Attempt to fix dead-lock (bug #3807): remove from host list and unlock host mutex...
[pazpar2-moved-to-github.git] / src / connection.c
1 /* This file is part of Pazpar2.
2    Copyright (C) 2006-2010 Index Data
3
4 Pazpar2 is free software; you can redistribute it and/or modify it under
5 the terms of the GNU General Public License as published by the Free
6 Software Foundation; either version 2, or (at your option) any later
7 version.
8
9 Pazpar2 is distributed in the hope that it will be useful, but WITHOUT ANY
10 WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 for more details.
13
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
17
18 */
19
20 /** \file connection.c
21     \brief Z39.50 connection (low-level client)
22 */
23
24 #if HAVE_CONFIG_H
25 #include <config.h>
26 #endif
27
28 #include <stdlib.h>
29 #include <stdio.h>
30 #include <string.h>
31 #if HAVE_SYS_TIME_H
32 #include <sys/time.h>
33 #endif
34 #if HAVE_UNISTD_H
35 #include <unistd.h>
36 #endif
37
38 #include <signal.h>
39 #include <assert.h>
40
41 #include <yaz/log.h>
42 #include <yaz/comstack.h>
43 #include <yaz/tcpip.h>
44 #include "connection.h"
45 #include "session.h"
46 #include "host.h"
47 #include "client.h"
48 #include "settings.h"
49
50 /* connection counting (1) , disable connection counting (0) */
51 #if 0
52 static YAZ_MUTEX g_mutex = 0;
53 static int no_connections = 0;
54
55 static void connection_use(int delta)
56 {
57     if (!g_mutex)
58         yaz_mutex_create(&g_mutex);
59     yaz_mutex_enter(g_mutex);
60     no_connections += delta;
61     yaz_mutex_leave(g_mutex);
62     yaz_log(YLOG_LOG, "%s connections=%d", delta > 0 ? "INC" : "DEC",
63             no_connections);
64 }
65 #else
66 #define connection_use(x)
67 #endif
68
69
70 /** \brief Represents a physical, reusable  connection to a remote Z39.50 host
71  */
72 struct connection {
73     IOCHAN iochan;
74     ZOOM_connection link;
75     struct host *host;
76     struct client *client;
77     char *zproxy;
78     enum {
79         Conn_Resolving,
80         Conn_Connecting,
81         Conn_Open
82     } state;
83     int operation_timeout;
84     int session_timeout;
85     struct connection *next; // next for same host or next in free list
86 };
87
88 static int connection_connect(struct connection *con, iochan_man_t iochan_man);
89
90 static int connection_is_idle(struct connection *co)
91 {
92     ZOOM_connection link = co->link;
93     int event;
94
95     if (co->state != Conn_Open || !link)
96         return 0;
97
98     if (!ZOOM_connection_is_idle(link))
99         return 0;
100     event = ZOOM_connection_peek_event(link);
101     if (event == ZOOM_EVENT_NONE)
102         return 1;
103     else
104         return 0;
105 }
106
107 ZOOM_connection connection_get_link(struct connection *co)
108 {
109     return co->link;
110 }
111
112 static void remove_connection_from_host(struct connection *con)
113 {
114     struct connection **conp = &con->host->connections;
115     assert(con);
116     while (*conp)
117     {
118         if (*conp == con)
119         {
120             *conp = (*conp)->next;
121             break;
122         }
123         conp = &(*conp)->next;
124     }
125     yaz_cond_broadcast(con->host->cond_ready);
126 }
127
128 // Close connection and recycle structure
129 static void connection_destroy(struct connection *co)
130 {
131     if (co->link)
132     {
133         ZOOM_connection_destroy(co->link);
134         iochan_destroy(co->iochan);
135     }
136     yaz_log(YLOG_DEBUG, "Connection destroy %s", co->host->hostport);
137
138     if (co->client)
139     {
140         client_disconnect(co->client);
141     }
142
143     xfree(co->zproxy);
144     xfree(co);
145     connection_use(-1);
146 }
147
148 // Creates a new connection for client, associated with the host of 
149 // client's database
150 static struct connection *connection_create(struct client *cl,
151                                             int operation_timeout,
152                                             int session_timeout,
153                                             iochan_man_t iochan_man)
154 {
155     struct connection *co;
156     struct host *host = client_get_host(cl);
157
158     co = xmalloc(sizeof(*co));
159     co->host = host;
160
161     co->client = cl;
162     co->zproxy = 0;
163     client_set_connection(cl, co);
164     co->link = 0;
165     co->state = Conn_Resolving;
166     co->operation_timeout = operation_timeout;
167     co->session_timeout = session_timeout;
168     if (host->ipport)
169         connection_connect(co, iochan_man);
170
171     yaz_mutex_enter(host->mutex);
172     co->next = co->host->connections;
173     co->host->connections = co;
174     yaz_mutex_leave(host->mutex);
175
176     connection_use(1);
177     return co;
178 }
179
180 static void non_block_events(struct connection *co)
181 {
182     int got_records = 0;
183     IOCHAN iochan = co->iochan;
184     ZOOM_connection link = co->link;
185     while (1)
186     {
187         struct client *cl = co->client;
188         int ev;
189         int r = ZOOM_event_nonblock(1, &link);
190         if (!r)
191             break;
192         if (!cl)
193             continue;
194         ev = ZOOM_connection_last_event(link);
195         
196 #if 1
197         yaz_log(YLOG_DEBUG, "%p Connection ZOOM_EVENT_%s", co, ZOOM_get_event_str(ev));
198 #endif
199         switch (ev) 
200         {
201         case ZOOM_EVENT_END:
202             {
203                 const char *error, *addinfo;
204                 int err;
205                 if ((err = ZOOM_connection_error(link, &error, &addinfo)))
206                 {
207                     yaz_log(YLOG_LOG, "Error %s from %s",
208                             error, client_get_url(cl));
209                     client_set_diagnostic(cl, err);
210                     client_set_state(cl, Client_Error);
211                 }
212                 else
213                 {
214                     iochan_settimeout(iochan, co->session_timeout);
215                     client_set_state(cl, Client_Idle);
216                 }
217                 yaz_cond_broadcast(co->host->cond_ready);
218             }
219             break;
220         case ZOOM_EVENT_SEND_DATA:
221             break;
222         case ZOOM_EVENT_RECV_DATA:
223             break;
224         case ZOOM_EVENT_UNKNOWN:
225             break;
226         case ZOOM_EVENT_SEND_APDU:
227             client_set_state(co->client, Client_Working);
228             iochan_settimeout(iochan, co->operation_timeout);
229             break;
230         case ZOOM_EVENT_RECV_APDU:
231             break;
232         case ZOOM_EVENT_CONNECT:
233             yaz_log(YLOG_LOG, "Connected to %s", client_get_url(cl));
234             co->state = Conn_Open;
235             break;
236         case ZOOM_EVENT_RECV_SEARCH:
237             client_search_response(cl);
238             break;
239         case ZOOM_EVENT_RECV_RECORD:
240             client_record_response(cl);
241             got_records = 1;
242             break;
243         default:
244             yaz_log(YLOG_LOG, "Unhandled event (%d) from %s",
245                     ev, client_get_url(cl));
246         }
247     }
248     if (got_records)
249     {
250         struct client *cl = co->client;
251         if (cl)
252         {
253             client_check_preferred_watch(cl);
254             client_got_records(cl);
255         }
256     }
257 }
258
259 void connection_continue(struct connection *co)
260 {
261     int r = ZOOM_connection_exec_task(co->link);
262     if (!r)
263         yaz_log(YLOG_WARN, "No task was executed for connection");
264     iochan_setflags(co->iochan, ZOOM_connection_get_mask(co->link));
265     iochan_setfd(co->iochan, ZOOM_connection_get_socket(co->link));
266 }
267
268 static void connection_handler(IOCHAN iochan, int event)
269 {
270     struct connection *co = iochan_getdata(iochan);
271     struct client *cl;
272     struct host *host = co->host;
273
274     yaz_mutex_enter(host->mutex);
275     cl = co->client;
276     if (!cl) 
277     {
278         /* no client associated with it.. We are probably getting
279            a closed connection from the target.. Or, perhaps, an unexpected
280            package.. We will just close the connection */
281         yaz_log(YLOG_LOG, "timeout connection %p event=%d", co, event);
282         remove_connection_from_host(co);
283         yaz_mutex_leave(host->mutex);
284         connection_destroy(co);
285     }
286     else if (event & EVENT_TIMEOUT)
287     {
288         if (co->state == Conn_Connecting)
289         {
290             yaz_log(YLOG_WARN,  "connect timeout %s", client_get_url(cl));
291
292             client_set_state(cl, Client_Error);
293             connection_destroy(co);
294         }
295         else
296         {
297             yaz_log(YLOG_LOG,  "idle timeout %s", client_get_url(cl));
298             connection_destroy(co);
299         }
300         yaz_mutex_leave(host->mutex);
301     }
302     else
303     {
304         yaz_mutex_leave(host->mutex);
305
306         client_lock(cl);
307         non_block_events(co);
308
309         ZOOM_connection_fire_event_socket(co->link, event);
310         
311         non_block_events(co);
312         client_unlock(cl);
313
314         if (co->link)
315         {
316             iochan_setflags(iochan, ZOOM_connection_get_mask(co->link));
317             iochan_setfd(iochan, ZOOM_connection_get_socket(co->link));
318         }
319     }
320 }
321
322
323 // Disassociate connection from client
324 static void connection_release(struct connection *co)
325 {
326     struct client *cl = co->client;
327
328     if (!cl)
329         return;
330     client_set_connection(cl, 0);
331     co->client = 0;
332 }
333
334 void connect_resolver_host(struct host *host, iochan_man_t iochan_man)
335 {
336     struct connection *con;
337
338 start:
339     yaz_mutex_enter(host->mutex);
340     con = host->connections;
341     while (con)
342     {
343         if (con->state == Conn_Resolving)
344         {
345             if (!host->ipport) /* unresolved */
346             {
347                 remove_connection_from_host(con);
348                 yaz_mutex_leave(host->mutex);
349                 connection_destroy(con);
350                 goto start;
351                 /* start all over .. at some point it will be NULL */
352             }
353             else if (!con->client)
354             {
355                 remove_connection_from_host(con);
356                 yaz_mutex_leave(host->mutex);
357                 connection_destroy(con);
358                 /* start all over .. at some point it will be NULL */
359                 goto start;
360             }
361             else
362             {
363                 yaz_mutex_leave(host->mutex);
364                 connection_connect(con, iochan_man);
365                 client_start_search(con->client);
366                 goto start;
367             }
368         }
369         else
370         {
371             yaz_log(YLOG_LOG, "connect_resolver_host: state=%d", con->state);
372             con = con->next;
373         }
374     }
375     yaz_mutex_leave(host->mutex);
376 }
377
378 static struct host *connection_get_host(struct connection *con)
379 {
380     return con->host;
381 }
382
383 static int connection_connect(struct connection *con, iochan_man_t iochan_man)
384 {
385     ZOOM_connection link = 0;
386     struct host *host = connection_get_host(con);
387     ZOOM_options zoptions = ZOOM_options_create();
388     const char *auth;
389     const char *charset;
390     const char *sru;
391     const char *sru_version = 0;
392
393     struct session_database *sdb = client_get_database(con->client);
394     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
395     const char *apdulog = session_setting_oneval(sdb, PZ_APDULOG);
396
397     assert(host->ipport);
398     assert(con);
399
400     ZOOM_options_set(zoptions, "async", "1");
401     ZOOM_options_set(zoptions, "implementationName", PACKAGE_NAME);
402     ZOOM_options_set(zoptions, "implementationVersion", VERSION);
403         
404     if ((charset = session_setting_oneval(sdb, PZ_NEGOTIATION_CHARSET)))
405         ZOOM_options_set(zoptions, "charset", charset);
406     
407     if (zproxy && *zproxy)
408     {
409         con->zproxy = xstrdup(zproxy);
410         ZOOM_options_set(zoptions, "proxy", zproxy);
411     }
412     if (apdulog && *apdulog)
413         ZOOM_options_set(zoptions, "apdulog", apdulog);
414
415     if ((auth = session_setting_oneval(sdb, PZ_AUTHENTICATION)))
416         ZOOM_options_set(zoptions, "user", auth);
417     if ((sru = session_setting_oneval(sdb, PZ_SRU)) && *sru)
418         ZOOM_options_set(zoptions, "sru", sru);
419     if ((sru_version = session_setting_oneval(sdb, PZ_SRU_VERSION)) 
420         && *sru_version)
421         ZOOM_options_set(zoptions, "sru_version", sru_version);
422
423     if (!(link = ZOOM_connection_create(zoptions)))
424     {
425         yaz_log(YLOG_FATAL|YLOG_ERRNO, "Failed to create ZOOM Connection");
426         ZOOM_options_destroy(zoptions);
427         return -1;
428     }
429
430     if (sru && *sru)
431     {
432         char http_hostport[512];
433         strcpy(http_hostport, "http://");
434         strcat(http_hostport, host->hostport);
435         ZOOM_connection_connect(link, http_hostport, 0);
436     }
437     else if (zproxy && *zproxy)
438         ZOOM_connection_connect(link, host->hostport, 0);        
439     else
440         ZOOM_connection_connect(link, host->ipport, 0);
441     
442     con->link = link;
443     con->iochan = iochan_create(-1, connection_handler, 0, "connection_socket");
444     con->state = Conn_Connecting;
445     iochan_settimeout(con->iochan, con->operation_timeout);
446     iochan_setdata(con->iochan, con);
447     iochan_add(iochan_man, con->iochan);
448
449     /* this fragment is bad DRY: from client_prep_connection */
450     client_set_state(con->client, Client_Connecting);
451     ZOOM_options_destroy(zoptions);
452     return 0;
453 }
454
455 // Ensure that client has a connection associated
456 int client_prep_connection(struct client *cl,
457                            int operation_timeout, int session_timeout,
458                            iochan_man_t iochan_man,
459                            const struct timeval *abstime)
460 {
461     struct connection *co;
462     struct host *host = client_get_host(cl);
463     struct session_database *sdb = client_get_database(cl);
464     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
465
466     if (zproxy && zproxy[0] == '\0')
467         zproxy = 0;
468
469     if (!host)
470         return 0;
471
472     co = client_get_connection(cl);
473
474     yaz_log(YLOG_DEBUG, "Client prep %s", client_get_url(cl));
475
476     if (!co)
477     {
478         int max_connections = 0;
479         int reuse_connections = 1;
480         const char *v = session_setting_oneval(client_get_database(cl),
481                                                PZ_MAX_CONNECTIONS);
482         if (v && *v)
483             max_connections = atoi(v);
484
485         v = session_setting_oneval(client_get_database(cl),
486                 PZ_REUSE_CONNECTIONS);
487         if (v && *v)
488             reuse_connections = atoi(v);
489
490         // See if someone else has an idle connection
491         // We should look at timestamps here to select the longest-idle connection
492         yaz_mutex_enter(host->mutex);
493         while (1)
494         {
495             int num_connections = 0;
496             for (co = host->connections; co; co = co->next)
497                 num_connections++;
498             if (reuse_connections) {
499                 for (co = host->connections; co; co = co->next)
500                 {
501                     if (connection_is_idle(co) &&
502                         (!co->client || client_get_state(co->client) == Client_Idle) &&
503                         !strcmp(ZOOM_connection_option_get(co->link, "user"),
504                                 session_setting_oneval(client_get_database(cl),
505                                                        PZ_AUTHENTICATION)))
506                     {
507                         if (zproxy == 0 && co->zproxy == 0)
508                             break;
509                         if (zproxy && co->zproxy && !strcmp(zproxy, co->zproxy))
510                             break;
511                     }
512                 }
513                 if (co)
514                 {
515                     yaz_log(YLOG_LOG, "num_connections = %d (reusing)", num_connections);
516                     break;
517                 }
518             }
519             if (max_connections <= 0 || num_connections < max_connections)
520             {
521                 yaz_log(YLOG_LOG, "num_connections = %d (new); max = %d",
522                         num_connections, max_connections);
523                 break;
524             }
525             yaz_log(YLOG_LOG, "num_connections = %d (waiting) max = %d",
526                     num_connections, max_connections);
527             if (yaz_cond_wait(host->cond_ready, host->mutex, abstime))
528             {
529                 yaz_log(YLOG_LOG, "out of connections %s", client_get_url(cl));
530                 client_set_state(cl, Client_Error);
531                 yaz_mutex_leave(host->mutex);
532                 return 0;
533             }
534         }
535         if (co)
536         {
537             connection_release(co);
538             client_set_connection(cl, co);
539             co->client = cl;
540             /* ensure that connection is only assigned to this client
541                by marking the client non Idle */
542             client_set_state(cl, Client_Working);
543             yaz_mutex_leave(host->mutex);
544             co->operation_timeout = operation_timeout;
545             co->session_timeout = session_timeout;
546             /* tells ZOOM to reconnect if necessary. Disabled becuase
547                the ZOOM_connection_connect flushes the task queue */
548             ZOOM_connection_connect(co->link, 0, 0);
549         }
550         else
551         {
552             yaz_mutex_leave(host->mutex);
553             co = connection_create(cl, operation_timeout, session_timeout,
554                                    iochan_man);
555         }
556     }
557
558     if (co && co->link)
559         return 1;
560     else
561         return 0;
562 }
563
564 /*
565  * Local variables:
566  * c-basic-offset: 4
567  * c-file-style: "Stroustrup"
568  * indent-tabs-mode: nil
569  * End:
570  * vim: shiftwidth=4 tabstop=8 expandtab
571  */
572