ovsdb/jsonrpc-server.c

   1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #include <config.h>
  17
  18 #include "jsonrpc-server.h"
  19
  20 #include <errno.h>
  21
  22 #include "bitmap.h"
  23 #include "column.h"
  24 #include "dynamic-string.h"
  25 #include "json.h"
  26 #include "jsonrpc.h"
  27 #include "ovsdb-error.h"
  28 #include "ovsdb-parser.h"
  29 #include "ovsdb.h"
  30 #include "reconnect.h"
  31 #include "row.h"
  32 #include "server.h"
  33 #include "simap.h"
  34 #include "stream.h"
  35 #include "table.h"
  36 #include "timeval.h"
  37 #include "transaction.h"
  38 #include "trigger.h"
  39 #include "vlog.h"
  40
  41 VLOG_DEFINE_THIS_MODULE(ovsdb_jsonrpc_server);
  42
  43 struct ovsdb_jsonrpc_remote;
  44 struct ovsdb_jsonrpc_session;
  45
  46 /* Message rate-limiting. */
  47 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  48
  49 /* Sessions. */
  50 static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
  51     struct ovsdb_jsonrpc_remote *, struct jsonrpc_session *);
  52 static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
  53 static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
  54 static void ovsdb_jsonrpc_session_get_memory_usage_all(
  55     const struct ovsdb_jsonrpc_remote *, struct simap *usage);
  56 static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
  57 static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
  58 static void ovsdb_jsonrpc_session_set_all_options(
  59     struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
  60 static bool ovsdb_jsonrpc_session_get_status(
  61     const struct ovsdb_jsonrpc_remote *,
  62     struct ovsdb_jsonrpc_remote_status *);
  63 static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
  64 static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
  65
  66 /* Triggers. */
  67 static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
  68                                          struct ovsdb *,
  69                                          struct json *id, struct json *params);
  70 static struct ovsdb_jsonrpc_trigger *ovsdb_jsonrpc_trigger_find(
  71     struct ovsdb_jsonrpc_session *, const struct json *id, size_t hash);
  72 static void ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *);
  73 static void ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *);
  74 static void ovsdb_jsonrpc_trigger_complete_done(
  75     struct ovsdb_jsonrpc_session *);
  76
  77 /* Monitors. */
  78 static struct json *ovsdb_jsonrpc_monitor_create(
  79     struct ovsdb_jsonrpc_session *, struct ovsdb *, struct json *params);
  80 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
  81     struct ovsdb_jsonrpc_session *,
  82     struct json_array *params,
  83     const struct json *request_id);
  84 static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
  85 \f
  86 /* JSON-RPC database server. */
  87
  88 struct ovsdb_jsonrpc_server {
  89     struct ovsdb_server up;
  90     unsigned int n_sessions, max_sessions;
  91     struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
  92 };
  93
  94 /* A configured remote.  This is either a passive stream listener plus a list
  95  * of the currently connected sessions, or a list of exactly one active
  96  * session. */
  97 struct ovsdb_jsonrpc_remote {
  98     struct ovsdb_jsonrpc_server *server;
  99     struct pstream *listener;   /* Listener, if passive. */
 100     struct list sessions;       /* List of "struct ovsdb_jsonrpc_session"s. */
 101     uint8_t dscp;
 102 };
 103
 104 static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
 105     struct ovsdb_jsonrpc_server *, const char *name,
 106     const struct ovsdb_jsonrpc_options *options
 107 );
 108 static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 109
 110 /* Creates and returns a new server to provide JSON-RPC access to an OVSDB.
 111  *
 112  * The caller must call ovsdb_jsonrpc_server_add_db() for each database to
 113  * which 'server' should provide access. */
 114 struct ovsdb_jsonrpc_server *
 115 ovsdb_jsonrpc_server_create(void)
 116 {
 117     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
 118     ovsdb_server_init(&server->up);
 119     server->max_sessions = 64;
 120     shash_init(&server->remotes);
 121     return server;
 122 }
 123
 124 /* Adds 'db' to the set of databases served out by 'svr'.  Returns true if
 125  * successful, false if 'db''s name is the same as some database already in
 126  * 'server'. */
 127 bool
 128 ovsdb_jsonrpc_server_add_db(struct ovsdb_jsonrpc_server *svr, struct ovsdb *db)
 129 {
 130     return ovsdb_server_add_db(&svr->up, db);
 131 }
 132
 133 void
 134 ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
 135 {
 136     struct shash_node *node, *next;
 137
 138     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 139         ovsdb_jsonrpc_server_del_remote(node);
 140     }
 141     shash_destroy(&svr->remotes);
 142     ovsdb_server_destroy(&svr->up);
 143     free(svr);
 144 }
 145
 146 struct ovsdb_jsonrpc_options *
 147 ovsdb_jsonrpc_default_options(const char *target)
 148 {
 149     struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
 150     options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
 151     options->probe_interval = (stream_or_pstream_needs_probes(target)
 152                                ? RECONNECT_DEFAULT_PROBE_INTERVAL
 153                                : 0);
 154     return options;
 155 }
 156
 157 /* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
 158  * options in the struct ovsdb_jsonrpc_options supplied as the data values.
 159  *
 160  * A remote is an active or passive stream connection method, e.g. "pssl:" or
 161  * "tcp:1.2.3.4". */
 162 void
 163 ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 164                                  const struct shash *new_remotes)
 165 {
 166     struct shash_node *node, *next;
 167
 168     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 169         if (!shash_find(new_remotes, node->name)) {
 170             VLOG_INFO("%s: remote deconfigured", node->name);
 171             ovsdb_jsonrpc_server_del_remote(node);
 172         }
 173     }
 174     SHASH_FOR_EACH (node, new_remotes) {
 175         const struct ovsdb_jsonrpc_options *options = node->data;
 176         struct ovsdb_jsonrpc_remote *remote;
 177
 178         remote = shash_find_data(&svr->remotes, node->name);
 179         if (!remote) {
 180             remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
 181             if (!remote) {
 182                 continue;
 183             }
 184         }
 185
 186         ovsdb_jsonrpc_session_set_all_options(remote, options);
 187     }
 188 }
 189
 190 static struct ovsdb_jsonrpc_remote *
 191 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
 192                                 const char *name,
 193                                 const struct ovsdb_jsonrpc_options *options)
 194 {
 195     struct ovsdb_jsonrpc_remote *remote;
 196     struct pstream *listener;
 197     int error;
 198
 199     error = jsonrpc_pstream_open(name, &listener, options->dscp);
 200     if (error && error != EAFNOSUPPORT) {
 201         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, strerror(error));
 202         return NULL;
 203     }
 204
 205     remote = xmalloc(sizeof *remote);
 206     remote->server = svr;
 207     remote->listener = listener;
 208     list_init(&remote->sessions);
 209     remote->dscp = options->dscp;
 210     shash_add(&svr->remotes, name, remote);
 211
 212     if (!listener) {
 213         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name, true));
 214     }
 215     return remote;
 216 }
 217
 218 static void
 219 ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
 220 {
 221     struct ovsdb_jsonrpc_remote *remote = node->data;
 222
 223     ovsdb_jsonrpc_session_close_all(remote);
 224     pstream_close(remote->listener);
 225     shash_delete(&remote->server->remotes, node);
 226     free(remote);
 227 }
 228
 229 /* Stores status information for the remote named 'target', which should have
 230  * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
 231  * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
 232  * a remote named 'target' or if that remote is an inbound remote that has no
 233  * active connections) returns false.  On failure, 'status' will be zeroed.
 234  */
 235 bool
 236 ovsdb_jsonrpc_server_get_remote_status(
 237     const struct ovsdb_jsonrpc_server *svr, const char *target,
 238     struct ovsdb_jsonrpc_remote_status *status)
 239 {
 240     const struct ovsdb_jsonrpc_remote *remote;
 241
 242     memset(status, 0, sizeof *status);
 243
 244     remote = shash_find_data(&svr->remotes, target);
 245     return remote && ovsdb_jsonrpc_session_get_status(remote, status);
 246 }
 247
 248 void
 249 ovsdb_jsonrpc_server_free_remote_status(
 250     struct ovsdb_jsonrpc_remote_status *status)
 251 {
 252     free(status->locks_held);
 253     free(status->locks_waiting);
 254     free(status->locks_lost);
 255 }
 256
 257 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
 258  * reconnect. */
 259 void
 260 ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
 261 {
 262     struct shash_node *node;
 263
 264     SHASH_FOR_EACH (node, &svr->remotes) {
 265         struct ovsdb_jsonrpc_remote *remote = node->data;
 266
 267         ovsdb_jsonrpc_session_reconnect_all(remote);
 268     }
 269 }
 270
 271 void
 272 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 273 {
 274     struct shash_node *node;
 275
 276     SHASH_FOR_EACH (node, &svr->remotes) {
 277         struct ovsdb_jsonrpc_remote *remote = node->data;
 278
 279         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 280             struct stream *stream;
 281             int error;
 282
 283             error = pstream_accept(remote->listener, &stream);
 284             if (!error) {
 285                 struct jsonrpc_session *js;
 286                 js = jsonrpc_session_open_unreliably(jsonrpc_open(stream),
 287                                                      remote->dscp);
 288                 ovsdb_jsonrpc_session_create(remote, js);
 289             } else if (error != EAGAIN) {
 290                 VLOG_WARN_RL(&rl, "%s: accept failed: %s",
 291                              pstream_get_name(remote->listener),
 292                              strerror(error));
 293             }
 294         }
 295
 296         ovsdb_jsonrpc_session_run_all(remote);
 297     }
 298 }
 299
 300 void
 301 ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 302 {
 303     struct shash_node *node;
 304
 305     SHASH_FOR_EACH (node, &svr->remotes) {
 306         struct ovsdb_jsonrpc_remote *remote = node->data;
 307
 308         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 309             pstream_wait(remote->listener);
 310         }
 311
 312         ovsdb_jsonrpc_session_wait_all(remote);
 313     }
 314 }
 315
 316 /* Adds some memory usage statistics for 'svr' into 'usage', for use with
 317  * memory_report(). */
 318 void
 319 ovsdb_jsonrpc_server_get_memory_usage(const struct ovsdb_jsonrpc_server *svr,
 320                                       struct simap *usage)
 321 {
 322     struct shash_node *node;
 323
 324     simap_increase(usage, "sessions", svr->n_sessions);
 325     SHASH_FOR_EACH (node, &svr->remotes) {
 326         struct ovsdb_jsonrpc_remote *remote = node->data;
 327
 328         ovsdb_jsonrpc_session_get_memory_usage_all(remote, usage);
 329     }
 330 }
 331 \f
 332 /* JSON-RPC database server session. */
 333
 334 struct ovsdb_jsonrpc_session {
 335     struct list node;           /* Element in remote's sessions list. */
 336     struct ovsdb_session up;
 337     struct ovsdb_jsonrpc_remote *remote;
 338
 339     /* Triggers. */
 340     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
 341
 342     /* Monitors. */
 343     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
 344
 345     /* Network connectivity. */
 346     struct jsonrpc_session *js;  /* JSON-RPC session. */
 347     unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
 348 };
 349
 350 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 351 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 352 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
 353 static void ovsdb_jsonrpc_session_get_memory_usage(
 354     const struct ovsdb_jsonrpc_session *, struct simap *usage);
 355 static void ovsdb_jsonrpc_session_set_options(
 356     struct ovsdb_jsonrpc_session *, const struct ovsdb_jsonrpc_options *);
 357 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
 358                                              struct jsonrpc_msg *);
 359 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
 360                                              struct jsonrpc_msg *);
 361
 362 static struct ovsdb_jsonrpc_session *
 363 ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
 364                              struct jsonrpc_session *js)
 365 {
 366     struct ovsdb_jsonrpc_session *s;
 367
 368     s = xzalloc(sizeof *s);
 369     ovsdb_session_init(&s->up, &remote->server->up);
 370     s->remote = remote;
 371     list_push_back(&remote->sessions, &s->node);
 372     hmap_init(&s->triggers);
 373     hmap_init(&s->monitors);
 374     s->js = js;
 375     s->js_seqno = jsonrpc_session_get_seqno(js);
 376
 377     remote->server->n_sessions++;
 378
 379     return s;
 380 }
 381
 382 static void
 383 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 384 {
 385     ovsdb_jsonrpc_monitor_remove_all(s);
 386     ovsdb_jsonrpc_session_unlock_all(s);
 387     ovsdb_jsonrpc_trigger_complete_all(s);
 388
 389     hmap_destroy(&s->monitors);
 390     hmap_destroy(&s->triggers);
 391
 392     jsonrpc_session_close(s->js);
 393     list_remove(&s->node);
 394     s->remote->server->n_sessions--;
 395     ovsdb_session_destroy(&s->up);
 396     free(s);
 397 }
 398
 399 static int
 400 ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
 401 {
 402     jsonrpc_session_run(s->js);
 403     if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
 404         s->js_seqno = jsonrpc_session_get_seqno(s->js);
 405         ovsdb_jsonrpc_trigger_complete_all(s);
 406         ovsdb_jsonrpc_monitor_remove_all(s);
 407         ovsdb_jsonrpc_session_unlock_all(s);
 408     }
 409
 410     ovsdb_jsonrpc_trigger_complete_done(s);
 411
 412     if (!jsonrpc_session_get_backlog(s->js)) {
 413         struct jsonrpc_msg *msg = jsonrpc_session_recv(s->js);
 414         if (msg) {
 415             if (msg->type == JSONRPC_REQUEST) {
 416                 ovsdb_jsonrpc_session_got_request(s, msg);
 417             } else if (msg->type == JSONRPC_NOTIFY) {
 418                 ovsdb_jsonrpc_session_got_notify(s, msg);
 419             } else {
 420                 VLOG_WARN("%s: received unexpected %s message",
 421                           jsonrpc_session_get_name(s->js),
 422                           jsonrpc_msg_type_to_string(msg->type));
 423                 jsonrpc_session_force_reconnect(s->js);
 424                 jsonrpc_msg_destroy(msg);
 425             }
 426         }
 427     }
 428     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 429 }
 430
 431 static void
 432 ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
 433                                   const struct ovsdb_jsonrpc_options *options)
 434 {
 435     jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
 436     jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
 437     jsonrpc_session_set_dscp(session->js, options->dscp);
 438 }
 439
 440 static void
 441 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 442 {
 443     struct ovsdb_jsonrpc_session *s, *next;
 444
 445     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 446         int error = ovsdb_jsonrpc_session_run(s);
 447         if (error) {
 448             ovsdb_jsonrpc_session_close(s);
 449         }
 450     }
 451 }
 452
 453 static void
 454 ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
 455 {
 456     jsonrpc_session_wait(s->js);
 457     if (!jsonrpc_session_get_backlog(s->js)) {
 458         jsonrpc_session_recv_wait(s->js);
 459     }
 460 }
 461
 462 static void
 463 ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 464 {
 465     struct ovsdb_jsonrpc_session *s;
 466
 467     LIST_FOR_EACH (s, node, &remote->sessions) {
 468         ovsdb_jsonrpc_session_wait(s);
 469     }
 470 }
 471
 472 static void
 473 ovsdb_jsonrpc_session_get_memory_usage(const struct ovsdb_jsonrpc_session *s,
 474                                        struct simap *usage)
 475 {
 476     simap_increase(usage, "triggers", hmap_count(&s->triggers));
 477     simap_increase(usage, "monitors", hmap_count(&s->monitors));
 478     simap_increase(usage, "backlog", jsonrpc_session_get_backlog(s->js));
 479 }
 480
 481 static void
 482 ovsdb_jsonrpc_session_get_memory_usage_all(
 483     const struct ovsdb_jsonrpc_remote *remote,
 484     struct simap *usage)
 485 {
 486     struct ovsdb_jsonrpc_session *s;
 487
 488     LIST_FOR_EACH (s, node, &remote->sessions) {
 489         ovsdb_jsonrpc_session_get_memory_usage(s, usage);
 490     }
 491 }
 492
 493 static void
 494 ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 495 {
 496     struct ovsdb_jsonrpc_session *s, *next;
 497
 498     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 499         ovsdb_jsonrpc_session_close(s);
 500     }
 501 }
 502
 503 /* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
 504  * reconnect. */
 505 static void
 506 ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 507 {
 508     struct ovsdb_jsonrpc_session *s, *next;
 509
 510     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 511         jsonrpc_session_force_reconnect(s->js);
 512         if (!jsonrpc_session_is_alive(s->js)) {
 513             ovsdb_jsonrpc_session_close(s);
 514         }
 515     }
 516 }
 517
 518 /* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
 519  * 'options'. */
 520 static void
 521 ovsdb_jsonrpc_session_set_all_options(
 522     struct ovsdb_jsonrpc_remote *remote,
 523     const struct ovsdb_jsonrpc_options *options)
 524 {
 525     struct ovsdb_jsonrpc_session *s;
 526
 527     if (remote->listener) {
 528         int error;
 529
 530         error = pstream_set_dscp(remote->listener, options->dscp);
 531         if (error) {
 532             VLOG_ERR("%s: set_dscp failed %s",
 533                      pstream_get_name(remote->listener), strerror(error));
 534         } else {
 535             remote->dscp = options->dscp;
 536         }
 537         /*
 538          * XXX race window between setting dscp to listening socket
 539          * and accepting socket. Accepted socket may have old dscp value.
 540          * Ignore this race window for now.
 541          */
 542     }
 543     LIST_FOR_EACH (s, node, &remote->sessions) {
 544         ovsdb_jsonrpc_session_set_options(s, options);
 545     }
 546 }
 547
 548 static bool
 549 ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
 550                                  struct ovsdb_jsonrpc_remote_status *status)
 551 {
 552     const struct ovsdb_jsonrpc_session *s;
 553     const struct jsonrpc_session *js;
 554     struct ovsdb_lock_waiter *waiter;
 555     struct reconnect_stats rstats;
 556     struct ds locks_held, locks_waiting, locks_lost;
 557
 558     if (list_is_empty(&remote->sessions)) {
 559         return false;
 560     }
 561     s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
 562     js = s->js;
 563
 564     status->is_connected = jsonrpc_session_is_connected(js);
 565     status->last_error = jsonrpc_session_get_status(js);
 566
 567     jsonrpc_session_get_reconnect_stats(js, &rstats);
 568     status->state = rstats.state;
 569     status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
 570         ? UINT_MAX : rstats.msec_since_connect / 1000;
 571     status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
 572         ? UINT_MAX : rstats.msec_since_disconnect / 1000;
 573
 574     ds_init(&locks_held);
 575     ds_init(&locks_waiting);
 576     ds_init(&locks_lost);
 577     HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
 578         struct ds *string;
 579
 580         string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
 581                   : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
 582                   : &locks_lost);
 583         if (string->length) {
 584             ds_put_char(string, ' ');
 585         }
 586         ds_put_cstr(string, waiter->lock_name);
 587     }
 588     status->locks_held = ds_steal_cstr(&locks_held);
 589     status->locks_waiting = ds_steal_cstr(&locks_waiting);
 590     status->locks_lost = ds_steal_cstr(&locks_lost);
 591
 592     status->n_connections = list_size(&remote->sessions);
 593
 594     return true;
 595 }
 596
 597 /* Examines 'request' to determine the database to which it relates, and then
 598  * searches 's' to find that database:
 599  *
 600  *    - If successful, returns the database and sets '*replyp' to NULL.
 601  *
 602  *    - If no such database exists, returns NULL and sets '*replyp' to an
 603  *      appropriate JSON-RPC error reply, owned by the caller. */
 604 static struct ovsdb *
 605 ovsdb_jsonrpc_lookup_db(const struct ovsdb_jsonrpc_session *s,
 606                         const struct jsonrpc_msg *request,
 607                         struct jsonrpc_msg **replyp)
 608 {
 609     struct json_array *params;
 610     struct ovsdb_error *error;
 611     const char *db_name;
 612     struct ovsdb *db;
 613
 614     params = json_array(request->params);
 615     if (!params->n || params->elems[0]->type != JSON_STRING) {
 616         error = ovsdb_syntax_error(
 617             request->params, NULL,
 618             "%s request params must begin with <db-name>", request->method);
 619         goto error;
 620     }
 621
 622     db_name = params->elems[0]->u.string;
 623     db = shash_find_data(&s->up.server->dbs, db_name);
 624     if (!db) {
 625         error = ovsdb_syntax_error(
 626             request->params, "unknown database",
 627             "%s request specifies unknown database %s",
 628             request->method, db_name);
 629         goto error;
 630     }
 631
 632     *replyp = NULL;
 633     return db;
 634
 635 error:
 636     *replyp = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 637     ovsdb_error_destroy(error);
 638     return NULL;
 639 }
 640
 641 static struct ovsdb_error *
 642 ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
 643                                       const char **lock_namep)
 644 {
 645     const struct json_array *params;
 646
 647     params = json_array(request->params);
 648     if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
 649         !ovsdb_parser_is_id(json_string(params->elems[0]))) {
 650         *lock_namep = NULL;
 651         return ovsdb_syntax_error(request->params, NULL,
 652                                   "%s request params must be <id>",
 653                                   request->method);
 654     }
 655
 656     *lock_namep = json_string(params->elems[0]);
 657     return NULL;
 658 }
 659
 660 static void
 661 ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
 662                              const char *lock_name,
 663                              const char *method)
 664 {
 665     struct ovsdb_jsonrpc_session *s;
 666     struct json *params;
 667
 668     s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
 669     params = json_array_create_1(json_string_create(lock_name));
 670     jsonrpc_session_send(s->js, jsonrpc_create_notify(method, params));
 671 }
 672
 673 static struct jsonrpc_msg *
 674 ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
 675                            struct jsonrpc_msg *request,
 676                            enum ovsdb_lock_mode mode)
 677 {
 678     struct ovsdb_lock_waiter *waiter;
 679     struct jsonrpc_msg *reply;
 680     struct ovsdb_error *error;
 681     struct ovsdb_session *victim;
 682     const char *lock_name;
 683     struct json *result;
 684
 685     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 686     if (error) {
 687         goto error;
 688     }
 689
 690     /* Report error if this session has issued a "lock" or "steal" without a
 691      * matching "unlock" for this lock. */
 692     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 693     if (waiter) {
 694         error = ovsdb_syntax_error(
 695             request->params, NULL,
 696             "must issue \"unlock\" before new \"%s\"", request->method);
 697         goto error;
 698     }
 699
 700     /* Get the lock, add us as a waiter. */
 701     waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
 702                                &victim);
 703     if (victim) {
 704         ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
 705     }
 706
 707     result = json_object_create();
 708     json_object_put(result, "locked",
 709                     json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
 710
 711     return jsonrpc_create_reply(result, request->id);
 712
 713 error:
 714     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 715     ovsdb_error_destroy(error);
 716     return reply;
 717 }
 718
 719 static void
 720 ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
 721 {
 722     struct ovsdb_lock_waiter *waiter, *next;
 723
 724     HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
 725         ovsdb_jsonrpc_session_unlock__(waiter);
 726     }
 727 }
 728
 729 static void
 730 ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
 731 {
 732     struct ovsdb_lock *lock = waiter->lock;
 733
 734     if (lock) {
 735         struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
 736         if (new_owner) {
 737             ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
 738         } else {
 739             /* ovsdb_server_lock() might have freed 'lock'. */
 740         }
 741     }
 742
 743     ovsdb_lock_waiter_destroy(waiter);
 744 }
 745
 746 static struct jsonrpc_msg *
 747 ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
 748                              struct jsonrpc_msg *request)
 749 {
 750     struct ovsdb_lock_waiter *waiter;
 751     struct jsonrpc_msg *reply;
 752     struct ovsdb_error *error;
 753     const char *lock_name;
 754
 755     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 756     if (error) {
 757         goto error;
 758     }
 759
 760     /* Report error if this session has not issued a "lock" or "steal" for this
 761      * lock. */
 762     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 763     if (!waiter) {
 764         error = ovsdb_syntax_error(
 765             request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
 766         goto error;
 767     }
 768
 769     ovsdb_jsonrpc_session_unlock__(waiter);
 770
 771     return jsonrpc_create_reply(json_object_create(), request->id);
 772
 773 error:
 774     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 775     ovsdb_error_destroy(error);
 776     return reply;
 777 }
 778
 779 static struct jsonrpc_msg *
 780 execute_transaction(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 781                     struct jsonrpc_msg *request)
 782 {
 783     ovsdb_jsonrpc_trigger_create(s, db, request->id, request->params);
 784     request->id = NULL;
 785     request->params = NULL;
 786     jsonrpc_msg_destroy(request);
 787     return NULL;
 788 }
 789
 790 static void
 791 ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
 792                                   struct jsonrpc_msg *request)
 793 {
 794     struct jsonrpc_msg *reply;
 795
 796     if (!strcmp(request->method, "transact")) {
 797         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 798         if (!reply) {
 799             reply = execute_transaction(s, db, request);
 800         }
 801     } else if (!strcmp(request->method, "monitor")) {
 802         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 803         if (!reply) {
 804             reply = jsonrpc_create_reply(
 805                 ovsdb_jsonrpc_monitor_create(s, db, request->params),
 806                 request->id);
 807         }
 808     } else if (!strcmp(request->method, "monitor_cancel")) {
 809         reply = ovsdb_jsonrpc_monitor_cancel(s, json_array(request->params),
 810                                              request->id);
 811     } else if (!strcmp(request->method, "get_schema")) {
 812         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 813         if (!reply) {
 814             reply = jsonrpc_create_reply(ovsdb_schema_to_json(db->schema),
 815                                          request->id);
 816         }
 817     } else if (!strcmp(request->method, "list_dbs")) {
 818         size_t n_dbs = shash_count(&s->up.server->dbs);
 819         struct shash_node *node;
 820         struct json **dbs;
 821         size_t i;
 822
 823         dbs = xmalloc(n_dbs * sizeof *dbs);
 824         i = 0;
 825         SHASH_FOR_EACH (node, &s->up.server->dbs) {
 826             dbs[i++] = json_string_create(node->name);
 827         }
 828         reply = jsonrpc_create_reply(json_array_create(dbs, n_dbs),
 829                                      request->id);
 830     } else if (!strcmp(request->method, "lock")) {
 831         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
 832     } else if (!strcmp(request->method, "steal")) {
 833         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
 834     } else if (!strcmp(request->method, "unlock")) {
 835         reply = ovsdb_jsonrpc_session_unlock(s, request);
 836     } else if (!strcmp(request->method, "echo")) {
 837         reply = jsonrpc_create_reply(json_clone(request->params), request->id);
 838     } else {
 839         reply = jsonrpc_create_error(json_string_create("unknown method"),
 840                                      request->id);
 841     }
 842
 843     if (reply) {
 844         jsonrpc_msg_destroy(request);
 845         jsonrpc_session_send(s->js, reply);
 846     }
 847 }
 848
 849 static void
 850 execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
 851 {
 852     if (json_array(request->params)->n == 1) {
 853         struct ovsdb_jsonrpc_trigger *t;
 854         struct json *id;
 855
 856         id = request->params->u.array.elems[0];
 857         t = ovsdb_jsonrpc_trigger_find(s, id, json_hash(id, 0));
 858         if (t) {
 859             ovsdb_jsonrpc_trigger_complete(t);
 860         }
 861     }
 862 }
 863
 864 static void
 865 ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
 866                                  struct jsonrpc_msg *request)
 867 {
 868     if (!strcmp(request->method, "cancel")) {
 869         execute_cancel(s, request);
 870     }
 871     jsonrpc_msg_destroy(request);
 872 }
 873 \f
 874 /* JSON-RPC database server triggers.
 875  *
 876  * (Every transaction is treated as a trigger even if it doesn't actually have
 877  * any "wait" operations.) */
 878
 879 struct ovsdb_jsonrpc_trigger {
 880     struct ovsdb_trigger trigger;
 881     struct hmap_node hmap_node; /* In session's "triggers" hmap. */
 882     struct json *id;
 883 };
 884
 885 static void
 886 ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 887                              struct json *id, struct json *params)
 888 {
 889     struct ovsdb_jsonrpc_trigger *t;
 890     size_t hash;
 891
 892     /* Check for duplicate ID. */
 893     hash = json_hash(id, 0);
 894     t = ovsdb_jsonrpc_trigger_find(s, id, hash);
 895     if (t) {
 896         struct jsonrpc_msg *msg;
 897
 898         msg = jsonrpc_create_error(json_string_create("duplicate request ID"),
 899                                    id);
 900         jsonrpc_session_send(s->js, msg);
 901         json_destroy(id);
 902         json_destroy(params);
 903         return;
 904     }
 905
 906     /* Insert into trigger table. */
 907     t = xmalloc(sizeof *t);
 908     ovsdb_trigger_init(&s->up, db, &t->trigger, params, time_msec());
 909     t->id = id;
 910     hmap_insert(&s->triggers, &t->hmap_node, hash);
 911
 912     /* Complete early if possible. */
 913     if (ovsdb_trigger_is_complete(&t->trigger)) {
 914         ovsdb_jsonrpc_trigger_complete(t);
 915     }
 916 }
 917
 918 static struct ovsdb_jsonrpc_trigger *
 919 ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 920                            const struct json *id, size_t hash)
 921 {
 922     struct ovsdb_jsonrpc_trigger *t;
 923
 924     HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
 925         if (json_equal(t->id, id)) {
 926             return t;
 927         }
 928     }
 929
 930     return NULL;
 931 }
 932
 933 static void
 934 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 935 {
 936     struct ovsdb_jsonrpc_session *s;
 937
 938     s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
 939
 940     if (jsonrpc_session_is_connected(s->js)) {
 941         struct jsonrpc_msg *reply;
 942         struct json *result;
 943
 944         result = ovsdb_trigger_steal_result(&t->trigger);
 945         if (result) {
 946             reply = jsonrpc_create_reply(result, t->id);
 947         } else {
 948             reply = jsonrpc_create_error(json_string_create("canceled"),
 949                                          t->id);
 950         }
 951         jsonrpc_session_send(s->js, reply);
 952     }
 953
 954     json_destroy(t->id);
 955     ovsdb_trigger_destroy(&t->trigger);
 956     hmap_remove(&s->triggers, &t->hmap_node);
 957     free(t);
 958 }
 959
 960 static void
 961 ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 962 {
 963     struct ovsdb_jsonrpc_trigger *t, *next;
 964     HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
 965         ovsdb_jsonrpc_trigger_complete(t);
 966     }
 967 }
 968
 969 static void
 970 ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
 971 {
 972     while (!list_is_empty(&s->up.completions)) {
 973         struct ovsdb_jsonrpc_trigger *t
 974             = CONTAINER_OF(s->up.completions.next,
 975                            struct ovsdb_jsonrpc_trigger, trigger.node);
 976         ovsdb_jsonrpc_trigger_complete(t);
 977     }
 978 }
 979 \f
 980 /* JSON-RPC database table monitors. */
 981
 982 enum ovsdb_jsonrpc_monitor_selection {
 983     OJMS_INITIAL = 1 << 0,      /* All rows when monitor is created. */
 984     OJMS_INSERT = 1 << 1,       /* New rows. */
 985     OJMS_DELETE = 1 << 2,       /* Deleted rows. */
 986     OJMS_MODIFY = 1 << 3        /* Modified rows. */
 987 };
 988
 989 /* A particular column being monitored. */
 990 struct ovsdb_jsonrpc_monitor_column {
 991     const struct ovsdb_column *column;
 992     enum ovsdb_jsonrpc_monitor_selection select;
 993 };
 994
 995 /* A particular table being monitored. */
 996 struct ovsdb_jsonrpc_monitor_table {
 997     const struct ovsdb_table *table;
 998
 999     /* This is the union (bitwise-OR) of the 'select' values in all of the
1000      * members of 'columns' below. */
1001     enum ovsdb_jsonrpc_monitor_selection select;
1002
1003     /* Columns being monitored. */
1004     struct ovsdb_jsonrpc_monitor_column *columns;
1005     size_t n_columns;
1006 };
1007
1008 /* A collection of tables being monitored. */
1009 struct ovsdb_jsonrpc_monitor {
1010     struct ovsdb_replica replica;
1011     struct ovsdb_jsonrpc_session *session;
1012     struct ovsdb *db;
1013     struct hmap_node node;      /* In ovsdb_jsonrpc_session's "monitors". */
1014
1015     struct json *monitor_id;
1016     struct shash tables;     /* Holds "struct ovsdb_jsonrpc_monitor_table"s. */
1017 };
1018
1019 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class;
1020
1021 struct ovsdb_jsonrpc_monitor *ovsdb_jsonrpc_monitor_find(
1022     struct ovsdb_jsonrpc_session *, const struct json *monitor_id);
1023 static void ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *);
1024 static struct json *ovsdb_jsonrpc_monitor_get_initial(
1025     const struct ovsdb_jsonrpc_monitor *);
1026
1027 static bool
1028 parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
1029 {
1030     const struct json *json;
1031
1032     json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
1033     return json ? json_boolean(json) : default_value;
1034 }
1035
1036 struct ovsdb_jsonrpc_monitor *
1037 ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
1038                            const struct json *monitor_id)
1039 {
1040     struct ovsdb_jsonrpc_monitor *m;
1041
1042     HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
1043         if (json_equal(m->monitor_id, monitor_id)) {
1044             return m;
1045         }
1046     }
1047
1048     return NULL;
1049 }
1050
1051 static void
1052 ovsdb_jsonrpc_add_monitor_column(struct ovsdb_jsonrpc_monitor_table *mt,
1053                                  const struct ovsdb_column *column,
1054                                  enum ovsdb_jsonrpc_monitor_selection select,
1055                                  size_t *allocated_columns)
1056 {
1057     struct ovsdb_jsonrpc_monitor_column *c;
1058
1059     if (mt->n_columns >= *allocated_columns) {
1060         mt->columns = x2nrealloc(mt->columns, allocated_columns,
1061                                  sizeof *mt->columns);
1062     }
1063
1064     c = &mt->columns[mt->n_columns++];
1065     c->column = column;
1066     c->select = select;
1067 }
1068
1069 static int
1070 compare_ovsdb_jsonrpc_monitor_column(const void *a_, const void *b_)
1071 {
1072     const struct ovsdb_jsonrpc_monitor_column *a = a_;
1073     const struct ovsdb_jsonrpc_monitor_column *b = b_;
1074
1075     return a->column < b->column ? -1 : a->column > b->column;
1076 }
1077
1078 static struct ovsdb_error * WARN_UNUSED_RESULT
1079 ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_jsonrpc_monitor_table *mt,
1080                                     const struct json *monitor_request,
1081                                     size_t *allocated_columns)
1082 {
1083     const struct ovsdb_table_schema *ts = mt->table->schema;
1084     enum ovsdb_jsonrpc_monitor_selection select;
1085     const struct json *columns, *select_json;
1086     struct ovsdb_parser parser;
1087     struct ovsdb_error *error;
1088
1089     ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
1090     columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
1091     select_json = ovsdb_parser_member(&parser, "select",
1092                                       OP_OBJECT | OP_OPTIONAL);
1093     error = ovsdb_parser_finish(&parser);
1094     if (error) {
1095         return error;
1096     }
1097
1098     if (select_json) {
1099         select = 0;
1100         ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
1101         if (parse_bool(&parser, "initial", true)) {
1102             select |= OJMS_INITIAL;
1103         }
1104         if (parse_bool(&parser, "insert", true)) {
1105             select |= OJMS_INSERT;
1106         }
1107         if (parse_bool(&parser, "delete", true)) {
1108             select |= OJMS_DELETE;
1109         }
1110         if (parse_bool(&parser, "modify", true)) {
1111             select |= OJMS_MODIFY;
1112         }
1113         error = ovsdb_parser_finish(&parser);
1114         if (error) {
1115             return error;
1116         }
1117     } else {
1118         select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
1119     }
1120     mt->select |= select;
1121
1122     if (columns) {
1123         size_t i;
1124
1125         if (columns->type != JSON_ARRAY) {
1126             return ovsdb_syntax_error(columns, NULL,
1127                                       "array of column names expected");
1128         }
1129
1130         for (i = 0; i < columns->u.array.n; i++) {
1131             const struct ovsdb_column *column;
1132             const char *s;
1133
1134             if (columns->u.array.elems[i]->type != JSON_STRING) {
1135                 return ovsdb_syntax_error(columns, NULL,
1136                                           "array of column names expected");
1137             }
1138
1139             s = columns->u.array.elems[i]->u.string;
1140             column = shash_find_data(&mt->table->schema->columns, s);
1141             if (!column) {
1142                 return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
1143                                           "column name", s);
1144             }
1145             ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1146                                              allocated_columns);
1147         }
1148     } else {
1149         struct shash_node *node;
1150
1151         SHASH_FOR_EACH (node, &ts->columns) {
1152             const struct ovsdb_column *column = node->data;
1153             if (column->index != OVSDB_COL_UUID) {
1154                 ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1155                                                  allocated_columns);
1156             }
1157         }
1158     }
1159
1160     return NULL;
1161 }
1162
1163 static struct json *
1164 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
1165                              struct json *params)
1166 {
1167     struct ovsdb_jsonrpc_monitor *m = NULL;
1168     struct json *monitor_id, *monitor_requests;
1169     struct ovsdb_error *error = NULL;
1170     struct shash_node *node;
1171     struct json *json;
1172
1173     if (json_array(params)->n != 3) {
1174         error = ovsdb_syntax_error(params, NULL, "invalid parameters");
1175         goto error;
1176     }
1177     monitor_id = params->u.array.elems[1];
1178     monitor_requests = params->u.array.elems[2];
1179     if (monitor_requests->type != JSON_OBJECT) {
1180         error = ovsdb_syntax_error(monitor_requests, NULL,
1181                                    "monitor-requests must be object");
1182         goto error;
1183     }
1184
1185     if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
1186         error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
1187         goto error;
1188     }
1189
1190     m = xzalloc(sizeof *m);
1191     ovsdb_replica_init(&m->replica, &ovsdb_jsonrpc_replica_class);
1192     ovsdb_add_replica(db, &m->replica);
1193     m->session = s;
1194     m->db = db;
1195     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
1196     m->monitor_id = json_clone(monitor_id);
1197     shash_init(&m->tables);
1198
1199     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
1200         const struct ovsdb_table *table;
1201         struct ovsdb_jsonrpc_monitor_table *mt;
1202         size_t allocated_columns;
1203         const struct json *mr_value;
1204         size_t i;
1205
1206         table = ovsdb_get_table(m->db, node->name);
1207         if (!table) {
1208             error = ovsdb_syntax_error(NULL, NULL,
1209                                        "no table named %s", node->name);
1210             goto error;
1211         }
1212
1213         mt = xzalloc(sizeof *mt);
1214         mt->table = table;
1215         shash_add(&m->tables, table->schema->name, mt);
1216
1217         /* Parse columns. */
1218         mr_value = node->data;
1219         allocated_columns = 0;
1220         if (mr_value->type == JSON_ARRAY) {
1221             const struct json_array *array = &mr_value->u.array;
1222
1223             for (i = 0; i < array->n; i++) {
1224                 error = ovsdb_jsonrpc_parse_monitor_request(
1225                     mt, array->elems[i], &allocated_columns);
1226                 if (error) {
1227                     goto error;
1228                 }
1229             }
1230         } else {
1231             error = ovsdb_jsonrpc_parse_monitor_request(
1232                 mt, mr_value, &allocated_columns);
1233             if (error) {
1234                 goto error;
1235             }
1236         }
1237
1238         /* Check for duplicate columns. */
1239         qsort(mt->columns, mt->n_columns, sizeof *mt->columns,
1240               compare_ovsdb_jsonrpc_monitor_column);
1241         for (i = 1; i < mt->n_columns; i++) {
1242             if (mt->columns[i].column == mt->columns[i - 1].column) {
1243                 error = ovsdb_syntax_error(mr_value, NULL, "column %s "
1244                                            "mentioned more than once",
1245                                            mt->columns[i].column->name);
1246                 goto error;
1247             }
1248         }
1249     }
1250
1251     return ovsdb_jsonrpc_monitor_get_initial(m);
1252
1253 error:
1254     if (m) {
1255         ovsdb_remove_replica(m->db, &m->replica);
1256     }
1257
1258     json = ovsdb_error_to_json(error);
1259     ovsdb_error_destroy(error);
1260     return json;
1261 }
1262
1263 static struct jsonrpc_msg *
1264 ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
1265                              struct json_array *params,
1266                              const struct json *request_id)
1267 {
1268     if (params->n != 1) {
1269         return jsonrpc_create_error(json_string_create("invalid parameters"),
1270                                     request_id);
1271     } else {
1272         struct ovsdb_jsonrpc_monitor *m;
1273
1274         m = ovsdb_jsonrpc_monitor_find(s, params->elems[0]);
1275         if (!m) {
1276             return jsonrpc_create_error(json_string_create("unknown monitor"),
1277                                         request_id);
1278         } else {
1279             ovsdb_remove_replica(m->db, &m->replica);
1280             return jsonrpc_create_reply(json_object_create(), request_id);
1281         }
1282     }
1283 }
1284
1285 static void
1286 ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
1287 {
1288     struct ovsdb_jsonrpc_monitor *m, *next;
1289
1290     HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
1291         ovsdb_remove_replica(m->db, &m->replica);
1292     }
1293 }
1294
1295 static struct ovsdb_jsonrpc_monitor *
1296 ovsdb_jsonrpc_monitor_cast(struct ovsdb_replica *replica)
1297 {
1298     ovs_assert(replica->class == &ovsdb_jsonrpc_replica_class);
1299     return CONTAINER_OF(replica, struct ovsdb_jsonrpc_monitor, replica);
1300 }
1301
1302 struct ovsdb_jsonrpc_monitor_aux {
1303     bool initial;               /* Sending initial contents of table? */
1304     const struct ovsdb_jsonrpc_monitor *monitor;
1305     struct json *json;          /* JSON for the whole transaction. */
1306
1307     /* Current table.  */
1308     struct ovsdb_jsonrpc_monitor_table *mt;
1309     struct json *table_json;    /* JSON for table's transaction. */
1310 };
1311
1312 static bool
1313 any_reportable_change(const struct ovsdb_jsonrpc_monitor_table *mt,
1314                       const unsigned long int *changed)
1315 {
1316     size_t i;
1317
1318     for (i = 0; i < mt->n_columns; i++) {
1319         const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
1320         unsigned int idx = c->column->index;
1321
1322         if (c->select & OJMS_MODIFY && bitmap_is_set(changed, idx)) {
1323             return true;
1324         }
1325     }
1326
1327     return false;
1328 }
1329
1330 static bool
1331 ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
1332                                 const struct ovsdb_row *new,
1333                                 const unsigned long int *changed,
1334                                 void *aux_)
1335 {
1336     struct ovsdb_jsonrpc_monitor_aux *aux = aux_;
1337     const struct ovsdb_jsonrpc_monitor *m = aux->monitor;
1338     struct ovsdb_table *table = new ? new->table : old->table;
1339     enum ovsdb_jsonrpc_monitor_selection type;
1340     struct json *old_json, *new_json;
1341     struct json *row_json;
1342     char uuid[UUID_LEN + 1];
1343     size_t i;
1344
1345     if (!aux->mt || table != aux->mt->table) {
1346         aux->mt = shash_find_data(&m->tables, table->schema->name);
1347         aux->table_json = NULL;
1348         if (!aux->mt) {
1349             /* We don't care about rows in this table at all.  Tell the caller
1350              * to skip it.  */
1351             return false;
1352         }
1353     }
1354
1355     type = (aux->initial ? OJMS_INITIAL
1356             : !old ? OJMS_INSERT
1357             : !new ? OJMS_DELETE
1358             : OJMS_MODIFY);
1359     if (!(aux->mt->select & type)) {
1360         /* We don't care about this type of change (but do want to be called
1361          * back for changes to other rows in the same table). */
1362         return true;
1363     }
1364
1365     if (type == OJMS_MODIFY && !any_reportable_change(aux->mt, changed)) {
1366         /* Nothing of interest changed. */
1367         return true;
1368     }
1369
1370     old_json = new_json = NULL;
1371     if (type & (OJMS_DELETE | OJMS_MODIFY)) {
1372         old_json = json_object_create();
1373     }
1374     if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1375         new_json = json_object_create();
1376     }
1377     for (i = 0; i < aux->mt->n_columns; i++) {
1378         const struct ovsdb_jsonrpc_monitor_column *c = &aux->mt->columns[i];
1379         const struct ovsdb_column *column = c->column;
1380         unsigned int idx = c->column->index;
1381
1382         if (!(type & c->select)) {
1383             /* We don't care about this type of change for this particular
1384              * column (but we will care about it for some other column). */
1385             continue;
1386         }
1387
1388         if ((type == OJMS_MODIFY && bitmap_is_set(changed, idx))
1389             || type == OJMS_DELETE) {
1390             json_object_put(old_json, column->name,
1391                             ovsdb_datum_to_json(&old->fields[idx],
1392                                                 &column->type));
1393         }
1394         if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1395             json_object_put(new_json, column->name,
1396                             ovsdb_datum_to_json(&new->fields[idx],
1397                                                 &column->type));
1398         }
1399     }
1400
1401     /* Create JSON object for transaction overall. */
1402     if (!aux->json) {
1403         aux->json = json_object_create();
1404     }
1405
1406     /* Create JSON object for transaction on this table. */
1407     if (!aux->table_json) {
1408         aux->table_json = json_object_create();
1409         json_object_put(aux->json, aux->mt->table->schema->name,
1410                         aux->table_json);
1411     }
1412
1413     /* Create JSON object for transaction on this row. */
1414     row_json = json_object_create();
1415     if (old_json) {
1416         json_object_put(row_json, "old", old_json);
1417     }
1418     if (new_json) {
1419         json_object_put(row_json, "new", new_json);
1420     }
1421
1422     /* Add JSON row to JSON table. */
1423     snprintf(uuid, sizeof uuid,
1424              UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
1425     json_object_put(aux->table_json, uuid, row_json);
1426
1427     return true;
1428 }
1429
1430 static void
1431 ovsdb_jsonrpc_monitor_init_aux(struct ovsdb_jsonrpc_monitor_aux *aux,
1432                                const struct ovsdb_jsonrpc_monitor *m,
1433                                bool initial)
1434 {
1435     aux->initial = initial;
1436     aux->monitor = m;
1437     aux->json = NULL;
1438     aux->mt = NULL;
1439     aux->table_json = NULL;
1440 }
1441
1442 static struct ovsdb_error *
1443 ovsdb_jsonrpc_monitor_commit(struct ovsdb_replica *replica,
1444                              const struct ovsdb_txn *txn,
1445                              bool durable OVS_UNUSED)
1446 {
1447     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1448     struct ovsdb_jsonrpc_monitor_aux aux;
1449
1450     ovsdb_jsonrpc_monitor_init_aux(&aux, m, false);
1451     ovsdb_txn_for_each_change(txn, ovsdb_jsonrpc_monitor_change_cb, &aux);
1452     if (aux.json) {
1453         struct jsonrpc_msg *msg;
1454         struct json *params;
1455
1456         params = json_array_create_2(json_clone(aux.monitor->monitor_id),
1457                                      aux.json);
1458         msg = jsonrpc_create_notify("update", params);
1459         jsonrpc_session_send(aux.monitor->session->js, msg);
1460     }
1461
1462     return NULL;
1463 }
1464
1465 static struct json *
1466 ovsdb_jsonrpc_monitor_get_initial(const struct ovsdb_jsonrpc_monitor *m)
1467 {
1468     struct ovsdb_jsonrpc_monitor_aux aux;
1469     struct shash_node *node;
1470
1471     ovsdb_jsonrpc_monitor_init_aux(&aux, m, true);
1472     SHASH_FOR_EACH (node, &m->tables) {
1473         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1474
1475         if (mt->select & OJMS_INITIAL) {
1476             struct ovsdb_row *row;
1477
1478             HMAP_FOR_EACH (row, hmap_node, &mt->table->rows) {
1479                 ovsdb_jsonrpc_monitor_change_cb(NULL, row, NULL, &aux);
1480             }
1481         }
1482     }
1483     return aux.json ? aux.json : json_object_create();
1484 }
1485
1486 static void
1487 ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *replica)
1488 {
1489     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1490     struct shash_node *node;
1491
1492     json_destroy(m->monitor_id);
1493     SHASH_FOR_EACH (node, &m->tables) {
1494         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1495         free(mt->columns);
1496         free(mt);
1497     }
1498     shash_destroy(&m->tables);
1499     hmap_remove(&m->session->monitors, &m->node);
1500     free(m);
1501 }
1502
1503 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class = {
1504     ovsdb_jsonrpc_monitor_commit,
1505     ovsdb_jsonrpc_monitor_destroy
1506 };