| /* |
| * Copyright (C) 2013 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 com.android.inputmethod.latin.utils; |
| |
| import java.util.Queue; |
| import java.util.concurrent.ArrayBlockingQueue; |
| import java.util.concurrent.ConcurrentLinkedQueue; |
| import java.util.concurrent.ThreadPoolExecutor; |
| import java.util.concurrent.TimeUnit; |
| |
| /** |
| * An object that executes submitted tasks using a thread. |
| */ |
| public class PrioritizedSerialExecutor { |
| public static final String TAG = PrioritizedSerialExecutor.class.getSimpleName(); |
| |
| private final Object mLock = new Object(); |
| |
| private final Queue<Runnable> mTasks; |
| private final Queue<Runnable> mPrioritizedTasks; |
| private boolean mIsShutdown; |
| private final ThreadPoolExecutor mThreadPoolExecutor; |
| |
| // The task which is running now. |
| private Runnable mActive; |
| |
| public PrioritizedSerialExecutor() { |
| mTasks = new ConcurrentLinkedQueue<Runnable>(); |
| mPrioritizedTasks = new ConcurrentLinkedQueue<Runnable>(); |
| mIsShutdown = false; |
| mThreadPoolExecutor = new ThreadPoolExecutor(1 /* corePoolSize */, 1 /* maximumPoolSize */, |
| 0 /* keepAliveTime */, TimeUnit.MILLISECONDS, new ArrayBlockingQueue<Runnable>(1)); |
| } |
| |
| /** |
| * Clears all queued tasks. |
| */ |
| public void clearAllTasks() { |
| synchronized(mLock) { |
| mTasks.clear(); |
| mPrioritizedTasks.clear(); |
| } |
| } |
| |
| /** |
| * Enqueues the given task into the task queue. |
| * @param r the enqueued task |
| */ |
| public void execute(final Runnable r) { |
| synchronized(mLock) { |
| if (!mIsShutdown) { |
| mTasks.offer(new Runnable() { |
| @Override |
| public void run() { |
| try { |
| r.run(); |
| } finally { |
| scheduleNext(); |
| } |
| } |
| }); |
| if (mActive == null) { |
| scheduleNext(); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Enqueues the given task into the prioritized task queue. |
| * @param r the enqueued task |
| */ |
| public void executePrioritized(final Runnable r) { |
| synchronized(mLock) { |
| if (!mIsShutdown) { |
| mPrioritizedTasks.offer(new Runnable() { |
| @Override |
| public void run() { |
| try { |
| r.run(); |
| } finally { |
| scheduleNext(); |
| } |
| } |
| }); |
| if (mActive == null) { |
| scheduleNext(); |
| } |
| } |
| } |
| } |
| |
| private boolean fetchNextTasksLocked() { |
| mActive = mPrioritizedTasks.poll(); |
| if (mActive == null) { |
| mActive = mTasks.poll(); |
| } |
| return mActive != null; |
| } |
| |
| private void scheduleNext() { |
| synchronized(mLock) { |
| if (fetchNextTasksLocked()) { |
| mThreadPoolExecutor.execute(mActive); |
| } |
| } |
| } |
| |
| public void remove(final Runnable r) { |
| synchronized(mLock) { |
| mTasks.remove(r); |
| mPrioritizedTasks.remove(r); |
| } |
| } |
| |
| public void replaceAndExecute(final Runnable oldTask, final Runnable newTask) { |
| synchronized(mLock) { |
| if (oldTask != null) remove(oldTask); |
| execute(newTask); |
| } |
| } |
| |
| public void shutdown() { |
| synchronized(mLock) { |
| mIsShutdown = true; |
| } |
| } |
| |
| public boolean isTerminated() { |
| synchronized(mLock) { |
| if (!mIsShutdown) { |
| return false; |
| } |
| return mPrioritizedTasks.isEmpty() && mTasks.isEmpty() && mActive == null; |
| } |
| } |
| } |