ThreadBarrier.cpp

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00001 /*******************************************************************************
00002 * Copyright (C) 2004 Vintela, Inc. All rights reserved.
00003 * Copyright (C) 2005 Novell, Inc. All rights reserved.
00004 *
00005 * Redistribution and use in source and binary forms, with or without
00006 * modification, are permitted provided that the following conditions are met:
00007 *
00008 *  - Redistributions of source code must retain the above copyright notice,
00009 *    this list of conditions and the following disclaimer.
00010 *
00011 *  - Redistributions in binary form must reproduce the above copyright notice,
00012 *    this list of conditions and the following disclaimer in the documentation
00013 *    and/or other materials provided with the distribution.
00014 *
00015 *  - Neither the name of Vintela, Inc., Novell, Inc., nor the names of its
00016 *    contributors may be used to endorse or promote products derived from this
00017 *    software without specific prior written permission.
00018 *
00019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS''
00020 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00021 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00022 * ARE DISCLAIMED. IN NO EVENT SHALL Vintela, Inc., Novell, Inc., OR THE 
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00029 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00030 *******************************************************************************/
00031 
00032 
00037 #include "blocxx/BLOCXX_config.h"
00038 #include "blocxx/ThreadBarrier.hpp"
00039 #include "blocxx/Assertion.hpp"
00040 #include "blocxx/Format.hpp"
00041 #include "blocxx/ExceptionIds.hpp"
00042 #include "blocxx/IntrusiveCountableBase.hpp"
00043 
00044 #if defined(BLOCXX_USE_PTHREAD) && defined(BLOCXX_HAVE_PTHREAD_BARRIER) && !defined(BLOCXX_VALGRIND_SUPPORT)
00045  #include <pthread.h>
00046 #else
00047  // This is for the generic less-efficient version
00048  #include "blocxx/Condition.hpp"
00049  #include "blocxx/NonRecursiveMutex.hpp"
00050  #include "blocxx/NonRecursiveMutexLock.hpp"
00051 #endif
00052 
00054 namespace BLOCXX_NAMESPACE
00055 {
00056 
00057 BLOCXX_DEFINE_EXCEPTION_WITH_ID(ThreadBarrier);
00058 
00059 #if defined(BLOCXX_USE_PTHREAD) && defined(BLOCXX_HAVE_PTHREAD_BARRIER) && !defined(BLOCXX_VALGRIND_SUPPORT) // valgrind doesn't support pthread_barrier_*()
00060 class ThreadBarrierImpl : public IntrusiveCountableBase
00061 {
00062 public:
00063    ThreadBarrierImpl(UInt32 threshold)
00064    {
00065       BLOCXX_ASSERT(threshold != 0);
00066       int res = pthread_barrier_init(&barrier, NULL, threshold);
00067       if (res != 0)
00068       {
00069          BLOCXX_THROW(ThreadBarrierException, Format("pthread_barrier_init failed: %1(%2)", res, strerror(res)).c_str());
00070       }
00071    }
00072    ~ThreadBarrierImpl()
00073    {
00074       int res = pthread_barrier_destroy(&barrier);
00075       if (res != 0)
00076       {
00077          // can't throw... just log it or something...
00078       }
00079    }
00080    
00081    void wait()
00082    {
00083       int res = pthread_barrier_wait(&barrier);
00084       if (res != 0 && res != PTHREAD_BARRIER_SERIAL_THREAD)
00085       {
00086          BLOCXX_THROW(ThreadBarrierException, Format("pthread_barrier_wait failed: %1(%2)", res, strerror(res)).c_str());
00087       }
00088    }
00089 private: 
00090    pthread_barrier_t barrier;
00091 };
00092 
00093 #else
00094 
00095 // This is the generic less-efficient version
00096 
00097 class ThreadBarrierImpl : public IntrusiveCountableBase
00098 {
00099 public:
00110    struct SubBarrier
00111    {
00112       SubBarrier() : m_waitingCount(0) {}
00114       UInt32 m_waitingCount;
00116       Condition m_cond;
00117    };
00118    ThreadBarrierImpl(UInt32 threshold)
00119       : m_threshold(threshold)
00120          , m_curSubBarrier(0)
00121    {
00122    }
00123    void wait()
00124    {
00125       NonRecursiveMutexLock l(m_mutex);
00126       // Select the current SubBarrier
00127       SubBarrier& curBarrier = m_curSubBarrier?m_subBarrier0:m_subBarrier1;
00128       ++curBarrier.m_waitingCount;
00129       if (curBarrier.m_waitingCount == m_threshold)
00130       {
00131          // reset the sub barrier so it can be reused
00132          curBarrier.m_waitingCount = 0;
00133          // swap current barriers
00134          m_curSubBarrier = 1 - m_curSubBarrier;
00135          // now wake up all the threads that were stopped
00136          curBarrier.m_cond.notifyAll();
00137       }
00138       else
00139       {
00140          // because of spurious wake-ups we need to put this in a loop.
00141          // we need to wait until the count is 0, which will only happen
00142          // once m_threshold threads have called wait()
00143          while (curBarrier.m_waitingCount != 0)
00144          {
00145             curBarrier.m_cond.wait(l);
00146          }
00147       }
00148    }
00149 private:
00151    UInt32 m_threshold;
00154    int m_curSubBarrier;
00155    NonRecursiveMutex m_mutex;
00156    SubBarrier m_subBarrier0;
00157    SubBarrier m_subBarrier1;
00158 };
00159 
00160 #endif
00161 
00163 ThreadBarrier::ThreadBarrier(UInt32 threshold)
00164    : m_impl(new ThreadBarrierImpl(threshold))
00165 {
00166    BLOCXX_ASSERT(threshold != 0);
00167 }
00169 void ThreadBarrier::wait()
00170 {
00171    m_impl->wait();
00172 }
00174 ThreadBarrier::~ThreadBarrier()
00175 {
00176 }
00178 ThreadBarrier::ThreadBarrier(const ThreadBarrier& x)
00179    : m_impl(x.m_impl)
00180 {
00181 }
00183 ThreadBarrier& ThreadBarrier::operator=(const ThreadBarrier& x)
00184 {
00185    m_impl = x.m_impl;
00186    return *this;
00187 }
00188 
00189 } // end namespace BLOCXX_NAMESPACE
00190 

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