1 |
dl |
1.1 |
/* |
2 |
|
|
* Written by Doug Lea with assistance from members of JCP JSR-166 |
3 |
dl |
1.22 |
* Expert Group and released to the public domain, as explained at |
4 |
|
|
* http://creativecommons.org/licenses/publicdomain |
5 |
dl |
1.1 |
*/ |
6 |
|
|
|
7 |
|
|
package java.util.concurrent; |
8 |
|
|
|
9 |
|
|
import java.util.List; |
10 |
dl |
1.15 |
import java.util.Collection; |
11 |
tim |
1.8 |
import java.security.PrivilegedAction; |
12 |
|
|
import java.security.PrivilegedExceptionAction; |
13 |
dl |
1.1 |
|
14 |
|
|
/** |
15 |
dl |
1.25 |
* An {@link Executor} that provides methods to manage termination and |
16 |
dl |
1.20 |
* methods that can produce a {@link Future} for tracking progress of |
17 |
dl |
1.25 |
* one or more asynchronous tasks. |
18 |
dl |
1.17 |
* |
19 |
dl |
1.25 |
* <p> |
20 |
dl |
1.7 |
* An <tt>ExecutorService</tt> can be shut down, which will cause it |
21 |
|
|
* to stop accepting new tasks. After being shut down, the executor |
22 |
|
|
* will eventually terminate, at which point no tasks are actively |
23 |
dl |
1.1 |
* executing, no tasks are awaiting execution, and no new tasks can be |
24 |
|
|
* submitted. |
25 |
|
|
* |
26 |
dl |
1.20 |
* <p> Method <tt>submit</tt> extends base method {@link |
27 |
|
|
* Executor#execute} by creating and returning a {@link Future} that |
28 |
|
|
* can be used to cancel execution and/or wait for completion. |
29 |
|
|
* Methods <tt>invokeAny</tt> and <tt>invokeAll</tt> perform the most |
30 |
|
|
* commonly useful forms of bulk execution, executing a collection of |
31 |
|
|
* tasks and then waiting for at least one, or all, to |
32 |
|
|
* complete. (Class {@link ExecutorCompletionService} can be used to |
33 |
|
|
* write customized variants of these methods.) |
34 |
dl |
1.17 |
* |
35 |
dl |
1.7 |
* <p>The {@link Executors} class provides factory methods for the |
36 |
|
|
* executor services provided in this package. |
37 |
dl |
1.1 |
* |
38 |
dl |
1.23 |
* <h3>Usage Example</h3> |
39 |
|
|
* |
40 |
|
|
* Here is a sketch of a network service in which threads in a thread |
41 |
|
|
* pool service incoming requests. It uses the preconfigured {@link |
42 |
|
|
* Executors#newFixedThreadPool} factory method: |
43 |
|
|
* |
44 |
|
|
* <pre> |
45 |
|
|
* class NetworkService { |
46 |
|
|
* private final ServerSocket serverSocket; |
47 |
|
|
* private final ExecutorService pool; |
48 |
|
|
* |
49 |
|
|
* public NetworkService(int port, int poolSize) throws IOException { |
50 |
|
|
* serverSocket = new ServerSocket(port); |
51 |
|
|
* pool = Executors.newFixedThreadPool(poolSize); |
52 |
|
|
* } |
53 |
|
|
* |
54 |
|
|
* public void serve() { |
55 |
|
|
* try { |
56 |
|
|
* for (;;) { |
57 |
|
|
* pool.execute(new Handler(serverSocket.accept())); |
58 |
|
|
* } |
59 |
|
|
* } catch (IOException ex) { |
60 |
|
|
* pool.shutdown(); |
61 |
|
|
* } |
62 |
|
|
* } |
63 |
|
|
* } |
64 |
|
|
* |
65 |
|
|
* class Handler implements Runnable { |
66 |
|
|
* private final Socket socket; |
67 |
|
|
* Handler(Socket socket) { this.socket = socket; } |
68 |
|
|
* public void run() { |
69 |
|
|
* // read and service request |
70 |
|
|
* } |
71 |
|
|
* } |
72 |
|
|
* </pre> |
73 |
dl |
1.1 |
* @since 1.5 |
74 |
dl |
1.5 |
* @author Doug Lea |
75 |
dl |
1.1 |
*/ |
76 |
|
|
public interface ExecutorService extends Executor { |
77 |
tim |
1.8 |
|
78 |
dl |
1.17 |
/** |
79 |
|
|
* Initiates an orderly shutdown in which previously submitted |
80 |
|
|
* tasks are executed, but no new tasks will be |
81 |
|
|
* accepted. Invocation has no additional effect if already shut |
82 |
|
|
* down. |
83 |
|
|
* @throws SecurityException if a security manager exists and |
84 |
|
|
* shutting down this ExecutorService may manipulate threads that |
85 |
|
|
* the caller is not permitted to modify because it does not hold |
86 |
|
|
* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>, |
87 |
|
|
* or the security manager's <tt>checkAccess</tt> method denies access. |
88 |
|
|
*/ |
89 |
|
|
void shutdown(); |
90 |
|
|
|
91 |
|
|
/** |
92 |
|
|
* Attempts to stop all actively executing tasks, halts the |
93 |
|
|
* processing of waiting tasks, and returns a list of the tasks that were |
94 |
|
|
* awaiting execution. |
95 |
|
|
* |
96 |
|
|
* <p>There are no guarantees beyond best-effort attempts to stop |
97 |
|
|
* processing actively executing tasks. For example, typical |
98 |
|
|
* implementations will cancel via {@link Thread#interrupt}, so if any |
99 |
|
|
* tasks mask or fail to respond to interrupts, they may never terminate. |
100 |
|
|
* |
101 |
|
|
* @return list of tasks that never commenced execution |
102 |
|
|
* @throws SecurityException if a security manager exists and |
103 |
|
|
* shutting down this ExecutorService may manipulate threads that |
104 |
|
|
* the caller is not permitted to modify because it does not hold |
105 |
|
|
* {@link java.lang.RuntimePermission}<tt>("modifyThread")</tt>, |
106 |
|
|
* or the security manager's <tt>checkAccess</tt> method denies access. |
107 |
|
|
*/ |
108 |
|
|
List<Runnable> shutdownNow(); |
109 |
|
|
|
110 |
|
|
/** |
111 |
|
|
* Returns <tt>true</tt> if this executor has been shut down. |
112 |
|
|
* |
113 |
|
|
* @return <tt>true</tt> if this executor has been shut down |
114 |
|
|
*/ |
115 |
|
|
boolean isShutdown(); |
116 |
|
|
|
117 |
|
|
/** |
118 |
|
|
* Returns <tt>true</tt> if all tasks have completed following shut down. |
119 |
|
|
* Note that <tt>isTerminated</tt> is never <tt>true</tt> unless |
120 |
|
|
* either <tt>shutdown</tt> or <tt>shutdownNow</tt> was called first. |
121 |
|
|
* |
122 |
|
|
* @return <tt>true</tt> if all tasks have completed following shut down |
123 |
|
|
*/ |
124 |
|
|
boolean isTerminated(); |
125 |
|
|
|
126 |
|
|
/** |
127 |
|
|
* Blocks until all tasks have completed execution after a shutdown |
128 |
|
|
* request, or the timeout occurs, or the current thread is |
129 |
|
|
* interrupted, whichever happens first. |
130 |
|
|
* |
131 |
|
|
* @param timeout the maximum time to wait |
132 |
|
|
* @param unit the time unit of the timeout argument |
133 |
|
|
* @return <tt>true</tt> if this executor terminated and <tt>false</tt> |
134 |
|
|
* if the timeout elapsed before termination |
135 |
|
|
* @throws InterruptedException if interrupted while waiting |
136 |
|
|
*/ |
137 |
|
|
boolean awaitTermination(long timeout, TimeUnit unit) |
138 |
|
|
throws InterruptedException; |
139 |
|
|
|
140 |
|
|
|
141 |
tim |
1.8 |
/** |
142 |
|
|
* Submits a value-returning task for execution and returns a Future |
143 |
dl |
1.19 |
* representing the pending results of the task. |
144 |
tim |
1.8 |
* |
145 |
dl |
1.19 |
* <p> |
146 |
dl |
1.20 |
* If you would like to immediately block waiting |
147 |
dl |
1.19 |
* for a task, you can use constructions of the form |
148 |
|
|
* <tt>result = exec.submit(aCallable).get();</tt> |
149 |
dl |
1.20 |
* |
150 |
|
|
* <p> Note: The {@link Executors} class includes a set of methods |
151 |
|
|
* that can convert some other common closure-like objects, |
152 |
|
|
* for example, {@link java.security.PrivilegedAction} to |
153 |
|
|
* {@link Callable} form so they can be submitted. |
154 |
|
|
* |
155 |
tim |
1.8 |
* @param task the task to submit |
156 |
|
|
* @return a Future representing pending completion of the task |
157 |
|
|
* @throws RejectedExecutionException if task cannot be scheduled |
158 |
|
|
* for execution |
159 |
dl |
1.20 |
* @throws NullPointerException if task null |
160 |
tim |
1.8 |
*/ |
161 |
|
|
<T> Future<T> submit(Callable<T> task); |
162 |
|
|
|
163 |
|
|
/** |
164 |
dl |
1.18 |
* Submits a Runnable task for execution and returns a Future |
165 |
dl |
1.20 |
* representing that task that will upon completion return |
166 |
|
|
* the given result |
167 |
|
|
* |
168 |
|
|
* @param task the task to submit |
169 |
|
|
* @param result the result to return |
170 |
|
|
* @return a Future representing pending completion of the task, |
171 |
|
|
* and whose <tt>get()</tt> method will return the given result |
172 |
|
|
* upon completion. |
173 |
|
|
* @throws RejectedExecutionException if task cannot be scheduled |
174 |
|
|
* for execution |
175 |
|
|
* @throws NullPointerException if task null |
176 |
|
|
*/ |
177 |
|
|
<T> Future<T> submit(Runnable task, T result); |
178 |
|
|
|
179 |
|
|
/** |
180 |
|
|
* Submits a Runnable task for execution and returns a Future |
181 |
dl |
1.18 |
* representing that task. |
182 |
dl |
1.1 |
* |
183 |
dl |
1.17 |
* @param task the task to submit |
184 |
dl |
1.18 |
* @return a Future representing pending completion of the task, |
185 |
|
|
* and whose <tt>get()</tt> method will return <tt>null</tt> |
186 |
|
|
* upon completion. |
187 |
dl |
1.17 |
* @throws RejectedExecutionException if task cannot be scheduled |
188 |
|
|
* for execution |
189 |
dl |
1.20 |
* @throws NullPointerException if task null |
190 |
dl |
1.1 |
*/ |
191 |
dl |
1.18 |
Future<?> submit(Runnable task); |
192 |
dl |
1.15 |
|
193 |
dl |
1.11 |
/** |
194 |
dl |
1.17 |
* Executes the given tasks, returning their results |
195 |
dl |
1.15 |
* when all complete. |
196 |
dl |
1.12 |
* Note that a <em>completed</em> task could have |
197 |
|
|
* terminated either normally or by throwing an exception. |
198 |
dl |
1.21 |
* The results of this method are undefined if the given |
199 |
|
|
* collection is modified while this operation is in progress. |
200 |
dl |
1.11 |
* @param tasks the collection of tasks |
201 |
dl |
1.13 |
* @return A list of Futures representing the tasks, in the same |
202 |
dl |
1.21 |
* sequential order as produced by the iterator for the given task |
203 |
|
|
* list, each of which has completed. |
204 |
dl |
1.11 |
* @throws InterruptedException if interrupted while waiting, in |
205 |
|
|
* which case unfinished tasks are cancelled. |
206 |
dl |
1.13 |
* @throws NullPointerException if tasks or any of its elements are <tt>null</tt> |
207 |
|
|
* @throws RejectedExecutionException if any task cannot be scheduled |
208 |
|
|
* for execution |
209 |
dl |
1.11 |
*/ |
210 |
dl |
1.15 |
|
211 |
dl |
1.16 |
<T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks) |
212 |
dl |
1.11 |
throws InterruptedException; |
213 |
|
|
|
214 |
|
|
/** |
215 |
dl |
1.17 |
* Executes the given tasks, returning their results |
216 |
dl |
1.15 |
* when all complete or the timeout expires, whichever happens first. |
217 |
dl |
1.11 |
* Upon return, tasks that have not completed are cancelled. |
218 |
dl |
1.12 |
* Note that a <em>completed</em> task could have |
219 |
|
|
* terminated either normally or by throwing an exception. |
220 |
dl |
1.21 |
* The results of this method are undefined if the given |
221 |
|
|
* collection is modified while this operation is in progress. |
222 |
dl |
1.11 |
* @param tasks the collection of tasks |
223 |
|
|
* @param timeout the maximum time to wait |
224 |
dl |
1.15 |
* @param unit the time unit of the timeout argument |
225 |
dl |
1.13 |
* @return A list of Futures representing the tasks, in the same |
226 |
dl |
1.26 |
* sequential order as produced by the iterator for the given |
227 |
dl |
1.21 |
* task list. If the operation did not time out, each task will |
228 |
|
|
* have completed. If it did time out, some of thiese tasks will |
229 |
|
|
* not have completed. |
230 |
dl |
1.11 |
* @throws InterruptedException if interrupted while waiting, in |
231 |
|
|
* which case unfinished tasks are cancelled. |
232 |
dl |
1.17 |
* @throws NullPointerException if tasks, any of its elements, or |
233 |
dl |
1.15 |
* unit are <tt>null</tt> |
234 |
dl |
1.13 |
* @throws RejectedExecutionException if any task cannot be scheduled |
235 |
|
|
* for execution |
236 |
dl |
1.11 |
*/ |
237 |
dl |
1.16 |
<T> List<Future<T>> invokeAll(Collection<Callable<T>> tasks, |
238 |
dl |
1.18 |
long timeout, TimeUnit unit) |
239 |
dl |
1.11 |
throws InterruptedException; |
240 |
|
|
|
241 |
|
|
/** |
242 |
dl |
1.17 |
* Executes the given tasks, returning the result |
243 |
dl |
1.15 |
* of one that has completed successfully (i.e., without throwing |
244 |
|
|
* an exception), if any do. Upon normal or exceptional return, |
245 |
|
|
* tasks that have not completed are cancelled. |
246 |
dl |
1.21 |
* The results of this method are undefined if the given |
247 |
|
|
* collection is modified while this operation is in progress. |
248 |
dl |
1.11 |
* @param tasks the collection of tasks |
249 |
dl |
1.15 |
* @return The result returned by one of the tasks. |
250 |
|
|
* @throws InterruptedException if interrupted while waiting |
251 |
|
|
* @throws NullPointerException if tasks or any of its elements |
252 |
|
|
* are <tt>null</tt> |
253 |
|
|
* @throws IllegalArgumentException if tasks empty |
254 |
|
|
* @throws ExecutionException if no task successfully completes |
255 |
|
|
* @throws RejectedExecutionException if tasks cannot be scheduled |
256 |
dl |
1.13 |
* for execution |
257 |
dl |
1.11 |
*/ |
258 |
dl |
1.15 |
<T> T invokeAny(Collection<Callable<T>> tasks) |
259 |
|
|
throws InterruptedException, ExecutionException; |
260 |
dl |
1.11 |
|
261 |
|
|
/** |
262 |
dl |
1.17 |
* Executes the given tasks, returning the result |
263 |
dl |
1.15 |
* of one that has completed successfully (i.e., without throwing |
264 |
|
|
* an exception), if any do before the given timeout elapses. |
265 |
|
|
* Upon normal or exceptional return, tasks that have not |
266 |
|
|
* completed are cancelled. |
267 |
dl |
1.21 |
* The results of this method are undefined if the given |
268 |
|
|
* collection is modified while this operation is in progress. |
269 |
dl |
1.11 |
* @param tasks the collection of tasks |
270 |
|
|
* @param timeout the maximum time to wait |
271 |
|
|
* @param unit the time unit of the timeout argument |
272 |
dl |
1.15 |
* @return The result returned by one of the tasks. |
273 |
|
|
* @throws InterruptedException if interrupted while waiting |
274 |
dl |
1.17 |
* @throws NullPointerException if tasks, any of its elements, or |
275 |
dl |
1.15 |
* unit are <tt>null</tt> |
276 |
|
|
* @throws TimeoutException if the given timeout elapses before |
277 |
|
|
* any task successfully completes |
278 |
|
|
* @throws ExecutionException if no task successfully completes |
279 |
|
|
* @throws RejectedExecutionException if tasks cannot be scheduled |
280 |
dl |
1.13 |
* for execution |
281 |
dl |
1.11 |
*/ |
282 |
dl |
1.15 |
<T> T invokeAny(Collection<Callable<T>> tasks, |
283 |
|
|
long timeout, TimeUnit unit) |
284 |
|
|
throws InterruptedException, ExecutionException, TimeoutException; |
285 |
dl |
1.3 |
|
286 |
dl |
1.1 |
} |