TaskCompletionSource.java

/*
 * Copyright 2017 Google Inc.
 *
 * 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 com.google.firebase.tasks;

import com.google.firebase.internal.NonNull;

/**
 * Provides the ability to create an incomplete {@link Task} and later complete it by either calling
 * {@link #setResult} or {@link #setException}.
 */
public class TaskCompletionSource<T> {

  private final TaskImpl<T> task = new TaskImpl<>();

  /**
   * Completes the Task with the specified result.
   *
   * @throws IllegalStateException if the Task is already complete
   */
  public void setResult(T result) {
    task.setResult(result);
  }

  /**
   * Completes the Task with the specified result, unless the Task has already completed. If the
   * Task has already completed, the call does nothing.
   *
   * @return {@code true} if the result was set successfully, {@code false} otherwise
   */
  public boolean trySetResult(T result) {
    return task.trySetResult(result);
  }

  /**
   * Completes the Task with the specified exception.
   *
   * @throws IllegalStateException if the Task is already complete
   */
  public void setException(@NonNull Exception e) {
    task.setException(e);
  }

  /**
   * Completes the Task with the specified exception, unless the Task has already completed. If the
   * Task has already completed, the call does nothing.
   *
   * @return {@code true} if the exception was set successfully, {@code false} otherwise
   */
  public boolean trySetException(@NonNull Exception e) {
    return task.trySetException(e);
  }

  /** Returns the Task. */
  @NonNull
  public Task<T> getTask() {
    return task;
  }
}