Fix the fix on unlimited connections.
[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     remove_connection_from_host(co);
144     xfree(co->zproxy);
145     xfree(co);
146     connection_use(-1);
147 }
148
149 // Creates a new connection for client, associated with the host of 
150 // client's database
151 static struct connection *connection_create(struct client *cl,
152                                             int operation_timeout,
153                                             int session_timeout,
154                                             iochan_man_t iochan_man)
155 {
156     struct connection *co;
157     struct host *host = client_get_host(cl);
158
159     co = xmalloc(sizeof(*co));
160     co->host = host;
161
162     co->client = cl;
163     co->zproxy = 0;
164     client_set_connection(cl, co);
165     co->link = 0;
166     co->state = Conn_Resolving;
167     co->operation_timeout = operation_timeout;
168     co->session_timeout = session_timeout;
169     if (host->ipport)
170         connection_connect(co, iochan_man);
171
172     yaz_mutex_enter(host->mutex);
173     co->next = co->host->connections;
174     co->host->connections = co;
175     yaz_mutex_leave(host->mutex);
176
177     connection_use(1);
178     return co;
179 }
180
181 static void non_block_events(struct connection *co)
182 {
183     int got_records = 0;
184     IOCHAN iochan = co->iochan;
185     ZOOM_connection link = co->link;
186     while (1)
187     {
188         struct client *cl = co->client;
189         int ev;
190         int r = ZOOM_event_nonblock(1, &link);
191         if (!r)
192             break;
193         if (!cl)
194             continue;
195         ev = ZOOM_connection_last_event(link);
196         
197 #if 0
198         yaz_log(YLOG_LOG, "ZOOM_EVENT_%s", ZOOM_get_event_str(ev));
199 #endif
200         switch (ev) 
201         {
202         case ZOOM_EVENT_END:
203             {
204                 const char *error, *addinfo;
205                 int err;
206                 if ((err = ZOOM_connection_error(link, &error, &addinfo)))
207                 {
208                     yaz_log(YLOG_LOG, "Error %s from %s",
209                             error, client_get_url(cl));
210                 }
211                 iochan_settimeout(iochan, co->session_timeout);
212                 client_set_diagnostic(cl, err);
213                 client_set_state(cl, Client_Idle);
214                 yaz_cond_broadcast(co->host->cond_ready);
215             }
216             break;
217         case ZOOM_EVENT_SEND_DATA:
218             break;
219         case ZOOM_EVENT_RECV_DATA:
220             break;
221         case ZOOM_EVENT_UNKNOWN:
222             break;
223         case ZOOM_EVENT_SEND_APDU:
224             client_set_state(co->client, Client_Working);
225             iochan_settimeout(iochan, co->operation_timeout);
226             break;
227         case ZOOM_EVENT_RECV_APDU:
228             break;
229         case ZOOM_EVENT_CONNECT:
230             yaz_log(YLOG_LOG, "Connected to %s", client_get_url(cl));
231             co->state = Conn_Open;
232             break;
233         case ZOOM_EVENT_RECV_SEARCH:
234             client_search_response(cl);
235             break;
236         case ZOOM_EVENT_RECV_RECORD:
237             client_record_response(cl);
238             got_records = 1;
239             break;
240         default:
241             yaz_log(YLOG_LOG, "Unhandled event (%d) from %s",
242                     ev, client_get_url(cl));
243         }
244     }
245     if (got_records)
246     {
247         struct client *cl = co->client;
248         if (cl)
249         {
250             client_got_records(cl);
251         }
252     }
253 }
254
255 void connection_continue(struct connection *co)
256 {
257     int r = ZOOM_connection_exec_task(co->link);
258     if (!r)
259         yaz_log(YLOG_WARN, "No task was executed for connection");
260     iochan_setflags(co->iochan, ZOOM_connection_get_mask(co->link));
261     iochan_setfd(co->iochan, ZOOM_connection_get_socket(co->link));
262 }
263
264 static void connection_handler(IOCHAN iochan, int event)
265 {
266     struct connection *co = iochan_getdata(iochan);
267     struct client *cl;
268     struct host *host = co->host;
269
270     yaz_mutex_enter(host->mutex);
271     cl = co->client;
272     if (!cl) 
273     {
274         /* no client associated with it.. We are probably getting
275            a closed connection from the target.. Or, perhaps, an unexpected
276            package.. We will just close the connection */
277         yaz_log(YLOG_LOG, "timeout connection %p event=%d", co, event);
278         connection_destroy(co);
279         yaz_mutex_leave(host->mutex);
280     }
281     else if (event & EVENT_TIMEOUT)
282     {
283         if (co->state == Conn_Connecting)
284         {
285             yaz_log(YLOG_WARN,  "connect timeout %s", client_get_url(cl));
286
287             client_set_state(cl, Client_Error);
288             connection_destroy(co);
289         }
290         else if (client_get_state(co->client) == Client_Idle)
291         {
292             yaz_log(YLOG_LOG,  "idle timeout %s", client_get_url(cl));
293             connection_destroy(co);
294         }
295         else
296         {
297             yaz_log(YLOG_LOG,  "ignore timeout %s", client_get_url(cl));
298         }
299         yaz_mutex_leave(host->mutex);
300     }
301     else
302     {
303         yaz_mutex_leave(host->mutex);
304
305         client_lock(cl);
306         non_block_events(co);
307
308         ZOOM_connection_fire_event_socket(co->link, event);
309         
310         non_block_events(co);
311         client_unlock(cl);
312
313         if (co->link)
314         {
315             iochan_setflags(iochan, ZOOM_connection_get_mask(co->link));
316             iochan_setfd(iochan, ZOOM_connection_get_socket(co->link));
317         }
318     }
319 }
320
321
322 // Disassociate connection from client
323 static void connection_release(struct connection *co)
324 {
325     struct client *cl = co->client;
326
327     if (!cl)
328         return;
329     client_set_connection(cl, 0);
330     co->client = 0;
331 }
332
333 void connect_resolver_host(struct host *host, iochan_man_t iochan_man)
334 {
335     struct connection *con;
336
337 start:
338     yaz_mutex_enter(host->mutex);
339     con = host->connections;
340     while (con)
341     {
342         if (con->state == Conn_Resolving)
343         {
344             if (!host->ipport) /* unresolved */
345             {
346                 yaz_mutex_leave(host->mutex);
347                 connection_destroy(con);
348                 goto start;
349                 /* start all over .. at some point it will be NULL */
350             }
351             else if (!con->client)
352             {
353                 yaz_mutex_leave(host->mutex);
354                 connection_destroy(con);
355                 /* start all over .. at some point it will be NULL */
356                 goto start;
357             }
358             else
359             {
360                 yaz_mutex_leave(host->mutex);
361                 connection_connect(con, iochan_man);
362                 client_start_search(con->client);
363                 goto start;
364             }
365         }
366         else
367         {
368             yaz_log(YLOG_LOG, "connect_resolver_host: state=%d", con->state);
369             con = con->next;
370         }
371     }
372     yaz_mutex_leave(host->mutex);
373 }
374
375 static struct host *connection_get_host(struct connection *con)
376 {
377     return con->host;
378 }
379
380 static int connection_connect(struct connection *con, iochan_man_t iochan_man)
381 {
382     ZOOM_connection link = 0;
383     struct host *host = connection_get_host(con);
384     ZOOM_options zoptions = ZOOM_options_create();
385     const char *auth;
386     const char *charset;
387     const char *sru;
388     const char *sru_version = 0;
389
390     struct session_database *sdb = client_get_database(con->client);
391     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
392     const char *apdulog = session_setting_oneval(sdb, PZ_APDULOG);
393
394     assert(host->ipport);
395     assert(con);
396
397     ZOOM_options_set(zoptions, "async", "1");
398     ZOOM_options_set(zoptions, "implementationName", PACKAGE_NAME);
399     ZOOM_options_set(zoptions, "implementationVersion", VERSION);
400         
401     if ((charset = session_setting_oneval(sdb, PZ_NEGOTIATION_CHARSET)))
402         ZOOM_options_set(zoptions, "charset", charset);
403     
404     if (zproxy && *zproxy)
405     {
406         con->zproxy = xstrdup(zproxy);
407         ZOOM_options_set(zoptions, "proxy", zproxy);
408     }
409     if (apdulog && *apdulog)
410         ZOOM_options_set(zoptions, "apdulog", apdulog);
411
412     if ((auth = session_setting_oneval(sdb, PZ_AUTHENTICATION)))
413         ZOOM_options_set(zoptions, "user", auth);
414     if ((sru = session_setting_oneval(sdb, PZ_SRU)) && *sru)
415         ZOOM_options_set(zoptions, "sru", sru);
416     if ((sru_version = session_setting_oneval(sdb, PZ_SRU_VERSION)) 
417         && *sru_version)
418         ZOOM_options_set(zoptions, "sru_version", sru_version);
419
420     if (!(link = ZOOM_connection_create(zoptions)))
421     {
422         yaz_log(YLOG_FATAL|YLOG_ERRNO, "Failed to create ZOOM Connection");
423         ZOOM_options_destroy(zoptions);
424         return -1;
425     }
426
427     if (sru && *sru)
428     {
429         char http_hostport[512];
430         strcpy(http_hostport, "http://");
431         strcat(http_hostport, host->hostport);
432         ZOOM_connection_connect(link, http_hostport, 0);
433     }
434     else
435         ZOOM_connection_connect(link, host->ipport, 0);
436     
437     con->link = link;
438     con->iochan = iochan_create(0, connection_handler, 0, "connection_socket");
439     con->state = Conn_Connecting;
440     iochan_settimeout(con->iochan, con->operation_timeout);
441     iochan_setdata(con->iochan, con);
442     iochan_add(iochan_man, con->iochan);
443
444     /* this fragment is bad DRY: from client_prep_connection */
445     client_set_state(con->client, Client_Connecting);
446     ZOOM_options_destroy(zoptions);
447     return 0;
448 }
449
450 // Ensure that client has a connection associated
451 int client_prep_connection(struct client *cl,
452                            int operation_timeout, int session_timeout,
453                            iochan_man_t iochan_man,
454                            const struct timeval *abstime)
455 {
456     struct connection *co;
457     struct host *host = client_get_host(cl);
458     struct session_database *sdb = client_get_database(cl);
459     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
460
461     if (zproxy && zproxy[0] == '\0')
462         zproxy = 0;
463
464     if (!host)
465         return 0;
466
467     co = client_get_connection(cl);
468
469     yaz_log(YLOG_DEBUG, "Client prep %s", client_get_url(cl));
470
471     if (!co)
472     {
473         int max_connections = 0;
474         const char *v = session_setting_oneval(client_get_database(cl),
475                                                PZ_MAX_CONNECTIONS);
476         if (v && *v)
477             max_connections = atoi(v);
478         
479         // See if someone else has an idle connection
480         // We should look at timestamps here to select the longest-idle connection
481         yaz_mutex_enter(host->mutex);
482         while (1)
483         {
484             int num_connections = 0;
485             for (co = host->connections; co; co = co->next)
486                 num_connections++;
487             for (co = host->connections; co; co = co->next)
488             {
489                 if (connection_is_idle(co) &&
490                     (!co->client || client_get_state(co->client) == Client_Idle) &&
491                     !strcmp(ZOOM_connection_option_get(co->link, "user"),
492                             session_setting_oneval(client_get_database(cl),
493                                                    PZ_AUTHENTICATION)))
494                 {
495                     if (zproxy == 0 && co->zproxy == 0)
496                         break;
497                     if (zproxy && co->zproxy && !strcmp(zproxy, co->zproxy))
498                         break;
499                 }
500             }
501             if (co)
502             {
503                 yaz_log(YLOG_LOG, "num_connections = %d (reusing)",
504                         num_connections);
505                 break;
506             }
507             if (max_connections <= 0 || num_connections < max_connections)
508             {
509                 yaz_log(YLOG_LOG, "num_connections = %d (new); max = %d",
510                         num_connections, max_connections);
511                 break;
512             }
513             yaz_log(YLOG_LOG, "num_connections = %d (waiting) max = %d",
514                     num_connections, max_connections);
515             if (yaz_cond_wait(host->cond_ready, host->mutex, abstime))
516             {
517                 yaz_log(YLOG_LOG, "out of connections %s", client_get_url(cl));
518                 client_set_state(cl, Client_Error);
519                 yaz_mutex_leave(host->mutex);
520                 return 0;
521             }
522         }
523         if (co)
524         {
525             connection_release(co);
526             client_set_connection(cl, co);
527             co->client = cl;
528             /* ensure that connection is only assigned to this client
529                by marking the client non Idle */
530             client_set_state(cl, Client_Working);
531             yaz_mutex_leave(host->mutex);
532             co->operation_timeout = operation_timeout;
533             co->session_timeout = session_timeout;
534             /* tells ZOOM to reconnect if necessary. Disabled becuase
535                the ZOOM_connection_connect flushes the task queue */
536             ZOOM_connection_connect(co->link, 0, 0);
537         }
538         else
539         {
540             yaz_mutex_leave(host->mutex);
541             co = connection_create(cl, operation_timeout, session_timeout,
542                                    iochan_man);
543         }
544     }
545
546     if (co && co->link)
547         return 1;
548     else
549         return 0;
550 }
551
552 /*
553  * Local variables:
554  * c-basic-offset: 4
555  * c-file-style: "Stroustrup"
556  * indent-tabs-mode: nil
557  * End:
558  * vim: shiftwidth=4 tabstop=8 expandtab
559  */
560