source: lib/events_libevent.c @ 3a9b123

Last change on this file since 3a9b123 was 939370c, checked in by Wilmer van der Gaast <wilmer@…>, at 2008-12-14T10:19:41Z

events_libevent now detects when the event currently being handled is
removed. This could otherwise cause unpredictable behaviour, especially
for timers.

  • Property mode set to 100644
File size: 7.7 KB
Line 
1  /********************************************************************\
2  * BitlBee -- An IRC to other IM-networks gateway                     *
3  *                                                                    *
4  * Copyright 2002-2006 Wilmer van der Gaast and others                *
5  \********************************************************************/
6
7/*
8 * Event handling (using libevent)
9 */
10
11/*
12  This program is free software; you can redistribute it and/or modify
13  it under the terms of the GNU General Public License as published by
14  the Free Software Foundation; either version 2 of the License, or
15  (at your option) any later version.
16
17  This program is distributed in the hope that it will be useful,
18  but WITHOUT ANY WARRANTY; without even the implied warranty of
19  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
20  GNU General Public License for more details.
21
22  You should have received a copy of the GNU General Public License with
23  the Debian GNU/Linux distribution in /usr/share/common-licenses/GPL;
24  if not, write to the Free Software Foundation, Inc., 59 Temple Place,
25  Suite 330, Boston, MA  02111-1307  USA
26*/
27
28#define BITLBEE_CORE
29#include <stdio.h>
30#include <stdlib.h>
31#include <string.h>
32#include <unistd.h>
33#include <sys/types.h>
34#include <sys/time.h>
35#include <event.h>
36#include "proxy.h"
37
38static void b_main_restart();
39static guint id_next = 1; /* Next ID to be allocated to an event handler. */
40static guint id_cur = 0; /* Event ID that we're currently handling. */
41static guint id_dead; /* Set to 1 if b_event_remove removes id_cur. */
42static GHashTable *id_hash;
43static int quitting = 0; /* Prepare to quit, stop handling events. */
44
45/* Since libevent doesn't handle two event handlers for one fd-condition
46   very well (which happens sometimes when BitlBee changes event handlers
47   for a combination), let's buid some indexes so we can delete them here
48   already, just in time. */
49static GHashTable *read_hash;
50static GHashTable *write_hash;
51
52struct event_base *leh;
53struct event_base *old_leh;
54
55struct b_event_data
56{
57        guint id;
58        struct event evinfo;
59        gint timeout;
60        b_event_handler function;
61        void *data;
62};
63
64void b_main_init()
65{
66        if( leh != NULL )
67        {
68                /* Clean up the hash tables? */
69               
70                b_main_restart();
71                old_leh = leh;
72        }
73       
74        leh = event_init();
75       
76        id_hash = g_hash_table_new( g_int_hash, g_int_equal );
77        read_hash = g_hash_table_new( g_int_hash, g_int_equal );
78        write_hash = g_hash_table_new( g_int_hash, g_int_equal );
79}
80
81void b_main_run()
82{
83        /* This while loop is necessary to exit the event loop and start a
84           different one (necessary for ForkDaemon mode). */
85        while( event_base_dispatch( leh ) == 0 && !quitting )
86        {
87                if( old_leh != NULL )
88                {
89                        /* For some reason this just isn't allowed...
90                           Possibly a bug in older versions, will see later.
91                        event_base_free( old_leh ); */
92                        old_leh = NULL;
93                }
94               
95                event_debug( "New event loop.\n" );
96        }
97}
98
99static void b_main_restart()
100{
101        struct timeval tv;
102       
103        memset( &tv, 0, sizeof( struct timeval ) );
104        event_base_loopexit( leh, &tv );
105       
106        event_debug( "b_main_restart()\n" );
107}
108
109void b_main_quit()
110{
111        /* Tell b_main_run() that it shouldn't restart the loop. Also,
112           libevent sometimes generates events before really quitting,
113           we want to stop them. */
114        quitting = 1;
115       
116        b_main_restart();
117}
118
119static void b_event_passthrough( int fd, short event, void *data )
120{
121        struct b_event_data *b_ev = data;
122        b_input_condition cond = 0;
123        gboolean st;
124       
125        if( fd >= 0 )
126        {
127                if( event & EV_READ )
128                        cond |= GAIM_INPUT_READ;
129                if( event & EV_WRITE )
130                        cond |= GAIM_INPUT_WRITE;
131        }
132       
133        event_debug( "b_event_passthrough( %d, %d, 0x%x ) (%d)\n", fd, event, (int) data, b_ev->id );
134       
135        /* Since the called function might cancel this handler already
136           (which free()s b_ev), we have to remember the ID here. */
137        id_cur = b_ev->id;
138        id_dead = 0;
139       
140        if( quitting )
141        {
142                b_event_remove( id_cur );
143                return;
144        }
145       
146        st = b_ev->function( b_ev->data, fd, cond );
147        if( id_dead )
148        {
149                /* This event was killed already, don't touch it! */
150                return;
151        }
152        else if( !st )
153        {
154                event_debug( "Handler returned FALSE: " );
155                b_event_remove( id_cur );
156        }
157        else if( fd == -1 )
158        {
159                /* fd == -1 means it was a timer. These can't be auto-repeated
160                   so it has to be recreated every time. */
161                struct timeval tv;
162               
163                tv.tv_sec = b_ev->timeout / 1000;
164                tv.tv_usec = ( b_ev->timeout % 1000 ) * 1000;
165               
166                evtimer_add( &b_ev->evinfo, &tv );
167        }
168}
169
170gint b_input_add( gint fd, b_input_condition condition, b_event_handler function, gpointer data )
171{
172        struct b_event_data *b_ev;
173       
174        event_debug( "b_input_add( %d, %d, 0x%x, 0x%x ) ", fd, condition, function, data );
175       
176        if( ( condition & GAIM_INPUT_READ  && ( b_ev = g_hash_table_lookup( read_hash,  &fd ) ) ) ||
177            ( condition & GAIM_INPUT_WRITE && ( b_ev = g_hash_table_lookup( write_hash, &fd ) ) ) )
178        {
179                /* We'll stick with this libevent entry, but give it a new BitlBee id. */
180                g_hash_table_remove( id_hash, &b_ev->id );
181               
182                event_debug( "(replacing old handler (id = %d)) = %d\n", b_ev->id, id_next );
183               
184                b_ev->id = id_next++;
185                b_ev->function = function;
186                b_ev->data = data;
187        }
188        else
189        {
190                GIOCondition out_cond;
191               
192                event_debug( "(new) = %d\n", id_next );
193               
194                b_ev = g_new0( struct b_event_data, 1 );
195                b_ev->id = id_next++;
196                b_ev->function = function;
197                b_ev->data = data;
198               
199                out_cond = EV_PERSIST;
200                if( condition & GAIM_INPUT_READ )
201                        out_cond |= EV_READ;
202                if( condition & GAIM_INPUT_WRITE )
203                        out_cond |= EV_WRITE;
204               
205                event_set( &b_ev->evinfo, fd, out_cond, b_event_passthrough, b_ev );
206                event_add( &b_ev->evinfo, NULL );
207               
208                if( out_cond & EV_READ )
209                        g_hash_table_insert( read_hash, &b_ev->evinfo.ev_fd, b_ev );
210                if( out_cond & EV_WRITE )
211                        g_hash_table_insert( write_hash, &b_ev->evinfo.ev_fd, b_ev );
212        }
213       
214        g_hash_table_insert( id_hash, &b_ev->id, b_ev );
215        return b_ev->id;
216}
217
218/* TODO: Persistence for timers! */
219gint b_timeout_add( gint timeout, b_event_handler function, gpointer data )
220{
221        struct b_event_data *b_ev = g_new0( struct b_event_data, 1 );
222        struct timeval tv;
223       
224        b_ev->id = id_next++;
225        b_ev->timeout = timeout;
226        b_ev->function = function;
227        b_ev->data = data;
228       
229        tv.tv_sec = timeout / 1000;
230        tv.tv_usec = ( timeout % 1000 ) * 1000;
231       
232        evtimer_set( &b_ev->evinfo, b_event_passthrough, b_ev );
233        evtimer_add( &b_ev->evinfo, &tv );
234       
235        event_debug( "b_timeout_add( %d, 0x%x, 0x%x ) = %d\n", timeout, function, data, b_ev->id );
236       
237        g_hash_table_insert( id_hash, &b_ev->id, b_ev );
238       
239        return b_ev->id;
240}
241
242void b_event_remove( gint id )
243{
244        struct b_event_data *b_ev = g_hash_table_lookup( id_hash, &id );
245       
246        event_debug( "b_event_remove( %d )\n", id );
247        if( b_ev )
248        {
249                if( id == id_cur )
250                        id_dead = TRUE;
251               
252                g_hash_table_remove( id_hash, &b_ev->id );
253                if( b_ev->evinfo.ev_fd >= 0 )
254                {
255                        if( b_ev->evinfo.ev_events & EV_READ )
256                                g_hash_table_remove( read_hash, &b_ev->evinfo.ev_fd );
257                        if( b_ev->evinfo.ev_events & EV_WRITE )
258                                g_hash_table_remove( write_hash, &b_ev->evinfo.ev_fd );
259                }
260               
261                event_del( &b_ev->evinfo );
262                g_free( b_ev );
263        }
264        else
265        {
266                event_debug( "Already removed?\n" );
267        }
268}
269
270void closesocket( int fd )
271{
272        struct b_event_data *b_ev;
273       
274        /* Since epoll() (the main reason we use libevent) automatically removes sockets from
275           the epoll() list when a socket gets closed and some modules have a habit of
276           closing sockets before removing event handlers, our and libevent's administration
277           get a little bit messed up. So this little function will remove the handlers
278           properly before closing a socket. */
279       
280        if( ( b_ev = g_hash_table_lookup( read_hash, &fd ) ) )
281        {
282                event_debug( "Warning: fd %d still had a read event handler when shutting down.\n", fd );
283                b_event_remove( b_ev->id );
284        }
285        if( ( b_ev = g_hash_table_lookup( write_hash, &fd ) ) )
286        {
287                event_debug( "Warning: fd %d still had a write event handler when shutting down.\n", fd );
288                b_event_remove( b_ev->id );
289        }
290       
291        close( fd );
292}
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