source: lib/events_libevent.c @ daf544a

  /********************************************************************\
  * BitlBee -- An IRC to other IM-networks gateway                     *
  *                                                                    *
  * Copyright 2002-2006 Wilmer van der Gaast and others                *
  \********************************************************************/

/*
 * Event handling (using libevent)
 */

/*
  This program is free software; you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation; either version 2 of the License, or
  (at your option) any later version.

  This program 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 with
  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
  Suite 330, Boston, MA  02111-1307  USA
*/

#define BITLBEE_CORE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/time.h>
#include <event.h>
#include "proxy.h"

static void b_main_restart();
static guint id_next = 1; /* Next ID to be allocated to an event handler. */
static guint id_cur = 0; /* Event ID that we're currently handling. */
static guint id_dead; /* Set to 1 if b_event_remove removes id_cur. */
static GHashTable *id_hash;
static int quitting = 0; /* Prepare to quit, stop handling events. */

/* Since libevent doesn't handle two event handlers for one fd-condition
   very well (which happens sometimes when BitlBee changes event handlers
   for a combination), let's buid some indexes so we can delete them here
   already, just in time. */
static GHashTable *read_hash;
static GHashTable *write_hash;

struct event_base *leh;
struct event_base *old_leh;

struct b_event_data
{
        guint id;
        struct event evinfo;
        gint timeout;
        b_event_handler function;
        void *data;
        guint flags;
};

void b_main_init()
{
        if( leh != NULL )
        {
                /* Clean up the hash tables? */
                
                b_main_restart();
                old_leh = leh;
        }
        
        leh = event_init();
        
        id_hash = g_hash_table_new( g_int_hash, g_int_equal );
        read_hash = g_hash_table_new( g_int_hash, g_int_equal );
        write_hash = g_hash_table_new( g_int_hash, g_int_equal );
}

void b_main_run()
{
        /* This while loop is necessary to exit the event loop and start a
           different one (necessary for ForkDaemon mode). */
        while( event_base_dispatch( leh ) == 0 && !quitting )
        {
                if( old_leh != NULL )
                {
                        /* For some reason this just isn't allowed...
                           Possibly a bug in older versions, will see later.
                        event_base_free( old_leh ); */
                        old_leh = NULL;
                }
                
                event_debug( "New event loop.\n" );
        }
}

static void b_main_restart()
{
        struct timeval tv;
        
        memset( &tv, 0, sizeof( struct timeval ) );
        event_base_loopexit( leh, &tv );
        
        event_debug( "b_main_restart()\n" );
}

void b_main_quit()
{
        /* Tell b_main_run() that it shouldn't restart the loop. Also,
           libevent sometimes generates events before really quitting,
           we want to stop them. */
        quitting = 1;
        
        b_main_restart();
}

static void b_event_passthrough( int fd, short event, void *data )
{
        struct b_event_data *b_ev = data;
        b_input_condition cond = 0;
        gboolean st;
        
        if( fd >= 0 )
        {
                if( event & EV_READ )
                        cond |= B_EV_IO_READ;
                if( event & EV_WRITE )
                        cond |= B_EV_IO_WRITE;
        }
        
        event_debug( "b_event_passthrough( %d, %d, 0x%x ) (%d)\n", fd, event, (int) data, b_ev->id );
        
        /* Since the called function might cancel this handler already
           (which free()s b_ev), we have to remember the ID here. */
        id_cur = b_ev->id;
        id_dead = 0;
        
        if( quitting )
        {
                b_event_remove( id_cur );
                return;
        }
        
        st = b_ev->function( b_ev->data, fd, cond );
        if( id_dead )
        {
                /* This event was killed already, don't touch it! */
                return;
        }
        else if( !st && !( b_ev->flags & B_EV_FLAG_FORCE_REPEAT ) )
        {
                event_debug( "Handler returned FALSE: " );
                b_event_remove( id_cur );
        }
        else if( fd == -1 )
        {
                /* fd == -1 means it was a timer. These can't be auto-repeated
                   so it has to be recreated every time. */
                struct timeval tv;
                
                tv.tv_sec = b_ev->timeout / 1000;
                tv.tv_usec = ( b_ev->timeout % 1000 ) * 1000;
                
                evtimer_add( &b_ev->evinfo, &tv );
        }
}

gint b_input_add( gint fd, b_input_condition condition, b_event_handler function, gpointer data )
{
        struct b_event_data *b_ev;
        
        event_debug( "b_input_add( %d, %d, 0x%x, 0x%x ) ", fd, condition, function, data );
        
        if( ( condition & B_EV_IO_READ  && ( b_ev = g_hash_table_lookup( read_hash,  &fd ) ) ) ||
            ( condition & B_EV_IO_WRITE && ( b_ev = g_hash_table_lookup( write_hash, &fd ) ) ) )
        {
                /* We'll stick with this libevent entry, but give it a new BitlBee id. */
                g_hash_table_remove( id_hash, &b_ev->id );
                
                event_debug( "(replacing old handler (id = %d)) = %d\n", b_ev->id, id_next );
                
                b_ev->id = id_next++;
                b_ev->function = function;
                b_ev->data = data;
        }
        else
        {
                GIOCondition out_cond;
                
                event_debug( "(new) = %d\n", id_next );
                
                b_ev = g_new0( struct b_event_data, 1 );
                b_ev->id = id_next++;
                b_ev->function = function;
                b_ev->data = data;
                
                out_cond = EV_PERSIST;
                if( condition & B_EV_IO_READ )
                        out_cond |= EV_READ;
                if( condition & B_EV_IO_WRITE )
                        out_cond |= EV_WRITE;
                
                event_set( &b_ev->evinfo, fd, out_cond, b_event_passthrough, b_ev );
                event_add( &b_ev->evinfo, NULL );
                
                if( out_cond & EV_READ )
                        g_hash_table_insert( read_hash, &b_ev->evinfo.ev_fd, b_ev );
                if( out_cond & EV_WRITE )
                        g_hash_table_insert( write_hash, &b_ev->evinfo.ev_fd, b_ev );
        }
        
        b_ev->flags = condition;
        g_hash_table_insert( id_hash, &b_ev->id, b_ev );
        return b_ev->id;
}

/* TODO: Persistence for timers! */
gint b_timeout_add( gint timeout, b_event_handler function, gpointer data )
{
        struct b_event_data *b_ev = g_new0( struct b_event_data, 1 );
        struct timeval tv;
        
        b_ev->id = id_next++;
        b_ev->timeout = timeout;
        b_ev->function = function;
        b_ev->data = data;
        
        tv.tv_sec = timeout / 1000;
        tv.tv_usec = ( timeout % 1000 ) * 1000;
        
        evtimer_set( &b_ev->evinfo, b_event_passthrough, b_ev );
        evtimer_add( &b_ev->evinfo, &tv );
        
        event_debug( "b_timeout_add( %d, 0x%x, 0x%x ) = %d\n", timeout, function, data, b_ev->id );
        
        g_hash_table_insert( id_hash, &b_ev->id, b_ev );
        
        return b_ev->id;
}

void b_event_remove( gint id )
{
        struct b_event_data *b_ev = g_hash_table_lookup( id_hash, &id );
        
        event_debug( "b_event_remove( %d )\n", id );
        if( b_ev )
        {
                if( id == id_cur )
                        id_dead = TRUE;
                
                g_hash_table_remove( id_hash, &b_ev->id );
                if( b_ev->evinfo.ev_fd >= 0 )
                {
                        if( b_ev->evinfo.ev_events & EV_READ )
                                g_hash_table_remove( read_hash, &b_ev->evinfo.ev_fd );
                        if( b_ev->evinfo.ev_events & EV_WRITE )
                                g_hash_table_remove( write_hash, &b_ev->evinfo.ev_fd );
                }
                
                event_del( &b_ev->evinfo );
                g_free( b_ev );
        }
        else
        {
                event_debug( "Already removed?\n" );
        }
}

void closesocket( int fd )
{
        struct b_event_data *b_ev;
        
        /* Since epoll() (the main reason we use libevent) automatically removes sockets from
           the epoll() list when a socket gets closed and some modules have a habit of
           closing sockets before removing event handlers, our and libevent's administration
           get a little bit messed up. So this little function will remove the handlers
           properly before closing a socket. */
        
        if( ( b_ev = g_hash_table_lookup( read_hash, &fd ) ) )
        {
                event_debug( "Warning: fd %d still had a read event handler when shutting down.\n", fd );
                b_event_remove( b_ev->id );
        }
        if( ( b_ev = g_hash_table_lookup( write_hash, &fd ) ) )
        {
                event_debug( "Warning: fd %d still had a write event handler when shutting down.\n", fd );
                b_event_remove( b_ev->id );
        }
        
        close( fd );
}