abstract provider
This commit is contained in:
Ilia Kurtov
parent
8ce3d5fd89
commit
cfd48cb997
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@ -0,0 +1,220 @@
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/*
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* Copyright (c) 2015 RoboSwag (Gavriil Sitnikov, Vsevolod Ivanov)
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*
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* This file is part of RoboSwag library.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package ru.touchin.roboswag.components.listing;
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import android.support.annotation.NonNull;
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import android.support.annotation.Nullable;
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import android.util.SparseArray;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.List;
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import ru.touchin.roboswag.core.log.Lc;
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import ru.touchin.roboswag.core.utils.android.RxAndroidUtils;
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import rx.Observable;
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import rx.Scheduler;
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/**
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* Created by Ilia Kurtov on 12.05.2016.
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* TODO: fill description
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*/
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public abstract class AbstractSimplePagingProvider<T> extends ItemsProvider<T> {
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public static final int DEFAULT_PAGE_SIZE = 25;
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protected final Scheduler scheduler = RxAndroidUtils.createLooperScheduler();
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private final Object lock = new Object();
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private final int pageSize;
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private final SparseArray<List<T>> loadedPages = new SparseArray<>();
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private final SparseArray<Observable<List<T>>> loadingPages = new SparseArray<>();
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@Nullable
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private Integer maxLoadedPage;
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private boolean isLastPageLoaded;
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public AbstractSimplePagingProvider(final int pageSize) {
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super();
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this.pageSize = pageSize;
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}
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public int getPageSize() {
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return pageSize;
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}
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@Override
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public int getSize() {
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synchronized (lock) {
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return (maxLoadedPage != null ? maxLoadedPage * pageSize + loadedPages.get(maxLoadedPage).size() : 0)
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+ (isLastPageLoaded ? 0 : 1);
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}
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}
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@NonNull
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public List<T> getLoadedItems() {
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final List<T> result = new ArrayList<>();
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if (maxLoadedPage != null) {
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for (int i = 0; i <= maxLoadedPage; i++) {
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final List<T> page = loadedPages.get(i);
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if (page != null) {
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result.addAll(page);
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}
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}
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}
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return result;
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}
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private int pageIndexOf(final int position) {
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return position / pageSize;
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}
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private int indexOnPage(final int position) {
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return position % pageSize;
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}
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@Nullable
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@Override
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public T getItem(final int position) {
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synchronized (lock) {
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final List<T> page = loadedPages.get(pageIndexOf(position));
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final int indexOnPage = indexOnPage(position);
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return page != null && page.size() > indexOnPage ? page.get(indexOnPage) : null;
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}
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}
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@Override
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@NonNull
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public Observable<T> loadItem(final int position) {
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final int indexOfPage = pageIndexOf(position);
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final int indexOnPage = indexOnPage(position);
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return Observable.<T>create(subscriber -> {
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final List<T> page = loadedPages.get(indexOfPage);
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subscriber.onNext(page != null && page.size() > indexOnPage ? page.get(indexOnPage) : null);
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subscriber.onCompleted();
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}).switchMap(item -> {
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if (item != null || (isLastPageLoaded && maxLoadedPage != null && maxLoadedPage <= indexOfPage)) {
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return Observable.just(item);
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}
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Observable<List<T>> loadingPage = loadingPages.get(indexOfPage);
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if (loadingPage == null) {
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loadingPage = createPageLoadingObservable(indexOfPage);
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loadingPages.put(indexOfPage, loadingPage);
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}
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return loadingPage.map(page -> {
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int index = 0;
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for (final T nextItem : page) {
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if (index == indexOnPage) {
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return nextItem;
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}
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index++;
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}
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return null;
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});
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}).subscribeOn(scheduler);
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}
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private boolean shouldReplaceMaxLoaded(@NonNull final List<T> pageItems, final int indexOfPage) {
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return (indexOfPage == 0 || !pageItems.isEmpty()) && (maxLoadedPage == null || maxLoadedPage < indexOfPage);
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}
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@NonNull
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private Observable<List<T>> createPageLoadingObservable(final int indexOfPage) {
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return observeItems(indexOfPage)
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.observeOn(scheduler)
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.map(this::validatePageItems)
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.doOnNext(pageItems -> {
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synchronized (lock) {
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final int oldSize = getSize();
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final boolean oldIsLastPageLoaded = isLastPageLoaded;
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if (pageItems.size() < pageSize) {
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if (maxLoadedPage != null && maxLoadedPage > indexOfPage) {
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maxLoadedPage = indexOfPage == 0 || !pageItems.isEmpty() ? indexOfPage : null;
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downgradeMaxLoadedPages(indexOfPage);
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isLastPageLoaded = false;
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}
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if (shouldReplaceMaxLoaded(pageItems, indexOfPage)) {
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maxLoadedPage = indexOfPage;
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}
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isLastPageLoaded = isLastPageLoaded
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|| (maxLoadedPage != null
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&& (maxLoadedPage == indexOfPage || maxLoadedPage == indexOfPage - 1));
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} else if (shouldReplaceMaxLoaded(pageItems, indexOfPage)) {
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maxLoadedPage = indexOfPage;
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}
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if (indexOfPage == 0 || !pageItems.isEmpty()) {
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loadedPages.put(indexOfPage, pageItems);
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}
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loadingPages.remove(indexOfPage);
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updateItemsChanges(indexOfPage, pageItems, oldSize, oldIsLastPageLoaded);
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}
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}).replay(1)
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.refCount();
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}
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protected abstract Observable<List<T>> observeItems(final int indexOfPage);
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private void downgradeMaxLoadedPages(final int maximum) {
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for (int i = 0; i <= loadedPages.size(); i++) {
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final int key = loadedPages.keyAt(i);
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if (key > maximum || loadedPages.get(key).size() < pageSize) {
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loadedPages.remove(key);
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} else if (maxLoadedPage == null || maxLoadedPage < key) {
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maxLoadedPage = key;
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}
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}
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}
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private void updateItemsChanges(final int indexOfPage, @NonNull final List<T> pageItems, final int oldSize, final boolean oldIsLastPageLoaded) {
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final List<Change> changes = new ArrayList<>();
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final int size = getSize();
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if (size == oldSize) {
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if (!pageItems.isEmpty()) {
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changes.add(new Change(Change.Type.CHANGED, indexOfPage * pageSize, pageItems.size()));
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}
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} else if (size > oldSize) {
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if (!oldIsLastPageLoaded) {
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changes.add(new Change(Change.Type.CHANGED, oldSize - 1, 1));
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}
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changes.add(new Change(Change.Type.INSERTED, oldSize, size - oldSize));
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} else {
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changes.add(new Change(Change.Type.REMOVED, size, oldSize - size));
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if (!isLastPageLoaded) {
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changes.add(new Change(Change.Type.CHANGED, size - 1, 1));
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}
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}
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if (!changes.isEmpty()) {
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notifyChanges(changes);
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}
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}
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@NonNull
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private List<T> validatePageItems(@NonNull final Collection<T> pageItems) {
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if (pageItems.size() > pageSize) {
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Lc.assertion("Unexpectedly big pageItems: " + pageItems.size() + '/' + pageSize);
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return Collections.unmodifiableList(new ArrayList<>(pageItems).subList(0, pageSize));
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} else {
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return Collections.unmodifiableList(new ArrayList<>(pageItems));
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}
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}
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}
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@ -20,35 +20,19 @@
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package ru.touchin.roboswag.components.listing;
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import android.support.annotation.NonNull;
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import android.support.annotation.Nullable;
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import android.util.SparseArray;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Collections;
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import java.util.List;
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import ru.touchin.roboswag.core.log.Lc;
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import ru.touchin.roboswag.core.utils.android.RxAndroidUtils;
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import rx.Observable;
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import rx.Scheduler;
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/**
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* Created by Gavriil Sitnikov on 07/12/2015.
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* TODO: fill description
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*/
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public class SimplePagingProvider<T> extends ItemsProvider<T> {
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public class SimplePagingProvider<T> extends AbstractSimplePagingProvider<T> {
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public static final int DEFAULT_PAGE_SIZE = 25;
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private final Scheduler scheduler = RxAndroidUtils.createLooperScheduler();
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private final Object lock = new Object();
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private final int pageSize;
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private final SparseArray<List<T>> loadedPages = new SparseArray<>();
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@Nullable
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private Integer maxLoadedPage;
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private boolean isLastPageLoaded;
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private final SparseArray<Observable<List<T>>> loadingPages = new SparseArray<>();
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@NonNull
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private final PagesProvider<T> pagesProvider;
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@ -57,168 +41,13 @@ public class SimplePagingProvider<T> extends ItemsProvider<T> {
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}
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public SimplePagingProvider(@NonNull final PagesProvider<T> pagesProvider, final int pageSize) {
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super();
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super(pageSize);
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this.pagesProvider = pagesProvider;
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this.pageSize = pageSize;
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}
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public int getPageSize() {
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return pageSize;
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}
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@Override
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public int getSize() {
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synchronized (lock) {
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return (maxLoadedPage != null ? maxLoadedPage * pageSize + loadedPages.get(maxLoadedPage).size() : 0)
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+ (isLastPageLoaded ? 0 : 1);
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}
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}
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@NonNull
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public List<T> getLoadedItems() {
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final List<T> result = new ArrayList<>();
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if (maxLoadedPage != null) {
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for (int i = 0; i <= maxLoadedPage; i++) {
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final List<T> page = loadedPages.get(i);
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if (page != null) {
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result.addAll(page);
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}
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}
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}
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return result;
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}
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private int pageIndexOf(final int position) {
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return position / pageSize;
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}
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private int indexOnPage(final int position) {
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return position % pageSize;
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}
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@Nullable
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@Override
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public T getItem(final int position) {
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synchronized (lock) {
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final List<T> page = loadedPages.get(pageIndexOf(position));
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final int indexOnPage = indexOnPage(position);
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return page != null && page.size() > indexOnPage ? page.get(indexOnPage) : null;
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}
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}
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@Override
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@NonNull
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public Observable<T> loadItem(final int position) {
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final int indexOfPage = pageIndexOf(position);
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final int indexOnPage = indexOnPage(position);
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return Observable.<T>create(subscriber -> {
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final List<T> page = loadedPages.get(indexOfPage);
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subscriber.onNext(page != null && page.size() > indexOnPage ? page.get(indexOnPage) : null);
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subscriber.onCompleted();
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}).switchMap(item -> {
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if (item != null || (isLastPageLoaded && maxLoadedPage != null && maxLoadedPage <= indexOfPage)) {
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return Observable.just(item);
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}
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Observable<List<T>> loadingPage = loadingPages.get(indexOfPage);
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if (loadingPage == null) {
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loadingPage = createPageLoadingObservable(indexOfPage);
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loadingPages.put(indexOfPage, loadingPage);
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}
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return loadingPage.map(page -> {
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int index = 0;
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for (final T nextItem : page) {
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if (index == indexOnPage) {
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return nextItem;
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}
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index++;
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}
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return null;
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});
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}).subscribeOn(scheduler);
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}
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private boolean shouldReplaceMaxLoaded(@NonNull final List<T> pageItems, final int indexOfPage) {
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return (indexOfPage == 0 || !pageItems.isEmpty()) && (maxLoadedPage == null || maxLoadedPage < indexOfPage);
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}
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@NonNull
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private Observable<List<T>> createPageLoadingObservable(final int indexOfPage) {
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return pagesProvider
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.loadPage(indexOfPage * pageSize, pageSize)
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.observeOn(scheduler)
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.map(this::validatePageItems)
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.doOnNext(pageItems -> {
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synchronized (lock) {
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final int oldSize = getSize();
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final boolean oldIsLastPageLoaded = isLastPageLoaded;
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if (pageItems.size() < pageSize) {
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if (maxLoadedPage != null && maxLoadedPage > indexOfPage) {
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maxLoadedPage = indexOfPage == 0 || !pageItems.isEmpty() ? indexOfPage : null;
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downgradeMaxLoadedPages(indexOfPage);
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isLastPageLoaded = false;
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}
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if (shouldReplaceMaxLoaded(pageItems, indexOfPage)) {
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maxLoadedPage = indexOfPage;
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}
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isLastPageLoaded = isLastPageLoaded
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|| (maxLoadedPage != null
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&& (maxLoadedPage == indexOfPage || maxLoadedPage == indexOfPage - 1));
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} else if (shouldReplaceMaxLoaded(pageItems, indexOfPage)) {
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maxLoadedPage = indexOfPage;
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}
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if (indexOfPage == 0 || !pageItems.isEmpty()) {
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loadedPages.put(indexOfPage, pageItems);
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}
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loadingPages.remove(indexOfPage);
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updateItemsChanges(indexOfPage, pageItems, oldSize, oldIsLastPageLoaded);
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}
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}).replay(1)
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.refCount();
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}
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private void downgradeMaxLoadedPages(final int maximum) {
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for (int i = 0; i <= loadedPages.size(); i++) {
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final int key = loadedPages.keyAt(i);
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if (key > maximum || loadedPages.get(key).size() < pageSize) {
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loadedPages.remove(key);
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} else if (maxLoadedPage == null || maxLoadedPage < key) {
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maxLoadedPage = key;
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}
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}
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}
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private void updateItemsChanges(final int indexOfPage, @NonNull final List<T> pageItems, final int oldSize, final boolean oldIsLastPageLoaded) {
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final List<Change> changes = new ArrayList<>();
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final int size = getSize();
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if (size == oldSize) {
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if (!pageItems.isEmpty()) {
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changes.add(new Change(Change.Type.CHANGED, indexOfPage * pageSize, pageItems.size()));
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}
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} else if (size > oldSize) {
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if (!oldIsLastPageLoaded) {
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changes.add(new Change(Change.Type.CHANGED, oldSize - 1, 1));
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}
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changes.add(new Change(Change.Type.INSERTED, oldSize, size - oldSize));
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} else {
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changes.add(new Change(Change.Type.REMOVED, size, oldSize - size));
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if (!isLastPageLoaded) {
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changes.add(new Change(Change.Type.CHANGED, size - 1, 1));
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}
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}
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if (!changes.isEmpty()) {
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notifyChanges(changes);
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}
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}
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@NonNull
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private List<T> validatePageItems(@NonNull final Collection<T> pageItems) {
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if (pageItems.size() > pageSize) {
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Lc.assertion("Unexpectedly big pageItems: " + pageItems.size() + '/' + pageSize);
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return Collections.unmodifiableList(new ArrayList<>(pageItems).subList(0, pageSize));
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} else {
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return Collections.unmodifiableList(new ArrayList<>(pageItems));
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}
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protected Observable<List<T>> observeItems(final int indexOfPage) {
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return pagesProvider.loadPage(indexOfPage * getPageSize(), getPageSize()).map(ArrayList::new);
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}
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public interface PagesProvider<T> {
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