corrade-vassal – Rev 1
?pathlinks?
/*
* CVS identifier:
*
* $Id: ThreadPool.java,v 1.9 2002/05/22 15:00:55 grosbois Exp $
*
* Class: ThreadPool
*
* Description: A pool of threads
*
*
*
* COPYRIGHT:
*
* This software module was originally developed by Raphaël Grosbois and
* Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
* Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
* Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
* Centre France S.A) in the course of development of the JPEG2000
* standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
* software module is an implementation of a part of the JPEG 2000
* Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
* Systems AB and Canon Research Centre France S.A (collectively JJ2000
* Partners) agree not to assert against ISO/IEC and users of the JPEG
* 2000 Standard (Users) any of their rights under the copyright, not
* including other intellectual property rights, for this software module
* with respect to the usage by ISO/IEC and Users of this software module
* or modifications thereof for use in hardware or software products
* claiming conformance to the JPEG 2000 Standard. Those intending to use
* this software module in hardware or software products are advised that
* their use may infringe existing patents. The original developers of
* this software module, JJ2000 Partners and ISO/IEC assume no liability
* for use of this software module or modifications thereof. No license
* or right to this software module is granted for non JPEG 2000 Standard
* conforming products. JJ2000 Partners have full right to use this
* software module for his/her own purpose, assign or donate this
* software module to any third party and to inhibit third parties from
* using this software module for non JPEG 2000 Standard conforming
* products. This copyright notice must be included in all copies or
* derivative works of this software module.
*
* Copyright (c) 1999/2000 JJ2000 Partners.
* */
using System;
namespace CSJ2K.j2k.util
{
/// <summary> This class implements a thread pool. The thread pool contains a set of
/// threads which can be given work to do.
///
/// <P>If the Java Virtual Machine (JVM) uses native threads, then the
/// different threads will be able to execute in different processors in
/// parallel on multiprocessors machines. However, under some JVMs and
/// operating systems using native threads is not sufficient to allow the JVM
/// access to multiple processors. This is the case when native threads are
/// implemented using POSIX threads on lightweight processes
/// (i.e. PTHREAD_SCOPE_PROCESS sopce scheduling), which is the case on most
/// UNIX operating systems. In order to do provide access to multiple
/// processors it is necessary to set the concurrency level to the number of
/// processors or slightly higher. This can be achieved by setting the Java
/// system property with the name defined by CONCURRENCY_PROP_NAME to some
/// non-negative number. This will make use of the 'NativeServices' class and
/// supporting native libraries. See 'NativeServices' for details. See
/// 'CONCURRENCY_PROP_NAME' for the name of the property.
///
/// <P>Initially the thread pool contains a user specified number of idle
/// threads. Idle threads can be given a target which is run. While running the
/// target the thread temporarily leaves the idle list. When the target
/// finishes, it joins the idle list again, waiting for a new target. When a
/// target is finished a thread can be notified on a particular object that is
/// given as a lock.
///
/// <P>Jobs can be submitted using Runnable interfaces, using the 'runTarget()'
/// methods. When the job is submitted, an idle thread will be obtained, the
/// 'run()' method of the 'Runnable' interface will be executed and when it
/// completes the thread will be returned to the idle list. In general the
/// 'run()' method should complete in a rather short time, so that the threds
/// of the pool are not starved.
///
/// <P>If using the non-asynchronous calls to 'runTarget()', it is important
/// that any target's 'run()' method, or any method called from it, does not
/// use non-asynchronous calls to 'runTarget()' on the same thread pool where
/// it was started. Otherwise this could create a dead-lock when there are not
/// enough idle threads.
///
/// <P>The pool also has a global error and runtime exception condition (one
/// for 'Error' and one for 'RuntimeException'). If a target's 'run()' method
/// throws an 'Error' or 'RuntimeException' the corresponding exception
/// condition is set and the exception object saved. In any subsequent call to
/// 'checkTargetErrors()' the saved exception object is thrown. Likewise, if a
/// target's 'run()' method throws any other subclass of 'Throwable' a new
/// 'RuntimeException' is created and saved. It will be thrown on a subsequent
/// call to 'checkTargetErrors()'. If more than one exception occurs between
/// calls to 'checkTargetErrors()' only the last one is saved. Any 'Error'
/// condition has precedence on all 'RuntimeException' conditions. The threads
/// in the pool are unaffected by any exceptions thrown by targets.
///
/// <P>The only exception to the above is the 'ThreadDeath' exception. If a
/// target's 'run()' method throws the 'ThreadDeath' exception a warning
/// message is printed and the exception is propagated, which will terminate
/// the thread in which it occurs. This could lead to instabilities of the
/// pool. The 'ThreadDeath' exception should never be thrown by the program. It
/// is thrown by the Java(TM) Virtual Machine when Thread.stop() is
/// called. This method is deprecated and should never be called.
///
/// <P>All the threads in the pool are "daemon" threads and will automatically
/// terminate when no daemon threads are running.
///
/// </summary>
/// <seealso cref="NativeServices">
///
/// </seealso>
/// <seealso cref="CONCURRENCY_PROP_NAME">
///
/// </seealso>
/// <seealso cref="Runnable">
///
/// </seealso>
/// <seealso cref="Thread">
///
/// </seealso>
/// <seealso cref="Error">
///
/// </seealso>
/// <seealso cref="RuntimeException">
///
///
/// </seealso>
public class ThreadPool
{
/// <summary> Returns the size of the pool. That is the number of threads in this
/// pool (idle + busy).
///
/// </summary>
/// <returns> The pool's size.
///
///
/// </returns>
virtual public int Size
{
get
{
return idle.Length;
}
}
/// <summary>The name of the property that sets the concurrency level:
/// jj2000.j2k.util.ThreadPool.concurrency
/// </summary>
public const System.String CONCURRENCY_PROP_NAME = "jj2000.j2k.util.ThreadPool.concurrency";
/// <summary>The array of idle threads and the lock for the manipulation of the
/// idle thread list.
/// </summary>
private ThreadPoolThread[] idle;
/// <summary>The number of idle threads </summary>
private int nidle;
/// <summary>The name of the pool </summary>
private System.String poolName;
/// <summary>The priority for the pool </summary>
private int poolPriority;
/// <summary>The last error thrown by a target. Null if none </summary>
// NOTE: needs to be volatile, so that only one copy exits in memory
private volatile System.ApplicationException targetE;
/// <summary>The last runtime exception thrown by a target. Null if none </summary>
// NOTE: needs to be volatile, so that only one copy exits in memory
private volatile System.SystemException targetRE;
//UPGRADE_NOTE: Field 'EnclosingInstance' was added to class 'ThreadPoolThread' to access its enclosing instance. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1019'"
/// <summary> The threads that are managed by the pool.
///
/// </summary>
internal class ThreadPoolThread:SupportClass.ThreadClass
{
private void InitBlock(ThreadPool enclosingInstance)
{
this.enclosingInstance = enclosingInstance;
}
private ThreadPool enclosingInstance;
public ThreadPool Enclosing_Instance
{
get
{
return enclosingInstance;
}
}
private IThreadRunnable target;
private System.Object lock_Renamed;
private bool doNotifyAll;
/// <summary> Creates a ThreadPoolThread object, setting its name according to
/// the given 'idx', daemon type and the priority to the one of the
/// pool.
///
/// </summary>
/// <param name="idx">The index of this thread in the pool
///
/// </param>
/// <param name="name">The name of the thread
///
/// </param>
public ThreadPoolThread(ThreadPool enclosingInstance, int idx, System.String name):base(name)
{
InitBlock(enclosingInstance);
IsBackground = true;
//UPGRADE_TODO: The differences in the type of parameters for method 'java.lang.Thread.setPriority' may cause compilation errors. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1092'"
Priority = (System.Threading.ThreadPriority) Enclosing_Instance.poolPriority;
}
/// <summary> The method that is run by the thread. This method first joins the
/// idle state in the pool and then enters an infinite loop. In this
/// loop it waits until a target to run exists and runs it. Once the
/// target's run() method is done it re-joins the idle state and
/// notifies the waiting lock object, if one exists.
///
/// <P>An interrupt on this thread has no effect other than forcing a
/// check on the target. Normally the target is checked every time the
/// thread is woken up by notify, no interrupts should be done.
///
/// <P>Any exception thrown by the target's 'run()' method is catched
/// and this thread is not affected, except for 'ThreadDeath'. If a
/// 'ThreadDeath' exception is catched a warning message is printed by
/// the 'FacilityManager' and the exception is propagated up. For
/// exceptions which are subclasses of 'Error' or 'RuntimeException'
/// the corresponding error condition is set and this thread is not
/// affected. For any other exceptions a new 'RuntimeException' is
/// created and the error condition is set, this thread is not affected.
///
/// </summary>
override public void Run()
{
// Join the idle threads list
Enclosing_Instance.putInIdleList(this);
// Permanently lock the object while running so that target can
// not be changed until we are waiting again. While waiting for a
// target the lock is released.
lock (this)
{
while (true)
{
// Wait until we get a target
while (target == null)
{
try
{
System.Threading.Monitor.Wait(this);
}
catch (System.Threading.ThreadInterruptedException)
{
}
}
// Run the target and catch all possible errors
try
{
target.Run();
}
//UPGRADE_NOTE: Exception 'java.lang.ThreadDeath' was converted to 'System.ApplicationException' which has different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1100'"
catch (System.Threading.ThreadAbortException td)
{
// We have been instructed to abruptly terminate
// the thread, which should never be done. This can
// cause another thread, or the system, to lock.
FacilityManager.getMsgLogger().printmsg(CSJ2K.j2k.util.MsgLogger_Fields.WARNING, "Thread.stop() called on a ThreadPool " + "thread or ThreadDeath thrown. This is " + "deprecated. Lock-up might occur.");
throw td;
}
catch (System.ApplicationException e)
{
Enclosing_Instance.targetE = e;
}
catch (System.SystemException re)
{
Enclosing_Instance.targetRE = re;
}
//UPGRADE_NOTE: Exception 'java.lang.Throwable' was converted to 'System.Exception' which has different behavior. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1100'"
catch (System.Exception)
{
// A totally unexpected error has occurred
// (Thread.stop(Throwable) has been used, which should
// never be.
Enclosing_Instance.targetRE = new System.SystemException("Unchecked exception " + "thrown by target's " + "run() method in pool " + Enclosing_Instance.poolName + ".");
}
// Join idle threads
Enclosing_Instance.putInIdleList(this);
// Release the target and notify lock (i.e. wakeup)
target = null;
if (lock_Renamed != null)
{
lock (lock_Renamed)
{
if (doNotifyAll)
{
System.Threading.Monitor.PulseAll(lock_Renamed);
}
else
{
System.Threading.Monitor.Pulse(lock_Renamed);
}
}
}
}
}
}
/// <summary> Assigns a target to this thread, with an optional notify lock and a
/// notify mode. The another target is currently running the method
/// will block until it terminates. After setting the new target the
/// runner thread will be wakenup and execytion will start.
///
/// </summary>
/// <param name="target">The runnable object containing the 'run()' method to
/// run.
///
/// </param>
/// <param name="lock">An object on which notify will be called once the
/// target's run method has finished. A thread to be notified should be
/// waiting on that object. If null no thread is notified.
///
/// </param>
/// <param name="notifyAll">If true 'notifyAll()', instead of 'notify()', will
/// be called on tghe lock.
///
/// </param>
//UPGRADE_NOTE: Synchronized keyword was removed from method 'setTarget'. Lock expression was added. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1027'"
internal virtual void setTarget(IThreadRunnable target, System.Object lock_Renamed, bool notifyAll)
{
lock (this)
{
// Set the target
this.target = target;
this.lock_Renamed = lock_Renamed;
doNotifyAll = notifyAll;
// Wakeup the thread
System.Threading.Monitor.Pulse(this);
}
}
}
/// <summary> Creates a new thread pool of the given size, thread priority and pool
/// name.
///
/// <P>If the Java system property of the name defined by
/// 'CONCURRENCY_PROP_NAME' is set, then an attempt will be made to load
/// the library that supports concurrency setting (see
/// 'NativeServices'). If that succeds the concurrency level will be set to
/// the specified value. Otherwise a warning is printed.
///
/// </summary>
/// <param name="size">The size of the pool (number of threads to create in the
/// pool).
///
/// </param>
/// <param name="priority">The priority to give to the threads in the pool. If
/// less than 'Thread.MIN_PRIORITY' it will be the same as the priority of
/// the calling thread.
///
/// </param>
/// <param name="name">The name of the pool. If null a default generic name is
/// chosen.
///
/// </param>
/// <seealso cref="NativeServices">
///
/// </seealso>
/// <seealso cref="CONCURRENCY_PROP_NAME">
///
/// </seealso>
public ThreadPool(int size, int priority, System.String name)
{
int i;
ThreadPoolThread t;
//System.String prop;
//int clevel;
// Initialize variables checking for special cases
if (size <= 0)
{
throw new System.ArgumentException("Pool must be of positive size");
}
if (priority < (int) System.Threading.ThreadPriority.Lowest)
{
poolPriority = (System.Int32) SupportClass.ThreadClass.Current().Priority;
}
else
{
poolPriority = (priority < (int) System.Threading.ThreadPriority.Highest)?priority:(int) System.Threading.ThreadPriority.Highest;
}
if (name == null)
{
poolName = "Anonymous ThreadPool";
}
else
{
poolName = name;
}
// Allocate internal variables
idle = new ThreadPoolThread[size];
nidle = 0;
// Create and start the threads
for (i = 0; i < size; i++)
{
t = new ThreadPoolThread(this, i, poolName + "-" + i);
t.Start();
}
}
/// <summary> Runs the run method of the specified target in an idle thread of this
/// pool. When the target's run method completes, the thread waiting on the
/// lock object is notified, if any. If there is currently no idle thread
/// the method will block until a thread of the pool becomes idle or the
/// calling thread is interrupted.
///
/// <P>This method is the same as <tt>runTarget(t,l,true,false)</tt>.
///
/// </summary>
/// <param name="t">The target. The 'run()' method of this object will be run in
/// an idle thread of the pool.
///
/// </param>
/// <param name="l">The lock object. A thread waiting on the lock of the 'l'
/// object will be notified, through the 'notify()' call, when the target's
/// run method completes. If null no thread is notified.
///
/// </param>
/// <returns> True if the target was submitted to some thread. False if no
/// idle thread could be found and the target was not submitted for
/// execution.
///
///
/// </returns>
public virtual bool runTarget(IThreadRunnable t, System.Object l)
{
return runTarget(t, l, false, false);
}
/// <summary> Runs the run method of the specified target in an idle thread of this
/// pool. When the target's run method completes, the thread waiting on the
/// lock object is notified, if any. If there is currently no idle thread
/// and the asynchronous mode is not used the method will block until a
/// thread of the pool becomes idle or the calling thread is
/// interrupted. If the asynchronous mode is used then the method will not
/// block and will return false.
///
/// <P>This method is the same as <tt>runTarget(t,l,async,false)</tt>.
///
/// </summary>
/// <param name="t">The target. The 'run()' method of this object will be run in
/// an idle thread of the pool.
///
/// </param>
/// <param name="l">The lock object. A thread waiting on the lock of the 'l'
/// object will be notified, through the 'notify()' call, when the target's
/// run method completes. If null no thread is notified.
///
/// </param>
/// <param name="async">If true the asynchronous mode will be used.
///
/// </param>
/// <returns> True if the target was submitted to some thread. False if no
/// idle thread could be found and the target was not submitted for
/// execution.
///
///
/// </returns>
public virtual bool runTarget(IThreadRunnable t, System.Object l, bool async)
{
return runTarget(t, l, async, false);
}
/// <summary> Runs the run method of the specified target in an idle thread of this
/// pool. When the target's run method completes, the thread waiting on the
/// lock object is notified, if any. If there is currently no idle thread
/// and the asynchronous mode is not used the method will block until a
/// thread of the pool becomes idle or the calling thread is
/// interrupted. If the asynchronous mode is used then the method will not
/// block and will return false.
///
/// </summary>
/// <param name="t">The target. The 'run()' method of this object will be run in
/// an idle thread of the pool.
///
/// </param>
/// <param name="l">The lock object. A thread waiting on the lock of the 'l'
/// object will be notified, through the 'notify()' call, when the target's
/// run method completes. If null no thread is notified.
///
/// </param>
/// <param name="async">If true the asynchronous mode will be used.
///
/// </param>
/// <param name="notifyAll">If true, threads waiting on the lock of the 'l' object
/// will be notified trough the 'notifyAll()' instead of the normal
/// 'notify()' call. This is not normally needed.
///
/// </param>
/// <returns> True if the target was submitted to some thread. False if no
/// idle thread could be found and the target was not submitted for
/// execution.
///
///
/// </returns>
public virtual bool runTarget(IThreadRunnable t, System.Object l, bool async, bool notifyAll)
{
ThreadPoolThread runner; // The thread to run the target
// Get a thread to run
runner = getIdle(async);
// If no runner return failure
if (runner == null)
return false;
// Set the runner
runner.setTarget(t, l, notifyAll);
return true;
}
/// <summary> Checks that no error or runtime exception in any target have occurred
/// so far. If an error or runtime exception has occurred in a target's run
/// method they are thrown by this method.
///
/// </summary>
/// <exception cref="Error">If an error condition has been thrown by a target
/// 'run()' method.
///
/// </exception>
/// <exception cref="RuntimeException">If a runtime exception has been thrown by a
/// target 'run()' method.
///
/// </exception>
public virtual void checkTargetErrors()
{
// Check for Error
if (targetE != null)
throw targetE;
// Check for RuntimeException
if (targetRE != null)
throw targetRE;
}
/// <summary> Clears the current target error conditions, if any. Note that a thread
/// in the pool might have set the error conditions since the last check
/// and that those error conditions will be lost. Likewise, before
/// returning from this method another thread might set the error
/// conditions. There is no guarantee that no error conditions exist when
/// returning from this method.
///
/// <P>In order to ensure that no error conditions exist when returning
/// from this method cooperation from the targets and the thread using this
/// pool is necessary (i.e. currently no targets running or waiting to
/// run).
///
/// </summary>
public virtual void clearTargetErrors()
{
// Clear the error and runtime exception conditions
targetE = null;
targetRE = null;
}
/// <summary> Puts the thread 't' in the idle list. The thread 't' should be in fact
/// idle and ready to accept a new target when it joins the idle list.
///
/// <P> An idle thread that is already in the list should never add itself
/// to the list before it is removed. For efficiency reasons there is no
/// check to see if the thread is already in the list of idle threads.
///
/// <P> If the idle list was empty 'notify()' will be called on the 'idle'
/// array, to wake up a thread that might be waiting (within the
/// 'getIdle()' method) on an idle thread to become available.
///
/// </summary>
/// <param name="t">The thread to put in the idle list.
///
/// </param>
private void putInIdleList(ThreadPoolThread t)
{
// NOTE: if already in idle => catastrophe! (should be OK since //
// this is private method)
// Lock the idle array to avoid races with 'getIdle()'
lock (idle)
{
idle[nidle] = t;
nidle++;
// If idle array was empty wakeup any waiting threads.
if (nidle == 1)
System.Threading.Monitor.Pulse(idle);
}
}
/// <summary> Returns and idle thread and removes it from the list of idle
/// threads. In asynchronous mode it will immediately return an idle
/// thread, or null if none is available. In non-asynchronous mode it will
/// block until a thread of the pool becomes idle or the calling thread is
/// interrupted.
///
/// <P>If in non-asynchronous mode and there are currently no idle threads
/// available the calling thread will wait on the 'idle' array lock, until
/// notified by 'putInIdleList()' that an idle thread might have become
/// available.
///
/// </summary>
/// <param name="async">If true asynchronous mode is used.
///
/// </param>
/// <returns> An idle thread of the pool, that has been removed from the idle
/// list, or null if none is available.
///
/// </returns>
private ThreadPoolThread getIdle(bool async)
{
// Lock the idle array to avoid races with 'putInIdleList()'
lock (idle)
{
if (async)
{
// In asynchronous mode just return null if no idle thread
if (nidle == 0)
return null;
}
else
{
// In synchronous mode wait until a thread becomes idle
while (nidle == 0)
{
try
{
System.Threading.Monitor.Wait(idle);
}
catch (System.Threading.ThreadInterruptedException)
{
// If we were interrupted just return null
return null;
}
}
}
// Decrease the idle count and return one of the idle threads
nidle--;
return idle[nidle];
}
}
}
}
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