| /* |
| * Copyright 2018 The Android Open Source Project |
| * |
| * 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 androidx.recyclerview.widget; |
| |
| import android.os.Handler; |
| import android.os.Looper; |
| |
| import androidx.annotation.NonNull; |
| import androidx.annotation.RestrictTo; |
| |
| import java.util.concurrent.Executor; |
| import java.util.concurrent.Executors; |
| |
| /** |
| * Configuration object for {@link ListAdapter}, {@link AsyncListDiffer}, and similar |
| * background-thread list diffing adapter logic. |
| * <p> |
| * At minimum, defines item diffing behavior with a {@link DiffUtil.ItemCallback}, used to compute |
| * item differences to pass to a RecyclerView adapter. |
| * |
| * @param <T> Type of items in the lists, and being compared. |
| */ |
| public final class AsyncDifferConfig<T> { |
| @NonNull |
| private final Executor mMainThreadExecutor; |
| @NonNull |
| private final Executor mBackgroundThreadExecutor; |
| @NonNull |
| private final DiffUtil.ItemCallback<T> mDiffCallback; |
| |
| private AsyncDifferConfig( |
| @NonNull Executor mainThreadExecutor, |
| @NonNull Executor backgroundThreadExecutor, |
| @NonNull DiffUtil.ItemCallback<T> diffCallback) { |
| mMainThreadExecutor = mainThreadExecutor; |
| mBackgroundThreadExecutor = backgroundThreadExecutor; |
| mDiffCallback = diffCallback; |
| } |
| |
| /** @hide */ |
| @SuppressWarnings("WeakerAccess") |
| @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) |
| @NonNull |
| public Executor getMainThreadExecutor() { |
| return mMainThreadExecutor; |
| } |
| |
| @SuppressWarnings("WeakerAccess") |
| @NonNull |
| public Executor getBackgroundThreadExecutor() { |
| return mBackgroundThreadExecutor; |
| } |
| |
| @SuppressWarnings("WeakerAccess") |
| @NonNull |
| public DiffUtil.ItemCallback<T> getDiffCallback() { |
| return mDiffCallback; |
| } |
| |
| /** |
| * Builder class for {@link AsyncDifferConfig}. |
| * |
| * @param <T> |
| */ |
| public static final class Builder<T> { |
| private Executor mMainThreadExecutor; |
| private Executor mBackgroundThreadExecutor; |
| private final DiffUtil.ItemCallback<T> mDiffCallback; |
| |
| public Builder(@NonNull DiffUtil.ItemCallback<T> diffCallback) { |
| mDiffCallback = diffCallback; |
| } |
| |
| /** |
| * If provided, defines the main thread executor used to dispatch adapter update |
| * notifications on the main thread. |
| * <p> |
| * If not provided, it will default to the main thread. |
| * |
| * @param executor The executor which can run tasks in the UI thread. |
| * @return this |
| * |
| * @hide |
| */ |
| @RestrictTo(RestrictTo.Scope.LIBRARY_GROUP) |
| @NonNull |
| public Builder<T> setMainThreadExecutor(Executor executor) { |
| mMainThreadExecutor = executor; |
| return this; |
| } |
| |
| /** |
| * If provided, defines the background executor used to calculate the diff between an old |
| * and a new list. |
| * <p> |
| * If not provided, defaults to two thread pool executor, shared by all ListAdapterConfigs. |
| * |
| * @param executor The background executor to run list diffing. |
| * @return this |
| */ |
| @SuppressWarnings({"unused", "WeakerAccess"}) |
| @NonNull |
| public Builder<T> setBackgroundThreadExecutor(Executor executor) { |
| mBackgroundThreadExecutor = executor; |
| return this; |
| } |
| |
| private static class MainThreadExecutor implements Executor { |
| final Handler mHandler = new Handler(Looper.getMainLooper()); |
| @Override |
| public void execute(@NonNull Runnable command) { |
| mHandler.post(command); |
| } |
| } |
| |
| /** |
| * Creates a {@link AsyncListDiffer} with the given parameters. |
| * |
| * @return A new AsyncDifferConfig. |
| */ |
| @NonNull |
| public AsyncDifferConfig<T> build() { |
| if (mMainThreadExecutor == null) { |
| mMainThreadExecutor = sMainThreadExecutor; |
| } |
| if (mBackgroundThreadExecutor == null) { |
| synchronized (sExecutorLock) { |
| if (sDiffExecutor == null) { |
| sDiffExecutor = Executors.newFixedThreadPool(2); |
| } |
| } |
| mBackgroundThreadExecutor = sDiffExecutor; |
| } |
| return new AsyncDifferConfig<>( |
| mMainThreadExecutor, |
| mBackgroundThreadExecutor, |
| mDiffCallback); |
| } |
| |
| // TODO: remove the below once supportlib has its own appropriate executors |
| private static final Object sExecutorLock = new Object(); |
| private static Executor sDiffExecutor = null; |
| |
| // TODO: use MainThreadExecutor from supportlib once one exists |
| private static final Executor sMainThreadExecutor = new MainThreadExecutor(); |
| } |
| } |