/*
 * $Id$
 * Portable Audio I/O Library
 * UNIX platform-specific support functions
 *
 * Based on the Open Source API proposed by Ross Bencina
 * Copyright (c) 1999-2000 Ross Bencina
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files
 * (the "Software"), to deal in the Software without restriction,
 * including without limitation the rights to use, copy, modify, merge,
 * publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * The text above constitutes the entire PortAudio license; however,
 * the PortAudio community also makes the following non-binding requests:
 *
 * Any person wishing to distribute modifications to the Software is
 * requested to send the modifications to the original developer so that
 * they can be incorporated into the canonical version. It is also
 * requested that these non-binding requests be included along with the
 * license above.
 */

/** @file
 @ingroup unix_src
*/

#include <pthread.h>
#include <unistd.h>
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <assert.h>
#include <string.h> /* For memset */
#include <math.h>
#include <errno.h>

#if defined(__APPLE__) && !defined(HAVE_MACH_ABSOLUTE_TIME)
#define HAVE_MACH_ABSOLUTE_TIME
#endif
#ifdef HAVE_MACH_ABSOLUTE_TIME
#include <mach/mach_time.h>
#endif

#include "pa_util.h"
#include "pa_unix_util.h"
#include "pa_debugprint.h"

/*
   Track memory allocations to avoid leaks.
 */

#if PA_TRACK_MEMORY
static int numAllocations_ = 0;
#endif


void *PaUtil_AllocateMemory( long size )
{
    void *result = malloc( size );

#if PA_TRACK_MEMORY
    if( result != NULL ) numAllocations_ += 1;
#endif
    return result;
}


void PaUtil_FreeMemory( void *block )
{
    if( block != NULL )
    {
        free( block );
#if PA_TRACK_MEMORY
        numAllocations_ -= 1;
#endif

    }
}


int PaUtil_CountCurrentlyAllocatedBlocks( void )
{
#if PA_TRACK_MEMORY
    return numAllocations_;
#else
    return 0;
#endif
}


void Pa_Sleep( long msec )
{
#ifdef HAVE_NANOSLEEP
    struct timespec req = {0}, rem = {0};
    PaTime time = msec / 1.e3;
    req.tv_sec = (time_t)time;
    assert(time - req.tv_sec < 1.0);
    req.tv_nsec = (long)((time - req.tv_sec) * 1.e9);
    nanosleep(&req, &rem);
    /* XXX: Try sleeping the remaining time (contained in rem) if interrupted by a signal? */
#else
    while( msec > 999 )     /* For OpenBSD and IRIX, argument */
        {                   /* to usleep must be < 1000000.   */
        usleep( 999000 );
        msec -= 999;
        }
    usleep( msec * 1000 );
#endif
}

#ifdef HAVE_MACH_ABSOLUTE_TIME
/*
    Discussion on the CoreAudio mailing list suggests that calling
    gettimeofday (or anything else in the BSD layer) is not real-time
    safe, so we use mach_absolute_time on OSX. This implementation is
    based on these two links:

    Technical Q&A QA1398 - Mach Absolute Time Units
    http://developer.apple.com/mac/library/qa/qa2004/qa1398.html

    Tutorial: Performance and Time.
    http://www.macresearch.org/tutorial_performance_and_time
*/

/* Scaler to convert the result of mach_absolute_time to seconds */
static double machSecondsConversionScaler_ = 0.0;
#endif

void PaUtil_InitializeClock( void )
{
#ifdef HAVE_MACH_ABSOLUTE_TIME
    mach_timebase_info_data_t info;
    kern_return_t err = mach_timebase_info( &info );
    if( err == 0  )
        machSecondsConversionScaler_ = 1e-9 * (double) info.numer / (double) info.denom;
#endif
}


PaTime PaUtil_GetTime( void )
{
#ifdef HAVE_MACH_ABSOLUTE_TIME
    return mach_absolute_time() * machSecondsConversionScaler_;
#elif defined(HAVE_CLOCK_GETTIME)
    struct timespec tp;
    clock_gettime(CLOCK_REALTIME, &tp);
    return (PaTime)(tp.tv_sec + tp.tv_nsec * 1e-9);
#else
    struct timeval tv;
    gettimeofday( &tv, NULL );
    return (PaTime) tv.tv_usec * 1e-6 + tv.tv_sec;
#endif
}

PaError PaUtil_InitializeThreading( PaUtilThreading *threading )
{
    (void) paUtilErr_;
    return paNoError;
}

void PaUtil_TerminateThreading( PaUtilThreading *threading )
{
}

PaError PaUtil_StartThreading( PaUtilThreading *threading, void *(*threadRoutine)(void *), void *data )
{
    pthread_create( &threading->callbackThread, NULL, threadRoutine, data );
    return paNoError;
}

PaError PaUtil_CancelThreading( PaUtilThreading *threading, int wait, PaError *exitResult )
{
    PaError result = paNoError;
    void *pret;

    if( exitResult )
        *exitResult = paNoError;

    /* If pthread_cancel is not supported (Android platform) whole this function can lead to indefinite waiting if
       working thread (callbackThread) has'n received any stop signals from outside, please keep
       this in mind when considering using PaUtil_CancelThreading
    */
#ifdef PTHREAD_CANCELED
    /* Only kill the thread if it isn't in the process of stopping (flushing adaptation buffers) */
    if( !wait )
        pthread_cancel( threading->callbackThread );   /* XXX: Safe to call this if the thread has exited on its own? */
#endif
    pthread_join( threading->callbackThread, &pret );

#ifdef PTHREAD_CANCELED
    if( pret && PTHREAD_CANCELED != pret )
#else
    /* !wait means the thread may have been canceled */
    if( pret && wait )
#endif
    {
        if( exitResult )
            *exitResult = *(PaError *) pret;
        free( pret );
    }

    return result;
}

/* Threading */
/* paUnixMainThread
 * We have to be a bit careful with defining this global variable,
 * as explained below. */
#ifdef __APPLE__
/* apple/gcc has a "problem" with global vars and dynamic libs.
   Initializing it seems to fix the problem.
   Described a bit in this thread:
   http://gcc.gnu.org/ml/gcc/2005-06/msg00179.html
*/
pthread_t paUnixMainThread = 0;
#else
/*pthreads are opaque. We don't know that assigning it an int value
  always makes sense, so we don't initialize it unless we have to.*/
pthread_t paUnixMainThread = 0;
#endif

PaError PaUnixThreading_Initialize( void )
{
    paUnixMainThread = pthread_self();
    return paNoError;
}

static PaError BoostPriority( PaUnixThread* self )
{
    PaError result = paNoError;
    struct sched_param spm = { 0 };
    /* Priority should only matter between contending FIFO threads? */
    spm.sched_priority = 1;

    assert( self );

    if( pthread_setschedparam( self->thread, SCHED_FIFO, &spm ) != 0 )
    {
        PA_UNLESS( errno == EPERM, paInternalError );  /* Lack permission to raise priority */
        PA_DEBUG(( "Failed bumping priority\n" ));
        result = 0;
    }
    else
    {
        result = 1; /* Success */
    }
error:
    return result;
}

PaError PaUnixThread_New( PaUnixThread* self, void* (*threadFunc)( void* ), void* threadArg, PaTime waitForChild,
        int rtSched )
{
    PaError result = paNoError;
    pthread_attr_t attr;
    int started = 0;

    memset( self, 0, sizeof (PaUnixThread) );
    PaUnixMutex_Initialize( &self->mtx );
    PA_ASSERT_CALL( pthread_cond_init( &self->cond, NULL ), 0 );

    self->parentWaiting = 0 != waitForChild;

    /* Spawn thread */

/* Temporarily disabled since we should test during configuration for presence of required mman.h header */
#if 0
#if defined _POSIX_MEMLOCK && (_POSIX_MEMLOCK != -1)
    if( rtSched )
    {
        if( mlockall( MCL_CURRENT | MCL_FUTURE ) < 0 )
        {
            int savedErrno = errno;             /* In case errno gets overwritten */
            assert( savedErrno != EINVAL );     /* Most likely a programmer error */
            PA_UNLESS( (savedErrno == EPERM), paInternalError );
            PA_DEBUG(( "%s: Failed locking memory\n", __FUNCTION__ ));
        }
        else
            PA_DEBUG(( "%s: Successfully locked memory\n", __FUNCTION__ ));
    }
#endif
#endif

    PA_UNLESS( !pthread_attr_init( &attr ), paInternalError );
    /* Priority relative to other processes */
    PA_UNLESS( !pthread_attr_setscope( &attr, PTHREAD_SCOPE_SYSTEM ), paInternalError );

    PA_UNLESS( !pthread_create( &self->thread, &attr, threadFunc, threadArg ), paInternalError );
    started = 1;

    if( rtSched )
    {
#if 0
        if( self->useWatchdog )
        {
            int err;
            struct sched_param wdSpm = { 0 };
            /* Launch watchdog, watchdog sets callback thread priority */
            int prio = PA_MIN( self->rtPrio + 4, sched_get_priority_max( SCHED_FIFO ) );
            wdSpm.sched_priority = prio;

            PA_UNLESS( !pthread_attr_init( &attr ), paInternalError );
            PA_UNLESS( !pthread_attr_setinheritsched( &attr, PTHREAD_EXPLICIT_SCHED ), paInternalError );
            PA_UNLESS( !pthread_attr_setscope( &attr, PTHREAD_SCOPE_SYSTEM ), paInternalError );
            PA_UNLESS( !pthread_attr_setschedpolicy( &attr, SCHED_FIFO ), paInternalError );
            PA_UNLESS( !pthread_attr_setschedparam( &attr, &wdSpm ), paInternalError );
            if( (err = pthread_create( &self->watchdogThread, &attr, &WatchdogFunc, self )) )
            {
                PA_UNLESS( err == EPERM, paInternalError );
                /* Permission error, go on without realtime privileges */
                PA_DEBUG(( "Failed bumping priority\n" ));
            }
            else
            {
                int policy;
                self->watchdogRunning = 1;
                PA_ENSURE_SYSTEM( pthread_getschedparam( self->watchdogThread, &policy, &wdSpm ), 0 );
                /* Check if priority is right, policy could potentially differ from SCHED_FIFO (but that's alright) */
                if( wdSpm.sched_priority != prio )
                {
                    PA_DEBUG(( "Watchdog priority not set correctly (%d)\n", wdSpm.sched_priority ));
                    PA_ENSURE( paInternalError );
                }
            }
        }
        else
#endif
            PA_ENSURE( BoostPriority( self ) );

        {
            int policy;
            struct sched_param spm;
            pthread_getschedparam(self->thread, &policy, &spm);
        }
    }

    if( self->parentWaiting )
    {
        PaTime till;
        struct timespec ts;
        int res = 0;
        PaTime now;

        PA_ENSURE( PaUnixMutex_Lock( &self->mtx ) );

        /* Wait for stream to be started */
        now = PaUtil_GetTime();
        till = now + waitForChild;

        while( self->parentWaiting && !res )
        {
            if( waitForChild > 0 )
            {
                ts.tv_sec = (time_t) floor( till );
                ts.tv_nsec = (long) ((till - floor( till )) * 1e9);
                res = pthread_cond_timedwait( &self->cond, &self->mtx.mtx, &ts );
            }
            else
            {
                res = pthread_cond_wait( &self->cond, &self->mtx.mtx );
            }
        }

        PA_ENSURE( PaUnixMutex_Unlock( &self->mtx ) );

        PA_UNLESS( !res || ETIMEDOUT == res, paInternalError );
        PA_DEBUG(( "%s: Waited for %g seconds for stream to start\n", __FUNCTION__, PaUtil_GetTime() - now ));
        if( ETIMEDOUT == res )
        {
            PA_ENSURE( paTimedOut );
        }
    }

end:
    return result;
error:
    if( started )
    {
        PaUnixThread_Terminate( self, 0, NULL );
    }

    goto end;
}

PaError PaUnixThread_Terminate( PaUnixThread* self, int wait, PaError* exitResult )
{
    PaError result = paNoError;
    void* pret;

    if( exitResult )
    {
        *exitResult = paNoError;
    }
#if 0
    if( watchdogExitResult )
        *watchdogExitResult = paNoError;

    if( th->watchdogRunning )
    {
        pthread_cancel( th->watchdogThread );
        PA_ENSURE_SYSTEM( pthread_join( th->watchdogThread, &pret ), 0 );

        if( pret && pret != PTHREAD_CANCELED )
        {
            if( watchdogExitResult )
                *watchdogExitResult = *(PaError *) pret;
            free( pret );
        }
    }
#endif

    /* Only kill the thread if it isn't in the process of stopping (flushing adaptation buffers) */
    /* TODO: Make join time out */
    self->stopRequested = wait;
    if( !wait )
    {
        PA_DEBUG(( "%s: Canceling thread %d\n", __FUNCTION__, self->thread ));
        /* XXX: Safe to call this if the thread has exited on its own? */
#ifdef PTHREAD_CANCELED
        pthread_cancel( self->thread );
#endif
    }
    PA_DEBUG(( "%s: Joining thread %d\n", __FUNCTION__, self->thread ));
    PA_ENSURE_SYSTEM( pthread_join( self->thread, &pret ), 0 );

#ifdef PTHREAD_CANCELED
    if( pret && PTHREAD_CANCELED != pret )
#else
    /* !wait means the thread may have been canceled */
    if( pret && wait )
#endif
    {
        if( exitResult )
        {
            *exitResult = *(PaError*)pret;
        }
        free( pret );
    }

error:
    PA_ASSERT_CALL( PaUnixMutex_Terminate( &self->mtx ), paNoError );
    PA_ASSERT_CALL( pthread_cond_destroy( &self->cond ), 0 );

    return result;
}

PaError PaUnixThread_PrepareNotify( PaUnixThread* self )
{
    PaError result = paNoError;
    PA_UNLESS( self->parentWaiting, paInternalError );

    PA_ENSURE( PaUnixMutex_Lock( &self->mtx ) );
    self->locked = 1;

error:
    return result;
}

PaError PaUnixThread_NotifyParent( PaUnixThread* self )
{
    PaError result = paNoError;
    PA_UNLESS( self->parentWaiting, paInternalError );

    if( !self->locked )
    {
        PA_ENSURE( PaUnixMutex_Lock( &self->mtx ) );
        self->locked = 1;
    }
    self->parentWaiting = 0;
    pthread_cond_signal( &self->cond );
    PA_ENSURE( PaUnixMutex_Unlock( &self->mtx ) );
    self->locked = 0;

error:
    return result;
}

int PaUnixThread_StopRequested( PaUnixThread* self )
{
    return self->stopRequested;
}

PaError PaUnixMutex_Initialize( PaUnixMutex* self )
{
    PaError result = paNoError;
    PA_ASSERT_CALL( pthread_mutex_init( &self->mtx, NULL ), 0 );
    return result;
}

PaError PaUnixMutex_Terminate( PaUnixMutex* self )
{
    PaError result = paNoError;
    PA_ASSERT_CALL( pthread_mutex_destroy( &self->mtx ), 0 );
    return result;
}

/** Lock mutex.
 *
 * We're disabling thread cancellation while the thread is holding a lock, so mutexes are
 * properly unlocked at termination time.
 */
PaError PaUnixMutex_Lock( PaUnixMutex* self )
{
    PaError result = paNoError;

#ifdef PTHREAD_CANCEL
    int oldState;
    PA_ENSURE_SYSTEM( pthread_setcancelstate( PTHREAD_CANCEL_DISABLE, &oldState ), 0 );
#endif
    PA_ENSURE_SYSTEM( pthread_mutex_lock( &self->mtx ), 0 );

error:
    return result;
}

/** Unlock mutex.
 *
 * Thread cancellation is enabled again after the mutex is properly unlocked.
 */
PaError PaUnixMutex_Unlock( PaUnixMutex* self )
{
    PaError result = paNoError;

    PA_ENSURE_SYSTEM( pthread_mutex_unlock( &self->mtx ), 0 );
#ifdef PTHREAD_CANCEL
    int oldState;
    PA_ENSURE_SYSTEM( pthread_setcancelstate( PTHREAD_CANCEL_ENABLE, &oldState ), 0 );
#endif

error:
    return result;
}


#if 0
static void OnWatchdogExit( void *userData )
{
    PaAlsaThreading *th = (PaAlsaThreading *) userData;
    struct sched_param spm = { 0 };
    assert( th );

    PA_ASSERT_CALL( pthread_setschedparam( th->callbackThread, SCHED_OTHER, &spm ), 0 );    /* Lower before exiting */
    PA_DEBUG(( "Watchdog exiting\n" ));
}

static void *WatchdogFunc( void *userData )
{
    PaError result = paNoError, *pres = NULL;
    int err;
    PaAlsaThreading *th = (PaAlsaThreading *) userData;
    unsigned intervalMsec = 500;
    const PaTime maxSeconds = 3.;   /* Max seconds between callbacks */
    PaTime timeThen = PaUtil_GetTime(), timeNow, timeElapsed, cpuTimeThen, cpuTimeNow, cpuTimeElapsed;
    double cpuLoad, avgCpuLoad = 0.;
    int throttled = 0;

    assert( th );

    /* Execute OnWatchdogExit when exiting */
    pthread_cleanup_push( &OnWatchdogExit, th );

    /* Boost priority of callback thread */
    PA_ENSURE( result = BoostPriority( th ) );
    if( !result )
    {
        /* Boost failed, might as well exit */
        pthread_exit( NULL );
    }

    cpuTimeThen = th->callbackCpuTime;
    {
        int policy;
        struct sched_param spm = { 0 };
        pthread_getschedparam( pthread_self(), &policy, &spm );
        PA_DEBUG(( "%s: Watchdog priority is %d\n", __FUNCTION__, spm.sched_priority ));
    }

    while( 1 )
    {
        double lowpassCoeff = 0.9, lowpassCoeff1 = 0.99999 - lowpassCoeff;

        /* Test before and after in case whatever underlying sleep call isn't interrupted by pthread_cancel */
        pthread_testcancel();
        Pa_Sleep( intervalMsec );
        pthread_testcancel();

        if( PaUtil_GetTime() - th->callbackTime > maxSeconds )
        {
            PA_DEBUG(( "Watchdog: Terminating callback thread\n" ));
            /* Tell thread to terminate */
            err = pthread_kill( th->callbackThread, SIGKILL );
            pthread_exit( NULL );
        }

        PA_DEBUG(( "%s: PortAudio reports CPU load: %g\n", __FUNCTION__, PaUtil_GetCpuLoad( th->cpuLoadMeasurer ) ));

        /* Check if we should throttle, or unthrottle :P */
        cpuTimeNow = th->callbackCpuTime;
        cpuTimeElapsed = cpuTimeNow - cpuTimeThen;
        cpuTimeThen = cpuTimeNow;

        timeNow = PaUtil_GetTime();
        timeElapsed = timeNow - timeThen;
        timeThen = timeNow;
        cpuLoad = cpuTimeElapsed / timeElapsed;
        avgCpuLoad = avgCpuLoad * lowpassCoeff + cpuLoad * lowpassCoeff1;
        /*
        if( throttled )
            PA_DEBUG(( "Watchdog: CPU load: %g, %g\n", avgCpuLoad, cpuTimeElapsed ));
            */
        if( PaUtil_GetCpuLoad( th->cpuLoadMeasurer ) > .925 )
        {
            static int policy;
            static struct sched_param spm = { 0 };
            static const struct sched_param defaultSpm = { 0 };
            PA_DEBUG(( "%s: Throttling audio thread, priority %d\n", __FUNCTION__, spm.sched_priority ));

            pthread_getschedparam( th->callbackThread, &policy, &spm );
            if( !pthread_setschedparam( th->callbackThread, SCHED_OTHER, &defaultSpm ) )
            {
                throttled = 1;
            }
            else
                PA_DEBUG(( "Watchdog: Couldn't lower priority of audio thread: %s\n", strerror( errno ) ));

            /* Give other processes a go, before raising priority again */
            PA_DEBUG(( "%s: Watchdog sleeping for %lu msecs before unthrottling\n", __FUNCTION__, th->throttledSleepTime ));
            Pa_Sleep( th->throttledSleepTime );

            /* Reset callback priority */
            if( pthread_setschedparam( th->callbackThread, SCHED_FIFO, &spm ) != 0 )
            {
                PA_DEBUG(( "%s: Couldn't raise priority of audio thread: %s\n", __FUNCTION__, strerror( errno ) ));
            }

            if( PaUtil_GetCpuLoad( th->cpuLoadMeasurer ) >= .99 )
                intervalMsec = 50;
            else
                intervalMsec = 100;

            /*
            lowpassCoeff = .97;
            lowpassCoeff1 = .99999 - lowpassCoeff;
            */
        }
        else if( throttled && avgCpuLoad < .8 )
        {
            intervalMsec = 500;
            throttled = 0;

            /*
            lowpassCoeff = .9;
            lowpassCoeff1 = .99999 - lowpassCoeff;
            */
        }
    }

    pthread_cleanup_pop( 1 );   /* Execute cleanup on exit */

error:
    /* Shouldn't get here in the normal case */

    /* Pass on error code */
    pres = malloc( sizeof (PaError) );
    *pres = result;

    pthread_exit( pres );
}

static void CallbackUpdate( PaAlsaThreading *th )
{
    th->callbackTime = PaUtil_GetTime();
    th->callbackCpuTime = PaUtil_GetCpuLoad( th->cpuLoadMeasurer );
}

/*
static void *CanaryFunc( void *userData )
{
    const unsigned intervalMsec = 1000;
    PaUtilThreading *th = (PaUtilThreading *) userData;

    while( 1 )
    {
        th->canaryTime = PaUtil_GetTime();

        pthread_testcancel();
        Pa_Sleep( intervalMsec );
    }

    pthread_exit( NULL );
}
*/
#endif
