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;
}