SingleThreadNamedTaskExecutor.java revision b5fc08b7f16a32d3865f44b7f26d8aaa5304a2ad 
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
17package com.android.quicksearchbox.util;
18
19import android.util.Log;
20
21import java.util.concurrent.LinkedBlockingQueue;
22import java.util.concurrent.ThreadFactory;
23
24/**
25 * Executor that uses a single thread and an unbounded work queue.
26 */
27public 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                    task.run();
85                } catch (RuntimeException ex) {
86                    Log.e(TAG, "Task " + task.getName() + " failed", ex);
87                }
88            }
89        }
90    }
91
92    public static Factory<NamedTaskExecutor> factory(final ThreadFactory threadFactory) {
93        return new Factory<NamedTaskExecutor>() {
94            public NamedTaskExecutor create() {
95                return new SingleThreadNamedTaskExecutor(threadFactory);
96            }
97        };
98    }
99
100}
101