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 
SingleThreadNamedTaskExecutor(ThreadFactory threadFactory)36     public SingleThreadNamedTaskExecutor(ThreadFactory threadFactory) {
37         mQueue = new LinkedBlockingQueue<NamedTask>();
38         mWorker = threadFactory.newThread(new Worker());
39         mWorker.start();
40     }
41 
cancelPendingTasks()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 
close()50     public void close() {
51         mClosed = true;
52         mWorker.interrupt();
53         mQueue.clear();
54     }
55 
execute(NamedTask task)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 {
run()64         public void run() {
65             try {
66                 loop();
67             } finally {
68                 if (!mClosed) Log.w(TAG, "Worker exited before close");
69             }
70         }
71 
loop()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 
factory(final ThreadFactory threadFactory)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