pa_linux_alsa.c

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/*
 * $Id: pa_linux_alsa.c,v 1.1.2.71 2005/04/15 18:20:18 aknudsen Exp $
 * PortAudio Portable Real-Time Audio Library
 * Latest Version at: http://www.portaudio.com
 * ALSA implementation by Joshua Haberman and Arve Knudsen
 *
 * Copyright (c) 2002 Joshua Haberman <[e-mail]>
 * Copyright (c) 2005 Arve Knudsen <[e-mail]>
 *
 * Based on the Open Source API proposed by Ross Bencina
 * Copyright (c) 1999-2002 Ross Bencina, Phil Burk
 *
 * 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.
 *
 * 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.
 *
 * 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.
 */

#define ALSA_PCM_NEW_HW_PARAMS_API
#define ALSA_PCM_NEW_SW_PARAMS_API
#include <alsa/asoundlib.h>
#undef ALSA_PCM_NEW_HW_PARAMS_API
#undef ALSA_PCM_NEW_SW_PARAMS_API

#include <sys/poll.h>
#include <string.h> /* strlen() */
#include <limits.h>
#include <math.h>
#include <pthread.h>
#include <signal.h>
#include <time.h>
#include <sys/mman.h>
#include <signal.h> /* For sig_atomic_t */

#include "portaudio.h"
#include "pa_util.h"
#include "pa_unix_util.h"
#include "pa_allocation.h"
#include "pa_hostapi.h"
#include "pa_stream.h"
#include "pa_cpuload.h"
#include "pa_process.h"

#include "pa_linux_alsa.h"

/* Check return value of ALSA function, and map it to PaError */
#define ENSURE_(expr, code) \
    do { \
        if( UNLIKELY( (aErr_ = (expr)) < 0 ) ) \
        { \
            /* PaUtil_SetLastHostErrorInfo should only be used in the main thread */ \
            if( (code) == paUnanticipatedHostError && pthread_self() != callbackThread_ ) \
            { \
                PaUtil_SetLastHostErrorInfo( paALSA, aErr_, snd_strerror( aErr_ ) ); \
            } \
            PaUtil_DebugPrint(( "Expression '" #expr "' failed in '" __FILE__ "', line: " STRINGIZE( __LINE__ ) "\n" )); \
            result = (code); \
            goto error; \
        } \
    } while( 0 );

#define ASSERT_CALL_(expr, success) \
    aErr_ = (expr); \
    assert( aErr_ == success );

static int aErr_;               /* Used with ENSURE_ */
static pthread_t callbackThread_;

typedef enum
{
    StreamDirection_In,
    StreamDirection_Out
} StreamDirection;

/* Threading utility struct */
typedef struct PaAlsaThreading
{
    pthread_t watchdogThread;
    pthread_t callbackThread;
    int watchdogRunning;
    int rtSched;
    int rtPrio;
    int useWatchdog;
    unsigned long throttledSleepTime;
    volatile PaTime callbackTime;
    volatile PaTime callbackCpuTime;
    PaUtilCpuLoadMeasurer *cpuLoadMeasurer;
} PaAlsaThreading;

typedef struct
{
    PaSampleFormat hostSampleFormat;
    unsigned long framesPerBuffer;
    int numUserChannels, numHostChannels;
    int userInterleaved, hostInterleaved;

    snd_pcm_t *pcm;
    snd_pcm_uframes_t bufferSize;
    snd_pcm_format_t nativeFormat;
    unsigned int nfds;
    int ready;  /* Marked ready from poll */
    void **userBuffers;
    snd_pcm_uframes_t offset;
    StreamDirection streamDir;

    snd_pcm_channel_area_t *channelAreas;  /* Needed for channel adaption */
} PaAlsaStreamComponent;

/* Implementation specific stream structure */
typedef struct PaAlsaStream
{
    PaUtilStreamRepresentation streamRepresentation;
    PaUtilCpuLoadMeasurer cpuLoadMeasurer;
    PaUtilBufferProcessor bufferProcessor;
    PaAlsaThreading threading;

    unsigned long framesPerUserBuffer;

    int primeBuffers;
    int callbackMode;              /* bool: are we running in callback mode? */
    int pcmsSynced;	            /* Have we successfully synced pcms */

    /* the callback thread uses these to poll the sound device(s), waiting
     * for data to be ready/available */
    struct pollfd *pfds;
    int pollTimeout;

    /* Used in communication between threads */
    volatile sig_atomic_t callback_finished; /* bool: are we in the "callback finished" state? */
    volatile sig_atomic_t callbackAbort;    /* Drop frames? */
    volatile sig_atomic_t callbackStop;     /* Signal a stop */
    volatile sig_atomic_t isActive;         /* Is stream in active state? (Between StartStream and StopStream || !paContinue) */
    pthread_mutex_t stateMtx;               /* Used to synchronize access to stream state */
    pthread_mutex_t startMtx;               /* Used to synchronize stream start in callback mode */
    pthread_cond_t startCond;               /* Wait untill audio is started in callback thread */

    int neverDropInput;

    PaTime underrun;
    PaTime overrun;

    PaAlsaStreamComponent capture, playback;
}
PaAlsaStream;

/* PaAlsaHostApiRepresentation - host api datastructure specific to this implementation */

typedef struct PaAlsaHostApiRepresentation
{
    PaUtilHostApiRepresentation commonHostApiRep;
    PaUtilStreamInterface callbackStreamInterface;
    PaUtilStreamInterface blockingStreamInterface;

    PaUtilAllocationGroup *allocations;

    PaHostApiIndex hostApiIndex;
}
PaAlsaHostApiRepresentation;

typedef struct PaAlsaDeviceInfo
{
    PaDeviceInfo commonDeviceInfo;
    char *alsaName;
    int isPlug;
    int minInputChannels;
    int minOutputChannels;
}
PaAlsaDeviceInfo;

/* Threading utilities */

static void InitializeThreading( PaAlsaThreading *th, PaUtilCpuLoadMeasurer *clm )
{
    th->watchdogRunning = 0;
    th->rtSched = 0;
    th->callbackTime = 0;
    th->callbackCpuTime = 0;
    th->useWatchdog = 1;
    th->throttledSleepTime = 0;
    th->cpuLoadMeasurer = clm;

    th->rtPrio = (sched_get_priority_max( SCHED_FIFO ) - sched_get_priority_min( SCHED_FIFO )) / 2
            + sched_get_priority_min( SCHED_FIFO );
}

static PaError KillCallbackThread( PaAlsaThreading *th, int wait, PaError *exitResult, PaError *watchdogExitResult )
{
    PaError result = paNoError;
    void *pret;

    if( exitResult )
        *exitResult = paNoError;
    if( watchdogExitResult )
        *watchdogExitResult = paNoError;

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

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

    /* Only kill the thread if it isn't in the process of stopping (flushing adaptation buffers) */
    /* TODO: Make join time out */
    if( !wait )
        pthread_cancel( th->callbackThread );   /* XXX: Safe to call this if the thread has exited on its own? */
    ASSERT_CALL_( pthread_join( th->callbackThread, &pret ), 0 );

    if( pret && pret != PTHREAD_CANCELED )
    {
        if( exitResult )
            *exitResult = *(PaError *) pret;
        free( pret );
    }

    return result;
}

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

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

static PaError BoostPriority( PaAlsaThreading *th )
{
    PaError result = paNoError;
    struct sched_param spm = { 0 };
    spm.sched_priority = th->rtPrio;

    assert( th );

    if( pthread_setschedparam( th->callbackThread, 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;
}

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 );

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

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

    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 };