Home | History | Annotate | Download | only in util 
      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.android.quicksearchbox.util;
     18 
     19 import android.util.Log;
     20 
     21 import java.util.concurrent.LinkedBlockingQueue;
     22 import java.util.concurrent.ThreadFactory;
     23 
     24 /**
     25  * Executor that uses a single thread and an unbounded work queue.
     26  */
     27 public class SingleThreadNamedTaskExecutor implements NamedTaskExecutor {
     28 
     29     private static final boolean DBG = false;
     30     private static final String TAG = "QSB.SingleThreadNamedTaskExecutor";
     31 
     32     private final LinkedBlockingQueue<NamedTask> mQueue;
     33     private final Thread mWorker;
     34     private volatile boolean mClosed = false;
     35 
     36     public SingleThreadNamedTaskExecutor(ThreadFactory threadFactory) {
     37         mQueue = new LinkedBlockingQueue<NamedTask>();
     38         mWorker = threadFactory.newThread(new Worker());
     39         mWorker.start();
     40     }
     41 
     42     public void cancelPendingTasks() {
     43         if (DBG) Log.d(TAG, "Cancelling " + mQueue.size() + " tasks: " + mWorker.getName());
     44         if (mClosed) {
     45             throw new IllegalStateException("cancelPendingTasks() after close()");
     46         }
     47         mQueue.clear();
     48     }
     49 
     50     public void close() {
     51         mClosed = true;
     52         mWorker.interrupt();
     53         mQueue.clear();
     54     }
     55 
     56     public void execute(NamedTask task) {
     57         if (mClosed) {
     58             throw new IllegalStateException("execute() after close()");
     59         }
     60         mQueue.add(task);
     61     }
     62 
     63     private class Worker implements Runnable {
     64         public void run() {
     65             try {
     66                 loop();
     67             } finally {
     68                 if (!mClosed) Log.w(TAG, "Worker exited before close");
     69             }
     70         }
     71 
     72         private void loop() {
     73             Thread currentThread = Thread.currentThread();
     74             String threadName = currentThread.getName();
     75             while (!mClosed) {
     76                 NamedTask task;
     77                 try {
     78                     task = mQueue.take();
     79                 } catch (InterruptedException ex) {
     80                     continue;
     81                 }
     82                 currentThread.setName(threadName + " " + task.getName());
     83                 try {
     84                     if (DBG) Log.d(TAG, "Running task " + task.getName());
     85                     task.run();
     86                     if (DBG) Log.d(TAG, "Task " + task.getName() + " complete");
     87                 } catch (RuntimeException ex) {
     88                     Log.e(TAG, "Task " + task.getName() + " failed", ex);
     89                 }
     90             }
     91         }
     92     }
     93 
     94     public static Factory<NamedTaskExecutor> factory(final ThreadFactory threadFactory) {
     95         return new Factory<NamedTaskExecutor>() {
     96             public NamedTaskExecutor create() {
     97                 return new SingleThreadNamedTaskExecutor(threadFactory);
     98             }
     99         };
    100     }
    101 
    102 }
    103