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, "%p Connection ZOOM_EVENT_%s", co, 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                     client_set_diagnostic(cl, err);
 211                     client_set_state(cl, Client_Error);
 212                 }
 213                 else
 214                 {
 215                     iochan_settimeout(iochan, co->session_timeout);
 216                     client_set_state(cl, Client_Idle);
 217                 }
 218                 yaz_cond_broadcast(co->host->cond_ready);
 219             }
 220             break;
 221         case ZOOM_EVENT_SEND_DATA:
 222             break;
 223         case ZOOM_EVENT_RECV_DATA:
 224             break;
 225         case ZOOM_EVENT_UNKNOWN:
 226             break;
 227         case ZOOM_EVENT_SEND_APDU:
 228             client_set_state(co->client, Client_Working);
 229             iochan_settimeout(iochan, co->operation_timeout);
 230             break;
 231         case ZOOM_EVENT_RECV_APDU:
 232             break;
 233         case ZOOM_EVENT_CONNECT:
 234             yaz_log(YLOG_LOG, "Connected to %s", client_get_url(cl));
 235             co->state = Conn_Open;
 236             break;
 237         case ZOOM_EVENT_RECV_SEARCH:
 238             client_search_response(cl);
 239             break;
 240         case ZOOM_EVENT_RECV_RECORD:
 241             client_record_response(cl);
 242             got_records = 1;
 243             break;
 244         default:
 245             yaz_log(YLOG_LOG, "Unhandled event (%d) from %s",
 246                     ev, client_get_url(cl));
 247         }
 248     }
 249     if (got_records)
 250     {
 251         struct client *cl = co->client;
 252         if (cl)
 253         {
 254             client_check_preferred_watch(cl);
 255             client_got_records(cl);
 256         }
 257     }
 258 }
 259
 260 void connection_continue(struct connection *co)
 261 {
 262     int r = ZOOM_connection_exec_task(co->link);
 263     if (!r)
 264         yaz_log(YLOG_WARN, "No task was executed for connection");
 265     iochan_setflags(co->iochan, ZOOM_connection_get_mask(co->link));
 266     iochan_setfd(co->iochan, ZOOM_connection_get_socket(co->link));
 267 }
 268
 269 static void connection_handler(IOCHAN iochan, int event)
 270 {
 271     struct connection *co = iochan_getdata(iochan);
 272     struct client *cl;
 273     struct host *host = co->host;
 274
 275     yaz_mutex_enter(host->mutex);
 276     cl = co->client;
 277     if (!cl)
 278     {
 279         /* no client associated with it.. We are probably getting
 280            a closed connection from the target.. Or, perhaps, an unexpected
 281            package.. We will just close the connection */
 282         yaz_log(YLOG_LOG, "timeout connection %p event=%d", co, event);
 283         connection_destroy(co);
 284         yaz_mutex_leave(host->mutex);
 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                 yaz_mutex_leave(host->mutex);
 348                 connection_destroy(con);
 349                 goto start;
 350                 /* start all over .. at some point it will be NULL */
 351             }
 352             else if (!con->client)
 353             {
 354                 yaz_mutex_leave(host->mutex);
 355                 connection_destroy(con);
 356                 /* start all over .. at some point it will be NULL */
 357                 goto start;
 358             }
 359             else
 360             {
 361                 yaz_mutex_leave(host->mutex);
 362                 connection_connect(con, iochan_man);
 363                 client_start_search(con->client);
 364                 goto start;
 365             }
 366         }
 367         else
 368         {
 369             yaz_log(YLOG_LOG, "connect_resolver_host: state=%d", con->state);
 370             con = con->next;
 371         }
 372     }
 373     yaz_mutex_leave(host->mutex);
 374 }
 375
 376 static struct host *connection_get_host(struct connection *con)
 377 {
 378     return con->host;
 379 }
 380
 381 static int connection_connect(struct connection *con, iochan_man_t iochan_man)
 382 {
 383     ZOOM_connection link = 0;
 384     struct host *host = connection_get_host(con);
 385     ZOOM_options zoptions = ZOOM_options_create();
 386     const char *auth;
 387     const char *charset;
 388     const char *sru;
 389     const char *sru_version = 0;
 390
 391     struct session_database *sdb = client_get_database(con->client);
 392     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
 393     const char *apdulog = session_setting_oneval(sdb, PZ_APDULOG);
 394
 395     assert(host->ipport);
 396     assert(con);
 397
 398     ZOOM_options_set(zoptions, "async", "1");
 399     ZOOM_options_set(zoptions, "implementationName", PACKAGE_NAME);
 400     ZOOM_options_set(zoptions, "implementationVersion", VERSION);
 401
 402     if ((charset = session_setting_oneval(sdb, PZ_NEGOTIATION_CHARSET)))
 403         ZOOM_options_set(zoptions, "charset", charset);
 404
 405     if (zproxy && *zproxy)
 406     {
 407         con->zproxy = xstrdup(zproxy);
 408         ZOOM_options_set(zoptions, "proxy", zproxy);
 409     }
 410     if (apdulog && *apdulog)
 411         ZOOM_options_set(zoptions, "apdulog", apdulog);
 412
 413     if ((auth = session_setting_oneval(sdb, PZ_AUTHENTICATION)))
 414         ZOOM_options_set(zoptions, "user", auth);
 415     if ((sru = session_setting_oneval(sdb, PZ_SRU)) && *sru)
 416         ZOOM_options_set(zoptions, "sru", sru);
 417     if ((sru_version = session_setting_oneval(sdb, PZ_SRU_VERSION))
 418         && *sru_version)
 419         ZOOM_options_set(zoptions, "sru_version", sru_version);
 420
 421     if (!(link = ZOOM_connection_create(zoptions)))
 422     {
 423         yaz_log(YLOG_FATAL|YLOG_ERRNO, "Failed to create ZOOM Connection");
 424         ZOOM_options_destroy(zoptions);
 425         return -1;
 426     }
 427
 428     if (sru && *sru)
 429     {
 430         char http_hostport[512];
 431         strcpy(http_hostport, "http://");
 432         strcat(http_hostport, host->hostport);
 433         ZOOM_connection_connect(link, http_hostport, 0);
 434     }
 435     else
 436         ZOOM_connection_connect(link, host->ipport, 0);
 437
 438     con->link = link;
 439     con->iochan = iochan_create(-1, connection_handler, 0, "connection_socket");
 440     con->state = Conn_Connecting;
 441     iochan_settimeout(con->iochan, con->operation_timeout);
 442     iochan_setdata(con->iochan, con);
 443     iochan_add(iochan_man, con->iochan);
 444
 445     /* this fragment is bad DRY: from client_prep_connection */
 446     client_set_state(con->client, Client_Connecting);
 447     ZOOM_options_destroy(zoptions);
 448     return 0;
 449 }
 450
 451 // Ensure that client has a connection associated
 452 int client_prep_connection(struct client *cl,
 453                            int operation_timeout, int session_timeout,
 454                            iochan_man_t iochan_man,
 455                            const struct timeval *abstime)
 456 {
 457     struct connection *co;
 458     struct host *host = client_get_host(cl);
 459     struct session_database *sdb = client_get_database(cl);
 460     const char *zproxy = session_setting_oneval(sdb, PZ_ZPROXY);
 461
 462     if (zproxy && zproxy[0] == '\0')
 463         zproxy = 0;
 464
 465     if (!host)
 466         return 0;
 467
 468     co = client_get_connection(cl);
 469
 470     yaz_log(YLOG_DEBUG, "Client prep %s", client_get_url(cl));
 471
 472     if (!co)
 473     {
 474         int max_connections = 0;
 475         int reuse_connections = 1;
 476         const char *v = session_setting_oneval(client_get_database(cl),
 477                                                PZ_MAX_CONNECTIONS);
 478         if (v && *v)
 479             max_connections = atoi(v);
 480
 481         v = session_setting_oneval(client_get_database(cl),
 482                 PZ_REUSE_CONNECTIONS);
 483         if (v && *v)
 484             reuse_connections = atoi(v);
 485
 486         // See if someone else has an idle connection
 487         // We should look at timestamps here to select the longest-idle connection
 488         yaz_mutex_enter(host->mutex);
 489         while (1)
 490         {
 491             int num_connections = 0;
 492             for (co = host->connections; co; co = co->next)
 493                 num_connections++;
 494             if (reuse_connections) {
 495                 for (co = host->connections; co; co = co->next)
 496                 {
 497                     if (connection_is_idle(co) &&
 498                         (!co->client || client_get_state(co->client) == Client_Idle) &&
 499                         !strcmp(ZOOM_connection_option_get(co->link, "user"),
 500                                 session_setting_oneval(client_get_database(cl),
 501                                                        PZ_AUTHENTICATION)))
 502                     {
 503                         if (zproxy == 0 && co->zproxy == 0)
 504                             break;
 505                         if (zproxy && co->zproxy && !strcmp(zproxy, co->zproxy))
 506                             break;
 507                     }
 508                 }
 509                 if (co)
 510                 {
 511                     yaz_log(YLOG_LOG, "num_connections = %d (reusing)", num_connections);
 512                     break;
 513                 }
 514             }
 515             if (max_connections <= 0 || num_connections < max_connections)
 516             {
 517                 yaz_log(YLOG_LOG, "num_connections = %d (new); max = %d",
 518                         num_connections, max_connections);
 519                 break;
 520             }
 521             yaz_log(YLOG_LOG, "num_connections = %d (waiting) max = %d",
 522                     num_connections, max_connections);
 523             if (yaz_cond_wait(host->cond_ready, host->mutex, abstime))
 524             {
 525                 yaz_log(YLOG_LOG, "out of connections %s", client_get_url(cl));
 526                 client_set_state(cl, Client_Error);
 527                 yaz_mutex_leave(host->mutex);
 528                 return 0;
 529             }
 530         }
 531         if (co)
 532         {
 533             connection_release(co);
 534             client_set_connection(cl, co);
 535             co->client = cl;
 536             /* ensure that connection is only assigned to this client
 537                by marking the client non Idle */
 538             client_set_state(cl, Client_Working);
 539             yaz_mutex_leave(host->mutex);
 540             co->operation_timeout = operation_timeout;
 541             co->session_timeout = session_timeout;
 542             /* tells ZOOM to reconnect if necessary. Disabled becuase
 543                the ZOOM_connection_connect flushes the task queue */
 544             ZOOM_connection_connect(co->link, 0, 0);
 545         }
 546         else
 547         {
 548             yaz_mutex_leave(host->mutex);
 549             co = connection_create(cl, operation_timeout, session_timeout,
 550                                    iochan_man);
 551         }
 552     }
 553
 554     if (co && co->link)
 555         return 1;
 556     else
 557         return 0;
 558 }
 559
 560 /*
 561  * Local variables:
 562  * c-basic-offset: 4
 563  * c-file-style: "Stroustrup"
 564  * indent-tabs-mode: nil
 565  * End:
 566  * vim: shiftwidth=4 tabstop=8 expandtab
 567  */
 568