change executor to single thread and add priority for execution

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

@@ -7,6 +7,7 @@ import android.support.annotation.Nullable;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.Executors;
 
+import ru.touchin.roboswag.core.utils.ProcessPriorityThreadFactory;
 import rx.Observable;
 import rx.Scheduler;
 import rx.Subscriber;
@@ -25,6 +26,9 @@ public class SequenceObservableExecutor {
 
     @NonNull
     private final Scheduler sendingScheduler = Schedulers.from(Executors.newSingleThreadExecutor());
+    @NonNull
+    private final Scheduler executeScheduler = Schedulers.from(Executors.newSingleThreadExecutor(
+            new ProcessPriorityThreadFactory(Thread.MIN_PRIORITY)));
 
     @NonNull
     public Observable<?> execute(@NonNull final Observable<?> completable) {
@@ -52,8 +56,7 @@ public class SequenceObservableExecutor {
             scheduleSubscription = sendingScheduler.createWorker().schedule(() -> {
                 final CountDownLatch blocker = new CountDownLatch(1);
                 executeSubscription = completable
-                        //TODO think how to replace it
-                        .subscribeOn(Schedulers.newThread())
+                        .subscribeOn(executeScheduler)
                         .doOnUnsubscribe(blocker::countDown)
                         .subscribe(Actions.empty(), subscriber::onError, subscriber::onCompleted);
                 try {

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

@@ -0,0 +1,50 @@
+/*
+ *  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.utils;
+
+import android.support.annotation.NonNull;
+
+import java.util.concurrent.ThreadFactory;
+
+/**
+ * Created by Ilia Kurtov on 25/05/2017 with a help from https://stackoverflow.com/a/21187003/4312184
+ * ThreadFactory that can change default thread priority. Suitable for creating Schedulers fo RxJava like this:
+ * final Scheduler scheduler = Schedulers.from(Executors.newSingleThreadExecutor(new ProcessPriorityThreadFactory(Thread.MIN_PRIORITY)));
+ */
+public final class ProcessPriorityThreadFactory implements ThreadFactory {
+
+    private final int threadPriority;
+
+    /**
+     * threadPriority can be in a range from {@link Thread#MIN_PRIORITY} to {@link Thread#MAX_PRIORITY}
+     * @param threadPriority priority for the Thread.
+     */
+    public ProcessPriorityThreadFactory(final int threadPriority) {
+        this.threadPriority = threadPriority;
+    }
+
+    @Override
+    public Thread newThread(@NonNull final Runnable runnable) {
+        final Thread thread = new Thread(runnable);
+        thread.setPriority(threadPriority);
+        return thread;
+    }
+
+}