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/*
* 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 static com.google.common.base.Preconditions.checkNotNull;
import com.google.firebase.internal.GuardedBy;
import com.google.firebase.internal.NonNull;
import java.util.Arrays;
import java.util.Collection;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
/**
* {@link Task} utility methods.
*
* @deprecated Use ApiFutures and ThreadManager interface instead.
*/
public final class Tasks {
private Tasks() {}
/** Returns a completed Task with the specified result. */
public static Task forResult(T result) {
TaskImpl task = new TaskImpl<>();
task.setResult(result);
return task;
}
/** Returns a completed Task with the specified exception. */
public static Task forException(@NonNull Exception exception) {
TaskImpl task = new TaskImpl<>();
task.setException(exception);
return task;
}
/**
* Returns a Task that will be completed with the result of the specified Callable.
*
* The Callable will be called on a shared thread pool.
*
* @deprecated Use {@link #call(Executor, Callable)}
*/
public static Task call(@NonNull Callable callable) {
return call(TaskExecutors.DEFAULT_THREAD_POOL, callable);
}
/**
* Returns a Task that will be completed with the result of the specified Callable.
*
* @param executor the Executor to use to call the Callable
*/
public static Task call(@NonNull Executor executor, @NonNull final Callable callable) {
checkNotNull(executor, "Executor must not be null");
checkNotNull(callable, "Callback must not be null");
final TaskImpl task = new TaskImpl<>();
executor.execute(
new Runnable() {
@Override
public void run() {
try {
task.setResult(callable.call());
} catch (Exception e) {
task.setException(e);
}
}
});
return task;
}
/**
* Blocks until the specified Task is complete.
*
* @return the Task's result
* @throws ExecutionException if the Task fails
* @throws InterruptedException if an interrupt occurs while waiting for the Task to complete
*/
public static T await(@NonNull Task task) throws ExecutionException, InterruptedException {
checkNotNull(task, "Task must not be null");
if (task.isComplete()) {
return getResultOrThrowExecutionException(task);
}
AwaitListener listener = new AwaitListener();
addListener(task, listener);
listener.await();
return getResultOrThrowExecutionException(task);
}
/**
* Blocks until the specified Task is complete.
*
* @return the Task's result
* @throws ExecutionException if the Task fails
* @throws InterruptedException if an interrupt occurs while waiting for the Task to complete
* @throws TimeoutException if the specified timeout is reached before the Task completes
*/
public static T await(@NonNull Task task, long timeout, @NonNull TimeUnit unit)
throws ExecutionException, InterruptedException, TimeoutException {
checkNotNull(task, "Task must not be null");
checkNotNull(unit, "TimeUnit must not be null");
if (task.isComplete()) {
return getResultOrThrowExecutionException(task);
}
AwaitListener listener = new AwaitListener();
addListener(task, listener);
if (!listener.await(timeout, unit)) {
throw new TimeoutException("Timed out waiting for Task");
}
return getResultOrThrowExecutionException(task);
}
/**
* Returns a Task that completes successfully when all of the specified Tasks complete
* successfully. Does not accept nulls.
*
* @throws NullPointerException if any of the provided Tasks are null
*/
public static Task whenAll(final Collection> tasks) {
if (tasks.isEmpty()) {
return Tasks.forResult(null);
}
for (Task task : tasks) {
if (task == null) {
throw new NullPointerException("null tasks are not accepted");
}
}
TaskImpl whenAllTask = new TaskImpl<>();
WhenAllListener listener = new WhenAllListener(tasks.size(), whenAllTask);
for (Task task : tasks) {
addListener(task, listener);
}
return whenAllTask;
}
/**
* Returns a Task that completes successfully when all of the specified Tasks complete
* successfully. Does not accept nulls.
*
* @throws NullPointerException if any of the provided Tasks are null
*/
public static Task whenAll(Task... tasks) {
if (tasks.length == 0) {
return Tasks.forResult(null);
}
return whenAll(Arrays.asList(tasks));
}
private static T getResultOrThrowExecutionException(Task task) throws ExecutionException {
if (task.isSuccessful()) {
return task.getResult();
} else {
throw new ExecutionException(task.getException());
}
}
private static void addListener(Task task, CombinedListener listener) {
// Use a direct executor to avoid an additional thread-hop.
task.addOnSuccessListener(TaskExecutors.DIRECT, listener);
task.addOnFailureListener(TaskExecutors.DIRECT, listener);
}
interface CombinedListener extends OnSuccessListener