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/*
* Copyright 2012 LinkedIn, 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.linkedin.parseq;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
/**
* This class provides a set of factory methods for create common
* {@link Task}s.
*
* @author Chris Pettitt (cpettitt@linkedin.com)
* @author Chi Chan (ckchan@linkedin.com)
*/
public class Tasks
{
private Tasks() {}
/**
* Creates a new {@link Task} that have a value of type Void. Because the
* returned task has no value, it is typically used to produce side-effects.
*
* @param name a name that describes the action
* @param runnable the action that will be executed when the task is run
* @return the new task
*/
public static Task<Void> action(final String name, final Runnable runnable)
{
return new ActionTask(name, runnable);
}
/**
* Creates a new {@link Task} that's value will be set to the value returned
* from the supplied callable. This task is useful when doing basic
* computation that does not require asynchrony. It is not appropriate for
* long running or blocking tasks.
*
* @param name a name that describes the action
* @param callable the callable to execute when this task is run
* @param <T> the type of the return value for this task
* @return the new task
*/
public static <T> Task<T> callable(final String name,
final Callable<? extends T> callable)
{
return new CallableTask<T>(name, callable);
}
/**
* Creates a new {@link Task} that's value will be set to the value returned
* from the supplied callable. This task is useful when doing basic
* computation that does not require asynchrony. It is not appropriate for
* long running or blocking tasks.
*
* @param name a name that describes the action
* @param callable the callable to execute when this task is run
* @param <T> the type of the return value for this task
* @return the new task
*/
public static <T> Task<T> callable(final String name,
final ThrowableCallable<? extends T> callable)
{
return new CallableTask<T>(name, callable);
}
/**
* Creates a new task that will run the given tasks sequentially (e.g.
* task1 will be finished before task2 starts). The value of the seq task will
* be the result of the last task in the sequence.
*/
public static <T> Task<T> seq(Task<?> task1,
Task<T> task2)
{
return vaseq(task1, task2);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<T> task3)
{
return vaseq(task1, task2, task3);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<T> task4)
{
return vaseq(task1, task2, task3, task4);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<T> task5)
{
return vaseq(task1, task2, task3, task4, task5);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<?> task5,
Task<T> task6)
{
return vaseq(task1, task2, task3, task4, task5, task6);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<?> task5,
Task<?> task6,
Task<T> task7)
{
return vaseq(task1, task2, task3, task4, task5, task6, task7);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<?> task5,
Task<?> task6,
Task<?> task7,
Task<T> task8)
{
return vaseq(task1, task2, task3, task4, task5, task6, task7, task8);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<?> task5,
Task<?> task6,
Task<?> task7,
Task<?> task8,
Task<T> task9)
{
return vaseq(task1, task2, task3, task4, task5, task6, task7, task8, task9);
}
/**
* @see #seq(Task, Task)
*/
public static <T> Task<T> seq(Task<?> task1,
Task<?> task2,
Task<?> task3,
Task<?> task4,
Task<?> task5,
Task<?> task6,
Task<?> task7,
Task<?> task8,
Task<?> task9,
Task<T> task10)
{
return vaseq(task1, task2, task3, task4, task5, task6, task7, task8, task9, task10);
}
/**
* Creates a new task that, when run, will run each of the supplied tasks in
* order. The value of this new task is the value of the last task in the
* sequence. <strong>This method is not type-safe</strong>.
*
* @param tasks the tasks to run sequentially
* @param <T> the result value for the sequence of tasks
* @return a new task that will run the given tasks sequentially
*/
public static <T> Task<T> seq(final Iterable<? extends Task<?>> tasks)
{
return new SeqTask<T>("seq", tasks);
}
/**
* Creates a new task that will run the given tasks in parallel (e.g. task1
* can be executed at the same time as task2). When all tasks complete
* successfully, you can use {@link com.linkedin.parseq.ParTask#get()} to
* get a list of the results. If at least one task failed, then this task will
* also be marked as failed. Use {@link com.linkedin.parseq.ParTask#getTasks()}
* or {@link com.linkedin.parseq.ParTask#getSuccessful()} to get results in
* this case.
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2)
{
return vapar(task1, task2);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3)
{
return vapar(task1, task2, task3);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4)
{
return vapar(task1, task2, task3, task4);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5)
{
return vapar(task1, task2, task3, task4, task5);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5,
Task<? extends T> task6)
{
return vapar(task1, task2, task3, task4, task5, task6);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5,
Task<? extends T> task6,
Task<? extends T> task7)
{
return vapar(task1, task2, task3, task4, task5, task6, task7);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5,
Task<? extends T> task6,
Task<? extends T> task7,
Task<? extends T> task8)
{
return vapar(task1, task2, task3, task4, task5, task6, task7, task8);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5,
Task<? extends T> task6,
Task<? extends T> task7,
Task<? extends T> task8,
Task<? extends T> task9)
{
return vapar(task1, task2, task3, task4, task5, task6, task7, task8, task9);
}
/**
* @see #par(Task, Task)
*/
public static <T> ParTask<T> par(Task<? extends T> task1,
Task<? extends T> task2,
Task<? extends T> task3,
Task<? extends T> task4,
Task<? extends T> task5,
Task<? extends T> task6,
Task<? extends T> task7,
Task<? extends T> task8,
Task<? extends T> task9,
Task<? extends T> task10)
{
return vapar(task1, task2, task3, task4, task5, task6, task7, task8, task9, task10);
}
/**
* Creates a new task that will run each of the supplied tasks in parallel (e.g.
* tasks[0] can be run at the same time as task2). This is a type-safe,
* collection-based alternative to {@link #vapar(Task[])}.
* <p/>
* When all tasks complete successfully, you can use
* {@link com.linkedin.parseq.ParTask#get()} to get a list of the results. If
* at least one task failed, then this task will also be marked as failed. Use
* {@link com.linkedin.parseq.ParTask#getTasks()} or
* {@link com.linkedin.parseq.ParTask#getSuccessful()} to get results in this
* case.
*
* @param tasks the tasks to run in parallel
* @return The results of the tasks
*/
public static <T> ParTask<T> par(final Iterable<? extends Task<? extends T>> tasks)
{
return new ParTaskImpl<T>("par", tasks);
}
/**
* Creates a new task that wraps the given task. If the given task finishes
* before the timeout occurs then this task takes on the value of the task.
* If the task does not complete in the given time then this task will
* have a TimeoutException. The wrapped task may be cancelled when a timeout
* occurs.
*
* @param time the time to wait before timing out
* @param unit the units for the time
* @param task the task to wrap
* @param <T> the value type for the task
* @return the new timeout task
*/
public static <T> Task<T> timeoutWithError(final long time, final TimeUnit unit,
final Task<T> task)
{
return timeoutWithError("timeoutWithError", time, unit, task);
}
/**
* This method is similar to {@link #timeoutWithError(long, java.util.concurrent.TimeUnit, Task)},
* but it also takes a name that will be set on the returned task.
*
* @param name the name of this task
* @param time the time to wait before timing out
* @param unit the units for the time
* @param task the task to wrap
* @param <T> the value type for the task
* @return the new timeout task
* @see #timeoutWithError(long, java.util.concurrent.TimeUnit, Task)
*/
public static <T> Task<T> timeoutWithError(final String name,
final long time, final TimeUnit unit,
final Task<T> task)
{
return new TimeoutWithErrorTask<T>(name, time, unit, task);
}
/**
* Creates a new task that will run the given array of tasks sequentially
* (e.g. tasks[0] will be finished before tasks[1] is run). <strong>This
* method is not type-safe</strong> - prefer one of the {@code seq} options
* when possible. The value of this new task is the value of the last task in
* the sequence.
*
* @param tasks the tasks to run sequentially
* @param <T> the result value for the sequence of tasks
* @return a new task that will run the given tasks sequentially
*/
private static <T> Task<T> vaseq(final Task<?>... tasks)
{
return new SeqTask<T>("seq", Arrays.asList(tasks));
}
/**
* Creates a new task that will run each of the supplied tasks in parallel (e.g.
* tasks[0] can be run at the same time as task2). <strong>This method is not
* type-safe</strong> - prefer one of the {@code par} options when possible.
* <p/>
* When all tasks complete successfully, you can use
* {@link com.linkedin.parseq.ParTask#get()} to get a list of the results. If
* at least one task failed, then this task will also be marked as failed. Use
* {@link com.linkedin.parseq.ParTask#getTasks()} or
* {@link com.linkedin.parseq.ParTask#getSuccessful()} to get results in this
* case.
*
* @param tasks the tasks to run in parallel
* @return a new task that will run the given tasks in parallel
*/
private static <T> ParTask<T> vapar(final Task<?>... tasks)
{
final List<Task<T>> taskList = new ArrayList<Task<T>>(tasks.length);
for (Task<?> task : tasks)
{
@SuppressWarnings("unchecked")
final Task<T> typedTask = (Task<T>)task;
taskList.add(typedTask);
}
return par(taskList);
}
}