condition.cpp

Pegasus is an open-source implementationof the DMTF CIM and WBEM standards. It is designed to be por

//%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.
//
//==============================================================================
//
//%/////////////////////////////////////////////////////////////////////////////

#include "Condition.h"
#include "PegasusAssert.h"

PEGASUS_NAMESPACE_BEGIN

//==============================================================================
//
// PEGASUS_HAVE_PTHREADS
//
//==============================================================================

#if defined(PEGASUS_HAVE_PTHREADS)

Condition::Condition()
{
    pthread_cond_init(&_rep.cond, NULL);
}

Condition::~Condition()
{
    pthread_cond_destroy(&_rep.cond);
}

void Condition::signal()
{
    pthread_cond_signal(&_rep.cond);
}

void Condition::wait(Mutex& lock)
{
    pthread_cond_wait(&_rep.cond, &lock._rep.mutex);
}

#endif /* PEGASUS_HAVE_PTHREADS */

//==============================================================================
//
// PEGASUS_HAVE_WINDOWS_THREADS
//
//==============================================================================

#if defined(PEGASUS_HAVE_WINDOWS_THREADS)

ConditionWaiter* _get_waiter()
{
    // ATTN: since Windows Thread Local Storage does not have a cleanup
    // routine mechanism, the ConditionWaiter object (and its event) will
    // be leaked when the thread exists.

    static DWORD _waiter_tls = TlsAlloc();

    // Obtain (or create) the waiter for this thread.

    ConditionWaiter* waiter = (ConditionWaiter*)TlsGetValue(_waiter_tls);

    if (waiter == 0)
    {
        waiter = new ConditionWaiter;
        waiter->event = CreateEvent(0, TRUE, FALSE, 0);
        PEGASUS_DEBUG_ASSERT(waiter->event != NULL);
        TlsSetValue(_waiter_tls, waiter);
    }

    return waiter;
}

Condition::Condition()
{
}

Condition::~Condition()
{
    // Remove all of the waiters without deleting them (they are owned by
    // the thread-local-storage slot defined above and should never be
    // deleted.

    while (_rep.waiters.size())
        _rep.waiters.remove_front();
}

void Condition::signal()
{
    // Remove the waiter at the front of the queue.

    ConditionWaiter* waiter = _rep.waiters.remove_front();

    if (waiter)
        SetEvent(waiter->event);
}

void Condition::wait(Mutex& mutex)
{
    // Insert this thread's waiter at end of waiters queue.

    ConditionWaiter* waiter = _get_waiter();
    _rep.waiters.insert_back(waiter);

    // Unlock the mutex.

    size_t count = mutex._rep.count;

    for (size_t i = 0; i < count; i++)
        mutex.unlock();

    // Wait for a signal.

    DWORD rc = WaitForSingleObject(waiter->event, INFINITE);
    PEGASUS_DEBUG_ASSERT(rc == WAIT_OBJECT_0);

    // Relock the mutex.

    for (size_t i = 0; i < count; i++)
        mutex.lock();

    // Reset the event.

    ResetEvent(waiter->event);
}

#endif /* PEGASUS_HAVE_WINDOWS_THREADS */

PEGASUS_NAMESPACE_END