/*
    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.
*/

// Source file for miscellaneous entities that are infrequently referenced by 
// an executing program, and implementation of which requires dynamic linking.

#include "tbb_misc.h"

#if !defined(__TBB_HardwareConcurrency)

#include "dynamic_link.h"
#include <stdio.h>
#include <limits.h>

#if _WIN32||_WIN64
#include "tbb/machine/windows_api.h"
#if __TBB_WIN8UI_SUPPORT
#include <thread>
#endif
#else
#include <unistd.h>
#if __linux__
#include <sys/sysinfo.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#elif __sun
#include <sys/sysinfo.h>
#elif __FreeBSD__
#include <errno.h>
#include <string.h>
#include <sys/param.h>  // Required by <sys/cpuset.h>
#include <sys/cpuset.h>
#endif
#endif

namespace tbb {
namespace internal {

#if __TBB_OS_AFFINITY_SYSCALL_PRESENT

static void set_affinity_mask( size_t maskSize, const basic_mask_t* threadMask ) {
#if __linux__
    if( sched_setaffinity( 0, maskSize, threadMask ) )
#else /* FreeBSD */
    if( cpuset_setaffinity( CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, maskSize, threadMask ) )
#endif
        runtime_warning( "setaffinity syscall failed" );
}

static void get_affinity_mask( size_t maskSize, basic_mask_t* threadMask ) {
#if __linux__
    if( sched_getaffinity( 0, maskSize, threadMask ) )
#else /* FreeBSD */
    if( cpuset_getaffinity( CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, maskSize, threadMask ) )
#endif
        runtime_warning( "getaffinity syscall failed" );
}

static basic_mask_t* process_mask;
static int num_masks;
struct process_mask_cleanup_helper {
    ~process_mask_cleanup_helper() {
        if( process_mask ) {
            delete [] process_mask;
        }
     }
};
static process_mask_cleanup_helper process_mask_cleanup;

#define curMaskSize sizeof(basic_mask_t) * num_masks
affinity_helper::~affinity_helper() {
    if( threadMask ) {
        if( is_changed ) {
            set_affinity_mask( curMaskSize, threadMask );
        }
        delete [] threadMask;
    }
}
void affinity_helper::protect_affinity_mask() {
    if( threadMask == NULL && num_masks && process_mask ) {
        threadMask = new basic_mask_t [num_masks];
        memset( threadMask, 0, curMaskSize );
        get_affinity_mask( curMaskSize, threadMask );
        is_changed = memcmp( process_mask, threadMask, curMaskSize );
        if( is_changed ) {
            set_affinity_mask( curMaskSize, process_mask );
        }
    }
}
#undef curMaskSize

static atomic<do_once_state> hardware_concurrency_info;

static int theNumProcs;

static void initialize_hardware_concurrency_info () {
    int err;
    int availableProcs = 0;
    int numMasks = 1;
#if __linux__
#if __TBB_MAIN_THREAD_AFFINITY_BROKEN
    int maxProcs = INT_MAX; // To check the entire mask.
    int pid = 0; // Get the mask of the calling thread.
#else
    int maxProcs = sysconf(_SC_NPROCESSORS_ONLN);
    int pid = getpid();
#endif
    cpu_set_t *processMask;
    const size_t BasicMaskSize =  sizeof(cpu_set_t);
    for (;;) {
        int curMaskSize = BasicMaskSize * numMasks;
        processMask = new cpu_set_t[numMasks];
        memset( processMask, 0, curMaskSize );
        err = sched_getaffinity( pid, curMaskSize, processMask );
        if ( !err || errno != EINVAL || curMaskSize * CHAR_BIT >= 256 * 1024 )
            break;
        delete[] processMask;
        numMasks <<= 1;
    }
#else /* FreeBSD >= 7.1 */
    int maxProcs = sysconf(_SC_NPROCESSORS_ONLN);
    cpuset_t *processMask;
    const size_t BasicMaskSize = sizeof(cpuset_t);
    for (;;) {
        int curMaskSize = BasicMaskSize * numMasks;
        processMask = new cpuset_t[numMasks];
        memset( processMask, 0, curMaskSize );
        // CPU_LEVEL_WHICH - anonymous (current) mask, CPU_LEVEL_CPUSET - assigned mask
#if __TBB_MAIN_THREAD_AFFINITY_BROKEN
        err = cpuset_getaffinity( CPU_LEVEL_WHICH, CPU_WHICH_TID, -1, curMaskSize, processMask );
#else
        err = cpuset_getaffinity( CPU_LEVEL_WHICH, CPU_WHICH_PID, -1, curMaskSize, processMask );
#endif
        if ( !err || errno != ERANGE || curMaskSize * CHAR_BIT >= 16 * 1024 )
            break;
        delete[] processMask;
        numMasks <<= 1;
    }
#endif /* FreeBSD >= 7.1 */
    if ( !err ) {
        for ( int m = 0; availableProcs < maxProcs && m < numMasks; ++m ) {
            for ( size_t i = 0; (availableProcs < maxProcs) && (i < BasicMaskSize * CHAR_BIT); ++i ) {
                if ( CPU_ISSET( i, processMask + m ) )
                    ++availableProcs;
            }
        }
        num_masks = numMasks;
        process_mask = processMask;
    }
    else {
        availableProcs = (maxProcs == INT_MAX) ? sysconf(_SC_NPROCESSORS_ONLN) : maxProcs;
        delete[] processMask;
    }
    theNumProcs = availableProcs > 0 ? availableProcs : 1; // Fail safety strap
    __TBB_ASSERT( theNumProcs <= sysconf(_SC_NPROCESSORS_ONLN), NULL );
}

int AvailableHwConcurrency() {
    atomic_do_once( &initialize_hardware_concurrency_info, hardware_concurrency_info );
    return theNumProcs;
}

#elif __ANDROID__
// Work-around for Android that reads the correct number of available CPUs since system calls are unreliable.
// Format of "present" file is: ([<int>-<int>|<int>],)+
int AvailableHwConcurrency() {
    FILE *fp = fopen("/sys/devices/system/cpu/present", "r");
    if (fp == NULL) return 1;
    int num_args, lower, upper, num_cpus=0;
    while ((num_args = fscanf(fp, "%u-%u", &lower, &upper)) != EOF) {
        switch(num_args) {
            case 2: num_cpus += upper - lower + 1; break;
            case 1: num_cpus += 1; break;
        }
        fscanf(fp, ",");
    }
    return (num_cpus > 0) ? num_cpus : 1;
}

#elif defined(_SC_NPROCESSORS_ONLN)
int AvailableHwConcurrency() {
    int n = sysconf(_SC_NPROCESSORS_ONLN);
    return (n > 0) ? n : 1;
}

#elif _WIN32||_WIN64

static atomic<do_once_state> hardware_concurrency_info;

static const WORD TBB_ALL_PROCESSOR_GROUPS = 0xffff;

// Statically allocate an array for processor group information.
// Windows 7 supports maximum 4 groups, but let's look ahead a little.
static const WORD MaxProcessorGroups = 64;

struct ProcessorGroupInfo {
    DWORD_PTR   mask;                   ///< Affinity mask covering the whole group
    int         numProcs;               ///< Number of processors in the group
    int         numProcsRunningTotal;   ///< Subtotal of processors in this and preceding groups

    //! Total number of processor groups in the system
    static int NumGroups; 

    //! Index of the group with a slot reserved for the first master thread
    /** In the context of multiple processor groups support current implementation
        defines "the first master thread" as the first thread to invoke
        AvailableHwConcurrency(). 

        TODO:   Implement a dynamic scheme remapping workers depending on the pending
                master threads affinity. **/
    static int HoleIndex;
};

int ProcessorGroupInfo::NumGroups = 1;
int ProcessorGroupInfo::HoleIndex = 0;


ProcessorGroupInfo theProcessorGroups[MaxProcessorGroups];

struct TBB_GROUP_AFFINITY {
    DWORD_PTR Mask;
    WORD   Group;
    WORD   Reserved[3];
};

static DWORD (WINAPI *TBB_GetMaximumProcessorCount)( WORD groupIndex ) = NULL;
static WORD (WINAPI *TBB_GetMaximumProcessorGroupCount)() = NULL;
static BOOL (WINAPI *TBB_SetThreadGroupAffinity)( HANDLE hThread, 
                        const TBB_GROUP_AFFINITY* newAff, TBB_GROUP_AFFINITY *prevAff );
static BOOL (WINAPI *TBB_GetThreadGroupAffinity)( HANDLE hThread, TBB_GROUP_AFFINITY* );

static const dynamic_link_descriptor ProcessorGroupsApiLinkTable[] = {
      DLD(GetMaximumProcessorCount, TBB_GetMaximumProcessorCount)
    , DLD(GetMaximumProcessorGroupCount, TBB_GetMaximumProcessorGroupCount)
    , DLD(SetThreadGroupAffinity, TBB_SetThreadGroupAffinity)
    , DLD(GetThreadGroupAffinity, TBB_GetThreadGroupAffinity)
};

static void initialize_hardware_concurrency_info () {
#if __TBB_WIN8UI_SUPPORT
    unsigned int nproc = std::thread::hardware_concurrency();
#else /* __TBB_WIN8UI_SUPPORT */
    dynamic_link( "Kernel32.dll", ProcessorGroupsApiLinkTable,
                  sizeof(ProcessorGroupsApiLinkTable)/sizeof(dynamic_link_descriptor) );
    SYSTEM_INFO si;
    GetNativeSystemInfo(&si);
    DWORD_PTR pam, sam, m = 1;
    GetProcessAffinityMask( GetCurrentProcess(), &pam, &sam );
    int nproc = 0;
    for ( size_t i = 0; i < sizeof(DWORD_PTR) * CHAR_BIT; ++i, m <<= 1 ) {
        if ( pam & m )
            ++nproc;
    }
    __TBB_ASSERT( nproc <= (int)si.dwNumberOfProcessors, NULL );
    if ( nproc == (int)si.dwNumberOfProcessors && TBB_GetMaximumProcessorCount ) {
        // The process does not have restricting affinity mask and multiple processor groups are possible
        ProcessorGroupInfo::NumGroups = (int)TBB_GetMaximumProcessorGroupCount();
        __TBB_ASSERT( ProcessorGroupInfo::NumGroups <= MaxProcessorGroups, NULL );
        // Fail safety bootstrap. Release versions will limit available concurrency
        // level, while debug ones would assert.
        if ( ProcessorGroupInfo::NumGroups > MaxProcessorGroups )
            ProcessorGroupInfo::NumGroups = MaxProcessorGroups;
        if ( ProcessorGroupInfo::NumGroups > 1 ) {
            TBB_GROUP_AFFINITY ga;
            if ( TBB_GetThreadGroupAffinity( GetCurrentThread(), &ga ) )
                ProcessorGroupInfo::HoleIndex = ga.Group;
            int nprocs = 0;
            for ( WORD i = 0; i < ProcessorGroupInfo::NumGroups; ++i ) {
                ProcessorGroupInfo  &pgi = theProcessorGroups[i];
                pgi.numProcs = (int)TBB_GetMaximumProcessorCount(i);
                __TBB_ASSERT( pgi.numProcs <= (int)sizeof(DWORD_PTR) * CHAR_BIT, NULL );
                pgi.mask = pgi.numProcs == sizeof(DWORD_PTR) * CHAR_BIT ? ~(DWORD_PTR)0 : (DWORD_PTR(1) << pgi.numProcs) - 1;
                pgi.numProcsRunningTotal = nprocs += pgi.numProcs;
            }
            __TBB_ASSERT( nprocs == (int)TBB_GetMaximumProcessorCount( TBB_ALL_PROCESSOR_GROUPS ), NULL );
            return;
        }
    }
#endif /* __TBB_WIN8UI_SUPPORT */
    // Either the process has restricting affinity mask or only a single processor groups is present
    theProcessorGroups[0].numProcs = theProcessorGroups[0].numProcsRunningTotal = nproc;

    PrintExtraVersionInfo("Processor groups", "%d", ProcessorGroupInfo::NumGroups);
    if (ProcessorGroupInfo::NumGroups>1)
        for (int i=0; i<ProcessorGroupInfo::NumGroups; ++i)
            PrintExtraVersionInfo( "----- Group", "%d: size %d", i, theProcessorGroups[i].numProcs);
}

int AvailableHwConcurrency() {
    atomic_do_once( &initialize_hardware_concurrency_info, hardware_concurrency_info );
    return theProcessorGroups[ProcessorGroupInfo::NumGroups - 1].numProcsRunningTotal;
}

int NumberOfProcessorGroups() {
    __TBB_ASSERT( hardware_concurrency_info == initialization_complete, "NumberOfProcessorGroups is used before AvailableHwConcurrency" );
    return ProcessorGroupInfo::NumGroups;
}

// Offset for the slot reserved for the first master thread
#define HoleAdjusted(procIdx, grpIdx) (procIdx + (holeIdx <= grpIdx))

int FindProcessorGroupIndex ( int procIdx ) {
    // In case of oversubscription spread extra workers in a round robin manner
    int holeIdx;
    const int numProcs = theProcessorGroups[ProcessorGroupInfo::NumGroups - 1].numProcsRunningTotal;
    if ( procIdx >= numProcs - 1 ) {
        holeIdx = INT_MAX;
        procIdx = (procIdx - numProcs + 1) % numProcs;
    }
    else
        holeIdx = ProcessorGroupInfo::HoleIndex;
    __TBB_ASSERT( hardware_concurrency_info == initialization_complete, "FindProcessorGroupIndex is used before AvailableHwConcurrency" );
    // Approximate the likely group index assuming all groups are of the same size
    int i = procIdx / theProcessorGroups[0].numProcs;
    // Make sure the approximation is a valid group index
    if (i >= ProcessorGroupInfo::NumGroups) i = ProcessorGroupInfo::NumGroups-1;
    // Now adjust the approximation up or down
    if ( theProcessorGroups[i].numProcsRunningTotal > HoleAdjusted(procIdx, i) ) {
        while ( theProcessorGroups[i].numProcsRunningTotal - theProcessorGroups[i].numProcs > HoleAdjusted(procIdx, i) ) {
            __TBB_ASSERT( i > 0, NULL );
            --i;
        }
    }
    else {
        do {
            ++i;
        } while ( theProcessorGroups[i].numProcsRunningTotal <= HoleAdjusted(procIdx, i) );
    }
    __TBB_ASSERT( i < ProcessorGroupInfo::NumGroups, NULL );
    return i;
}

void MoveThreadIntoProcessorGroup( void* hThread, int groupIndex ) {
    __TBB_ASSERT( hardware_concurrency_info == initialization_complete, "MoveThreadIntoProcessorGroup is used before AvailableHwConcurrency" );
    if ( !TBB_SetThreadGroupAffinity )
        return;
    TBB_GROUP_AFFINITY ga = { theProcessorGroups[groupIndex].mask, (WORD)groupIndex, {0,0,0} };
    TBB_SetThreadGroupAffinity( hThread, &ga, NULL );
}

#else
    #error AvailableHwConcurrency is not implemented in this OS 
#endif /* OS */

} // namespace internal
} // namespace tbb

#endif /* !__TBB_HardwareConcurrency */
