851 lines
20 KiB
C++
851 lines
20 KiB
C++
///////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2005-2012, Industrial Light & Magic, a division of Lucas
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// Digital Ltd. LLC
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//
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Industrial Light & Magic nor the names of
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// its contributors may be used to endorse or promote products derived
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// from this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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//
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///////////////////////////////////////////////////////////////////////////
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//-----------------------------------------------------------------------------
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//
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// class Task, class ThreadPool, class TaskGroup
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//
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//-----------------------------------------------------------------------------
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#include "IlmThread.h"
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#include "IlmThreadMutex.h"
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#include "IlmThreadSemaphore.h"
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#include "IlmThreadPool.h"
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#include "Iex.h"
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#include <vector>
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#ifndef ILMBASE_FORCE_CXX03
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# include <memory>
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# include <atomic>
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# include <thread>
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#endif
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using namespace std;
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ILMTHREAD_INTERNAL_NAMESPACE_SOURCE_ENTER
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#if defined(__GNU_LIBRARY__) && ( __GLIBC__ < 2 || ( __GLIBC__ == 2 && __GLIBC_MINOR__ < 21 ) )
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# define ENABLE_SEM_DTOR_WORKAROUND
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#endif
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struct TaskGroup::Data
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{
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Data ();
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~Data ();
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void addTask () ;
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void removeTask ();
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#ifndef ILMBASE_FORCE_CXX03
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std::atomic<int> numPending;
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#else
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int numPending; // number of pending tasks to still execute
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#endif
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Semaphore isEmpty; // used to signal that the taskgroup is empty
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#if defined(ENABLE_SEM_DTOR_WORKAROUND) || defined(ILMBASE_FORCE_CXX03)
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// this mutex is also used to lock numPending in the legacy c++ mode...
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Mutex dtorMutex; // used to work around the glibc bug:
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// http://sources.redhat.com/bugzilla/show_bug.cgi?id=12674
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#endif
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};
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struct ThreadPool::Data
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{
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typedef ThreadPoolProvider *TPPointer;
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Data ();
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~Data();
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struct SafeProvider
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{
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SafeProvider (Data *d, ThreadPoolProvider *p) : _data( d ), _ptr( p )
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{
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}
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~SafeProvider()
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{
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if ( _data )
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_data->coalesceProviderUse();
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}
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SafeProvider (const SafeProvider &o)
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: _data( o._data ), _ptr( o._ptr )
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{
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if ( _data )
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_data->bumpProviderUse();
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}
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SafeProvider &operator= (const SafeProvider &o)
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{
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if ( this != &o )
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{
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if ( o._data )
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o._data->bumpProviderUse();
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if ( _data )
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_data->coalesceProviderUse();
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_data = o._data;
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_ptr = o._ptr;
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}
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return *this;
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}
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#ifndef ILMBASE_FORCE_CXX03
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SafeProvider( SafeProvider &&o )
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: _data( o._data ), _ptr( o._ptr )
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{
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o._data = nullptr;
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}
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SafeProvider &operator=( SafeProvider &&o )
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{
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std::swap( _data, o._data );
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std::swap( _ptr, o._ptr );
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return *this;
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}
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#endif
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inline ThreadPoolProvider *get () const
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{
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return _ptr;
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}
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ThreadPoolProvider *operator-> () const
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{
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return get();
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}
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Data *_data;
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ThreadPoolProvider *_ptr;
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};
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// NB: In C++20, there is full support for atomic shared_ptr, but that is not
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// yet in use or finalized. Once stabilized, add appropriate usage here
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inline SafeProvider getProvider ();
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inline void coalesceProviderUse ();
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inline void bumpProviderUse ();
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inline void setProvider (ThreadPoolProvider *p);
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#ifdef ILMBASE_FORCE_CXX03
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Semaphore provSem;
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Mutex provMutex;
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int provUsers;
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ThreadPoolProvider *provider;
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ThreadPoolProvider *oldprovider;
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#else
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std::atomic<ThreadPoolProvider *> provider;
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std::atomic<int> provUsers;
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#endif
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};
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namespace {
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class DefaultWorkerThread;
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struct DefaultWorkData
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{
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Semaphore taskSemaphore; // threads wait on this for ready tasks
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mutable Mutex taskMutex; // mutual exclusion for the tasks list
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vector<Task*> tasks; // the list of tasks to execute
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Semaphore threadSemaphore; // signaled when a thread starts executing
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mutable Mutex threadMutex; // mutual exclusion for threads list
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vector<DefaultWorkerThread*> threads; // the list of all threads
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#ifdef ILMBASE_FORCE_CXX03
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bool stopping; // flag indicating whether to stop threads
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mutable Mutex stopMutex; // mutual exclusion for stopping flag
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#else
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std::atomic<bool> hasThreads;
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std::atomic<bool> stopping;
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#endif
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inline bool stopped () const
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{
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#ifdef ILMBASE_FORCE_CXX03
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Lock lock (stopMutex);
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return stopping;
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#else
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return stopping.load( std::memory_order_relaxed );
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#endif
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}
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inline void stop ()
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{
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#ifdef ILMBASE_FORCE_CXX03
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Lock lock (stopMutex);
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#endif
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stopping = true;
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}
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};
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//
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// class WorkerThread
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//
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class DefaultWorkerThread: public Thread
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{
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public:
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DefaultWorkerThread (DefaultWorkData* data);
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virtual void run ();
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private:
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DefaultWorkData * _data;
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};
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DefaultWorkerThread::DefaultWorkerThread (DefaultWorkData* data):
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_data (data)
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{
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start();
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}
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void
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DefaultWorkerThread::run ()
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{
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//
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// Signal that the thread has started executing
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//
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_data->threadSemaphore.post();
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while (true)
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{
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//
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// Wait for a task to become available
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//
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_data->taskSemaphore.wait();
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{
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Lock taskLock (_data->taskMutex);
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//
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// If there is a task pending, pop off the next task in the FIFO
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//
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if (!_data->tasks.empty())
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{
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Task* task = _data->tasks.back();
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_data->tasks.pop_back();
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taskLock.release();
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TaskGroup* taskGroup = task->group();
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task->execute();
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delete task;
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taskGroup->_data->removeTask ();
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}
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else if (_data->stopped())
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{
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break;
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}
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}
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}
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}
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//
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// class DefaultThreadPoolProvider
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//
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class DefaultThreadPoolProvider : public ThreadPoolProvider
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{
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public:
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DefaultThreadPoolProvider(int count);
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virtual ~DefaultThreadPoolProvider();
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virtual int numThreads() const;
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virtual void setNumThreads(int count);
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virtual void addTask(Task *task);
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virtual void finish();
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private:
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DefaultWorkData _data;
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};
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DefaultThreadPoolProvider::DefaultThreadPoolProvider (int count)
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{
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setNumThreads(count);
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}
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DefaultThreadPoolProvider::~DefaultThreadPoolProvider ()
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{
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finish();
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}
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int
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DefaultThreadPoolProvider::numThreads () const
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{
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Lock lock (_data.threadMutex);
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return static_cast<int> (_data.threads.size());
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}
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void
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DefaultThreadPoolProvider::setNumThreads (int count)
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{
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//
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// Lock access to thread list and size
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//
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Lock lock (_data.threadMutex);
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size_t desired = static_cast<size_t>(count);
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if (desired > _data.threads.size())
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{
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//
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// Add more threads
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//
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while (_data.threads.size() < desired)
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_data.threads.push_back (new DefaultWorkerThread (&_data));
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}
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else if ((size_t)count < _data.threads.size())
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{
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//
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// Wait until all existing threads are finished processing,
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// then delete all threads.
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//
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finish ();
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//
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// Add in new threads
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//
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while (_data.threads.size() < desired)
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_data.threads.push_back (new DefaultWorkerThread (&_data));
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}
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#ifndef ILMBASE_FORCE_CXX03
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_data.hasThreads = !(_data.threads.empty());
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#endif
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}
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void
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DefaultThreadPoolProvider::addTask (Task *task)
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{
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//
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// Lock the threads, needed to access numThreads
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//
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#ifdef ILMBASE_FORCE_CXX03
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bool doPush;
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{
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Lock lock (_data.threadMutex);
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doPush = !_data.threads.empty();
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}
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#else
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bool doPush = _data.hasThreads.load( std::memory_order_relaxed );
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#endif
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if ( doPush )
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{
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//
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// Get exclusive access to the tasks queue
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//
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{
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Lock taskLock (_data.taskMutex);
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//
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// Push the new task into the FIFO
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//
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_data.tasks.push_back (task);
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}
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//
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// Signal that we have a new task to process
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//
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_data.taskSemaphore.post ();
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}
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else
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{
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// this path shouldn't normally happen since we have the
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// NullThreadPoolProvider, but just in case...
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task->execute ();
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task->group()->_data->removeTask ();
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delete task;
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}
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}
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void
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DefaultThreadPoolProvider::finish ()
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{
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_data.stop();
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//
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// Signal enough times to allow all threads to stop.
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//
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// Wait until all threads have started their run functions.
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// If we do not wait before we destroy the threads then it's
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// possible that the threads have not yet called their run
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// functions.
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// If this happens then the run function will be called off
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// of an invalid object and we will crash, most likely with
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// an error like: "pure virtual method called"
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//
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size_t curT = _data.threads.size();
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for (size_t i = 0; i != curT; ++i)
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{
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_data.taskSemaphore.post();
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_data.threadSemaphore.wait();
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}
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//
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// Join all the threads
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//
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for (size_t i = 0; i != curT; ++i)
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delete _data.threads[i];
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Lock lock1 (_data.taskMutex);
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#ifdef ILMBASE_FORCE_CXX03
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Lock lock2 (_data.stopMutex);
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#endif
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_data.threads.clear();
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_data.tasks.clear();
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_data.stopping = false;
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}
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class NullThreadPoolProvider : public ThreadPoolProvider
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{
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virtual ~NullThreadPoolProvider() {}
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virtual int numThreads () const { return 0; }
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virtual void setNumThreads (int count)
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{
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}
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virtual void addTask (Task *t)
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{
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t->execute ();
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t->group()->_data->removeTask ();
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delete t;
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}
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virtual void finish () {}
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};
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} //namespace
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//
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// struct TaskGroup::Data
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//
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TaskGroup::Data::Data (): isEmpty (1), numPending (0)
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{
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// empty
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}
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TaskGroup::Data::~Data ()
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{
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//
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// A TaskGroup acts like an "inverted" semaphore: if the count
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// is above 0 then waiting on the taskgroup will block. This
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// destructor waits until the taskgroup is empty before returning.
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//
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isEmpty.wait ();
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#ifdef ENABLE_SEM_DTOR_WORKAROUND
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// Update: this was fixed in v. 2.2.21, so this ifdef checks for that
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//
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// Alas, given the current bug in glibc we need a secondary
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// syncronisation primitive here to account for the fact that
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// destructing the isEmpty Semaphore in this thread can cause
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// an error for a separate thread that is issuing the post() call.
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// We are entitled to destruct the semaphore at this point, however,
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// that post() call attempts to access data out of the associated
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// memory *after* it has woken the waiting threads, including this one,
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// potentially leading to invalid memory reads.
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// http://sources.redhat.com/bugzilla/show_bug.cgi?id=12674
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Lock lock (dtorMutex);
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#endif
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}
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void
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TaskGroup::Data::addTask ()
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{
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//
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// in c++11, we use an atomic to protect numPending to avoid the
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// extra lock but for c++98, to add the ability for custom thread
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// pool we add the lock here
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//
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#if ILMBASE_FORCE_CXX03
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Lock lock (dtorMutex);
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#endif
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if (numPending++ == 0)
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isEmpty.wait ();
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}
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void
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TaskGroup::Data::removeTask ()
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{
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// Alas, given the current bug in glibc we need a secondary
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// syncronisation primitive here to account for the fact that
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// destructing the isEmpty Semaphore in a separate thread can
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// cause an error. Issuing the post call here the current libc
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// implementation attempts to access memory *after* it has woken
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// waiting threads.
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// Since other threads are entitled to delete the semaphore the
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// access to the memory location can be invalid.
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// http://sources.redhat.com/bugzilla/show_bug.cgi?id=12674
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// Update: this bug has been fixed, but how do we know which
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// glibc version we're in?
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// Further update:
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//
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// we could remove this if it is a new enough glibc, however
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// we've changed the API to enable a custom override of a
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// thread pool. In order to provide safe access to the numPending,
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// we need the lock anyway, except for c++11 or newer
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#ifdef ILMBASE_FORCE_CXX03
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Lock lock (dtorMutex);
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if (--numPending == 0)
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isEmpty.post ();
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#else
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if (--numPending == 0)
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{
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#ifdef ENABLE_SEM_DTOR_WORKAROUND
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Lock lock (dtorMutex);
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#endif
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isEmpty.post ();
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}
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#endif
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}
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//
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// struct ThreadPool::Data
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//
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ThreadPool::Data::Data ():
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provUsers (0), provider (NULL)
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#ifdef ILMBASE_FORCE_CXX03
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, oldprovider (NULL)
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#else
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#endif
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{
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// empty
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}
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ThreadPool::Data::~Data()
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{
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#ifdef ILMBASE_FORCE_CXX03
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provider->finish();
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#else
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ThreadPoolProvider *p = provider.load( std::memory_order_relaxed );
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p->finish();
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#endif
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}
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inline ThreadPool::Data::SafeProvider
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ThreadPool::Data::getProvider ()
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{
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#ifdef ILMBASE_FORCE_CXX03
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Lock provLock( provMutex );
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++provUsers;
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return SafeProvider( this, provider );
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#else
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provUsers.fetch_add( 1, std::memory_order_relaxed );
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return SafeProvider( this, provider.load( std::memory_order_relaxed ) );
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#endif
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}
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inline void
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ThreadPool::Data::coalesceProviderUse ()
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{
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#ifdef ILMBASE_FORCE_CXX03
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Lock provLock( provMutex );
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--provUsers;
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if ( provUsers == 0 )
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{
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if ( oldprovider )
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provSem.post();
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}
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#else
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int ov = provUsers.fetch_sub( 1, std::memory_order_relaxed );
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// ov is the previous value, so one means that now it might be 0
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if ( ov == 1 )
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{
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}
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#endif
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}
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inline void
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ThreadPool::Data::bumpProviderUse ()
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{
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#ifdef ILMBASE_FORCE_CXX03
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Lock lock (provMutex);
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++provUsers;
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|
#else
|
|
provUsers.fetch_add( 1, std::memory_order_relaxed );
|
|
#endif
|
|
}
|
|
|
|
|
|
inline void
|
|
ThreadPool::Data::setProvider (ThreadPoolProvider *p)
|
|
{
|
|
#ifdef ILMBASE_FORCE_CXX03
|
|
Lock provLock( provMutex );
|
|
|
|
if ( oldprovider )
|
|
throw IEX_INTERNAL_NAMESPACE::ArgExc ("Attempt to set the thread pool provider while"
|
|
" another thread is currently setting the provider.");
|
|
|
|
oldprovider = provider;
|
|
provider = p;
|
|
|
|
while ( provUsers > 0 )
|
|
{
|
|
provLock.release();
|
|
provSem.wait();
|
|
provLock.acquire();
|
|
}
|
|
if ( oldprovider )
|
|
{
|
|
oldprovider->finish();
|
|
delete oldprovider;
|
|
oldprovider = NULL;
|
|
}
|
|
#else
|
|
ThreadPoolProvider *old = provider.load( std::memory_order_relaxed );
|
|
do
|
|
{
|
|
if ( ! provider.compare_exchange_weak( old, p, std::memory_order_release, std::memory_order_relaxed ) )
|
|
continue;
|
|
} while ( false );
|
|
|
|
// wait for any other users to finish prior to deleting, given
|
|
// that these are just mostly to query the thread count or push a
|
|
// task to the queue (so fast), just spin...
|
|
//
|
|
// (well, and normally, people don't do this mid stream anyway, so
|
|
// this will be 0 99.999% of the time, but just to be safe)
|
|
//
|
|
while ( provUsers.load( std::memory_order_relaxed ) > 0 )
|
|
std::this_thread::yield();
|
|
|
|
if ( old )
|
|
{
|
|
old->finish();
|
|
delete old;
|
|
}
|
|
|
|
// NB: the shared_ptr mechanism is safer and means we don't have
|
|
// to have the provUsers counter since the shared_ptr keeps that
|
|
// for us. However, gcc 4.8/9 compilers which many people are
|
|
// still using even though it is 2018 forgot to add the shared_ptr
|
|
// functions... once that compiler is fully deprecated, switch to
|
|
// using the below, change provider to a std::shared_ptr and remove
|
|
// provUsers...
|
|
//
|
|
// std::shared_ptr<ThreadPoolProvider> newp( p );
|
|
// std::shared_ptr<ThreadPoolProvider> curp = std::atomic_load_explicit( &provider, std::memory_order_relaxed );
|
|
// do
|
|
// {
|
|
// if ( ! std::atomic_compare_exchange_weak_explicit( &provider, &curp, newp, std::memory_order_release, std::memory_order_relaxed ) )
|
|
// continue;
|
|
// } while ( false );
|
|
// if ( curp )
|
|
// curp->finish();
|
|
#endif
|
|
}
|
|
|
|
//
|
|
// class Task
|
|
//
|
|
|
|
Task::Task (TaskGroup* g): _group(g)
|
|
{
|
|
if ( g )
|
|
g->_data->addTask ();
|
|
}
|
|
|
|
|
|
Task::~Task()
|
|
{
|
|
// empty
|
|
}
|
|
|
|
|
|
TaskGroup*
|
|
Task::group ()
|
|
{
|
|
return _group;
|
|
}
|
|
|
|
|
|
TaskGroup::TaskGroup ():
|
|
_data (new Data())
|
|
{
|
|
// empty
|
|
}
|
|
|
|
|
|
TaskGroup::~TaskGroup ()
|
|
{
|
|
delete _data;
|
|
}
|
|
|
|
|
|
void
|
|
TaskGroup::finishOneTask ()
|
|
{
|
|
_data->removeTask ();
|
|
}
|
|
|
|
//
|
|
// class ThreadPoolProvider
|
|
//
|
|
|
|
|
|
ThreadPoolProvider::ThreadPoolProvider()
|
|
{
|
|
}
|
|
|
|
|
|
ThreadPoolProvider::~ThreadPoolProvider()
|
|
{
|
|
}
|
|
|
|
|
|
//
|
|
// class ThreadPool
|
|
//
|
|
|
|
ThreadPool::ThreadPool (unsigned nthreads):
|
|
_data (new Data)
|
|
{
|
|
if ( nthreads == 0 )
|
|
_data->setProvider( new NullThreadPoolProvider );
|
|
else
|
|
_data->setProvider( new DefaultThreadPoolProvider( int(nthreads) ) );
|
|
}
|
|
|
|
|
|
ThreadPool::~ThreadPool ()
|
|
{
|
|
delete _data;
|
|
}
|
|
|
|
|
|
int
|
|
ThreadPool::numThreads () const
|
|
{
|
|
return _data->getProvider ()->numThreads ();
|
|
}
|
|
|
|
|
|
void
|
|
ThreadPool::setNumThreads (int count)
|
|
{
|
|
if (count < 0)
|
|
throw IEX_INTERNAL_NAMESPACE::ArgExc ("Attempt to set the number of threads "
|
|
"in a thread pool to a negative value.");
|
|
|
|
bool doReset = false;
|
|
{
|
|
Data::SafeProvider sp = _data->getProvider ();
|
|
int curT = sp->numThreads ();
|
|
if ( curT == count )
|
|
return;
|
|
|
|
if ( curT == 0 )
|
|
{
|
|
NullThreadPoolProvider *npp = dynamic_cast<NullThreadPoolProvider *>( sp.get() );
|
|
if ( npp )
|
|
doReset = true;
|
|
}
|
|
else if ( count == 0 )
|
|
{
|
|
DefaultThreadPoolProvider *dpp = dynamic_cast<DefaultThreadPoolProvider *>( sp.get() );
|
|
if ( dpp )
|
|
doReset = true;
|
|
}
|
|
if ( ! doReset )
|
|
sp->setNumThreads( count );
|
|
}
|
|
|
|
if ( doReset )
|
|
{
|
|
if ( count == 0 )
|
|
_data->setProvider( new NullThreadPoolProvider );
|
|
else
|
|
_data->setProvider( new DefaultThreadPoolProvider( count ) );
|
|
}
|
|
}
|
|
|
|
|
|
void
|
|
ThreadPool::setThreadProvider (ThreadPoolProvider *provider)
|
|
{
|
|
_data->setProvider (provider);
|
|
}
|
|
|
|
|
|
void
|
|
ThreadPool::addTask (Task* task)
|
|
{
|
|
_data->getProvider ()->addTask (task);
|
|
}
|
|
|
|
|
|
ThreadPool&
|
|
ThreadPool::globalThreadPool ()
|
|
{
|
|
//
|
|
// The global thread pool
|
|
//
|
|
|
|
static ThreadPool gThreadPool (0);
|
|
|
|
return gThreadPool;
|
|
}
|
|
|
|
|
|
void
|
|
ThreadPool::addGlobalTask (Task* task)
|
|
{
|
|
globalThreadPool().addTask (task);
|
|
}
|
|
|
|
|
|
ILMTHREAD_INTERNAL_NAMESPACE_SOURCE_EXIT
|