util/concurrent/AbstractExecutorService.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/licenses/publicdomain
 */

package java.util.concurrent;

import java.util.*;

/**
 * Provides default implementation of {@link ExecutorService}
 * execution methods. This class implements the <tt>submit</tt>,
 * <tt>invokeAny</tt> and <tt>invokeAll</tt> methods using the default
 * {@link FutureTask} class provided in this package.  For example,
 * the the implementation of <tt>submit(Runnable)</tt> creates an
 * associated <tt>FutureTask</tt> that is executed and
 * returned. Subclasses overriding these methods to use different
 * {@link Future} implementations should do so consistently for each
 * of these methods.
 *
 * @since 1.5
 * @author Doug Lea
 */
public abstract class AbstractExecutorService implements ExecutorService {

    public Future<?> submit(Runnable task) {
        if (task == null) throw new NullPointerException();
        FutureTask<Object> ftask = new FutureTask<Object>(task, null);
        execute(ftask);
        return ftask;
    }

    public <T> Future<T> submit(Runnable task, T result) {
        if (task == null) throw new NullPointerException();
        FutureTask<T> ftask = new FutureTask<T>(task, result);
        execute(ftask);
        return ftask;
    }

    public <T> Future<T> submit(Callable<T> task) {
        if (task == null) throw new NullPointerException();
        FutureTask<T> ftask = new FutureTask<T>(task);
        execute(ftask);
        return ftask;
    }

    /**
     * the main mechanics of invokeAny.
     */
    private <T> T doInvokeAny(Collection<Callable<T>> tasks,
                            boolean timed, long nanos)
        throws InterruptedException, ExecutionException, TimeoutException {
        if (tasks == null)
            throw new NullPointerException();
        int ntasks = tasks.size();
        if (ntasks == 0)
            throw new IllegalArgumentException();
        List<Future<T>> futures= new ArrayList<Future<T>>(ntasks);
        ExecutorCompletionService<T> ecs = 
            new ExecutorCompletionService<T>(this);

        // For efficiency, especially in executors with limited
        // parallelism, check to see if previously submitted tasks are
        // done before submitting more of them. This interleaving,
        // plus the exception mechanics account for messiness of main
        // loop

        try {
            // Record exceptions so that if we fail to obtain any
            // result, we can throw the last exception we got.
            ExecutionException ee = null;
            long lastTime = (timed)? System.nanoTime() : 0;
            Iterator<Callable<T>> it = tasks.iterator();

            // Start one task for sure; the rest incrementally
            futures.add(ecs.submit(it.next()));
            --ntasks;
            int active = 1;

            for (;;) {
                Future<T> f = ecs.poll(); 
                if (f == null) {
                    if (ntasks > 0) {
                        --ntasks;
                        futures.add(ecs.submit(it.next()));
                        ++active;
                    }
                    else if (active == 0) 
                        break;
                    else if (timed) {
                        f = ecs.poll(nanos, TimeUnit.NANOSECONDS);
                        if (f == null)
                            throw new TimeoutException();
                        long now = System.nanoTime();
                        nanos -= now - lastTime;
                        lastTime = now;
                    }
                    else 
                        f = ecs.take();
                }
                if (f != null) {
                    --active;
                    try {
                        return f.get();
                    } catch(InterruptedException ie) {
                        throw ie;
                    } catch(ExecutionException eex) {
                        ee = eex;
                    } catch(RuntimeException rex) {
                        ee = new ExecutionException(rex);
                    }
                }
            }    

            if (ee == null)
                ee = new ExecutionException();
            throw ee;

        } finally {
            for (Future<T> f : futures) 
                f.cancel(true);
        }
    }

    public <T> T invokeAny(Collection<Callable<T>> tasks)
        throws InterruptedException, ExecutionException {
        try {
            return doInvokeAny(tasks, false, 0);
        } catch (TimeoutException cannotHappen) {
            assert false;
            return null;
        }
    }

    public <T> T invokeAny(Collection<Callable<T>> tasks, 
                           long timeout, TimeUnit unit) 
        throws InterruptedException, ExecutionException, TimeoutException {
        return doInvokeAny(tasks, true, unit.toNanos(timeout));
    }

    public <T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks)
        throws InterruptedException {
        if (tasks == null)
            throw new NullPointerException();
        List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
        boolean done = false;
        try {
            for (Callable<T> t : tasks) {
                FutureTask<T> f = new FutureTask<T>(t);
                futures.add(f);
                execute(f);
            }
            for (Future<T> f : futures) {
                if (!f.isDone()) {
                    try { 
                        f.get(); 
                    } catch(CancellationException ignore) {
                    } catch(ExecutionException ignore) {
                    }
                }
            }
            done = true;
            return futures;
        } finally {
            if (!done)
                for (Future<T> f : futures) 
                    f.cancel(true);
        }
    }

    public <T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks, 
                                         long timeout, TimeUnit unit) 
        throws InterruptedException {
        if (tasks == null || unit == null)
            throw new NullPointerException();
        long nanos = unit.toNanos(timeout);
        List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
        boolean done = false;
        try {
            for (Callable<T> t : tasks) 
                futures.add(new FutureTask<T>(t));

            long lastTime = System.nanoTime();

            // Interleave time checks and calls to execute in case
            // executor doesn't have any/much parallelism.
            Iterator<Future<T>> it = futures.iterator();
            while (it.hasNext()) {
                execute((Runnable)(it.next()));
                long now = System.nanoTime();
                nanos -= now - lastTime;
                lastTime = now;
                if (nanos <= 0)
                    return futures; 
            }

            for (Future<T> f : futures) {
                if (!f.isDone()) {
                    if (nanos <= 0) 
                        return futures; 
                    try { 
                        f.get(nanos, TimeUnit.NANOSECONDS); 
                    } catch(CancellationException ignore) {
                    } catch(ExecutionException ignore) {
                    } catch(TimeoutException toe) {
                        return futures;
                    }
                    long now = System.nanoTime();
                    nanos -= now - lastTime;
                    lastTime = now;
                }
            }
            done = true;
            return futures;
        } finally {
            if (!done)
                for (Future<T> f : futures) 
                    f.cancel(true);
        }
    }

}
Revision:	1.17
Committed:	Sat Dec 27 19:26:25 2003 UTC (20 years, 5 months ago) by dl
Branch:	MAIN
Changes since 1.16:	+2 -2 lines
Log Message:	Headers reference Creative Commons
#	User	Rev	Content
1	tim	1.1	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3	dl	1.17	* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/licenses/publicdomain
5	tim	1.1	*/
6
7			package java.util.concurrent;
8
9	dl	1.3	import java.util.*;
10	tim	1.1
11			/**
12	dl	1.2	* Provides default implementation of {@link ExecutorService}
13	dl	1.12	* execution methods. This class implements the <tt>submit</tt>,
14			* <tt>invokeAny</tt> and <tt>invokeAll</tt> methods using the default
15			* {@link FutureTask} class provided in this package. For example,
16			* the the implementation of <tt>submit(Runnable)</tt> creates an
17			* associated <tt>FutureTask</tt> that is executed and
18	dl	1.2	* returned. Subclasses overriding these methods to use different
19			* {@link Future} implementations should do so consistently for each
20			* of these methods.
21	tim	1.1	*
22			* @since 1.5
23			* @author Doug Lea
24			*/
25			public abstract class AbstractExecutorService implements ExecutorService {
26
27	dl	1.11	public Future<?> submit(Runnable task) {
28	dl	1.13	if (task == null) throw new NullPointerException();
29	dl	1.11	FutureTask<Object> ftask = new FutureTask<Object>(task, null);
30	tim	1.1	execute(ftask);
31			return ftask;
32			}
33
34	dl	1.13	public <T> Future<T> submit(Runnable task, T result) {
35			if (task == null) throw new NullPointerException();
36			FutureTask<T> ftask = new FutureTask<T>(task, result);
37			execute(ftask);
38			return ftask;
39			}
40
41	tim	1.1	public <T> Future<T> submit(Callable<T> task) {
42	dl	1.13	if (task == null) throw new NullPointerException();
43	tim	1.1	FutureTask<T> ftask = new FutureTask<T>(task);
44			execute(ftask);
45			return ftask;
46			}
47
48	dl	1.15	/**
49			* the main mechanics of invokeAny.
50			*/
51			private <T> T doInvokeAny(Collection<Callable<T>> tasks,
52			boolean timed, long nanos)
53			throws InterruptedException, ExecutionException, TimeoutException {
54	dl	1.3	if (tasks == null)
55			throw new NullPointerException();
56	dl	1.15	int ntasks = tasks.size();
57			if (ntasks == 0)
58	dl	1.7	throw new IllegalArgumentException();
59	dl	1.15	List<Future<T>> futures= new ArrayList<Future<T>>(ntasks);
60	dl	1.7	ExecutorCompletionService<T> ecs =
61			new ExecutorCompletionService<T>(this);
62	dl	1.15
63			// For efficiency, especially in executors with limited
64			// parallelism, check to see if previously submitted tasks are
65			// done before submitting more of them. This interleaving,
66			// plus the exception mechanics account for messiness of main
67			// loop
68
69	dl	1.3	try {
70	dl	1.15	// Record exceptions so that if we fail to obtain any
71			// result, we can throw the last exception we got.
72	dl	1.7	ExecutionException ee = null;
73	dl	1.15	long lastTime = (timed)? System.nanoTime() : 0;
74			Iterator<Callable<T>> it = tasks.iterator();
75
76			// Start one task for sure; the rest incrementally
77			futures.add(ecs.submit(it.next()));
78			--ntasks;
79			int active = 1;
80
81			for (;;) {
82			Future<T> f = ecs.poll();
83			if (f == null) {
84			if (ntasks > 0) {
85			--ntasks;
86			futures.add(ecs.submit(it.next()));
87			++active;
88			}
89			else if (active == 0)
90			break;
91			else if (timed) {
92			f = ecs.poll(nanos, TimeUnit.NANOSECONDS);
93			if (f == null)
94			throw new TimeoutException();
95			long now = System.nanoTime();
96			nanos -= now - lastTime;
97			lastTime = now;
98			}
99			else
100			f = ecs.take();
101			}
102			if (f != null) {
103			--active;
104			try {
105			return f.get();
106			} catch(InterruptedException ie) {
107			throw ie;
108			} catch(ExecutionException eex) {
109			ee = eex;
110			} catch(RuntimeException rex) {
111			ee = new ExecutionException(rex);
112			}
113	dl	1.7	}
114			}
115	dl	1.15
116			if (ee == null)
117			ee = new ExecutionException();
118			throw ee;
119
120	dl	1.3	} finally {
121	dl	1.6	for (Future<T> f : futures)
122	dl	1.4	f.cancel(true);
123	dl	1.3	}
124			}
125
126	dl	1.15	public <T> T invokeAny(Collection<Callable<T>> tasks)
127			throws InterruptedException, ExecutionException {
128			try {
129			return doInvokeAny(tasks, false, 0);
130			} catch (TimeoutException cannotHappen) {
131			assert false;
132			return null;
133			}
134			}
135
136	dl	1.7	public <T> T invokeAny(Collection<Callable<T>> tasks,
137			long timeout, TimeUnit unit)
138			throws InterruptedException, ExecutionException, TimeoutException {
139	dl	1.15	return doInvokeAny(tasks, true, unit.toNanos(timeout));
140	dl	1.3	}
141
142	dl	1.9	public <T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks)
143	dl	1.3	throws InterruptedException {
144			if (tasks == null)
145			throw new NullPointerException();
146	dl	1.6	List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
147			boolean done = false;
148	dl	1.3	try {
149			for (Callable<T> t : tasks) {
150	dl	1.6	FutureTask<T> f = new FutureTask<T>(t);
151	dl	1.3	futures.add(f);
152			execute(f);
153			}
154	dl	1.6	for (Future<T> f : futures) {
155			if (!f.isDone()) {
156			try {
157			f.get();
158			} catch(CancellationException ignore) {
159			} catch(ExecutionException ignore) {
160			}
161			}
162			}
163			done = true;
164	dl	1.3	return futures;
165			} finally {
166	dl	1.6	if (!done)
167	dl	1.4	for (Future<T> f : futures)
168			f.cancel(true);
169	dl	1.3	}
170			}
171
172	dl	1.9	public <T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks,
173	dl	1.6	long timeout, TimeUnit unit)
174	dl	1.3	throws InterruptedException {
175			if (tasks == null \|\| unit == null)
176			throw new NullPointerException();
177			long nanos = unit.toNanos(timeout);
178	dl	1.6	List<Future<T>> futures = new ArrayList<Future<T>>(tasks.size());
179			boolean done = false;
180	dl	1.3	try {
181	dl	1.16	for (Callable<T> t : tasks)
182			futures.add(new FutureTask<T>(t));
183
184			long lastTime = System.nanoTime();
185
186			// Interleave time checks and calls to execute in case
187			// executor doesn't have any/much parallelism.
188			Iterator<Future<T>> it = futures.iterator();
189			while (it.hasNext()) {
190			execute((Runnable)(it.next()));
191			long now = System.nanoTime();
192			nanos -= now - lastTime;
193			lastTime = now;
194			if (nanos <= 0)
195			return futures;
196	dl	1.3	}
197	dl	1.16
198	dl	1.6	for (Future<T> f : futures) {
199			if (!f.isDone()) {
200	dl	1.16	if (nanos <= 0)
201	dl	1.6	return futures;
202			try {
203			f.get(nanos, TimeUnit.NANOSECONDS);
204			} catch(CancellationException ignore) {
205			} catch(ExecutionException ignore) {
206			} catch(TimeoutException toe) {
207			return futures;
208			}
209	dl	1.8	long now = System.nanoTime();
210			nanos -= now - lastTime;
211			lastTime = now;
212	dl	1.6	}
213			}
214			done = true;
215	dl	1.3	return futures;
216			} finally {
217	dl	1.6	if (!done)
218	dl	1.4	for (Future<T> f : futures)
219			f.cancel(true);
220	dl	1.3	}
221			}
222
223	tim	1.1	}