transmission/libtransmission/trevent.c

/*
 * This file Copyright (C) 2007-2008 Charles Kerr <charles@rebelbase.com>
 *
 * This file is licensed by the GPL version 2.  Works owned by the
 * Transmission project are granted a special exemption to clause 2(b)
 * so that the bulk of its code can remain under the MIT license. 
 * This exemption does not extend to derived works not owned by
 * the Transmission project.
 *
 * $Id$
 */

#include <assert.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

#include <signal.h>

#ifdef WIN32
  #include <fcntl.h>
  #define pipe(f) _pipe(f, 1000, _O_BINARY)
#else
  #include <unistd.h>
#endif

#include <event.h>

#include "transmission.h"
#include "platform.h"
#include "trevent.h"
#include "utils.h"

/***
****
***/

typedef struct tr_event_handle
{
    uint8_t die;
    int fds[2];
    tr_lock * lock;
    tr_handle * h;
    tr_thread * thread;
    struct event_base * base;
    struct event pipeEvent;
}
tr_event_handle;

typedef int timer_func(void*);

struct tr_timer
{
    struct event event;
    struct timeval tv;
    timer_func * func;
    void * user_data;
    struct tr_event_handle * eh;
    uint8_t inCallback;
};

struct tr_run_data
{
    void (*func)( void * );
    void * user_data;
};

#define dbgmsg(fmt...) tr_deepLog( __FILE__, __LINE__, "event", ##fmt )

static void
readFromPipe( int fd, short eventType, void * veh )
{
    char ch;
    int ret;
    tr_event_handle * eh = veh;
    dbgmsg( "readFromPipe: eventType is %hd", eventType );

    /* read the command type */
    ch = '\0';
    do {
        ret = read( fd, &ch, 1 );
    } while( !eh->die && ret<0 && errno==EAGAIN );
    dbgmsg( "command is [%c], ret is %d, errno is %d", ch, ret, (int)errno );

    switch( ch )
    {
        case 'r': /* run in libevent thread */
        {
            struct tr_run_data data;
            const size_t nwant = sizeof( data );
            const ssize_t ngot = read( fd, &data, nwant );
            if( !eh->die && ( ngot == (ssize_t)nwant ) ) {
                dbgmsg( "invoking function in libevent thread" );
                (data.func)( data.user_data );
            }
            break;
        }
        case 't': /* create timer */
        {
            tr_timer * timer;
            const size_t nwant = sizeof( timer );
            const ssize_t ngot = read( fd, &timer, nwant );
            if( !eh->die && ( ngot == (ssize_t)nwant ) ) {
                dbgmsg( "adding timer in libevent thread" );
                evtimer_add( &timer->event, &timer->tv );
            }
            break;
        }
        case '\0': /* eof */
        {
            dbgmsg( "pipe eof reached... removing event listener" );
            event_del( &eh->pipeEvent );
            break;
        }
        default:
        {
            assert( 0 && "unhandled command type!" );
            break;
	}
    }
}

static void
logFunc( int severity, const char * message )
{
    if( severity >= _EVENT_LOG_ERR )
        tr_nerr( "%s", message );
    else
        tr_ndbg( "%s", message );
}

static void
libeventThreadFunc( void * veh )
{
    tr_event_handle * eh = (tr_event_handle *) veh;
    tr_dbg( "Starting libevent thread" );

#ifndef WIN32
    /* Don't exit when writing on a broken socket */
    signal( SIGPIPE, SIG_IGN );
#endif

    eh->base = event_init( );
    eh->h->events = eh;
    event_set_log_callback( logFunc );

    /* listen to the pipe's read fd */
    event_set( &eh->pipeEvent, eh->fds[0], EV_READ|EV_PERSIST, readFromPipe, veh );
    event_add( &eh->pipeEvent, NULL );

    event_dispatch( );

    tr_lockFree( eh->lock );
    event_base_free( eh->base );
    eh->h->events = NULL;
    tr_free( eh );
    tr_dbg( "Closing libevent thread" );
}

void
tr_eventInit( tr_handle * handle )
{
    tr_event_handle * eh;

    eh = tr_new0( tr_event_handle, 1 );
    eh->lock = tr_lockNew( );
    pipe( eh->fds );
    eh->h = handle;
    eh->thread = tr_threadNew( libeventThreadFunc, eh, "libeventThreadFunc" );
}

void
tr_eventClose( tr_handle * handle )
{
    handle->events->die = TRUE;
    tr_deepLog( __FILE__, __LINE__, NULL, "closing trevent pipe" );
    close( handle->events->fds[1] );
}

/**
***
**/

int
tr_amInEventThread( struct tr_handle * handle )
{
    return tr_amInThread( handle->events->thread );
}

/**
***
**/

static void
timerCallback( int fd UNUSED, short event UNUSED, void * vtimer )
{
    int more;
    struct tr_timer * timer = vtimer;

    timer->inCallback = 1;
    more = (*timer->func)( timer->user_data );
    timer->inCallback = 0;

    if( more )
        evtimer_add( &timer->event, &timer->tv );
    else
        tr_timerFree( &timer );
}

void
tr_timerFree( tr_timer ** ptimer )
{
    tr_timer * timer;

    /* zero out the argument passed in */
    assert( ptimer );
    timer = *ptimer;
    *ptimer = NULL;

    /* destroy the timer directly or via the command queue */
    if( timer && !timer->inCallback )
    {
        assert( tr_amInEventThread( timer->eh->h ) );
        event_del( &timer->event );
        tr_free( timer );
    }
}

tr_timer*
tr_timerNew( struct tr_handle * handle,
             timer_func         func,
             void             * user_data,
             uint64_t           interval_milliseconds )
{
    tr_timer * timer = tr_new0( tr_timer, 1 );
    timer->tv = tr_timevalMsec( interval_milliseconds );
    timer->func = func;
    timer->user_data = user_data;
    timer->eh = handle->events;
    evtimer_set( &timer->event, timerCallback, timer );

    if( tr_amInThread( handle->events->thread ) )
    {
        evtimer_add( &timer->event,  &timer->tv );
    }
    else
    {
        const char ch = 't';
        int fd = handle->events->fds[1];
        tr_lock * lock = handle->events->lock;

        tr_lockLock( lock );
        write( fd, &ch, 1 );
        write( fd, &timer, sizeof(timer) );
        tr_lockUnlock( lock );
    }

    return timer;
}

void
tr_runInEventThread( struct tr_handle * handle,
                     void               func( void* ),
                     void             * user_data )
{
    if( tr_amInThread( handle->events->thread ) )
    {
        (func)( user_data );
    }
    else
    {
        const char ch = 'r';
        int fd = handle->events->fds[1];
        tr_lock * lock = handle->events->lock;
        struct tr_run_data data;

        tr_lockLock( lock );
        write( fd, &ch, 1 );
        data.func = func;
        data.user_data = user_data;
        write( fd, &data, sizeof(data) );
        tr_lockUnlock( lock );
    }
}