Update bullet to Master 12409f1118a7c7a266f9071350c70789dfe73bb9

thirdparty/bullet/LinearMath/TaskScheduler/btTaskScheduler.cpp

@@ -0,0 +1,802 @@
+
+#include "LinearMath/btMinMax.h"
+#include "LinearMath/btAlignedObjectArray.h"
+#include "LinearMath/btThreads.h"
+#include "LinearMath/btQuickprof.h"
+#include <stdio.h>
+#include <algorithm>
+
+
+
+#if BT_THREADSAFE
+
+#include "btThreadSupportInterface.h"
+
+#if defined( _WIN32 )
+
+#define WIN32_LEAN_AND_MEAN
+
+#include <windows.h>
+
+#endif
+
+
+typedef unsigned long long btU64;
+static const int kCacheLineSize = 64;
+
+void btSpinPause()
+{
+#if defined( _WIN32 )
+    YieldProcessor();
+#endif
+}
+
+
+struct WorkerThreadStatus
+{
+    enum Type
+    {
+        kInvalid,
+        kWaitingForWork,
+        kWorking,
+        kSleeping,
+    };
+};
+
+
+ATTRIBUTE_ALIGNED64(class) WorkerThreadDirectives
+{
+    static const int kMaxThreadCount = BT_MAX_THREAD_COUNT;
+    // directives for all worker threads packed into a single cacheline
+    char m_threadDirs[kMaxThreadCount];
+
+public:
+    enum Type
+    {
+        kInvalid,
+        kGoToSleep,         // go to sleep
+        kStayAwakeButIdle,  // wait for not checking job queue
+        kScanForJobs,       // actively scan job queue for jobs
+    };
+    WorkerThreadDirectives()
+    {
+        for ( int i = 0; i < kMaxThreadCount; ++i )
+        {
+            m_threadDirs[ i ] = 0;
+        }
+    }
+
+    Type getDirective(int threadId)
+    {
+        btAssert(threadId < kMaxThreadCount);
+        return static_cast<Type>(m_threadDirs[threadId]);
+    }
+
+    void setDirectiveByRange(int threadBegin, int threadEnd, Type dir)
+    {
+        btAssert( threadBegin < threadEnd );
+        btAssert( threadEnd <= kMaxThreadCount );
+        char dirChar = static_cast<char>(dir);
+        for ( int i = threadBegin; i < threadEnd; ++i )
+        {
+            m_threadDirs[ i ] = dirChar;
+        }
+    }
+};
+
+class JobQueue;
+
+ATTRIBUTE_ALIGNED64(struct) ThreadLocalStorage
+{
+    int m_threadId;
+    WorkerThreadStatus::Type m_status;
+    int m_numJobsFinished;
+    btSpinMutex m_mutex;
+    btScalar m_sumResult;
+    WorkerThreadDirectives * m_directive;
+    JobQueue* m_queue;
+    btClock* m_clock;
+    unsigned int m_cooldownTime;
+};
+
+
+struct IJob
+{
+    virtual void executeJob(int threadId) = 0;
+};
+
+class ParallelForJob : public IJob
+{
+    const btIParallelForBody* m_body;
+    int m_begin;
+    int m_end;
+
+public:
+    ParallelForJob( int iBegin, int iEnd, const btIParallelForBody& body )
+    {
+        m_body = &body;
+        m_begin = iBegin;
+        m_end = iEnd;
+    }
+    virtual void executeJob(int threadId) BT_OVERRIDE
+    {
+        BT_PROFILE( "executeJob" );
+
+        // call the functor body to do the work
+        m_body->forLoop( m_begin, m_end );
+    }
+};
+
+
+class ParallelSumJob : public IJob
+{
+    const btIParallelSumBody* m_body;
+    ThreadLocalStorage* m_threadLocalStoreArray;
+    int m_begin;
+    int m_end;
+
+public:
+    ParallelSumJob( int iBegin, int iEnd, const btIParallelSumBody& body, ThreadLocalStorage* tls )
+    {
+        m_body = &body;
+        m_threadLocalStoreArray = tls;
+        m_begin = iBegin;
+        m_end = iEnd;
+    }
+    virtual void executeJob( int threadId ) BT_OVERRIDE
+    {
+        BT_PROFILE( "executeJob" );
+
+        // call the functor body to do the work
+        btScalar val = m_body->sumLoop( m_begin, m_end );
+#if BT_PARALLEL_SUM_DETERMINISTISM
+        // by truncating bits of the result, we can make the parallelSum deterministic (at the expense of precision)
+        const float TRUNC_SCALE = float(1<<19);
+        val = floor(val*TRUNC_SCALE+0.5f)/TRUNC_SCALE;  // truncate some bits
+#endif
+        m_threadLocalStoreArray[threadId].m_sumResult += val;
+    }
+};
+
+
+ATTRIBUTE_ALIGNED64(class) JobQueue
+{
+    btThreadSupportInterface* m_threadSupport;
+    btCriticalSection* m_queueLock;
+    btSpinMutex m_mutex;
+
+    btAlignedObjectArray<IJob*> m_jobQueue;
+    char* m_jobMem;
+    int m_jobMemSize;
+    bool m_queueIsEmpty;
+    int m_tailIndex;
+    int m_headIndex;
+    int m_allocSize;
+    bool m_useSpinMutex;
+    btAlignedObjectArray<JobQueue*> m_neighborContexts;
+    char m_cachePadding[kCacheLineSize];  // prevent false sharing
+
+    void freeJobMem()
+    {
+        if ( m_jobMem )
+        {
+            // free old
+            btAlignedFree(m_jobMem);
+            m_jobMem = NULL;
+        }
+    }
+    void resizeJobMem(int newSize)
+    {
+        if (newSize > m_jobMemSize)
+        {
+            freeJobMem();
+            m_jobMem = static_cast<char*>(btAlignedAlloc(newSize, kCacheLineSize));
+            m_jobMemSize = newSize;
+        }
+    }
+
+public:
+
+    JobQueue()
+    {
+        m_jobMem = NULL;
+        m_jobMemSize = 0;
+        m_threadSupport = NULL;
+        m_queueLock = NULL;
+        m_headIndex = 0;
+        m_tailIndex = 0;
+        m_useSpinMutex = false;
+    }
+    ~JobQueue()
+    {
+		exit();
+    }
+	void exit()
+    {
+		freeJobMem();
+        if (m_queueLock && m_threadSupport)
+        {
+            m_threadSupport->deleteCriticalSection(m_queueLock);
+            m_queueLock = NULL;
+			m_threadSupport = 0;
+        }
+	}
+
+    void init(btThreadSupportInterface* threadSup, btAlignedObjectArray<JobQueue>* contextArray)
+    {
+        m_threadSupport = threadSup;
+        if (threadSup)
+        {
+            m_queueLock = m_threadSupport->createCriticalSection();
+        }
+        setupJobStealing(contextArray, contextArray->size());
+    }
+    void setupJobStealing(btAlignedObjectArray<JobQueue>* contextArray, int numActiveContexts)
+    {
+        btAlignedObjectArray<JobQueue>& contexts = *contextArray;
+        int selfIndex = 0;
+        for (int i = 0; i < contexts.size(); ++i)
+        {
+            if ( this == &contexts[ i ] )
+            {
+                selfIndex = i;
+                break;
+            }
+        }
+        int numNeighbors = btMin(2, contexts.size() - 1);
+        int neighborOffsets[ ] = {-1, 1, -2, 2, -3, 3};
+        int numOffsets = sizeof(neighborOffsets)/sizeof(neighborOffsets[0]);
+        m_neighborContexts.reserve( numNeighbors );
+        m_neighborContexts.resizeNoInitialize(0);
+        for (int i = 0; i < numOffsets && m_neighborContexts.size() < numNeighbors; i++)
+        {
+            int neighborIndex = selfIndex + neighborOffsets[i];
+            if ( neighborIndex >= 0 && neighborIndex < numActiveContexts)
+            {
+                m_neighborContexts.push_back( &contexts[ neighborIndex ] );
+            }
+        }
+    }
+
+    bool isQueueEmpty() const {return m_queueIsEmpty;}
+    void lockQueue()
+    {
+        if ( m_useSpinMutex )
+        {
+            m_mutex.lock();
+        }
+        else
+        {
+            m_queueLock->lock();
+        }
+    }
+    void unlockQueue()
+    {
+        if ( m_useSpinMutex )
+        {
+            m_mutex.unlock();
+        }
+        else
+        {
+            m_queueLock->unlock();
+        }
+    }
+    void clearQueue(int jobCount, int jobSize)
+    {
+        lockQueue();
+        m_headIndex = 0;
+        m_tailIndex = 0;
+        m_allocSize = 0;
+        m_queueIsEmpty = true;
+        int jobBufSize = jobSize * jobCount;
+        // make sure we have enough memory allocated to store jobs
+        if ( jobBufSize > m_jobMemSize )
+        {
+            resizeJobMem( jobBufSize );
+        }
+        // make sure job queue is big enough
+        if ( jobCount > m_jobQueue.capacity() )
+        {
+            m_jobQueue.reserve( jobCount );
+        }
+        unlockQueue();
+        m_jobQueue.resizeNoInitialize( 0 );
+    }
+    void* allocJobMem(int jobSize)
+    {
+        btAssert(m_jobMemSize >= (m_allocSize + jobSize));
+        void* jobMem = &m_jobMem[m_allocSize];
+        m_allocSize += jobSize;
+        return jobMem;
+    }
+    void submitJob( IJob* job )
+    {
+        btAssert( reinterpret_cast<char*>( job ) >= &m_jobMem[ 0 ] && reinterpret_cast<char*>( job ) < &m_jobMem[ 0 ] + m_allocSize );
+        m_jobQueue.push_back( job );
+        lockQueue();
+        m_tailIndex++;
+        m_queueIsEmpty = false;
+        unlockQueue();
+    }
+    IJob* consumeJobFromOwnQueue()
+    {
+        if ( m_queueIsEmpty )
+        {
+            // lock free path. even if this is taken erroneously it isn't harmful
+            return NULL;
+        }
+        IJob* job = NULL;
+        lockQueue();
+        if ( !m_queueIsEmpty )
+        {
+            job = m_jobQueue[ m_headIndex++ ];
+            btAssert( reinterpret_cast<char*>( job ) >= &m_jobMem[ 0 ] && reinterpret_cast<char*>( job ) < &m_jobMem[ 0 ] + m_allocSize );
+            if ( m_headIndex == m_tailIndex )
+            {
+                m_queueIsEmpty = true;
+            }
+        }
+        unlockQueue();
+        return job;
+    }
+    IJob* consumeJob()
+    {
+        if (IJob* job = consumeJobFromOwnQueue())
+        {
+            return job;
+        }
+        // own queue is empty, try to steal from neighbor
+        for (int i = 0; i < m_neighborContexts.size(); ++i)
+        {
+            JobQueue* otherContext = m_neighborContexts[ i ];
+            if ( IJob* job = otherContext->consumeJobFromOwnQueue() )
+            {
+                return job;
+            }
+        }
+        return NULL;
+    }
+};
+
+
+static void WorkerThreadFunc( void* userPtr )
+{
+    BT_PROFILE( "WorkerThreadFunc" );
+    ThreadLocalStorage* localStorage = (ThreadLocalStorage*) userPtr;
+    JobQueue* jobQueue = localStorage->m_queue;
+
+    bool shouldSleep = false;
+    int threadId = localStorage->m_threadId;
+    while (! shouldSleep)
+    {
+        // do work
+        localStorage->m_mutex.lock();
+        while ( IJob* job = jobQueue->consumeJob() )
+        {
+            localStorage->m_status = WorkerThreadStatus::kWorking;
+            job->executeJob( threadId );
+            localStorage->m_numJobsFinished++;
+        }
+        localStorage->m_status = WorkerThreadStatus::kWaitingForWork;
+        localStorage->m_mutex.unlock();
+        btU64 clockStart = localStorage->m_clock->getTimeMicroseconds();
+        // while queue is empty,
+        while (jobQueue->isQueueEmpty())
+        {
+            // todo: spin wait a bit to avoid hammering the empty queue
+            btSpinPause();
+            if ( localStorage->m_directive->getDirective(threadId) == WorkerThreadDirectives::kGoToSleep )
+            {
+                shouldSleep = true;
+                break;
+            }
+            // if jobs are incoming,
+            if ( localStorage->m_directive->getDirective( threadId ) == WorkerThreadDirectives::kScanForJobs )
+            {
+                clockStart = localStorage->m_clock->getTimeMicroseconds(); // reset clock
+            }
+            else
+            {
+                for ( int i = 0; i < 50; ++i )
+                {
+                    btSpinPause();
+                    btSpinPause();
+                    btSpinPause();
+                    btSpinPause();
+                    if (localStorage->m_directive->getDirective( threadId ) == WorkerThreadDirectives::kScanForJobs || !jobQueue->isQueueEmpty())
+                    {
+                        break;
+                    }
+                }
+                // if no jobs incoming and queue has been empty for the cooldown time, sleep
+                btU64 timeElapsed = localStorage->m_clock->getTimeMicroseconds() - clockStart;
+                if (timeElapsed > localStorage->m_cooldownTime)
+                {
+                    shouldSleep = true;
+                    break;
+                }
+            }
+        }
+    }
+	{
+		BT_PROFILE("sleep");
+		// go sleep
+		localStorage->m_mutex.lock();
+		localStorage->m_status = WorkerThreadStatus::kSleeping;
+		localStorage->m_mutex.unlock();
+	}
+}
+
+
+class btTaskSchedulerDefault : public btITaskScheduler
+{
+    btThreadSupportInterface* m_threadSupport;
+    WorkerThreadDirectives* m_workerDirective;
+    btAlignedObjectArray<JobQueue> m_jobQueues;
+    btAlignedObjectArray<JobQueue*> m_perThreadJobQueues;
+    btAlignedObjectArray<ThreadLocalStorage> m_threadLocalStorage;
+    btSpinMutex m_antiNestingLock;  // prevent nested parallel-for
+    btClock m_clock;
+    int m_numThreads;
+    int m_numWorkerThreads;
+    int m_numActiveJobQueues;
+    int m_maxNumThreads;
+    int m_numJobs;
+    static const int kFirstWorkerThreadId = 1;
+public:
+
+    btTaskSchedulerDefault() : btITaskScheduler("ThreadSupport")
+    {
+        m_threadSupport = NULL;
+        m_workerDirective = NULL;
+    }
+
+    virtual ~btTaskSchedulerDefault()
+    {
+        waitForWorkersToSleep();
+
+		for ( int i = 0; i < m_jobQueues.size(); ++i )
+        {
+            m_jobQueues[i].exit();
+        }
+
+        if (m_threadSupport)
+        {
+            delete m_threadSupport;
+            m_threadSupport = NULL;
+        }
+        if (m_workerDirective)
+        {
+            btAlignedFree(m_workerDirective);
+            m_workerDirective = NULL;
+        }
+    }
+
+    void init()
+    {
+        btThreadSupportInterface::ConstructionInfo constructionInfo( "TaskScheduler", WorkerThreadFunc );
+        m_threadSupport = btThreadSupportInterface::create( constructionInfo );
+        m_workerDirective = static_cast<WorkerThreadDirectives*>(btAlignedAlloc(sizeof(*m_workerDirective), 64));
+
+        m_numWorkerThreads = m_threadSupport->getNumWorkerThreads();
+        m_maxNumThreads = m_threadSupport->getNumWorkerThreads() + 1;
+        m_numThreads = m_maxNumThreads;
+        // ideal to have one job queue for each physical processor (except for the main thread which needs no queue)
+        int numThreadsPerQueue = m_threadSupport->getLogicalToPhysicalCoreRatio();
+        int numJobQueues = (numThreadsPerQueue == 1) ? (m_maxNumThreads-1) : (m_maxNumThreads / numThreadsPerQueue);
+        m_jobQueues.resize(numJobQueues);
+        m_numActiveJobQueues = numJobQueues;
+        for ( int i = 0; i < m_jobQueues.size(); ++i )
+        {
+            m_jobQueues[i].init( m_threadSupport, &m_jobQueues );
+        }
+        m_perThreadJobQueues.resize(m_numThreads);
+        for ( int i = 0; i < m_numThreads; i++ )
+        {
+            JobQueue* jq = NULL;
+            // only worker threads get a job queue
+            if (i > 0)
+            {
+                if (numThreadsPerQueue == 1)
+                {
+                    // one queue per worker thread
+                    jq = &m_jobQueues[ i - kFirstWorkerThreadId ];
+                }
+                else
+                {
+                    // 2 threads share each queue
+                    jq = &m_jobQueues[ i / numThreadsPerQueue ];
+                }
+            }
+            m_perThreadJobQueues[i] = jq;
+        }
+        m_threadLocalStorage.resize(m_numThreads);
+        for ( int i = 0; i < m_numThreads; i++ )
+        {
+            ThreadLocalStorage& storage = m_threadLocalStorage[i];
+            storage.m_threadId = i;
+            storage.m_directive = m_workerDirective;
+            storage.m_status = WorkerThreadStatus::kSleeping;
+            storage.m_cooldownTime = 100; // 100 microseconds, threads go to sleep after this long if they have nothing to do
+            storage.m_clock = &m_clock;
+            storage.m_queue = m_perThreadJobQueues[i];
+        }
+        setWorkerDirectives( WorkerThreadDirectives::kGoToSleep ); // no work for them yet
+        setNumThreads( m_threadSupport->getCacheFriendlyNumThreads() );
+    }
+
+    void setWorkerDirectives(WorkerThreadDirectives::Type dir)
+    {
+        m_workerDirective->setDirectiveByRange(kFirstWorkerThreadId, m_numThreads, dir);
+    }
+
+    virtual int getMaxNumThreads() const BT_OVERRIDE
+    {
+        return m_maxNumThreads;
+    }
+
+    virtual int getNumThreads() const BT_OVERRIDE
+    {
+        return m_numThreads;
+    }
+
+    virtual void setNumThreads( int numThreads ) BT_OVERRIDE
+    {
+        m_numThreads = btMax( btMin(numThreads, int(m_maxNumThreads)), 1 );
+        m_numWorkerThreads = m_numThreads - 1;
+        m_numActiveJobQueues = 0;
+        // if there is at least 1 worker,
+        if ( m_numWorkerThreads > 0 )
+        {
+            // re-setup job stealing between queues to avoid attempting to steal from an inactive job queue
+            JobQueue* lastActiveContext = m_perThreadJobQueues[ m_numThreads - 1 ];
+            int iLastActiveContext = lastActiveContext - &m_jobQueues[0];
+            m_numActiveJobQueues = iLastActiveContext + 1;
+            for ( int i = 0; i < m_jobQueues.size(); ++i )
+            {
+                m_jobQueues[ i ].setupJobStealing( &m_jobQueues, m_numActiveJobQueues );
+            }
+        }
+        m_workerDirective->setDirectiveByRange(m_numThreads, BT_MAX_THREAD_COUNT, WorkerThreadDirectives::kGoToSleep);
+    }
+
+    void waitJobs()
+    {
+        BT_PROFILE( "waitJobs" );
+        // have the main thread work until the job queues are empty
+        int numMainThreadJobsFinished = 0;
+        for ( int i = 0; i < m_numActiveJobQueues; ++i )
+        {
+            while ( IJob* job = m_jobQueues[i].consumeJob() )
+            {
+                job->executeJob( 0 );
+                numMainThreadJobsFinished++;
+            }
+        }
+
+        // done with jobs for now, tell workers to rest (but not sleep)
+        setWorkerDirectives( WorkerThreadDirectives::kStayAwakeButIdle );
+
+        btU64 clockStart = m_clock.getTimeMicroseconds();
+        // wait for workers to finish any jobs in progress
+        while ( true )
+        {
+            int numWorkerJobsFinished = 0;
+            for ( int iThread = kFirstWorkerThreadId; iThread < m_numThreads; ++iThread )
+            {
+                ThreadLocalStorage* storage = &m_threadLocalStorage[iThread];
+                storage->m_mutex.lock();
+                numWorkerJobsFinished += storage->m_numJobsFinished;
+                storage->m_mutex.unlock();
+            }
+            if (numWorkerJobsFinished + numMainThreadJobsFinished == m_numJobs)
+            {
+                break;
+            }
+            btU64 timeElapsed = m_clock.getTimeMicroseconds() - clockStart;
+            btAssert(timeElapsed < 1000);
+            if (timeElapsed > 100000)
+            {
+                break;
+            }
+            btSpinPause();
+        }
+    }
+
+    void wakeWorkers(int numWorkersToWake)
+    {
+        BT_PROFILE( "wakeWorkers" );
+        btAssert( m_workerDirective->getDirective(1) == WorkerThreadDirectives::kScanForJobs );
+        int numDesiredWorkers = btMin(numWorkersToWake, m_numWorkerThreads);
+        int numActiveWorkers = 0;
+        for ( int iWorker = 0; iWorker < m_numWorkerThreads; ++iWorker )
+        {
+            // note this count of active workers is not necessarily totally reliable, because a worker thread could be
+            // just about to put itself to sleep. So we may on occasion fail to wake up all the workers. It should be rare.
+            ThreadLocalStorage& storage = m_threadLocalStorage[ kFirstWorkerThreadId + iWorker ];
+            if (storage.m_status != WorkerThreadStatus::kSleeping)
+            {
+                numActiveWorkers++;
+            }
+        }
+        for ( int iWorker = 0; iWorker < m_numWorkerThreads && numActiveWorkers < numDesiredWorkers; ++iWorker )
+        {
+            ThreadLocalStorage& storage = m_threadLocalStorage[ kFirstWorkerThreadId + iWorker ];
+            if (storage.m_status == WorkerThreadStatus::kSleeping)
+            {
+                m_threadSupport->runTask( iWorker, &storage );
+                numActiveWorkers++;
+            }
+        }
+    }
+
+    void waitForWorkersToSleep()
+    {
+        BT_PROFILE( "waitForWorkersToSleep" );
+        setWorkerDirectives( WorkerThreadDirectives::kGoToSleep );
+        m_threadSupport->waitForAllTasks();
+        for ( int i = kFirstWorkerThreadId; i < m_numThreads; i++ )
+        {
+            ThreadLocalStorage& storage = m_threadLocalStorage[i];
+            btAssert( storage.m_status == WorkerThreadStatus::kSleeping );
+        }
+    }
+
+    virtual void sleepWorkerThreadsHint() BT_OVERRIDE
+    {
+        BT_PROFILE( "sleepWorkerThreadsHint" );
+        // hint the task scheduler that we may not be using these threads for a little while
+        setWorkerDirectives( WorkerThreadDirectives::kGoToSleep );
+    }
+
+    void prepareWorkerThreads()
+    {
+        for ( int i = kFirstWorkerThreadId; i < m_numThreads; ++i )
+        {
+            ThreadLocalStorage& storage = m_threadLocalStorage[i];
+            storage.m_mutex.lock();
+            storage.m_numJobsFinished = 0;
+            storage.m_mutex.unlock();
+        }
+        setWorkerDirectives( WorkerThreadDirectives::kScanForJobs );
+    }
+
+    virtual void parallelFor( int iBegin, int iEnd, int grainSize, const btIParallelForBody& body ) BT_OVERRIDE
+    {
+        BT_PROFILE( "parallelFor_ThreadSupport" );
+        btAssert( iEnd >= iBegin );
+        btAssert( grainSize >= 1 );
+        int iterationCount = iEnd - iBegin;
+        if ( iterationCount > grainSize && m_numWorkerThreads > 0 && m_antiNestingLock.tryLock() )
+        {
+            typedef ParallelForJob JobType;
+            int jobCount = ( iterationCount + grainSize - 1 ) / grainSize;
+            m_numJobs = jobCount;
+            btAssert( jobCount >= 2 );  // need more than one job for multithreading
+            int jobSize = sizeof( JobType );
+
+            for (int i = 0; i < m_numActiveJobQueues; ++i)
+            {
+                m_jobQueues[i].clearQueue( jobCount, jobSize );
+            }
+            // prepare worker threads for incoming work
+            prepareWorkerThreads();
+            // submit all of the jobs
+            int iJob = 0;
+            int iThread = kFirstWorkerThreadId;  // first worker thread
+            for ( int i = iBegin; i < iEnd; i += grainSize )
+            {
+                btAssert( iJob < jobCount );
+                int iE = btMin( i + grainSize, iEnd );
+                JobQueue* jq = m_perThreadJobQueues[ iThread ];
+                btAssert(jq);
+                btAssert((jq - &m_jobQueues[0]) < m_numActiveJobQueues);
+                void* jobMem = jq->allocJobMem(jobSize);
+                JobType* job = new ( jobMem ) ParallelForJob( i, iE, body );  // placement new
+                jq->submitJob( job );
+                iJob++;
+                iThread++;
+                if ( iThread >= m_numThreads )
+                {
+                    iThread = kFirstWorkerThreadId;  // first worker thread
+                }
+            }
+            wakeWorkers( jobCount - 1 );
+
+            // put the main thread to work on emptying the job queue and then wait for all workers to finish
+            waitJobs();
+            m_antiNestingLock.unlock();
+        }
+        else
+        {
+            BT_PROFILE( "parallelFor_mainThread" );
+            // just run on main thread
+            body.forLoop( iBegin, iEnd );
+        }
+    }
+    virtual btScalar parallelSum( int iBegin, int iEnd, int grainSize, const btIParallelSumBody& body ) BT_OVERRIDE
+    {
+        BT_PROFILE( "parallelSum_ThreadSupport" );
+        btAssert( iEnd >= iBegin );
+        btAssert( grainSize >= 1 );
+        int iterationCount = iEnd - iBegin;
+        if ( iterationCount > grainSize && m_numWorkerThreads > 0 && m_antiNestingLock.tryLock() )
+        {
+            typedef ParallelSumJob JobType;
+            int jobCount = ( iterationCount + grainSize - 1 ) / grainSize;
+            m_numJobs = jobCount;
+            btAssert( jobCount >= 2 );  // need more than one job for multithreading
+            int jobSize = sizeof( JobType );
+            for (int i = 0; i < m_numActiveJobQueues; ++i)
+            {
+                m_jobQueues[i].clearQueue( jobCount, jobSize );
+            }
+
+            // initialize summation
+            for ( int iThread = 0; iThread < m_numThreads; ++iThread )
+            {
+                m_threadLocalStorage[iThread].m_sumResult = btScalar(0);
+            }
+
+            // prepare worker threads for incoming work
+            prepareWorkerThreads();
+            // submit all of the jobs
+            int iJob = 0;
+            int iThread = kFirstWorkerThreadId;  // first worker thread
+            for ( int i = iBegin; i < iEnd; i += grainSize )
+            {
+                btAssert( iJob < jobCount );
+                int iE = btMin( i + grainSize, iEnd );
+                JobQueue* jq = m_perThreadJobQueues[ iThread ];
+                btAssert(jq);
+                btAssert((jq - &m_jobQueues[0]) < m_numActiveJobQueues);
+                void* jobMem = jq->allocJobMem(jobSize);
+                JobType* job = new ( jobMem ) ParallelSumJob( i, iE, body, &m_threadLocalStorage[0] );  // placement new
+                jq->submitJob( job );
+                iJob++;
+                iThread++;
+                if ( iThread >= m_numThreads )
+                {
+                    iThread = kFirstWorkerThreadId;  // first worker thread
+                }
+            }
+            wakeWorkers( jobCount - 1 );
+
+            // put the main thread to work on emptying the job queue and then wait for all workers to finish
+            waitJobs();
+
+            // add up all the thread sums
+            btScalar sum = btScalar(0);
+            for ( int iThread = 0; iThread < m_numThreads; ++iThread )
+            {
+                sum += m_threadLocalStorage[ iThread ].m_sumResult;
+            }
+            m_antiNestingLock.unlock();
+            return sum;
+        }
+        else
+        {
+            BT_PROFILE( "parallelSum_mainThread" );
+            // just run on main thread
+            return body.sumLoop( iBegin, iEnd );
+        }
+    }
+};
+
+
+
+btITaskScheduler* btCreateDefaultTaskScheduler()
+{
+    btTaskSchedulerDefault* ts = new btTaskSchedulerDefault();
+    ts->init();
+    return ts;
+}
+
+#else // #if BT_THREADSAFE
+
+btITaskScheduler* btCreateDefaultTaskScheduler()
+{
+    return NULL;
+}
+
+#endif // #else // #if BT_THREADSAFE