/*
    Copyright 2005-2012 Intel Corporation.  All Rights Reserved.

    This file is part of Threading Building Blocks.

    Threading Building Blocks is free software; you can redistribute it
    and/or modify it under the terms of the GNU General Public License
    version 2 as published by the Free Software Foundation.

    Threading Building Blocks is distributed in the hope that it will be
    useful, but WITHOUT ANY WARRANTY; without even the implied warranty
    of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with Threading Building Blocks; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    As a special exception, you may use this file as part of a free software
    library without restriction.  Specifically, if other files instantiate
    templates or use macros or inline functions from this file, or you compile
    this file and link it with other files to produce an executable, this
    file does not by itself cause the resulting executable to be covered by
    the GNU General Public License.  This exception does not however
    invalidate any other reasons why the executable file might be covered by
    the GNU General Public License.
*/

// test critical section
//
#include "tbb/critical_section.h"
#include "tbb/task_scheduler_init.h"
#include "tbb/enumerable_thread_specific.h"
#include "tbb/tick_count.h"
#include "harness_assert.h"
#include "harness.h"
#include <math.h>

#include "harness_barrier.h"
Harness::SpinBarrier sBarrier;
tbb::critical_section cs;
const int MAX_WORK = 300;

struct BusyBody : NoAssign {
    tbb::enumerable_thread_specific<double> &locals;
    const int nThread;
    const int WorkRatiox100;
    int &unprotected_count;
    bool test_throw;

    BusyBody( int nThread_, int workRatiox100_, tbb::enumerable_thread_specific<double> &locals_, int &unprotected_count_, bool test_throw_) :
        locals(locals_), 
        nThread(nThread_), 
        WorkRatiox100(workRatiox100_), 
        unprotected_count(unprotected_count_),
        test_throw(test_throw_) { 
        sBarrier.initialize(nThread_);
    }

    void operator()(const int /* threadID */ ) const {
        int nIters = MAX_WORK/nThread;
        sBarrier.wait();
        tbb::tick_count t0 = tbb::tick_count::now();
        for(int j = 0; j < nIters; j++) {

            for(int i = 0; i < MAX_WORK * (100 - WorkRatiox100); i++) {
                locals.local() += 1.0;
            }
            cs.lock();
            ASSERT( !cs.try_lock(), "recursive try_lock must fail" );
#if TBB_USE_EXCEPTIONS && !__TBB_THROW_ACROSS_MODULE_BOUNDARY_BROKEN 
            if(test_throw && j == (nIters / 2)) {
                bool was_caught = false,
                     unknown_exception = false;
                try {
                    cs.lock();
                }
                catch(tbb::improper_lock& e) {
                    ASSERT( e.what(), "Error message is absent" );
                    was_caught = true;
                }
                catch(...) {
                    was_caught = unknown_exception = true;
                }
                ASSERT(was_caught, "Recursive lock attempt did not throw");
                ASSERT(!unknown_exception, "tbb::improper_lock exception is expected");
            }
#endif /* TBB_USE_EXCEPTIONS && !__TBB_THROW_ACROSS_MODULE_BOUNDARY_BROKEN  */
            for(int i = 0; i < MAX_WORK * WorkRatiox100; i++) {
                locals.local() += 1.0;
            }
            unprotected_count++;
            cs.unlock();
        }
        locals.local() = (tbb::tick_count::now() - t0).seconds();
    }
};

struct BusyBodyScoped : NoAssign {
    tbb::enumerable_thread_specific<double> &locals;
    const int nThread;
    const int WorkRatiox100;
    int &unprotected_count;
    bool test_throw;

    BusyBodyScoped( int nThread_, int workRatiox100_, tbb::enumerable_thread_specific<double> &locals_, int &unprotected_count_, bool test_throw_) :
        locals(locals_), 
        nThread(nThread_), 
        WorkRatiox100(workRatiox100_), 
        unprotected_count(unprotected_count_),
        test_throw(test_throw_) { 
        sBarrier.initialize(nThread_);
    }

    void operator()(const int /* threadID */ ) const {
        int nIters = MAX_WORK/nThread;
        sBarrier.wait();
        tbb::tick_count t0 = tbb::tick_count::now();
        for(int j = 0; j < nIters; j++) {

            for(int i = 0; i < MAX_WORK * (100 - WorkRatiox100); i++) {
                locals.local() += 1.0;
            }
            { 
                tbb::critical_section::scoped_lock my_lock(cs);
                for(int i = 0; i < MAX_WORK * WorkRatiox100; i++) {
                    locals.local() += 1.0;
                }
                unprotected_count++;
            }
        }
        locals.local() = (tbb::tick_count::now() - t0).seconds();
    }
};

void
RunOneCriticalSectionTest(int nThreads, int csWorkRatio, bool test_throw) {
    tbb::task_scheduler_init init(tbb::task_scheduler_init::deferred);
    tbb::enumerable_thread_specific<double> test_locals;
    int myCount = 0;
    BusyBody myBody(nThreads, csWorkRatio, test_locals, myCount, test_throw);
    BusyBodyScoped myScopedBody(nThreads, csWorkRatio, test_locals, myCount, test_throw);
    init.initialize(nThreads);
    tbb::tick_count t0;
    {
        t0 = tbb::tick_count::now();
        myCount = 0;
        NativeParallelFor(nThreads, myBody);
        ASSERT(myCount == (MAX_WORK - (MAX_WORK % nThreads)), NULL);
        REMARK("%d threads, work ratio %d per cent, time %g", nThreads, csWorkRatio, (tbb::tick_count::now() - t0).seconds());
        if (nThreads > 1) {
            double etsSum = 0;
            double etsMax = 0;
            double etsMin = 0;
            double etsSigmaSq = 0;
            double etsSigma = 0;

            for(tbb::enumerable_thread_specific<double>::const_iterator ci = test_locals.begin(); ci != test_locals.end(); ci++) {
                etsSum += *ci;
                if(etsMax==0.0) {
                    etsMin = *ci;
                }
                else {
                    if(etsMin > *ci) etsMin = *ci;
                }
                if(etsMax < *ci) etsMax = *ci;
            }
            double etsAvg = etsSum / (double)nThreads;
            for(tbb::enumerable_thread_specific<double>::const_iterator ci = test_locals.begin(); ci != test_locals.end(); ci++) {
                etsSigma = etsAvg - *ci;
                etsSigmaSq += etsSigma * etsSigma;
            }
            // an attempt to gauge the "fairness" of the scheduling of the threads.  We figure
            // the standard deviation, and compare it with the maximum deviation from the
            // average time.  If the difference is 0 that means all threads finished in the same
            // amount of time.  If non-zero, the difference is divided by the time, and the
            // negative log is taken.  If > 2, then the difference is on the order of 0.01*t
            // where T is the average time.  We aritrarily define this as "fair."
            etsSigma = sqrt(etsSigmaSq/double(nThreads)); 
            etsMax -= etsAvg;  // max - a == delta1
            etsMin = etsAvg - etsMin;  // a - min == delta2
            if(etsMax < etsMin) etsMax = etsMin;
            etsMax -= etsSigma;
            // ASSERT(etsMax >= 0, NULL);  // shouldn't the maximum difference from the mean be > the stddev?
            etsMax = (etsMax > 0.0) ? etsMax : 0.0;  // possible rounding error
            double fairness = etsMax / etsAvg;
            if(fairness == 0.0) {
                fairness = 100.0;
            }
            else fairness = - log10(fairness);
            if(fairness > 2.0 ) {
                REMARK("  Fair (%g)\n", fairness);
            }
            else {
                REMARK("  Unfair (%g)\n", fairness);
            }
        }
        myCount = 0;
        NativeParallelFor(nThreads, myScopedBody);
        ASSERT(myCount == (MAX_WORK - (MAX_WORK % nThreads)), NULL);

    }

    init.terminate();
}

void
RunParallelTests() {
    for(int p = MinThread; p <= MaxThread; p++) {
        for(int cs_ratio = 1; cs_ratio < 95; cs_ratio *= 2) {
            RunOneCriticalSectionTest(p, cs_ratio, /*test_throw*/true);
        }
    }
}

int TestMain () {
    if(MinThread <= 0) MinThread = 1;

    if(MaxThread > 0) {
        RunParallelTests();
    }

    return Harness::Done;
}
