org.lsst.ccs.messaging.util

Class KeyQueueExecutor

java.lang.Object

org.lsst.ccs.messaging.util.KeyQueueExecutor

public class KeyQueueExecutor
extends Object

Executor that uses String keys associated with submitted tasks to sequence their execution. Tasks submitted with overlapping key sets are guaranteed to execute sequentially in order of submission. Tasks that do not have common keys may run concurrently, up to the specified maximum number of threads.

Author:

onoprien

Constructor Summary

Constructors

Constructor and Description
KeyQueueExecutor(String name, int maxThreads) Constructs the executor.

Method Summary

Modifier and Type	Method and Description
boolean	awaitTermination(long timeout, TimeUnit unit) Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
void	execute(Runnable command, String... keys) Submits a Runnable for execution.
String	getName() Returns the name of this executor.
void	setLogger(Logger logger) Sets a logger for messages on abnormal conditions.
void	shutdown() Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
void	shutdownNow() Shuts down this executor.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

KeyQueueExecutor

public KeyQueueExecutor(String name,
                        int maxThreads)

Constructs the executor.

Parameters:

name - Name of this executor, used for naming threads.

maxThreads - Maximum number of task-executing threads that can run concurrently.

Method Detail

setLogger

public void setLogger(Logger logger)

Sets a logger for messages on abnormal conditions. This method should be called before submitting the first task. If this method is never called, nothing is logged.

Parameters:

logger - Logger for abnormal conditions warnings.

shutdown

public void shutdown()

Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.

shutdownNow

public void shutdownNow()

Shuts down this executor. Tasks that have not started execution are discarded.

awaitTermination

public boolean awaitTermination(long timeout,
                                TimeUnit unit)
                         throws InterruptedException

Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.

Parameters:

timeout - the maximum time to wait

unit - the time unit of the timeout argument

Returns:

true if this executor terminated and false if the timeout elapsed before termination

Throws:

InterruptedException - if interrupted while waiting

getName

public String getName()

Returns the name of this executor.

Returns:

Executor name.

execute

public void execute(Runnable command,
                    String... keys)

Submits a Runnable for execution. This method submits a task and returns without waiting for its completion. Tasks submitted with overlapping key sets are guaranteed to execute sequentially in order of submission. Tasks that do not have common keys may run concurrently, up to the specified maximum number of threads.

This class is thread-safe, its methods can be called on any thread. Visibility effects: all actions of the current thread prior to calling this method "happen before" actions on the thread executing the task. Actions of a task "happen before" actions of another task submitted later with overlapping key set.

Parameters:

command - Runnable to execute.

keys - Keys

Throws:

RejectedExecutionException - if this task cannot be accepted for execution.

NullPointerException - if command is null.