ovsdb/jsonrpc-server.c

   1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014, 2015 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 "poll-loop.h"
  31 #include "reconnect.h"
  32 #include "row.h"
  33 #include "server.h"
  34 #include "simap.h"
  35 #include "stream.h"
  36 #include "table.h"
  37 #include "timeval.h"
  38 #include "transaction.h"
  39 #include "trigger.h"
  40 #include "monitor.h"
  41 #include "openvswitch/vlog.h"
  42
  43 VLOG_DEFINE_THIS_MODULE(ovsdb_jsonrpc_server);
  44
  45 struct ovsdb_jsonrpc_remote;
  46 struct ovsdb_jsonrpc_session;
  47
  48 /* Message rate-limiting. */
  49 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  50
  51 /* Sessions. */
  52 static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
  53     struct ovsdb_jsonrpc_remote *, struct jsonrpc_session *);
  54 static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
  55 static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
  56 static void ovsdb_jsonrpc_session_get_memory_usage_all(
  57     const struct ovsdb_jsonrpc_remote *, struct simap *usage);
  58 static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
  59 static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
  60 static void ovsdb_jsonrpc_session_set_all_options(
  61     struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
  62 static bool ovsdb_jsonrpc_session_get_status(
  63     const struct ovsdb_jsonrpc_remote *,
  64     struct ovsdb_jsonrpc_remote_status *);
  65 static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
  66 static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
  67 static void ovsdb_jsonrpc_session_send(struct ovsdb_jsonrpc_session *,
  68                                        struct jsonrpc_msg *);
  69
  70 /* Triggers. */
  71 static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
  72                                          struct ovsdb *,
  73                                          struct json *id, struct json *params);
  74 static struct ovsdb_jsonrpc_trigger *ovsdb_jsonrpc_trigger_find(
  75     struct ovsdb_jsonrpc_session *, const struct json *id, size_t hash);
  76 static void ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *);
  77 static void ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *);
  78 static void ovsdb_jsonrpc_trigger_complete_done(
  79     struct ovsdb_jsonrpc_session *);
  80
  81 /* Monitors. */
  82 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_create(
  83     struct ovsdb_jsonrpc_session *, struct ovsdb *, struct json *params,
  84     const struct json *request_id);
  85 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
  86     struct ovsdb_jsonrpc_session *,
  87     struct json_array *params,
  88     const struct json *request_id);
  89 static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
  90 static void ovsdb_jsonrpc_monitor_flush_all(struct ovsdb_jsonrpc_session *);
  91 static bool ovsdb_jsonrpc_monitor_needs_flush(struct ovsdb_jsonrpc_session *);
  92 static struct json *ovsdb_jsonrpc_monitor_compose_update(
  93     struct ovsdb_jsonrpc_monitor *monitor, bool initial);
  94
  95 \f
  96 /* JSON-RPC database server. */
  97
  98 struct ovsdb_jsonrpc_server {
  99     struct ovsdb_server up;
 100     unsigned int n_sessions, max_sessions;
 101     struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
 102 };
 103
 104 /* A configured remote.  This is either a passive stream listener plus a list
 105  * of the currently connected sessions, or a list of exactly one active
 106  * session. */
 107 struct ovsdb_jsonrpc_remote {
 108     struct ovsdb_jsonrpc_server *server;
 109     struct pstream *listener;   /* Listener, if passive. */
 110     struct ovs_list sessions;   /* List of "struct ovsdb_jsonrpc_session"s. */
 111     uint8_t dscp;
 112 };
 113
 114 static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
 115     struct ovsdb_jsonrpc_server *, const char *name,
 116     const struct ovsdb_jsonrpc_options *options
 117 );
 118 static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 119
 120 /* Creates and returns a new server to provide JSON-RPC access to an OVSDB.
 121  *
 122  * The caller must call ovsdb_jsonrpc_server_add_db() for each database to
 123  * which 'server' should provide access. */
 124 struct ovsdb_jsonrpc_server *
 125 ovsdb_jsonrpc_server_create(void)
 126 {
 127     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
 128     ovsdb_server_init(&server->up);
 129     server->max_sessions = 330;   /* Random limit. */
 130     shash_init(&server->remotes);
 131     return server;
 132 }
 133
 134 /* Adds 'db' to the set of databases served out by 'svr'.  Returns true if
 135  * successful, false if 'db''s name is the same as some database already in
 136  * 'server'. */
 137 bool
 138 ovsdb_jsonrpc_server_add_db(struct ovsdb_jsonrpc_server *svr, struct ovsdb *db)
 139 {
 140     /* The OVSDB protocol doesn't have a way to notify a client that a
 141      * database has been added.  If some client tried to use the database
 142      * that we're adding and failed, then forcing it to reconnect seems like
 143      * a reasonable way to make it try again.
 144      *
 145      * If this is too big of a hammer in practice, we could be more selective,
 146      * e.g. disconnect only connections that actually tried to use a database
 147      * with 'db''s name. */
 148     ovsdb_jsonrpc_server_reconnect(svr);
 149
 150     return ovsdb_server_add_db(&svr->up, db);
 151 }
 152
 153 /* Removes 'db' from the set of databases served out by 'svr'.  Returns
 154  * true if successful, false if there is no database associated with 'db'. */
 155 bool
 156 ovsdb_jsonrpc_server_remove_db(struct ovsdb_jsonrpc_server *svr,
 157                                struct ovsdb *db)
 158 {
 159     /* There might be pointers to 'db' from 'svr', such as monitors or
 160      * outstanding transactions.  Disconnect all JSON-RPC connections to avoid
 161      * accesses to freed memory.
 162      *
 163      * If this is too big of a hammer in practice, we could be more selective,
 164      * e.g. disconnect only connections that actually reference 'db'. */
 165     ovsdb_jsonrpc_server_reconnect(svr);
 166
 167     return ovsdb_server_remove_db(&svr->up, db);
 168 }
 169
 170 void
 171 ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
 172 {
 173     struct shash_node *node, *next;
 174
 175     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 176         ovsdb_jsonrpc_server_del_remote(node);
 177     }
 178     shash_destroy(&svr->remotes);
 179     ovsdb_server_destroy(&svr->up);
 180     free(svr);
 181 }
 182
 183 struct ovsdb_jsonrpc_options *
 184 ovsdb_jsonrpc_default_options(const char *target)
 185 {
 186     struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
 187     options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
 188     options->probe_interval = (stream_or_pstream_needs_probes(target)
 189                                ? RECONNECT_DEFAULT_PROBE_INTERVAL
 190                                : 0);
 191     return options;
 192 }
 193
 194 /* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
 195  * options in the struct ovsdb_jsonrpc_options supplied as the data values.
 196  *
 197  * A remote is an active or passive stream connection method, e.g. "pssl:" or
 198  * "tcp:1.2.3.4". */
 199 void
 200 ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 201                                  const struct shash *new_remotes)
 202 {
 203     struct shash_node *node, *next;
 204
 205     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 206         struct ovsdb_jsonrpc_remote *remote = node->data;
 207         struct ovsdb_jsonrpc_options *options
 208             = shash_find_data(new_remotes, node->name);
 209
 210         if (!options) {
 211             VLOG_INFO("%s: remote deconfigured", node->name);
 212             ovsdb_jsonrpc_server_del_remote(node);
 213         } else if (options->dscp != remote->dscp) {
 214             ovsdb_jsonrpc_server_del_remote(node);
 215          }
 216     }
 217     SHASH_FOR_EACH (node, new_remotes) {
 218         const struct ovsdb_jsonrpc_options *options = node->data;
 219         struct ovsdb_jsonrpc_remote *remote;
 220
 221         remote = shash_find_data(&svr->remotes, node->name);
 222         if (!remote) {
 223             remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
 224             if (!remote) {
 225                 continue;
 226             }
 227         }
 228
 229         ovsdb_jsonrpc_session_set_all_options(remote, options);
 230     }
 231 }
 232
 233 static struct ovsdb_jsonrpc_remote *
 234 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
 235                                 const char *name,
 236                                 const struct ovsdb_jsonrpc_options *options)
 237 {
 238     struct ovsdb_jsonrpc_remote *remote;
 239     struct pstream *listener;
 240     int error;
 241
 242     error = jsonrpc_pstream_open(name, &listener, options->dscp);
 243     if (error && error != EAFNOSUPPORT) {
 244         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, ovs_strerror(error));
 245         return NULL;
 246     }
 247
 248     remote = xmalloc(sizeof *remote);
 249     remote->server = svr;
 250     remote->listener = listener;
 251     list_init(&remote->sessions);
 252     remote->dscp = options->dscp;
 253     shash_add(&svr->remotes, name, remote);
 254
 255     if (!listener) {
 256         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name, true));
 257     }
 258     return remote;
 259 }
 260
 261 static void
 262 ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
 263 {
 264     struct ovsdb_jsonrpc_remote *remote = node->data;
 265
 266     ovsdb_jsonrpc_session_close_all(remote);
 267     pstream_close(remote->listener);
 268     shash_delete(&remote->server->remotes, node);
 269     free(remote);
 270 }
 271
 272 /* Stores status information for the remote named 'target', which should have
 273  * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
 274  * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
 275  * a remote named 'target' or if that remote is an inbound remote that has no
 276  * active connections) returns false.  On failure, 'status' will be zeroed.
 277  */
 278 bool
 279 ovsdb_jsonrpc_server_get_remote_status(
 280     const struct ovsdb_jsonrpc_server *svr, const char *target,
 281     struct ovsdb_jsonrpc_remote_status *status)
 282 {
 283     const struct ovsdb_jsonrpc_remote *remote;
 284
 285     memset(status, 0, sizeof *status);
 286
 287     remote = shash_find_data(&svr->remotes, target);
 288     return remote && ovsdb_jsonrpc_session_get_status(remote, status);
 289 }
 290
 291 void
 292 ovsdb_jsonrpc_server_free_remote_status(
 293     struct ovsdb_jsonrpc_remote_status *status)
 294 {
 295     free(status->locks_held);
 296     free(status->locks_waiting);
 297     free(status->locks_lost);
 298 }
 299
 300 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
 301  * reconnect. */
 302 void
 303 ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
 304 {
 305     struct shash_node *node;
 306
 307     SHASH_FOR_EACH (node, &svr->remotes) {
 308         struct ovsdb_jsonrpc_remote *remote = node->data;
 309
 310         ovsdb_jsonrpc_session_reconnect_all(remote);
 311     }
 312 }
 313
 314 void
 315 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 316 {
 317     struct shash_node *node;
 318
 319     SHASH_FOR_EACH (node, &svr->remotes) {
 320         struct ovsdb_jsonrpc_remote *remote = node->data;
 321
 322         if (remote->listener) {
 323             if (svr->n_sessions < svr->max_sessions) {
 324                 struct stream *stream;
 325                 int error;
 326
 327                 error = pstream_accept(remote->listener, &stream);
 328                 if (!error) {
 329                     struct jsonrpc_session *js;
 330                     js = jsonrpc_session_open_unreliably(jsonrpc_open(stream),
 331                                                          remote->dscp);
 332                     ovsdb_jsonrpc_session_create(remote, js);
 333                 } else if (error != EAGAIN) {
 334                     VLOG_WARN_RL(&rl, "%s: accept failed: %s",
 335                                  pstream_get_name(remote->listener),
 336                                  ovs_strerror(error));
 337                 }
 338             } else {
 339                 VLOG_WARN_RL(&rl, "%s: connection exceeded maximum (%d)",
 340                              pstream_get_name(remote->listener),
 341                              svr->max_sessions);
 342             }
 343         }
 344
 345         ovsdb_jsonrpc_session_run_all(remote);
 346     }
 347 }
 348
 349 void
 350 ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 351 {
 352     struct shash_node *node;
 353
 354     SHASH_FOR_EACH (node, &svr->remotes) {
 355         struct ovsdb_jsonrpc_remote *remote = node->data;
 356
 357         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 358             pstream_wait(remote->listener);
 359         }
 360
 361         ovsdb_jsonrpc_session_wait_all(remote);
 362     }
 363 }
 364
 365 /* Adds some memory usage statistics for 'svr' into 'usage', for use with
 366  * memory_report(). */
 367 void
 368 ovsdb_jsonrpc_server_get_memory_usage(const struct ovsdb_jsonrpc_server *svr,
 369                                       struct simap *usage)
 370 {
 371     struct shash_node *node;
 372
 373     simap_increase(usage, "sessions", svr->n_sessions);
 374     SHASH_FOR_EACH (node, &svr->remotes) {
 375         struct ovsdb_jsonrpc_remote *remote = node->data;
 376
 377         ovsdb_jsonrpc_session_get_memory_usage_all(remote, usage);
 378     }
 379 }
 380 \f
 381 /* JSON-RPC database server session. */
 382
 383 struct ovsdb_jsonrpc_session {
 384     struct ovs_list node;       /* Element in remote's sessions list. */
 385     struct ovsdb_session up;
 386     struct ovsdb_jsonrpc_remote *remote;
 387
 388     /* Triggers. */
 389     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
 390
 391     /* Monitors. */
 392     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
 393
 394     /* Network connectivity. */
 395     struct jsonrpc_session *js;  /* JSON-RPC session. */
 396     unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
 397 };
 398
 399 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 400 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 401 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
 402 static void ovsdb_jsonrpc_session_get_memory_usage(
 403     const struct ovsdb_jsonrpc_session *, struct simap *usage);
 404 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
 405                                              struct jsonrpc_msg *);
 406 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
 407                                              struct jsonrpc_msg *);
 408
 409 static struct ovsdb_jsonrpc_session *
 410 ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
 411                              struct jsonrpc_session *js)
 412 {
 413     struct ovsdb_jsonrpc_session *s;
 414
 415     s = xzalloc(sizeof *s);
 416     ovsdb_session_init(&s->up, &remote->server->up);
 417     s->remote = remote;
 418     list_push_back(&remote->sessions, &s->node);
 419     hmap_init(&s->triggers);
 420     hmap_init(&s->monitors);
 421     s->js = js;
 422     s->js_seqno = jsonrpc_session_get_seqno(js);
 423
 424     remote->server->n_sessions++;
 425
 426     return s;
 427 }
 428
 429 static void
 430 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 431 {
 432     ovsdb_jsonrpc_monitor_remove_all(s);
 433     ovsdb_jsonrpc_session_unlock_all(s);
 434     ovsdb_jsonrpc_trigger_complete_all(s);
 435
 436     hmap_destroy(&s->monitors);
 437     hmap_destroy(&s->triggers);
 438
 439     jsonrpc_session_close(s->js);
 440     list_remove(&s->node);
 441     s->remote->server->n_sessions--;
 442     ovsdb_session_destroy(&s->up);
 443     free(s);
 444 }
 445
 446 static int
 447 ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
 448 {
 449     jsonrpc_session_run(s->js);
 450     if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
 451         s->js_seqno = jsonrpc_session_get_seqno(s->js);
 452         ovsdb_jsonrpc_trigger_complete_all(s);
 453         ovsdb_jsonrpc_monitor_remove_all(s);
 454         ovsdb_jsonrpc_session_unlock_all(s);
 455     }
 456
 457     ovsdb_jsonrpc_trigger_complete_done(s);
 458
 459     if (!jsonrpc_session_get_backlog(s->js)) {
 460         struct jsonrpc_msg *msg;
 461
 462         ovsdb_jsonrpc_monitor_flush_all(s);
 463
 464         msg = jsonrpc_session_recv(s->js);
 465         if (msg) {
 466             if (msg->type == JSONRPC_REQUEST) {
 467                 ovsdb_jsonrpc_session_got_request(s, msg);
 468             } else if (msg->type == JSONRPC_NOTIFY) {
 469                 ovsdb_jsonrpc_session_got_notify(s, msg);
 470             } else {
 471                 VLOG_WARN("%s: received unexpected %s message",
 472                           jsonrpc_session_get_name(s->js),
 473                           jsonrpc_msg_type_to_string(msg->type));
 474                 jsonrpc_session_force_reconnect(s->js);
 475                 jsonrpc_msg_destroy(msg);
 476             }
 477         }
 478     }
 479     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 480 }
 481
 482 static void
 483 ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
 484                                   const struct ovsdb_jsonrpc_options *options)
 485 {
 486     jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
 487     jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
 488     jsonrpc_session_set_dscp(session->js, options->dscp);
 489 }
 490
 491 static void
 492 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 493 {
 494     struct ovsdb_jsonrpc_session *s, *next;
 495
 496     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 497         int error = ovsdb_jsonrpc_session_run(s);
 498         if (error) {
 499             ovsdb_jsonrpc_session_close(s);
 500         }
 501     }
 502 }
 503
 504 static void
 505 ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
 506 {
 507     jsonrpc_session_wait(s->js);
 508     if (!jsonrpc_session_get_backlog(s->js)) {
 509         if (ovsdb_jsonrpc_monitor_needs_flush(s)) {
 510             poll_immediate_wake();
 511         } else {
 512             jsonrpc_session_recv_wait(s->js);
 513         }
 514     }
 515 }
 516
 517 static void
 518 ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 519 {
 520     struct ovsdb_jsonrpc_session *s;
 521
 522     LIST_FOR_EACH (s, node, &remote->sessions) {
 523         ovsdb_jsonrpc_session_wait(s);
 524     }
 525 }
 526
 527 static void
 528 ovsdb_jsonrpc_session_get_memory_usage(const struct ovsdb_jsonrpc_session *s,
 529                                        struct simap *usage)
 530 {
 531     simap_increase(usage, "triggers", hmap_count(&s->triggers));
 532     simap_increase(usage, "monitors", hmap_count(&s->monitors));
 533     simap_increase(usage, "backlog", jsonrpc_session_get_backlog(s->js));
 534 }
 535
 536 static void
 537 ovsdb_jsonrpc_session_get_memory_usage_all(
 538     const struct ovsdb_jsonrpc_remote *remote,
 539     struct simap *usage)
 540 {
 541     struct ovsdb_jsonrpc_session *s;
 542
 543     LIST_FOR_EACH (s, node, &remote->sessions) {
 544         ovsdb_jsonrpc_session_get_memory_usage(s, usage);
 545     }
 546 }
 547
 548 static void
 549 ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 550 {
 551     struct ovsdb_jsonrpc_session *s, *next;
 552
 553     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 554         ovsdb_jsonrpc_session_close(s);
 555     }
 556 }
 557
 558 /* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
 559  * reconnect. */
 560 static void
 561 ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 562 {
 563     struct ovsdb_jsonrpc_session *s, *next;
 564
 565     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 566         jsonrpc_session_force_reconnect(s->js);
 567         if (!jsonrpc_session_is_alive(s->js)) {
 568             ovsdb_jsonrpc_session_close(s);
 569         }
 570     }
 571 }
 572
 573 /* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
 574  * 'options'.
 575  *
 576  * (The dscp value can't be changed directly; the caller must instead close and
 577  * re-open the session.) */
 578 static void
 579 ovsdb_jsonrpc_session_set_all_options(
 580     struct ovsdb_jsonrpc_remote *remote,
 581     const struct ovsdb_jsonrpc_options *options)
 582 {
 583     struct ovsdb_jsonrpc_session *s;
 584
 585     LIST_FOR_EACH (s, node, &remote->sessions) {
 586         ovsdb_jsonrpc_session_set_options(s, options);
 587     }
 588 }
 589
 590 static bool
 591 ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
 592                                  struct ovsdb_jsonrpc_remote_status *status)
 593 {
 594     const struct ovsdb_jsonrpc_session *s;
 595     const struct jsonrpc_session *js;
 596     struct ovsdb_lock_waiter *waiter;
 597     struct reconnect_stats rstats;
 598     struct ds locks_held, locks_waiting, locks_lost;
 599
 600     status->bound_port = (remote->listener
 601                           ? pstream_get_bound_port(remote->listener)
 602                           : htons(0));
 603
 604     if (list_is_empty(&remote->sessions)) {
 605         return false;
 606     }
 607     s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
 608     js = s->js;
 609
 610     status->is_connected = jsonrpc_session_is_connected(js);
 611     status->last_error = jsonrpc_session_get_status(js);
 612
 613     jsonrpc_session_get_reconnect_stats(js, &rstats);
 614     status->state = rstats.state;
 615     status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
 616         ? UINT_MAX : rstats.msec_since_connect / 1000;
 617     status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
 618         ? UINT_MAX : rstats.msec_since_disconnect / 1000;
 619
 620     ds_init(&locks_held);
 621     ds_init(&locks_waiting);
 622     ds_init(&locks_lost);
 623     HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
 624         struct ds *string;
 625
 626         string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
 627                   : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
 628                   : &locks_lost);
 629         if (string->length) {
 630             ds_put_char(string, ' ');
 631         }
 632         ds_put_cstr(string, waiter->lock_name);
 633     }
 634     status->locks_held = ds_steal_cstr(&locks_held);
 635     status->locks_waiting = ds_steal_cstr(&locks_waiting);
 636     status->locks_lost = ds_steal_cstr(&locks_lost);
 637
 638     status->n_connections = list_size(&remote->sessions);
 639
 640     return true;
 641 }
 642
 643 /* Examines 'request' to determine the database to which it relates, and then
 644  * searches 's' to find that database:
 645  *
 646  *    - If successful, returns the database and sets '*replyp' to NULL.
 647  *
 648  *    - If no such database exists, returns NULL and sets '*replyp' to an
 649  *      appropriate JSON-RPC error reply, owned by the caller. */
 650 static struct ovsdb *
 651 ovsdb_jsonrpc_lookup_db(const struct ovsdb_jsonrpc_session *s,
 652                         const struct jsonrpc_msg *request,
 653                         struct jsonrpc_msg **replyp)
 654 {
 655     struct json_array *params;
 656     struct ovsdb_error *error;
 657     const char *db_name;
 658     struct ovsdb *db;
 659
 660     params = json_array(request->params);
 661     if (!params->n || params->elems[0]->type != JSON_STRING) {
 662         error = ovsdb_syntax_error(
 663             request->params, NULL,
 664             "%s request params must begin with <db-name>", request->method);
 665         goto error;
 666     }
 667
 668     db_name = params->elems[0]->u.string;
 669     db = shash_find_data(&s->up.server->dbs, db_name);
 670     if (!db) {
 671         error = ovsdb_syntax_error(
 672             request->params, "unknown database",
 673             "%s request specifies unknown database %s",
 674             request->method, db_name);
 675         goto error;
 676     }
 677
 678     *replyp = NULL;
 679     return db;
 680
 681 error:
 682     *replyp = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 683     ovsdb_error_destroy(error);
 684     return NULL;
 685 }
 686
 687 static struct ovsdb_error *
 688 ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
 689                                       const char **lock_namep)
 690 {
 691     const struct json_array *params;
 692
 693     params = json_array(request->params);
 694     if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
 695         !ovsdb_parser_is_id(json_string(params->elems[0]))) {
 696         *lock_namep = NULL;
 697         return ovsdb_syntax_error(request->params, NULL,
 698                                   "%s request params must be <id>",
 699                                   request->method);
 700     }
 701
 702     *lock_namep = json_string(params->elems[0]);
 703     return NULL;
 704 }
 705
 706 static void
 707 ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
 708                              const char *lock_name,
 709                              const char *method)
 710 {
 711     struct ovsdb_jsonrpc_session *s;
 712     struct json *params;
 713
 714     s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
 715     params = json_array_create_1(json_string_create(lock_name));
 716     ovsdb_jsonrpc_session_send(s, jsonrpc_create_notify(method, params));
 717 }
 718
 719 static struct jsonrpc_msg *
 720 ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
 721                            struct jsonrpc_msg *request,
 722                            enum ovsdb_lock_mode mode)
 723 {
 724     struct ovsdb_lock_waiter *waiter;
 725     struct jsonrpc_msg *reply;
 726     struct ovsdb_error *error;
 727     struct ovsdb_session *victim;
 728     const char *lock_name;
 729     struct json *result;
 730
 731     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 732     if (error) {
 733         goto error;
 734     }
 735
 736     /* Report error if this session has issued a "lock" or "steal" without a
 737      * matching "unlock" for this lock. */
 738     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 739     if (waiter) {
 740         error = ovsdb_syntax_error(
 741             request->params, NULL,
 742             "must issue \"unlock\" before new \"%s\"", request->method);
 743         goto error;
 744     }
 745
 746     /* Get the lock, add us as a waiter. */
 747     waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
 748                                &victim);
 749     if (victim) {
 750         ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
 751     }
 752
 753     result = json_object_create();
 754     json_object_put(result, "locked",
 755                     json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
 756
 757     return jsonrpc_create_reply(result, request->id);
 758
 759 error:
 760     reply = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 761     ovsdb_error_destroy(error);
 762     return reply;
 763 }
 764
 765 static void
 766 ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
 767 {
 768     struct ovsdb_lock_waiter *waiter, *next;
 769
 770     HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
 771         ovsdb_jsonrpc_session_unlock__(waiter);
 772     }
 773 }
 774
 775 static void
 776 ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
 777 {
 778     struct ovsdb_lock *lock = waiter->lock;
 779
 780     if (lock) {
 781         struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
 782         if (new_owner) {
 783             ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
 784         } else {
 785             /* ovsdb_server_lock() might have freed 'lock'. */
 786         }
 787     }
 788
 789     ovsdb_lock_waiter_destroy(waiter);
 790 }
 791
 792 static struct jsonrpc_msg *
 793 ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
 794                              struct jsonrpc_msg *request)
 795 {
 796     struct ovsdb_lock_waiter *waiter;
 797     struct jsonrpc_msg *reply;
 798     struct ovsdb_error *error;
 799     const char *lock_name;
 800
 801     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 802     if (error) {
 803         goto error;
 804     }
 805
 806     /* Report error if this session has not issued a "lock" or "steal" for this
 807      * lock. */
 808     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 809     if (!waiter) {
 810         error = ovsdb_syntax_error(
 811             request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
 812         goto error;
 813     }
 814
 815     ovsdb_jsonrpc_session_unlock__(waiter);
 816
 817     return jsonrpc_create_reply(json_object_create(), request->id);
 818
 819 error:
 820     reply = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 821     ovsdb_error_destroy(error);
 822     return reply;
 823 }
 824
 825 static struct jsonrpc_msg *
 826 execute_transaction(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 827                     struct jsonrpc_msg *request)
 828 {
 829     ovsdb_jsonrpc_trigger_create(s, db, request->id, request->params);
 830     request->id = NULL;
 831     request->params = NULL;
 832     jsonrpc_msg_destroy(request);
 833     return NULL;
 834 }
 835
 836 static void
 837 ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
 838                                   struct jsonrpc_msg *request)
 839 {
 840     struct jsonrpc_msg *reply;
 841
 842     if (!strcmp(request->method, "transact")) {
 843         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 844         if (!reply) {
 845             reply = execute_transaction(s, db, request);
 846         }
 847     } else if (!strcmp(request->method, "monitor")) {
 848         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 849         if (!reply) {
 850             reply = ovsdb_jsonrpc_monitor_create(s, db, request->params,
 851                                                  request->id);
 852         }
 853     } else if (!strcmp(request->method, "monitor_cancel")) {
 854         reply = ovsdb_jsonrpc_monitor_cancel(s, json_array(request->params),
 855                                              request->id);
 856     } else if (!strcmp(request->method, "get_schema")) {
 857         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 858         if (!reply) {
 859             reply = jsonrpc_create_reply(ovsdb_schema_to_json(db->schema),
 860                                          request->id);
 861         }
 862     } else if (!strcmp(request->method, "list_dbs")) {
 863         size_t n_dbs = shash_count(&s->up.server->dbs);
 864         struct shash_node *node;
 865         struct json **dbs;
 866         size_t i;
 867
 868         dbs = xmalloc(n_dbs * sizeof *dbs);
 869         i = 0;
 870         SHASH_FOR_EACH (node, &s->up.server->dbs) {
 871             dbs[i++] = json_string_create(node->name);
 872         }
 873         reply = jsonrpc_create_reply(json_array_create(dbs, n_dbs),
 874                                      request->id);
 875     } else if (!strcmp(request->method, "lock")) {
 876         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
 877     } else if (!strcmp(request->method, "steal")) {
 878         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
 879     } else if (!strcmp(request->method, "unlock")) {
 880         reply = ovsdb_jsonrpc_session_unlock(s, request);
 881     } else if (!strcmp(request->method, "echo")) {
 882         reply = jsonrpc_create_reply(json_clone(request->params), request->id);
 883     } else {
 884         reply = jsonrpc_create_error(json_string_create("unknown method"),
 885                                      request->id);
 886     }
 887
 888     if (reply) {
 889         jsonrpc_msg_destroy(request);
 890         ovsdb_jsonrpc_session_send(s, reply);
 891     }
 892 }
 893
 894 static void
 895 execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
 896 {
 897     if (json_array(request->params)->n == 1) {
 898         struct ovsdb_jsonrpc_trigger *t;
 899         struct json *id;
 900
 901         id = request->params->u.array.elems[0];
 902         t = ovsdb_jsonrpc_trigger_find(s, id, json_hash(id, 0));
 903         if (t) {
 904             ovsdb_jsonrpc_trigger_complete(t);
 905         }
 906     }
 907 }
 908
 909 static void
 910 ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
 911                                  struct jsonrpc_msg *request)
 912 {
 913     if (!strcmp(request->method, "cancel")) {
 914         execute_cancel(s, request);
 915     }
 916     jsonrpc_msg_destroy(request);
 917 }
 918
 919 static void
 920 ovsdb_jsonrpc_session_send(struct ovsdb_jsonrpc_session *s,
 921                            struct jsonrpc_msg *msg)
 922 {
 923     ovsdb_jsonrpc_monitor_flush_all(s);
 924     jsonrpc_session_send(s->js, msg);
 925 }
 926 \f
 927 /* JSON-RPC database server triggers.
 928  *
 929  * (Every transaction is treated as a trigger even if it doesn't actually have
 930  * any "wait" operations.) */
 931
 932 struct ovsdb_jsonrpc_trigger {
 933     struct ovsdb_trigger trigger;
 934     struct hmap_node hmap_node; /* In session's "triggers" hmap. */
 935     struct json *id;
 936 };
 937
 938 static void
 939 ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 940                              struct json *id, struct json *params)
 941 {
 942     struct ovsdb_jsonrpc_trigger *t;
 943     size_t hash;
 944
 945     /* Check for duplicate ID. */
 946     hash = json_hash(id, 0);
 947     t = ovsdb_jsonrpc_trigger_find(s, id, hash);
 948     if (t) {
 949         struct jsonrpc_msg *msg;
 950
 951         msg = jsonrpc_create_error(json_string_create("duplicate request ID"),
 952                                    id);
 953         ovsdb_jsonrpc_session_send(s, msg);
 954         json_destroy(id);
 955         json_destroy(params);
 956         return;
 957     }
 958
 959     /* Insert into trigger table. */
 960     t = xmalloc(sizeof *t);
 961     ovsdb_trigger_init(&s->up, db, &t->trigger, params, time_msec());
 962     t->id = id;
 963     hmap_insert(&s->triggers, &t->hmap_node, hash);
 964
 965     /* Complete early if possible. */
 966     if (ovsdb_trigger_is_complete(&t->trigger)) {
 967         ovsdb_jsonrpc_trigger_complete(t);
 968     }
 969 }
 970
 971 static struct ovsdb_jsonrpc_trigger *
 972 ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 973                            const struct json *id, size_t hash)
 974 {
 975     struct ovsdb_jsonrpc_trigger *t;
 976
 977     HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
 978         if (json_equal(t->id, id)) {
 979             return t;
 980         }
 981     }
 982
 983     return NULL;
 984 }
 985
 986 static void
 987 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 988 {
 989     struct ovsdb_jsonrpc_session *s;
 990
 991     s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
 992
 993     if (jsonrpc_session_is_connected(s->js)) {
 994         struct jsonrpc_msg *reply;
 995         struct json *result;
 996
 997         result = ovsdb_trigger_steal_result(&t->trigger);
 998         if (result) {
 999             reply = jsonrpc_create_reply(result, t->id);
1000         } else {
1001             reply = jsonrpc_create_error(json_string_create("canceled"),
1002                                          t->id);
1003         }
1004         ovsdb_jsonrpc_session_send(s, reply);
1005     }
1006
1007     json_destroy(t->id);
1008     ovsdb_trigger_destroy(&t->trigger);
1009     hmap_remove(&s->triggers, &t->hmap_node);
1010     free(t);
1011 }
1012
1013 static void
1014 ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
1015 {
1016     struct ovsdb_jsonrpc_trigger *t, *next;
1017     HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
1018         ovsdb_jsonrpc_trigger_complete(t);
1019     }
1020 }
1021
1022 static void
1023 ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
1024 {
1025     while (!list_is_empty(&s->up.completions)) {
1026         struct ovsdb_jsonrpc_trigger *t
1027             = CONTAINER_OF(s->up.completions.next,
1028                            struct ovsdb_jsonrpc_trigger, trigger.node);
1029         ovsdb_jsonrpc_trigger_complete(t);
1030     }
1031 }
1032 \f
1033 /* Jsonrpc front end monitor. */
1034 struct ovsdb_jsonrpc_monitor {
1035     struct ovsdb_jsonrpc_session *session;
1036     struct ovsdb *db;
1037     struct hmap_node node;      /* In ovsdb_jsonrpc_session's "monitors". */
1038     struct json *monitor_id;
1039     struct ovsdb_monitor *dbmon;
1040     uint64_t unflushed;         /* The first transaction that has not been
1041                                        flushed to the jsonrpc remote client. */
1042 };
1043
1044 static struct ovsdb_jsonrpc_monitor *
1045 ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
1046                            const struct json *monitor_id)
1047 {
1048     struct ovsdb_jsonrpc_monitor *m;
1049
1050     HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
1051         if (json_equal(m->monitor_id, monitor_id)) {
1052             return m;
1053         }
1054     }
1055
1056     return NULL;
1057 }
1058
1059 static bool
1060 parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
1061 {
1062     const struct json *json;
1063
1064     json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
1065     return json ? json_boolean(json) : default_value;
1066 }
1067
1068 static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
1069 ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_monitor *dbmon,
1070                                     const struct ovsdb_table *table,
1071                                     const struct json *monitor_request,
1072                                     size_t *allocated_columns)
1073 {
1074     const struct ovsdb_table_schema *ts = table->schema;
1075     enum ovsdb_monitor_selection select;
1076     const struct json *columns, *select_json;
1077     struct ovsdb_parser parser;
1078     struct ovsdb_error *error;
1079
1080     ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
1081     columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
1082     select_json = ovsdb_parser_member(&parser, "select",
1083                                       OP_OBJECT | OP_OPTIONAL);
1084     error = ovsdb_parser_finish(&parser);
1085     if (error) {
1086         return error;
1087     }
1088
1089     if (select_json) {
1090         select = 0;
1091         ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
1092         if (parse_bool(&parser, "initial", true)) {
1093             select |= OJMS_INITIAL;
1094         }
1095         if (parse_bool(&parser, "insert", true)) {
1096             select |= OJMS_INSERT;
1097         }
1098         if (parse_bool(&parser, "delete", true)) {
1099             select |= OJMS_DELETE;
1100         }
1101         if (parse_bool(&parser, "modify", true)) {
1102             select |= OJMS_MODIFY;
1103         }
1104         error = ovsdb_parser_finish(&parser);
1105         if (error) {
1106             return error;
1107         }
1108     } else {
1109         select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
1110     }
1111
1112     ovsdb_monitor_table_add_select(dbmon, table, select);
1113     if (columns) {
1114         size_t i;
1115
1116         if (columns->type != JSON_ARRAY) {
1117             return ovsdb_syntax_error(columns, NULL,
1118                                       "array of column names expected");
1119         }
1120
1121         for (i = 0; i < columns->u.array.n; i++) {
1122             const struct ovsdb_column *column;
1123             const char *s;
1124
1125             if (columns->u.array.elems[i]->type != JSON_STRING) {
1126                 return ovsdb_syntax_error(columns, NULL,
1127                                           "array of column names expected");
1128             }
1129
1130             s = columns->u.array.elems[i]->u.string;
1131             column = shash_find_data(&table->schema->columns, s);
1132             if (!column) {
1133                 return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
1134                                           "column name", s);
1135             }
1136             ovsdb_monitor_add_column(dbmon, table, column, select,
1137                                      allocated_columns);
1138         }
1139     } else {
1140         struct shash_node *node;
1141
1142         SHASH_FOR_EACH (node, &ts->columns) {
1143             const struct ovsdb_column *column = node->data;
1144             if (column->index != OVSDB_COL_UUID) {
1145                 ovsdb_monitor_add_column(dbmon, table, column, select,
1146                                          allocated_columns);
1147             }
1148         }
1149     }
1150
1151     return NULL;
1152 }
1153
1154 static struct jsonrpc_msg *
1155 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
1156                              struct json *params,
1157                              const struct json *request_id)
1158 {
1159     struct ovsdb_jsonrpc_monitor *m = NULL;
1160     struct ovsdb_monitor *dbmon = NULL;
1161     struct json *monitor_id, *monitor_requests;
1162     struct ovsdb_error *error = NULL;
1163     struct shash_node *node;
1164     struct json *json;
1165
1166     if (json_array(params)->n != 3) {
1167         error = ovsdb_syntax_error(params, NULL, "invalid parameters");
1168         goto error;
1169     }
1170     monitor_id = params->u.array.elems[1];
1171     monitor_requests = params->u.array.elems[2];
1172     if (monitor_requests->type != JSON_OBJECT) {
1173         error = ovsdb_syntax_error(monitor_requests, NULL,
1174                                    "monitor-requests must be object");
1175         goto error;
1176     }
1177
1178     if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
1179         error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
1180         goto error;
1181     }
1182
1183     m = xzalloc(sizeof *m);
1184     m->session = s;
1185     m->db = db;
1186     m->dbmon = ovsdb_monitor_create(db, m);
1187     m->unflushed = 0;
1188     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
1189     m->monitor_id = json_clone(monitor_id);
1190
1191     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
1192         const struct ovsdb_table *table;
1193         const char *column_name;
1194         size_t allocated_columns;
1195         const struct json *mr_value;
1196         size_t i;
1197
1198         table = ovsdb_get_table(m->db, node->name);
1199         if (!table) {
1200             error = ovsdb_syntax_error(NULL, NULL,
1201                                        "no table named %s", node->name);
1202             goto error;
1203         }
1204
1205         ovsdb_monitor_add_table(m->dbmon, table);
1206
1207         /* Parse columns. */
1208         mr_value = node->data;
1209         allocated_columns = 0;
1210         if (mr_value->type == JSON_ARRAY) {
1211             const struct json_array *array = &mr_value->u.array;
1212
1213             for (i = 0; i < array->n; i++) {
1214                 error = ovsdb_jsonrpc_parse_monitor_request(
1215                     m->dbmon, table, array->elems[i], &allocated_columns);
1216                 if (error) {
1217                     goto error;
1218                 }
1219             }
1220         } else {
1221             error = ovsdb_jsonrpc_parse_monitor_request(
1222                 m->dbmon, table, mr_value, &allocated_columns);
1223             if (error) {
1224                 goto error;
1225             }
1226         }
1227
1228         column_name = ovsdb_monitor_table_check_duplicates(m->dbmon, table);
1229
1230         if (column_name) {
1231             error = ovsdb_syntax_error(mr_value, NULL, "column %s "
1232                                        "mentioned more than once",
1233                                         column_name);
1234             goto error;
1235         }
1236     }
1237
1238     dbmon = ovsdb_monitor_add(m->dbmon);
1239     if (dbmon != m->dbmon) {
1240         /* Found an exisiting dbmon, reuse the current one. */
1241         ovsdb_monitor_remove_jsonrpc_monitor(m->dbmon, m);
1242         ovsdb_monitor_add_jsonrpc_monitor(dbmon, m);
1243         m->dbmon = dbmon;
1244     }
1245
1246     ovsdb_monitor_get_initial(m->dbmon);
1247     json = ovsdb_jsonrpc_monitor_compose_update(m, true);
1248     json = json ? json : json_object_create();
1249     return jsonrpc_create_reply(json, request_id);
1250
1251 error:
1252     if (m) {
1253         ovsdb_jsonrpc_monitor_destroy(m);
1254     }
1255
1256     json = ovsdb_error_to_json(error);
1257     ovsdb_error_destroy(error);
1258     return jsonrpc_create_error(json, request_id);
1259 }
1260
1261 static struct jsonrpc_msg *
1262 ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
1263                              struct json_array *params,
1264                              const struct json *request_id)
1265 {
1266     if (params->n != 1) {
1267         return jsonrpc_create_error(json_string_create("invalid parameters"),
1268                                     request_id);
1269     } else {
1270         struct ovsdb_jsonrpc_monitor *m;
1271
1272         m = ovsdb_jsonrpc_monitor_find(s, params->elems[0]);
1273         if (!m) {
1274             return jsonrpc_create_error(json_string_create("unknown monitor"),
1275                                         request_id);
1276         } else {
1277             ovsdb_jsonrpc_monitor_destroy(m);
1278             return jsonrpc_create_reply(json_object_create(), request_id);
1279         }
1280     }
1281 }
1282
1283 static void
1284 ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
1285 {
1286     struct ovsdb_jsonrpc_monitor *m, *next;
1287
1288     HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
1289         ovsdb_jsonrpc_monitor_destroy(m);
1290     }
1291 }
1292
1293 static struct json *
1294 ovsdb_jsonrpc_monitor_compose_update(struct ovsdb_jsonrpc_monitor *m,
1295                                      bool initial)
1296 {
1297     return ovsdb_monitor_get_update(m->dbmon, initial, &m->unflushed);
1298 }
1299
1300 static bool
1301 ovsdb_jsonrpc_monitor_needs_flush(struct ovsdb_jsonrpc_session *s)
1302 {
1303     struct ovsdb_jsonrpc_monitor *m;
1304
1305     HMAP_FOR_EACH (m, node, &s->monitors) {
1306         if (ovsdb_monitor_needs_flush(m->dbmon, m->unflushed)) {
1307             return true;
1308         }
1309     }
1310
1311     return false;
1312 }
1313
1314 void
1315 ovsdb_jsonrpc_monitor_destroy(struct ovsdb_jsonrpc_monitor *m)
1316 {
1317     json_destroy(m->monitor_id);
1318     hmap_remove(&m->session->monitors, &m->node);
1319     ovsdb_monitor_remove_jsonrpc_monitor(m->dbmon, m);
1320     free(m);
1321 }
1322
1323 static void
1324 ovsdb_jsonrpc_monitor_flush_all(struct ovsdb_jsonrpc_session *s)
1325 {
1326     struct ovsdb_jsonrpc_monitor *m;
1327
1328     HMAP_FOR_EACH (m, node, &s->monitors) {
1329         struct json *json;
1330
1331         json = ovsdb_jsonrpc_monitor_compose_update(m, false);
1332         if (json) {
1333             struct jsonrpc_msg *msg;
1334             struct json *params;
1335
1336             params = json_array_create_2(json_clone(m->monitor_id), json);
1337             msg = jsonrpc_create_notify("update", params);
1338             jsonrpc_session_send(s->js, msg);
1339         }
1340     }
1341 }