2 * Copyright (C) 2009 The Android Open Source Project
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
8 * http://www.apache.org/licenses/LICENSE-2.0
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.
16 package android.accounts;
18 import java.util.concurrent.Future;
19 import java.util.concurrent.TimeUnit;
20 import java.util.concurrent.ExecutionException;
21 import java.util.concurrent.TimeoutException;
22 import java.io.IOException;
25 * A <tt>AccountManagerFuture</tt> represents the result of an asynchronous
26 * {@link AccountManager} call. Methods are provided to check if the computation is
27 * complete, to wait for its completion, and to retrieve the result of
28 * the computation. The result can only be retrieved using method
29 * <tt>get</tt> when the computation has completed, blocking if
30 * necessary until it is ready. Cancellation is performed by the
31 * <tt>cancel</tt> method. Additional methods are provided to
32 * determine if the task completed normally or was cancelled. Once a
33 * computation has completed, the computation cannot be cancelled.
34 * If you would like to use a <tt>Future</tt> for the sake
35 * of cancellability but not provide a usable result, you can
36 * declare types of the form <tt>Future<?></tt> and
37 * return <tt>null</tt> as a result of the underlying task.
39 public interface AccountManagerFuture<V> {
41 * Attempts to cancel execution of this task. This attempt will
42 * fail if the task has already completed, has already been cancelled,
43 * or could not be cancelled for some other reason. If successful,
44 * and this task has not started when <tt>cancel</tt> is called,
45 * this task should never run. If the task has already started,
46 * then the <tt>mayInterruptIfRunning</tt> parameter determines
47 * whether the thread executing this task should be interrupted in
48 * an attempt to stop the task.
50 * <p>After this method returns, subsequent calls to {@link #isDone} will
51 * always return <tt>true</tt>. Subsequent calls to {@link #isCancelled}
52 * will always return <tt>true</tt> if this method returned <tt>true</tt>.
54 * @param mayInterruptIfRunning <tt>true</tt> if the thread executing this
55 * task should be interrupted; otherwise, in-progress tasks are allowed
57 * @return <tt>false</tt> if the task could not be cancelled,
58 * typically because it has already completed normally;
59 * <tt>true</tt> otherwise
61 boolean cancel(boolean mayInterruptIfRunning);
64 * Returns <tt>true</tt> if this task was cancelled before it completed
67 * @return <tt>true</tt> if this task was cancelled before it completed
69 boolean isCancelled();
72 * Returns <tt>true</tt> if this task completed.
74 * Completion may be due to normal termination, an exception, or
75 * cancellation -- in all of these cases, this method will return
78 * @return <tt>true</tt> if this task completed
83 * Accessor for the future result the {@link AccountManagerFuture} represents. This
84 * call will block until the result is available. In order to check if the result is
85 * available without blocking, one may call {@link #isDone()} and {@link #isCancelled()}.
86 * If the request that generated this result fails or is canceled then an exception
87 * will be thrown rather than the call returning normally.
88 * @return the actual result
89 * @throws android.accounts.OperationCanceledException if the request was canceled for any
91 * @throws android.accounts.AuthenticatorException if there was an error communicating with
92 * the authenticator or if the authenticator returned an invalid response
93 * @throws java.io.IOException if the authenticator returned an error response that indicates
94 * that it encountered an IOException while communicating with the authentication server
96 V getResult() throws OperationCanceledException, IOException, AuthenticatorException;
99 * Accessor for the future result the {@link AccountManagerFuture} represents. This
100 * call will block until the result is available. In order to check if the result is
101 * available without blocking, one may call {@link #isDone()} and {@link #isCancelled()}.
102 * If the request that generated this result fails or is canceled then an exception
103 * will be thrown rather than the call returning normally. If a timeout is specified then
104 * the request will automatically be canceled if it does not complete in that amount of time.
105 * @param timeout the maximum time to wait
106 * @param unit the time unit of the timeout argument. This must not be null.
107 * @return the actual result
108 * @throws android.accounts.OperationCanceledException if the request was canceled for any
110 * @throws android.accounts.AuthenticatorException if there was an error communicating with
111 * the authenticator or if the authenticator returned an invalid response
112 * @throws java.io.IOException if the authenticator returned an error response that indicates
113 * that it encountered an IOException while communicating with the authentication server
115 V getResult(long timeout, TimeUnit unit)
116 throws OperationCanceledException, IOException, AuthenticatorException;