- Main Page
- Related Pages
- Modules
- Namespaces
- Classes
- Examples

# threadTestCmd.cpp

    //-
    // ==========================================================================
    // Copyright 1995,2006,2008 Autodesk, Inc. All rights reserved.
    //
    // Use of this software is subject to the terms of the Autodesk
    // license agreement provided at the time of installation or download,
    // or which otherwise accompanies this software in either electronic
    // or hard copy form.
    // ==========================================================================
    //+

    #include <math.h>

    #include <maya/MIOStream.h>
    #include <maya/MSimple.h>
    #include <maya/MTimer.h>
    #include <maya/MGlobal.h>
    #include <maya/MThreadPool.h>

    DeclareSimpleCommand( threadTestCmd, PLUGIN_COMPANY, "2008");

    typedef struct _threadDataTag
    {
        int threadNo;
        long primesFound;
        long start, end;

    } threadData;

    typedef struct _taskDataTag
    {
        long start, end, totalPrimes;

    } taskData;

    #define NUM_TASKS   16

    // No global information used in function
    static bool TestForPrime(int val)
    {
        int limit, factor = 3;
        limit = (long)(sqrtf((float)val)+0.5f);
        while( (factor <= limit) && (val % factor))
            factor ++;

        return (factor > limit);
    }

    // Primes finder. This function is called from multiple threads
    MThreadRetVal Primes(void *data)
    {
        threadData *myData = (threadData *)data;
        for( int i = myData->start + myData->threadNo*2; i <= myData->end; i += 2*NUM_TASKS )
        {
            if( TestForPrime(i) )
                myData->primesFound++;
        }
        return (MThreadRetVal)0;
    }

    // Function to create thread tasks
    void DecomposePrimes(void *data, MThreadRootTask *root)
    {
        taskData *taskD = (taskData *)data;

        threadData tdata[NUM_TASKS];

        for( int i = 0; i < NUM_TASKS; ++i )
        {
            tdata[i].threadNo    = i;
            tdata[i].primesFound = 0;
            tdata[i].start       = taskD->start;
            tdata[i].end         = taskD->end;

            MThreadPool::createTask(Primes, (void *)&tdata[i], root);
        }

        MThreadPool::executeAndJoin(root);

        for( int i = 0; i < NUM_TASKS; ++i )
        {
            taskD->totalPrimes += tdata[i].primesFound;
        }
    }

    // Single threaded calculation
    int SerialPrimes(int start, int end)
    {
        int primesFound = 0;
        for( int i = start; i <= end; i+=2)
        {
            if( TestForPrime(i) )
                primesFound++;
        }
        return primesFound;
    }

    // Set up and tear down parallel tasks
    int ParallelPrimes(int start, int end)
    {
        MStatus stat = MThreadPool::init();
        if( MStatus::kSuccess != stat ) {
            MString str = MString("Error creating threadpool");
            MGlobal::displayError(str);
            return 0;
        }

        taskData tdata;
        tdata.totalPrimes = 0;
        tdata.start       = start;
        tdata.end         = end;
        MThreadPool::newParallelRegion(DecomposePrimes, (void *)&tdata);

        // pool is reference counted. Release reference to current thread instance
        MThreadPool::release();

        // release reference to whole pool which deletes all threads
        MThreadPool::release();

        return tdata.totalPrimes;
    }

    // MSimple command that invokes the serial and parallel thread calculations
    MStatus threadTestCmd::doIt( const MArgList& args )
    {
        MString introStr = MString("Computation of primes using the Maya API");
        MGlobal::displayInfo(introStr);

        if(args.length() != 2) {
            MString str = MString("Invalid number of arguments, usage: threadTestCmd 1 10000");
            MGlobal::displayError(str);
            return MStatus::kFailure;
        }

        MStatus stat;

        int start = args.asInt( 0, &stat );
        if ( MS::kSuccess != stat ) {
            MString str = MString("Invalid argument 1, usage: threadTestCmd 1 10000");
            MGlobal::displayError(str);
            return MStatus::kFailure;
        }

        int end = args.asInt( 1, &stat );
        if ( MS::kSuccess != stat ) {
            MString str = MString("Invalid argument 2, usage: threadTestCmd 1 10000");
            MGlobal::displayError(str);
            return MStatus::kFailure;
        }

        // start search on an odd number
        if((start % 2) == 0 ) start++;

        // run single threaded
        MTimer timer;
        timer.beginTimer();
        int serialPrimes = SerialPrimes(start, end);
        timer.endTimer();
        double serialTime = timer.elapsedTime();

        // run multithreaded
        timer.beginTimer();
        int parallelPrimes = ParallelPrimes(start, end);
        timer.endTimer();
        double parallelTime = timer.elapsedTime();

        // check for correctness
        if ( serialPrimes != parallelPrimes ) {
            MString str("Error: Computations inconsistent");
            MGlobal::displayError(str);
            return MStatus::kFailure;
        }

        // print results
        if(parallelTime>0.0) {
          double ratio = serialTime/parallelTime;
          MString str = MString("\nElapsed time for serial computation: ") + serialTime + MString("s\n");
          str += MString("Elapsed time for parallel computation: ") + parallelTime + MString("s\n");
          str += MString("Speedup: ") + ratio + MString("x\n");
          MGlobal::displayInfo(str);
        } else {
          MString str = MString("\nParallel time zero, no scaling measurement possible\n");
          MGlobal::displayInfo(str);
        }
        return MStatus::kSuccess;
    }