content: /*
   * Copyright (C) 2009 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package android.accounts;
  
  import java.util.concurrent.TimeUnit;
  import java.io.IOException;
  
  /**
   * A <tt>AccountManagerFuture</tt> represents the result of an asynchronous
   * {@link AccountManager} call.  Methods are provided to check if the computation is
   * complete, to wait for its completion, and to retrieve the result of
   * the computation.  The result can only be retrieved using method
   * <tt>get</tt> when the computation has completed, blocking if
   * necessary until it is ready.  Cancellation is performed by the
   * <tt>cancel</tt> method.  Additional methods are provided to
   * determine if the task completed normally or was cancelled. Once a
   * computation has completed, the computation cannot be cancelled.
   * If you would like to use a <tt>Future</tt> for the sake
   * of cancellability but not provide a usable result, you can
   * declare types of the form <tt>Future&lt;?&gt;</tt> and
   * return <tt>null</tt> as a result of the underlying task.
   */
  public interface AccountManagerFuture<V> {
      /**
       * Attempts to cancel execution of this task.  This attempt will
       * fail if the task has already completed, has already been cancelled,
       * or could not be cancelled for some other reason. If successful,
       * and this task has not started when <tt>cancel</tt> is called,
       * this task should never run.  If the task has already started,
       * then the <tt>mayInterruptIfRunning</tt> parameter determines
       * whether the thread executing this task should be interrupted in
       * an attempt to stop the task.
       *
       * <p>After this method returns, subsequent calls to {@link #isDone} will
       * always return <tt>true</tt>.  Subsequent calls to {@link #isCancelled}
       * will always return <tt>true</tt> if this method returned <tt>true</tt>.
       *
       * @param mayInterruptIfRunning <tt>true</tt> if the thread executing this
       * task should be interrupted; otherwise, in-progress tasks are allowed
       * to complete
       * @return <tt>false</tt> if the task could not be cancelled,
       * typically because it has already completed normally;
       * <tt>true</tt> otherwise
       */
      boolean cancel(boolean mayInterruptIfRunning);
  
      /**
       * Returns <tt>true</tt> if this task was cancelled before it completed
       * normally.
       *
       * @return <tt>true</tt> if this task was cancelled before it completed
       */
      boolean isCancelled();
  
      /**
       * Returns <tt>true</tt> if this task completed.
       *
       * Completion may be due to normal termination, an exception, or
       * cancellation -- in all of these cases, this method will return
       * <tt>true</tt>.
       *
       * @return <tt>true</tt> if this task completed
       */
      boolean isDone();
  
      /**
       * Accessor for the future result the {@link AccountManagerFuture} represents. This
       * call will block until the result is available. In order to check if the result is
       * available without blocking, one may call {@link #isDone()} and  {@link #isCancelled()}.
       * If the request that generated this result fails or is canceled then an exception
       * will be thrown rather than the call returning normally.
       * @return the actual result
       * @throws android.accounts.OperationCanceledException if the request was canceled for any
       * reason (including if it is forbidden
       * by policy to modify an account (of that type))
       * @throws android.accounts.AuthenticatorException if there was an error communicating with
       * the authenticator or if the authenticator returned an invalid response
       * @throws java.io.IOException if the authenticator returned an error response that indicates
       * that it encountered an IOException while communicating with the authentication server
       */
      V getResult() throws OperationCanceledException, IOException, AuthenticatorException;
  
      /**
       * Accessor for the future result the {@link AccountManagerFuture} represents. This
       * call will block until the result is available. In order to check if the result is
       * available without blocking, one may call {@link #isDone()} and  {@link #isCancelled()}.
       * If the request that generated this result fails or is canceled then an exception
       * will be thrown rather than the call returning normally. If a timeout is specified then
       * the request will automatically be canceled if it does not complete in that amount of time.
       * @param timeout the maximum time to wait
       * @param unit the time unit of the timeout argument. This must not be null.
       * @return the actual result
       * @throws android.accounts.OperationCanceledException if the request was canceled for any
       * reason
       * @throws android.accounts.AuthenticatorException if there was an error communicating with
       * the authenticator or if the authenticator returned an invalid response
       * @throws java.io.IOException if the authenticator returned an error response that indicates
       * that it encountered an IOException while communicating with the authentication server
       */
      V getResult(long timeout, TimeUnit unit)
              throws OperationCanceledException, IOException, AuthenticatorException;
  }