com.sun.grizzly.util
Class DefaultExecutorService

java.lang.Object
  extended by java.util.concurrent.AbstractExecutorService
      extended by com.sun.grizzly.util.DefaultExecutorService
All Implemented Interfaces:
Executor, ExecutorService

public class DefaultExecutorService
extends AbstractExecutorService

copy pasted the Doug Lea ThreadPoolExecutor and modified so workers are added if queue is non empty.
uses WorkerThreadImpl by default.


Constructor Summary
DefaultExecutorService(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, String threadprefixname)
          Creates a new ThreadPoolExecutor with the given initial parameters and default thread factory and rejected execution handler.
DefaultExecutorService(int corePoolSize, int maximumPoolSize, long keepAliveTime, TimeUnit unit, BlockingQueue<Runnable> workQueue, ThreadFactory threadFactory)
          Creates a new ThreadPoolExecutor with the given initial parameters.
 
Method Summary
protected  void afterExecute(Runnable r, Throwable t)
          Method invoked upon completion of execution of the given Runnable.
 void allowCoreThreadTimeOut(boolean value)
          Sets the policy governing whether core threads may time out and terminate if no tasks arrive within the keep-alive time, being replaced if needed when new tasks arrive.
 boolean allowsCoreThreadTimeOut()
          Returns true if this pool allows core threads to time out and terminate if no tasks arrive within the keepAlive time, being replaced if needed when new tasks arrive.
 boolean awaitTermination(long timeout, TimeUnit unit)
           
protected  void beforeExecute(Thread t, Runnable r)
          Method invoked prior to executing the given Runnable in the given thread.
 void execute(Runnable command)
          Executes the given task sometime in the future.
protected  void finalize()
          Invokes shutdown when this executor is no longer referenced and it has no threads.
 int getActiveCount()
          Returns the approximate number of threads that are actively executing tasks.
 long getCompletedTaskCount()
          Returns the approximate total number of tasks that have completed execution.
 int getCorePoolSize()
          Returns the core number of threads.
 long getKeepAliveTime(TimeUnit unit)
          Returns the thread keep-alive time, which is the amount of time that threads in excess of the core pool size may remain idle before being terminated.
 int getLargestPoolSize()
          Returns the largest number of threads that have ever simultaneously been in the pool.
 int getMaximumPoolSize()
          Returns the maximum allowed number of threads.
 int getPoolSize()
          Returns the current number of threads in the pool.
 BlockingQueue<Runnable> getQueue()
          Returns the task queue used by this executor.
 long getTaskCount()
          Returns the approximate total number of tasks that have ever been scheduled for execution.
 ThreadFactory getThreadFactory()
          Returns the thread factory used to create new threads.
 boolean isShutdown()
           
 boolean isTerminated()
           
 boolean isTerminating()
          Returns true if this executor is in the process of terminating after shutdown() or shutdownNow() but has not completely terminated.
 int prestartAllCoreThreads()
          Starts all core threads, causing them to idly wait for work.
 boolean prestartCoreThread()
          Starts a core thread, causing it to idly wait for work.
 void purge()
          Tries to remove from the work queue all Future tasks that have been cancelled.
 boolean remove(Runnable task)
          Removes this task from the executor's internal queue if it is present, thus causing it not to be run if it has not already started.
 void setCorePoolSize(int corePoolSize)
          Sets the core number of threads.
 void setKeepAliveTime(long time, TimeUnit unit)
          Sets the time limit for which threads may remain idle before being terminated.
 void setMaximumPoolSize(int maximumPoolSize)
          Sets the maximum allowed number of threads.
 void setThreadFactory(ThreadFactory threadFactory)
          Sets the thread factory used to create new threads.
 void shutdown()
          Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted.
 List<Runnable> shutdownNow()
          Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution.
protected  void terminated()
          Method invoked when the Executor has terminated.
 
Methods inherited from class java.util.concurrent.AbstractExecutorService
invokeAll, invokeAll, invokeAny, invokeAny, newTaskFor, newTaskFor, submit, submit, submit
 
Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

DefaultExecutorService

public DefaultExecutorService(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              String threadprefixname)
Creates a new ThreadPoolExecutor with the given initial parameters and default thread factory and rejected execution handler. It may be more convenient to use one of the Executors factory methods instead of this general purpose constructor.

Parameters:
corePoolSize - the number of threads to keep in the pool, even if they are idle, unless allowCoreThreadTimeOut is set
maximumPoolSize - the maximum number of threads to allow in the pool
keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.
unit - the time unit for the keepAliveTime argument
workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.
Throws:
IllegalArgumentException - if one of the following holds:
corePoolSize < 0
keepAliveTime < 0
maximumPoolSize <= 0
maximumPoolSize < corePoolSize
NullPointerException - if workQueue is null

DefaultExecutorService

public DefaultExecutorService(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory)
Creates a new ThreadPoolExecutor with the given initial parameters.

Parameters:
corePoolSize - the number of threads to keep in the pool, even if they are idle, unless allowCoreThreadTimeOut is set
maximumPoolSize - the maximum number of threads to allow in the pool
keepAliveTime - when the number of threads is greater than the core, this is the maximum time that excess idle threads will wait for new tasks before terminating.
unit - the time unit for the keepAliveTime argument
workQueue - the queue to use for holding tasks before they are executed. This queue will hold only the Runnable tasks submitted by the execute method.
threadFactory - the factory to use when the executor creates a new thread
handler - the handler to use when execution is blocked because the thread bounds and queue capacities are reached
Throws:
IllegalArgumentException - if one of the following holds:
corePoolSize < 0
keepAliveTime < 0
maximumPoolSize <= 0
maximumPoolSize < corePoolSize
NullPointerException - if workQueue or threadFactory or handler is null
Method Detail

execute

public void execute(Runnable command)
Executes the given task sometime in the future. The task may execute in a new thread or in an existing pooled thread. If the task cannot be submitted for execution, either because this executor has been shutdown or because its capacity has been reached, the task is handled by the current RejectedExecutionHandler.

Parameters:
command - the task to execute
Throws:
RejectedExecutionException - at discretion of RejectedExecutionHandler, if the task cannot be accepted for execution
NullPointerException - if command is null

shutdown

public void shutdown()
Initiates an orderly shutdown in which previously submitted tasks are executed, but no new tasks will be accepted. Invocation has no additional effect if already shut down.

Throws:
SecurityException

shutdownNow

public List<Runnable> shutdownNow()
Attempts to stop all actively executing tasks, halts the processing of waiting tasks, and returns a list of the tasks that were awaiting execution. These tasks are drained (removed) from the task queue upon return from this method.

There are no guarantees beyond best-effort attempts to stop processing actively executing tasks. This implementation cancels tasks via Thread.interrupt(), so any task that fails to respond to interrupts may never terminate.

Throws:
SecurityException

isShutdown

public boolean isShutdown()

isTerminating

public boolean isTerminating()
Returns true if this executor is in the process of terminating after shutdown() or shutdownNow() but has not completely terminated. This method may be useful for debugging. A return of true reported a sufficient period after shutdown may indicate that submitted tasks have ignored or suppressed interruption, causing this executor not to properly terminate.

Returns:
true if terminating but not yet terminated

isTerminated

public boolean isTerminated()

awaitTermination

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

finalize

protected void finalize()
Invokes shutdown when this executor is no longer referenced and it has no threads.

Overrides:
finalize in class Object

setThreadFactory

public void setThreadFactory(ThreadFactory threadFactory)
Sets the thread factory used to create new threads.

Parameters:
threadFactory - the new thread factory
Throws:
NullPointerException - if threadFactory is null
See Also:
getThreadFactory()

getThreadFactory

public ThreadFactory getThreadFactory()
Returns the thread factory used to create new threads.

Returns:
the current thread factory
See Also:
setThreadFactory(java.util.concurrent.ThreadFactory)

setCorePoolSize

public void setCorePoolSize(int corePoolSize)
Sets the core number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle. If larger, new threads will, if needed, be started to execute any queued tasks.

Parameters:
corePoolSize - the new core size
Throws:
IllegalArgumentException - if corePoolSize < 0
See Also:
getCorePoolSize()

getCorePoolSize

public int getCorePoolSize()
Returns the core number of threads.

Returns:
the core number of threads
See Also:
setCorePoolSize(int)

prestartCoreThread

public boolean prestartCoreThread()
Starts a core thread, causing it to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed. This method will return false if all core threads have already been started.

Returns:
true if a thread was started

prestartAllCoreThreads

public int prestartAllCoreThreads()
Starts all core threads, causing them to idly wait for work. This overrides the default policy of starting core threads only when new tasks are executed.

Returns:
the number of threads started

allowsCoreThreadTimeOut

public boolean allowsCoreThreadTimeOut()
Returns true if this pool allows core threads to time out and terminate if no tasks arrive within the keepAlive time, being replaced if needed when new tasks arrive. When true, the same keep-alive policy applying to non-core threads applies also to core threads. When false (the default), core threads are never terminated due to lack of incoming tasks.

Returns:
true if core threads are allowed to time out, else false
Since:
1.6

allowCoreThreadTimeOut

public void allowCoreThreadTimeOut(boolean value)
Sets the policy governing whether core threads may time out and terminate if no tasks arrive within the keep-alive time, being replaced if needed when new tasks arrive. When false, core threads are never terminated due to lack of incoming tasks. When true, the same keep-alive policy applying to non-core threads applies also to core threads. To avoid continual thread replacement, the keep-alive time must be greater than zero when setting true. This method should in general be called before the pool is actively used.

Parameters:
value - true if should time out, else false
Throws:
IllegalArgumentException - if value is true and the current keep-alive time is not greater than zero
Since:
1.6

setMaximumPoolSize

public void setMaximumPoolSize(int maximumPoolSize)
Sets the maximum allowed number of threads. This overrides any value set in the constructor. If the new value is smaller than the current value, excess existing threads will be terminated when they next become idle.

Parameters:
maximumPoolSize - the new maximum
Throws:
IllegalArgumentException - if the new maximum is less than or equal to zero, or less than the core pool size
See Also:
getMaximumPoolSize()

getMaximumPoolSize

public int getMaximumPoolSize()
Returns the maximum allowed number of threads.

Returns:
the maximum allowed number of threads
See Also:
setMaximumPoolSize(int)

setKeepAliveTime

public void setKeepAliveTime(long time,
                             TimeUnit unit)
Sets the time limit for which threads may remain idle before being terminated. If there are more than the core number of threads currently in the pool, after waiting this amount of time without processing a task, excess threads will be terminated. This overrides any value set in the constructor.

Parameters:
time - the time to wait. A time value of zero will cause excess threads to terminate immediately after executing tasks.
unit - the time unit of the time argument
Throws:
IllegalArgumentException - if time less than zero or if time is zero and allowsCoreThreadTimeOut
See Also:
getKeepAliveTime(java.util.concurrent.TimeUnit)

getKeepAliveTime

public long getKeepAliveTime(TimeUnit unit)
Returns the thread keep-alive time, which is the amount of time that threads in excess of the core pool size may remain idle before being terminated.

Parameters:
unit - the desired time unit of the result
Returns:
the time limit
See Also:
setKeepAliveTime(long, java.util.concurrent.TimeUnit)

getQueue

public BlockingQueue<Runnable> getQueue()
Returns the task queue used by this executor. Access to the task queue is intended primarily for debugging and monitoring. This queue may be in active use. Retrieving the task queue does not prevent queued tasks from executing.

Returns:
the task queue

remove

public boolean remove(Runnable task)
Removes this task from the executor's internal queue if it is present, thus causing it not to be run if it has not already started.

This method may be useful as one part of a cancellation scheme. It may fail to remove tasks that have been converted into other forms before being placed on the internal queue. For example, a task entered using submit might be converted into a form that maintains Future status. However, in such cases, method purge() may be used to remove those Futures that have been cancelled.

Parameters:
task - the task to remove
Returns:
true if the task was removed

purge

public void purge()
Tries to remove from the work queue all Future tasks that have been cancelled. This method can be useful as a storage reclamation operation, that has no other impact on functionality. Cancelled tasks are never executed, but may accumulate in work queues until worker threads can actively remove them. Invoking this method instead tries to remove them now. However, this method may fail to remove tasks in the presence of interference by other threads.


getPoolSize

public int getPoolSize()
Returns the current number of threads in the pool.

Returns:
the number of threads

getActiveCount

public int getActiveCount()
Returns the approximate number of threads that are actively executing tasks.

Returns:
the number of threads

getLargestPoolSize

public int getLargestPoolSize()
Returns the largest number of threads that have ever simultaneously been in the pool.

Returns:
the number of threads

getTaskCount

public long getTaskCount()
Returns the approximate total number of tasks that have ever been scheduled for execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation.

Returns:
the number of tasks

getCompletedTaskCount

public long getCompletedTaskCount()
Returns the approximate total number of tasks that have completed execution. Because the states of tasks and threads may change dynamically during computation, the returned value is only an approximation, but one that does not ever decrease across successive calls.

Returns:
the number of tasks

beforeExecute

protected void beforeExecute(Thread t,
                             Runnable r)
Method invoked prior to executing the given Runnable in the given thread. This method is invoked by thread t that will execute task r, and may be used to re-initialize ThreadLocals, or to perform logging.

This implementation does nothing, but may be customized in subclasses. Note: To properly nest multiple overridings, subclasses should generally invoke super.beforeExecute at the end of this method.

Parameters:
t - the thread that will run task r
r - the task that will be executed

afterExecute

protected void afterExecute(Runnable r,
                            Throwable t)
Method invoked upon completion of execution of the given Runnable. This method is invoked by the thread that executed the task. If non-null, the Throwable is the uncaught RuntimeException or Error that caused execution to terminate abruptly.

This implementation does nothing, but may be customized in subclasses. Note: To properly nest multiple overridings, subclasses should generally invoke super.afterExecute at the beginning of this method.

Note: When actions are enclosed in tasks (such as FutureTask) either explicitly or via methods such as submit, these task objects catch and maintain computational exceptions, and so they do not cause abrupt termination, and the internal exceptions are not passed to this method. If you would like to trap both kinds of failures in this method, you can further probe for such cases, as in this sample subclass that prints either the direct cause or the underlying exception if a task has been aborted:

 class ExtendedExecutor extends ThreadPoolExecutor {
   // ...
   protected void afterExecute(Runnable r, Throwable t) {
     super.afterExecute(r, t);
     if (t == null && r instanceof Future<?>) {
       try {
         Object result = ((Future<?>) r).get();
       } catch (CancellationException ce) {
           t = ce;
       } catch (ExecutionException ee) {
           t = ee.getCause();
       } catch (InterruptedException ie) {
           Thread.currentThread().interrupt(); // ignore/reset
       }
     }
     if (t != null)
       System.out.println(t);
   }
 }

Parameters:
r - the runnable that has completed
t - the exception that caused termination, or null if execution completed normally

terminated

protected void terminated()
Method invoked when the Executor has terminated. Default implementation does nothing. Note: To properly nest multiple overridings, subclasses should generally invoke super.terminated within this method.



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