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BUG#: 5314
TITLE: IPC Refactoring

DESCRIPTION: This patch cleans up the IPC related classes. It (1) reorganizes
related classes into their own headers, (2) makes the mutex class recursive to
eliminate recursive lock exclusion logic, (3) reimplements condition variables,
renames dozens of global functions.

//%2006////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2000, 2001, 2002 BMC Software; Hewlett-Packard Development
// Company, L.P.; IBM Corp.; The Open Group; Tivoli Systems.
// Copyright (c) 2003 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation, The Open Group.
// Copyright (c) 2004 BMC Software; Hewlett-Packard Development Company, L.P.;
// IBM Corp.; EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2005 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; VERITAS Software Corporation; The Open Group.
// Copyright (c) 2006 Hewlett-Packard Development Company, L.P.; IBM Corp.;
// EMC Corporation; Symantec Corporation; The Open Group.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// THE ABOVE COPYRIGHT NOTICE AND THIS PERMISSION NOTICE SHALL BE INCLUDED IN
// ALL COPIES OR SUBSTANTIAL PORTIONS OF THE SOFTWARE. THE SOFTWARE IS PROVIDED
// "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT
// LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
// HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//==============================================================================
//
// Author: Mike Day (mdday@us.ibm.com)
//
// Modified By: Markus Mueller
//              Roger Kumpf, Hewlett-Packard Company (roger_kumpf@hp.com)
//              Amit K Arora, IBM (amita@in.ibm.com) for PEP#101
//              David Dillard, VERITAS Software Corp.
//                  (david.dillard@veritas.com)
//              Sean Keenan, Hewlett-Packard Company (sean.keenan@hp.com)
//              Josephine Eskaline Joyce, IBM (jojustin@in.ibm.com) for Bug#2393
//
//%/////////////////////////////////////////////////////////////////////////////

#ifndef Pegasus_ThreadPool_h
#define Pegasus_ThreadPool_h

#include <Pegasus/Common/Config.h>
#include <Pegasus/Common/Linkage.h>
#include <Pegasus/Common/Thread.h>

PEGASUS_NAMESPACE_BEGIN 

class PEGASUS_COMMON_LINKAGE ThreadPool
{
public:

    /**
        Constructs a new ThreadPool object.
        @param initialSize The number of threads that are initially added to
            the thread pool.
        @param key A name for this thread pool that can be used to determine
            equality of two thread pool objects.  Only the first 16 characters
            of this value are used.
        @param minThreads The minimum number of threads that should be
            contained in this thread pool at any given time.
        @param maxThreads The maximum number of threads that should be
            contained in this thread pool at any given time.
        @param deallocateWait The minimum time that a thread should be idle
            before it is removed from the pool and cleaned up.
     */
    ThreadPool(Sint16 initialSize,
               const char *key,
               Sint16 minThreads,
               Sint16 maxThreads, struct timeval &deallocateWait);

    /**
        Destructs the ThreadPool object.
     */
     ~ThreadPool();

    /**
        Allocate and start a thread to do a unit of work.
        @param parm A generic parameter to pass to the thread
        @param work A pointer to the function that is to be executed by
                    the thread
        @param blocking A pointer to an optional semaphore which, if
                        specified, is signaled after the thread finishes
                        executing the work function
        @return PEGASUS_THREAD_OK if the thread is started successfully, 
		PEGASUS_THREAD_INSUFFICIENT_RESOURCES  if the
                resources necessary to start the thread are not currently
                available.  PEGASUS_THREAD_SETUP_FAILURE if the thread
                could not be setup properly. PEGASUS_THREAD_UNAVAILABLE
                if this service is shutting down and no more threads can
                be allocated.
        @exception IPCException
     */
    ThreadStatus allocate_and_awaken(void *parm,
                                     ThreadReturnType(PEGASUS_THREAD_CDECL *
                                                      work) (void *),
                                     Semaphore * blocking = 0);

    /**
        Cleans up idle threads if they have been running longer than the
        deallocate_wait configuration and more than the configured
        minimum number of threads is running.
        @return The number of threads that were cleaned up.
        @exception IPCException
     */
    Uint32 cleanupIdleThreads();

    void get_key(Sint8 * buf, int bufsize);

    inline void setMinThreads(Sint16 min)
    {
        _minThreads = min;
    }

    inline Sint16 getMinThreads() const
    {
        return _minThreads;
    }

    inline void setMaxThreads(Sint16 max)
    {
        _maxThreads = max;
    }

    inline Sint16 getMaxThreads() const
    {
        return _maxThreads;
    }

    inline Uint32 runningCount()
    {
        return _runningThreads.size();
    }

    inline Uint32 idleCount()
    {
        return _idleThreads.size();
    }

private:

    ThreadPool();               // Unimplemented
    ThreadPool(const ThreadPool &);     // Unimplemented
    ThreadPool & operator=(const ThreadPool &); // Unimplemented

    static ThreadReturnType PEGASUS_THREAD_CDECL _loop(void *);

    static Boolean _timeIntervalExpired(struct timeval *start,
                                        struct timeval *interval);

    static void _deleteSemaphore(void *p);

    void _cleanupThread(Thread * thread);
    Thread *_initializeThread();
    void _addToIdleThreadsQueue(Thread * th);

    Sint16 _maxThreads;
    Sint16 _minThreads;
    AtomicInt _currentThreads;
    struct timeval _deallocateWait;
    char _key[17];
    List < Thread, Mutex > _idleThreads;
    List < Thread, Mutex > _runningThreads;
    AtomicInt _dying;
};

PEGASUS_NAMESPACE_END

#endif // Pegasus_ThreadPool_h