Store.
-     */
-    @NonNull
-    public Store<TKey, TStoreObject> getStore() {
-        return store;
-    }
-
-    /**
-     * Returns {@link Converter} to convert values from store class to actual and back.
-     *
-     * @return Converter.
-     */
-    @NonNull
-    public Converter<TObject, TStoreObject> getConverter() {
-        return converter;
-    }
-
-    @NonNull
-    private Completable internalSet(@Nullable final TObject newValue, final boolean checkForEqualityBeforeSet) {
-        return (checkForEqualityBeforeSet ? storeValueObservable.take(1) : Observable.just(null))
-                .observeOn(scheduler)
-                .switchMap(oldStoreValue -> {
-                    final TStoreObject newStoreValue;
-                    try {
-                        newStoreValue = converter.toStoreObject(objectType, storeObjectType, newValue);
-                    } catch (final Converter.ConversionException exception) {
-                        STORABLE_LC_GROUP.w(exception, "Exception while trying to store value of '%s' from store %s by %s",
-                                key, newValue, store, converter);
-                        return Observable.error(exception);
-                    }
-                    if (checkForEqualityBeforeSet && ObjectUtils.equals(newStoreValue, oldStoreValue)) {
-                        return Observable.empty();
-                    }
-                    return store.storeObject(storeObjectType, key, newStoreValue)
-                            .doOnError(throwable -> STORABLE_LC_GROUP.w(throwable,
-                                    "Exception while trying to store value of '%s' from store %s by %s",
-                                    key, newValue, store, converter))
-                            .observeOn(scheduler)
-                            .andThen(Completable.fromAction(() -> {
-                                newStoreValueEvent.onNext(newStoreValue);
-                                if (checkForEqualityBeforeSet) {
-                                    STORABLE_LC_GROUP.i("Value of '%s' changed from '%s' to '%s'", key, oldStoreValue, newStoreValue);
-                                } else {
-                                    STORABLE_LC_GROUP.i("Value of '%s' force changed to '%s'", key, newStoreValue);
-                                }
-                            }))
-                            .toObservable();
-                })
-                .toCompletable();
-    }
-
-    /**
-     * Creates observable which is async setting value to store.
-     * It is not checking if stored value equals new value.
-     * In result it will be faster to not get value from store and compare but it will emit item to {@link #observe()} subscribers.
-     * NOTE: It could emit ONLY completed and errors events. It is not providing onNext event! //TODO: it's Completable :(
-     *
-     * @param newValue Value to set;
-     * @return Observable of setting process.
-     */
-    @NonNull
-    public Observable<?> forceSet(@Nullable final TObject newValue) {
-        return internalSet(newValue, false).toObservable();
-    }
-
-    /**
-     * Creates observable which is async setting value to store.
-     * It is checking if stored value equals new value.
-     * In result it will take time to get value from store and compare
-     * but it won't emit item to {@link #observe()} subscribers if stored value equals new value.
-     * NOTE: It could emit ONLY completed and errors events. It is not providing onNext event! //TODO: it's Completable :(
-     *
-     * @param newValue Value to set;
-     * @return Observable of setting process.
-     */
-    @NonNull
-    public Observable<?> set(@Nullable final TObject newValue) {
-        return internalSet(newValue, true).toObservable();
-    }
-
-    /**
-     * Sets value synchronously. You should NOT use this method normally. Use {@link #set(Object)} asynchronously instead.
-     *
-     * @param newValue Value to set;
-     */
-    @Deprecated
-    //deprecation: it should be used for debug only and in very rare cases.
-    public void setSync(@Nullable final TObject newValue) {
-        set(newValue).toBlocking().subscribe();
-    }
-
-    /**
-     * Returns Observable which is emitting item on subscribe and every time when someone have changed value.
-     * It could emit next and error events but not completed.
-     *
-     * @return Returns observable of value.
-     */
-    @NonNull
     public Observable<TObject> observe() {
-        return valueObservable;
+        return observeOptionalValue().map(Optional::getValue);
-    }
-
-    /**
-     * Returns Observable which is emitting only one item on subscribe. //TODO: it's Single :(
-     * It could emit next and error events but not completed.
-     *
-     * @return Returns observable of value.
-     */
-    @NonNull
-    public Observable<TObject> get() {
-        return valueObservable.take(1);
-    }
-
-    /**
-     * Gets value synchronously. You should NOT use this method normally. Use {@link #get()} or {@link #observe()} asynchronously instead.
-     *
-     * @return Returns value;
-     */
-    @Deprecated
-    //deprecation: it should be used for debug only and in very rare cases.
-    @Nullable
-    public TObject getSync() {
-        return get().toBlocking().first();
-    }
-
-    /**
-     * Enum that is representing strategy of observing item from store.
-     */
-    public enum ObserveStrategy {
-
-        /**
-         * Not caching value so on every {@link #get()} emit it will get value from {@link #getStore()} and converts it with {@link #getConverter()}.
-         */
-        NO_CACHE,
-        /**
-         * Caching only store value so on every {@link #get()} emit it will converts it with {@link #getConverter()}.
-         * Do not use such strategy if store object could be big (like byte-array of file).
-         */
-        CACHE_STORE_VALUE,
-        /**
-         * Caching value so it won't spend time for getting value from {@link #getStore()} and converts it by {@link #getConverter()}.
-         * But it will take time for getting value from {@link #getStore()} to set value.
-         * Do not use such strategy if object could be big (like Bitmap or long string).
-         * Do not use such strategy if object is mutable because multiple subscribers could then change it's state.
-         */
-        CACHE_ACTUAL_VALUE,
-        /**
-         * Caching value so it won't spend time for getting value from {@link #getStore()} and converts it by {@link #getConverter()}.
-         * It won't take time or getting value from {@link #getStore()} to set value.
-         * Do not use such strategy if store object could be big (like byte-array of file).
-         * Do not use such strategy if object could be big (like Bitmap or long string).
-         * Do not use such strategy if object is mutable because multiple subscribers could then change it's state.
-         */
-        CACHE_STORE_AND_ACTUAL_VALUE
-
-    }
-
-    /**
-     * Helper class to create various builders.
-     *
-     * @param <TKey>         Type of key to identify object;
-     * @param <TObject>      Type of actual object;
-     * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
-     */
-    public static class BuilderCore<TKey, TObject, TStoreObject> {
-
-        @NonNull
-        protected final TKey key;
-        @NonNull
-        protected final Type objectType;
-        @NonNull
-        private final Type storeObjectType;
-        @NonNull
-        private final Store<TKey, TStoreObject> store;
-        @NonNull
-        private final Converter<TObject, TStoreObject> converter;
-        @Nullable
-        private ObserveStrategy observeStrategy;
-        @Nullable
-        private Migration<TKey> migration;
-        @Nullable
-        private TObject defaultValue;
-        @Nullable
-        private Scheduler storeScheduler;
-        private long cacheTimeMillis;
-
-        protected BuilderCore(@NonNull final TKey key,
-                              @NonNull final Type objectType,
-                              @NonNull final Type storeObjectType,
-                              @NonNull final Store<TKey, TStoreObject> store,
-                              @NonNull final Converter<TObject, TStoreObject> converter) {
-            this(key, objectType, storeObjectType, store, converter, null, null, null, null, DEFAULT_CACHE_TIME_MILLIS);
-        }
-
-        protected BuilderCore(@NonNull final BuilderCore<TKey, TObject, TStoreObject> sourceBuilder) {
-            this(sourceBuilder.key, sourceBuilder.objectType, sourceBuilder.storeObjectType,
-                    sourceBuilder.store, sourceBuilder.converter, sourceBuilder.observeStrategy,
-                    sourceBuilder.migration, sourceBuilder.defaultValue, sourceBuilder.storeScheduler, sourceBuilder.cacheTimeMillis);
-        }
-
-        @SuppressWarnings({"PMD.ExcessiveParameterList", "CPD-START"})
-        //CPD: it is same code as constructor of Storable
-        //ExcessiveParameterList: that's why we are using builder to create it
-        private BuilderCore(@NonNull final TKey key,
-                            @NonNull final Type objectType,
-                            @NonNull final Type storeObjectType,
-                            @NonNull final Store<TKey, TStoreObject> store,
-                            @NonNull final Converter<TObject, TStoreObject> converter,
-                            @Nullable final ObserveStrategy observeStrategy,
-                            @Nullable final Migration<TKey> migration,
-                            @Nullable final TObject defaultValue,
-                            @Nullable final Scheduler storeScheduler,
-                            final long cacheTimeMillis) {
-            this.key = key;
-            this.objectType = objectType;
-            this.storeObjectType = storeObjectType;
-            this.store = store;
-            this.converter = converter;
-            this.observeStrategy = observeStrategy;
-            this.migration = migration;
-            this.defaultValue = defaultValue;
-            this.storeScheduler = storeScheduler;
-            this.cacheTimeMillis = cacheTimeMillis;
-        }
-
-        @SuppressWarnings("CPD-END")
-        protected void setStoreSchedulerInternal(@Nullable final Scheduler storeScheduler) {
-            this.storeScheduler = storeScheduler;
-        }
-
-        protected void setObserveStrategyInternal(@Nullable final ObserveStrategy observeStrategy) {
-            this.observeStrategy = observeStrategy;
-        }
-
-        protected void setMigrationInternal(@NonNull final Migration<TKey> migration) {
-            this.migration = migration;
-        }
-
-        protected void setCacheTimeInternal(final long cacheTime, @NonNull final TimeUnit timeUnit) {
-            this.cacheTimeMillis = timeUnit.toMillis(cacheTime);
-        }
-
-        @Nullable
-        protected TObject getDefaultValue() {
-            return defaultValue;
-        }
-
-        protected void setDefaultValueInternal(@NonNull final TObject defaultValue) {
-            this.defaultValue = defaultValue;
-        }
-
     }
 
     /**
@@ -540,8 +130,8 @@ public class Storable<TKey, TObject, TStoreObject> {
          * @return Builder that allows to specify other fields.
          */
         @NonNull
-        public NonNullStorableBuilder<TKey, TObject, TStoreObject> setDefaultValue(@NonNull final TObject defaultValue) {
+        public NonNullStorable.Builder<TKey, TObject, TStoreObject> setDefaultValue(@NonNull final TObject defaultValue) {
-            return new NonNullStorableBuilder<>(this, defaultValue);
+            return new NonNullStorable.Builder<>(this, defaultValue);
         }
 
         /**

src/main/java/ru/touchin/roboswag/core/observables/storable/Store.java

@@ -24,6 +24,7 @@ import android.support.annotation.Nullable;
 
 import java.lang.reflect.Type;
 
+import ru.touchin.roboswag.core.utils.Optional;
 import rx.Completable;
 import rx.Single;
 
@@ -64,6 +65,6 @@ public interface Store<TKey, TStoreObject> {
      * @return Object from store found by key;
      */
     @NonNull
-    Single<TStoreObject> loadObject(@NonNull Type storeObjectType, @NonNull TKey key);
+    Single<Optional<TStoreObject>> loadObject(@NonNull Type storeObjectType, @NonNull TKey key);
 
 }

src/main/java/ru/touchin/roboswag/core/observables/storable/builders/NonNullStorableBuilder.java

@@ -1,113 +0,0 @@
-/*
- *  Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
- *
- *  This file is part of RoboSwag library.
- *
- *  Licensed under the Apache License, Version 2.0 (the "License");
- *  you may not use this file except in compliance with the License.
- *  You may obtain a copy of the License at
- *
- *  http://www.apache.org/licenses/LICENSE-2.0
- *
- *  Unless required by applicable law or agreed to in writing, software
- *  distributed under the License is distributed on an "AS IS" BASIS,
- *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- *  See the License for the specific language governing permissions and
- *  limitations under the License.
- *
- */
-
-package ru.touchin.roboswag.core.observables.storable.builders;
-
-import android.support.annotation.NonNull;
-import android.support.annotation.Nullable;
-
-import java.util.concurrent.TimeUnit;
-
-import ru.touchin.roboswag.core.observables.storable.Migration;
-import ru.touchin.roboswag.core.observables.storable.Storable;
-import ru.touchin.roboswag.core.observables.storable.concrete.NonNullStorable;
-import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
-import rx.Scheduler;
-
-/**
- * Created by Gavriil Sitnikov on 15/05/2016.
- * Builder that is already contains not null default value.
- *
- * @param <TKey>         Type of key to identify object;
- * @param <TObject>      Type of actual object;
- * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
- */
-public class NonNullStorableBuilder<TKey, TObject, TStoreObject> extends Storable.BuilderCore<TKey, TObject, TStoreObject> {
-
-    public NonNullStorableBuilder(@NonNull final Storable.Builder<TKey, TObject, TStoreObject> sourceBuilder,
-                                  @NonNull final TObject defaultValue) {
-        super(sourceBuilder);
-        setDefaultValueInternal(defaultValue);
-    }
-
-    /**
-     * Sets specific {@link Scheduler} to store/load/convert values on it.
-     *
-     * @param storeScheduler Scheduler;
-     * @return Builder that allows to specify other fields.
-     */
-    @NonNull
-    public NonNullStorableBuilder<TKey, TObject, TStoreObject> setStoreScheduler(@Nullable final Scheduler storeScheduler) {
-        setStoreSchedulerInternal(storeScheduler);
-        return this;
-    }
-
-    /**
-     * Sets specific {@link Storable.ObserveStrategy} to cache value in memory in specific way.
-     *
-     * @param observeStrategy ObserveStrategy;
-     * @return Builder that allows to specify other fields.
-     */
-    @NonNull
-    public NonNullStorableBuilder<TKey, TObject, TStoreObject> setObserveStrategy(@Nullable final Storable.ObserveStrategy observeStrategy) {
-        setObserveStrategyInternal(observeStrategy);
-        return this;
-    }
-
-    /**
-     * Sets cache time for while value that cached by {@link #setObserveStrategy(Storable.ObserveStrategy)}
-     * will be in memory after everyone unsubscribe.
-     * It is important for example for cases when user switches between screens and hide/open app very fast.
-     *
-     * @param cacheTime Cache time value;
-     * @param timeUnit  Cache time units.
-     * @return Builder that allows to specify other fields.
-     */
-    @NonNull
-    public NonNullStorableBuilder<TKey, TObject, TStoreObject> setCacheTime(final long cacheTime, @NonNull final TimeUnit timeUnit) {
-        setCacheTimeInternal(cacheTime, timeUnit);
-        return this;
-    }
-
-    /**
-     * Sets specific {@link Migration} to migrate values from specific version to latest version.
-     *
-     * @param migration Migration;
-     * @return Builder that allows to specify other fields.
-     */
-    @NonNull
-    public NonNullStorableBuilder<TKey, TObject, TStoreObject> setMigration(@NonNull final Migration<TKey> migration) {
-        setMigrationInternal(migration);
-        return this;
-    }
-
-    /**
-     * Building {@link NonNullStorable} object.
-     *
-     * @return New {@link NonNullStorable}.
-     */
-    @NonNull
-    public NonNullStorable<TKey, TObject, TStoreObject> build() {
-        if (getDefaultValue() == null) {
-            throw new ShouldNotHappenException();
-        }
-        return new NonNullStorable<>(this);
-    }
-
-}

src/main/java/ru/touchin/roboswag/core/observables/storable/concrete/NonNullStorable.java

@@ -20,10 +20,16 @@
 package ru.touchin.roboswag.core.observables.storable.concrete;
 
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
+import java.util.concurrent.TimeUnit;
+
+import ru.touchin.roboswag.core.observables.storable.BaseStorable;
+import ru.touchin.roboswag.core.observables.storable.Migration;
 import ru.touchin.roboswag.core.observables.storable.Storable;
-import ru.touchin.roboswag.core.observables.storable.builders.NonNullStorableBuilder;
 import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
+import rx.Observable;
+import rx.Scheduler;
 
 /**
  * Created by Gavriil Sitnikov on 04/10/2015.
@@ -34,20 +40,109 @@ import ru.touchin.roboswag.core.utils.ShouldNotHappenException;
  * @param <TObject>      Type of actual object;
  * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
  */
-public class NonNullStorable<TKey, TObject, TStoreObject> extends Storable<TKey, TObject, TStoreObject> {
+public class NonNullStorable<TKey, TObject, TStoreObject> extends BaseStorable<TKey, TObject, TStoreObject, TObject> {
 
-    public NonNullStorable(@NonNull final NonNullStorableBuilder<TKey, TObject, TStoreObject> builderCore) {
+    public NonNullStorable(@NonNull final Builder<TKey, TObject, TStoreObject> builderCore) {
         super(builderCore);
     }
 
     @NonNull
     @Override
-    public TObject getSync() {
+    public Observable<TObject> observe() {
-        final TObject result = super.getSync();
+        return observeOptionalValue()
-        if (result == null) {
+                .map(optional -> {
-            throw new ShouldNotHappenException();
+                    if (optional.getValue() == null) {
-        }
+                        throw new ShouldNotHappenException();
-        return result;
+                    }
+                    return optional.getValue();
+                });
     }
 
+    /**
+     * Created by Gavriil Sitnikov on 15/05/2016.
+     * Builder that is already contains not null default value.
+     *
+     * @param <TKey>         Type of key to identify object;
+     * @param <TObject>      Type of actual object;
+     * @param <TStoreObject> Type of store object. Could be same as {@link TObject}.
+     */
+    @SuppressWarnings("CPD-START")
+    //CPD: it is same code as Builder of Storable because it's methods returning this and can't be inherited
+    public static class Builder<TKey, TObject, TStoreObject> extends BuilderCore<TKey, TObject, TStoreObject> {
+
+        public Builder(@NonNull final Storable.Builder<TKey, TObject, TStoreObject> sourceBuilder,
+                       @NonNull final TObject defaultValue) {
+            super(sourceBuilder);
+            if (defaultValue == null) {
+                throw new ShouldNotHappenException();
+            }
+            setDefaultValueInternal(defaultValue);
+        }
+
+        /**
+         * Sets specific {@link Scheduler} to store/load/convert values on it.
+         *
+         * @param storeScheduler Scheduler;
+         * @return Builder that allows to specify other fields.
+         */
+        @NonNull
+        public Builder<TKey, TObject, TStoreObject> setStoreScheduler(@Nullable final Scheduler storeScheduler) {
+            setStoreSchedulerInternal(storeScheduler);
+            return this;
+        }
+
+        /**
+         * Sets specific {@link ObserveStrategy} to cache value in memory in specific way.
+         *
+         * @param observeStrategy ObserveStrategy;
+         * @return Builder that allows to specify other fields.
+         */
+        @NonNull
+        public Builder<TKey, TObject, TStoreObject> setObserveStrategy(@Nullable final ObserveStrategy observeStrategy) {
+            setObserveStrategyInternal(observeStrategy);
+            return this;
+        }
+
+        /**
+         * Sets cache time for while value that cached by {@link #setObserveStrategy(ObserveStrategy)}
+         * will be in memory after everyone unsubscribe.
+         * It is important for example for cases when user switches between screens and hide/open app very fast.
+         *
+         * @param cacheTime Cache time value;
+         * @param timeUnit  Cache time units.
+         * @return Builder that allows to specify other fields.
+         */
+        @NonNull
+        public Builder<TKey, TObject, TStoreObject> setCacheTime(final long cacheTime, @NonNull final TimeUnit timeUnit) {
+            setCacheTimeInternal(cacheTime, timeUnit);
+            return this;
+        }
+
+        /**
+         * Sets specific {@link Migration} to migrate values from specific version to latest version.
+         *
+         * @param migration Migration;
+         * @return Builder that allows to specify other fields.
+         */
+        @NonNull
+        public Builder<TKey, TObject, TStoreObject> setMigration(@NonNull final Migration<TKey> migration) {
+            setMigrationInternal(migration);
+            return this;
+        }
+
+        /**
+         * Building {@link NonNullStorable} object.
+         *
+         * @return New {@link NonNullStorable}.
+         */
+        @NonNull
+        @SuppressWarnings("CPD-END")
+        public NonNullStorable<TKey, TObject, TStoreObject> build() {
+            if (getDefaultValue() == null) {
+                throw new ShouldNotHappenException();
+            }
+            return new NonNullStorable<>(this);
+        }
+
+    }
 }

src/main/java/ru/touchin/roboswag/core/utils/Optional.java

@@ -0,0 +1,71 @@
+/*
+ *  Copyright (c) 2017 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
+ *
+ *  This file is part of RoboSwag library.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ *
+ */
+
+package ru.touchin.roboswag.core.utils;
+
+import android.support.annotation.Nullable;
+
+import java.io.Serializable;
+
+/**
+ * Created by Gavriil Sitnikov on 16/04/2017.
+ * Holds nullable objects inside. It is needed to implement RxJava2 non-null emitting logic.
+ *
+ * @param <T> Type of object.
+ */
+public class Optional<T> implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    @Nullable
+    private final T value;
+
+    public Optional(@Nullable final T value) {
+        this.value = value;
+    }
+
+    /**
+     * Returns holding nullable object.
+     *
+     * @return Holding object.
+     */
+    @Nullable
+    public T getValue() {
+        return value;
+    }
+
+    @Override
+    public boolean equals(@Nullable final Object object) {
+        if (this == object) {
+            return true;
+        }
+        if (object == null || getClass() != object.getClass()) {
+            return false;
+        }
+
+        final Optional<?> that = (Optional<?>) object;
+        return ObjectUtils.equals(value, that.value);
+    }
+
+    @Override
+    public int hashCode() {
+        return value != null ? value.hashCode() : 0;
+    }
+
+}

src/main/java/ru/touchin/roboswag/core/utils/ServiceBinder.java

@@ -22,6 +22,7 @@ package ru.touchin.roboswag.core.utils;
 import android.app.Service;
 import android.os.Binder;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 
 /**
  * Created by Gavriil Sitnikov on 03/10/2015.
@@ -47,4 +48,23 @@ public class ServiceBinder<TService extends Service> extends Binder {
         return service;
     }
 
+    @Override
+    public boolean equals(@Nullable final Object object) {
+        if (this == object) {
+            return true;
+        }
+        if (object == null || getClass() != object.getClass()) {
+            return false;
+        }
+
+        final ServiceBinder that = (ServiceBinder) object;
+
+        return ObjectUtils.equals(service, that.service);
+    }
+
+    @Override
+    public int hashCode() {
+        return service.hashCode();
+    }
+
 }

src/main/java/ru/touchin/roboswag/core/utils/ThreadLocalValue.java

@@ -21,8 +21,6 @@ package ru.touchin.roboswag.core.utils;
 
 import android.support.annotation.NonNull;
 
-import rx.functions.Func0;
-
 /**
  * Created by Gavriil Sitnikov on 13/11/2015.
  * Thread local value with specified creator of value per thread.
@@ -30,24 +28,33 @@ import rx.functions.Func0;
 public class ThreadLocalValue<T> extends ThreadLocal<T> {
 
     @NonNull
-    private final Func0<T> creator;
+    private final Fabric<T> fabric;
 
-    public ThreadLocalValue(@NonNull final NonNullFunc<T> creator) {
+    public ThreadLocalValue(@NonNull final Fabric<T> fabric) {
         super();
-        this.creator = creator;
+        this.fabric = fabric;
     }
 
     @NonNull
     @Override
     protected T initialValue() {
-        return creator.call();
+        return fabric.create();
     }
 
-    public interface NonNullFunc<T> extends Func0<T> {
+    /**
+     * Fabric of thread-local objects.
+     *
+     * @param <T> Type of objects.
+     */
+    public interface Fabric<T> {
 
+        /**
+         * Creates object.
+         *
+         * @return new instance of object.
+         */
         @NonNull
-        @Override
+        T create();
-        T call();
 
     }
 

src/main/java/ru/touchin/roboswag/core/utils/pairs/HalfNullablePair.java

@@ -81,9 +81,7 @@ public class HalfNullablePair<TFirst, TSecond> implements Serializable {
 
     @Override
     public int hashCode() {
-        int result = first.hashCode();
+        return ObjectUtils.hashCode(first, second);
-        result = 31 * result + (second != null ? second.hashCode() : 0);
-        return result;
     }
 
 }

src/main/java/ru/touchin/roboswag/core/utils/pairs/NonNullPair.java

@@ -81,9 +81,7 @@ public class NonNullPair<TFirst, TSecond> implements Serializable {
 
     @Override
     public int hashCode() {
-        int result = first.hashCode();
+        return ObjectUtils.hashCode(first, second);
-        result = 31 * result + second.hashCode();
-        return result;
     }
 
 }

src/main/java/ru/touchin/roboswag/core/utils/pairs/NullablePair.java

@@ -85,9 +85,7 @@ public class NullablePair<TFirst, TSecond> implements Serializable { //todo: mb
 
     @Override
     public int hashCode() {
-        int result = first.hashCode();
+        return ObjectUtils.hashCode(first, second);
-        result = 31 * result + second.hashCode();
-        return result;
     }
 
 }