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 "monitor.h"
  26 #include "json.h"
  27 #include "jsonrpc.h"
  28 #include "ovsdb-error.h"
  29 #include "ovsdb-parser.h"
  30 #include "ovsdb.h"
  31 #include "poll-loop.h"
  32 #include "reconnect.h"
  33 #include "row.h"
  34 #include "server.h"
  35 #include "simap.h"
  36 #include "stream.h"
  37 #include "table.h"
  38 #include "timeval.h"
  39 #include "transaction.h"
  40 #include "trigger.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 /* Set false to defeature monitor2, causing jsonrpc to respond to monitor2
  49  * method with an error.  */
  50 static bool monitor2_enable__ = true;
  51
  52 /* Message rate-limiting. */
  53 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  54
  55 /* Sessions. */
  56 static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
  57     struct ovsdb_jsonrpc_remote *, struct jsonrpc_session *);
  58 static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
  59 static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
  60 static void ovsdb_jsonrpc_session_get_memory_usage_all(
  61     const struct ovsdb_jsonrpc_remote *, struct simap *usage);
  62 static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
  63 static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
  64 static void ovsdb_jsonrpc_session_set_all_options(
  65     struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
  66 static bool ovsdb_jsonrpc_session_get_status(
  67     const struct ovsdb_jsonrpc_remote *,
  68     struct ovsdb_jsonrpc_remote_status *);
  69 static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
  70 static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
  71 static void ovsdb_jsonrpc_session_send(struct ovsdb_jsonrpc_session *,
  72                                        struct jsonrpc_msg *);
  73
  74 /* Triggers. */
  75 static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
  76                                          struct ovsdb *,
  77                                          struct json *id, struct json *params);
  78 static struct ovsdb_jsonrpc_trigger *ovsdb_jsonrpc_trigger_find(
  79     struct ovsdb_jsonrpc_session *, const struct json *id, size_t hash);
  80 static void ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *);
  81 static void ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *);
  82 static void ovsdb_jsonrpc_trigger_complete_done(
  83     struct ovsdb_jsonrpc_session *);
  84
  85 /* Monitors. */
  86 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_create(
  87     struct ovsdb_jsonrpc_session *, struct ovsdb *, struct json *params,
  88     enum ovsdb_monitor_version, const struct json *request_id);
  89 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
  90     struct ovsdb_jsonrpc_session *,
  91     struct json_array *params,
  92     const struct json *request_id);
  93 static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
  94 static void ovsdb_jsonrpc_monitor_flush_all(struct ovsdb_jsonrpc_session *);
  95 static bool ovsdb_jsonrpc_monitor_needs_flush(struct ovsdb_jsonrpc_session *);
  96 static struct json *ovsdb_jsonrpc_monitor_compose_update(
  97     struct ovsdb_jsonrpc_monitor *monitor, bool initial);
  98
  99 \f
 100 /* JSON-RPC database server. */
 101
 102 struct ovsdb_jsonrpc_server {
 103     struct ovsdb_server up;
 104     unsigned int n_sessions;
 105     struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
 106 };
 107
 108 /* A configured remote.  This is either a passive stream listener plus a list
 109  * of the currently connected sessions, or a list of exactly one active
 110  * session. */
 111 struct ovsdb_jsonrpc_remote {
 112     struct ovsdb_jsonrpc_server *server;
 113     struct pstream *listener;   /* Listener, if passive. */
 114     struct ovs_list sessions;   /* List of "struct ovsdb_jsonrpc_session"s. */
 115     uint8_t dscp;
 116 };
 117
 118 static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
 119     struct ovsdb_jsonrpc_server *, const char *name,
 120     const struct ovsdb_jsonrpc_options *options
 121 );
 122 static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 123
 124 /* Creates and returns a new server to provide JSON-RPC access to an OVSDB.
 125  *
 126  * The caller must call ovsdb_jsonrpc_server_add_db() for each database to
 127  * which 'server' should provide access. */
 128 struct ovsdb_jsonrpc_server *
 129 ovsdb_jsonrpc_server_create(void)
 130 {
 131     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
 132     ovsdb_server_init(&server->up);
 133     shash_init(&server->remotes);
 134     return server;
 135 }
 136
 137 /* Adds 'db' to the set of databases served out by 'svr'.  Returns true if
 138  * successful, false if 'db''s name is the same as some database already in
 139  * 'server'. */
 140 bool
 141 ovsdb_jsonrpc_server_add_db(struct ovsdb_jsonrpc_server *svr, struct ovsdb *db)
 142 {
 143     /* The OVSDB protocol doesn't have a way to notify a client that a
 144      * database has been added.  If some client tried to use the database
 145      * that we're adding and failed, then forcing it to reconnect seems like
 146      * a reasonable way to make it try again.
 147      *
 148      * If this is too big of a hammer in practice, we could be more selective,
 149      * e.g. disconnect only connections that actually tried to use a database
 150      * with 'db''s name. */
 151     ovsdb_jsonrpc_server_reconnect(svr);
 152
 153     return ovsdb_server_add_db(&svr->up, db);
 154 }
 155
 156 /* Removes 'db' from the set of databases served out by 'svr'.  Returns
 157  * true if successful, false if there is no database associated with 'db'. */
 158 bool
 159 ovsdb_jsonrpc_server_remove_db(struct ovsdb_jsonrpc_server *svr,
 160                                struct ovsdb *db)
 161 {
 162     /* There might be pointers to 'db' from 'svr', such as monitors or
 163      * outstanding transactions.  Disconnect all JSON-RPC connections to avoid
 164      * accesses to freed memory.
 165      *
 166      * If this is too big of a hammer in practice, we could be more selective,
 167      * e.g. disconnect only connections that actually reference 'db'. */
 168     ovsdb_jsonrpc_server_reconnect(svr);
 169
 170     return ovsdb_server_remove_db(&svr->up, db);
 171 }
 172
 173 void
 174 ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
 175 {
 176     struct shash_node *node, *next;
 177
 178     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 179         ovsdb_jsonrpc_server_del_remote(node);
 180     }
 181     shash_destroy(&svr->remotes);
 182     ovsdb_server_destroy(&svr->up);
 183     free(svr);
 184 }
 185
 186 struct ovsdb_jsonrpc_options *
 187 ovsdb_jsonrpc_default_options(const char *target)
 188 {
 189     struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
 190     options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
 191     options->probe_interval = (stream_or_pstream_needs_probes(target)
 192                                ? RECONNECT_DEFAULT_PROBE_INTERVAL
 193                                : 0);
 194     return options;
 195 }
 196
 197 /* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
 198  * options in the struct ovsdb_jsonrpc_options supplied as the data values.
 199  *
 200  * A remote is an active or passive stream connection method, e.g. "pssl:" or
 201  * "tcp:1.2.3.4". */
 202 void
 203 ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 204                                  const struct shash *new_remotes)
 205 {
 206     struct shash_node *node, *next;
 207
 208     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 209         struct ovsdb_jsonrpc_remote *remote = node->data;
 210         struct ovsdb_jsonrpc_options *options
 211             = shash_find_data(new_remotes, node->name);
 212
 213         if (!options) {
 214             VLOG_INFO("%s: remote deconfigured", node->name);
 215             ovsdb_jsonrpc_server_del_remote(node);
 216         } else if (options->dscp != remote->dscp) {
 217             ovsdb_jsonrpc_server_del_remote(node);
 218          }
 219     }
 220     SHASH_FOR_EACH (node, new_remotes) {
 221         const struct ovsdb_jsonrpc_options *options = node->data;
 222         struct ovsdb_jsonrpc_remote *remote;
 223
 224         remote = shash_find_data(&svr->remotes, node->name);
 225         if (!remote) {
 226             remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
 227             if (!remote) {
 228                 continue;
 229             }
 230         }
 231
 232         ovsdb_jsonrpc_session_set_all_options(remote, options);
 233     }
 234 }
 235
 236 static struct ovsdb_jsonrpc_remote *
 237 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
 238                                 const char *name,
 239                                 const struct ovsdb_jsonrpc_options *options)
 240 {
 241     struct ovsdb_jsonrpc_remote *remote;
 242     struct pstream *listener;
 243     int error;
 244
 245     error = jsonrpc_pstream_open(name, &listener, options->dscp);
 246     if (error && error != EAFNOSUPPORT) {
 247         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, ovs_strerror(error));
 248         return NULL;
 249     }
 250
 251     remote = xmalloc(sizeof *remote);
 252     remote->server = svr;
 253     remote->listener = listener;
 254     list_init(&remote->sessions);
 255     remote->dscp = options->dscp;
 256     shash_add(&svr->remotes, name, remote);
 257
 258     if (!listener) {
 259         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name, true));
 260     }
 261     return remote;
 262 }
 263
 264 static void
 265 ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
 266 {
 267     struct ovsdb_jsonrpc_remote *remote = node->data;
 268
 269     ovsdb_jsonrpc_session_close_all(remote);
 270     pstream_close(remote->listener);
 271     shash_delete(&remote->server->remotes, node);
 272     free(remote);
 273 }
 274
 275 /* Stores status information for the remote named 'target', which should have
 276  * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
 277  * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
 278  * a remote named 'target' or if that remote is an inbound remote that has no
 279  * active connections) returns false.  On failure, 'status' will be zeroed.
 280  */
 281 bool
 282 ovsdb_jsonrpc_server_get_remote_status(
 283     const struct ovsdb_jsonrpc_server *svr, const char *target,
 284     struct ovsdb_jsonrpc_remote_status *status)
 285 {
 286     const struct ovsdb_jsonrpc_remote *remote;
 287
 288     memset(status, 0, sizeof *status);
 289
 290     remote = shash_find_data(&svr->remotes, target);
 291     return remote && ovsdb_jsonrpc_session_get_status(remote, status);
 292 }
 293
 294 void
 295 ovsdb_jsonrpc_server_free_remote_status(
 296     struct ovsdb_jsonrpc_remote_status *status)
 297 {
 298     free(status->locks_held);
 299     free(status->locks_waiting);
 300     free(status->locks_lost);
 301 }
 302
 303 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
 304  * reconnect. */
 305 void
 306 ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
 307 {
 308     struct shash_node *node;
 309
 310     SHASH_FOR_EACH (node, &svr->remotes) {
 311         struct ovsdb_jsonrpc_remote *remote = node->data;
 312
 313         ovsdb_jsonrpc_session_reconnect_all(remote);
 314     }
 315 }
 316
 317 void
 318 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 319 {
 320     struct shash_node *node;
 321
 322     SHASH_FOR_EACH (node, &svr->remotes) {
 323         struct ovsdb_jsonrpc_remote *remote = node->data;
 324
 325         if (remote->listener) {
 326             struct stream *stream;
 327             int error;
 328
 329             error = pstream_accept(remote->listener, &stream);
 330             if (!error) {
 331                 struct jsonrpc_session *js;
 332                 js = jsonrpc_session_open_unreliably(jsonrpc_open(stream),
 333                                                      remote->dscp);
 334                 ovsdb_jsonrpc_session_create(remote, js);
 335             } else if (error != EAGAIN) {
 336                 VLOG_WARN_RL(&rl, "%s: accept failed: %s",
 337                              pstream_get_name(remote->listener),
 338                              ovs_strerror(error));
 339             }
 340         }
 341
 342         ovsdb_jsonrpc_session_run_all(remote);
 343     }
 344 }
 345
 346 void
 347 ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 348 {
 349     struct shash_node *node;
 350
 351     SHASH_FOR_EACH (node, &svr->remotes) {
 352         struct ovsdb_jsonrpc_remote *remote = node->data;
 353
 354         if (remote->listener) {
 355             pstream_wait(remote->listener);
 356         }
 357
 358         ovsdb_jsonrpc_session_wait_all(remote);
 359     }
 360 }
 361
 362 /* Adds some memory usage statistics for 'svr' into 'usage', for use with
 363  * memory_report(). */
 364 void
 365 ovsdb_jsonrpc_server_get_memory_usage(const struct ovsdb_jsonrpc_server *svr,
 366                                       struct simap *usage)
 367 {
 368     struct shash_node *node;
 369
 370     simap_increase(usage, "sessions", svr->n_sessions);
 371     SHASH_FOR_EACH (node, &svr->remotes) {
 372         struct ovsdb_jsonrpc_remote *remote = node->data;
 373
 374         ovsdb_jsonrpc_session_get_memory_usage_all(remote, usage);
 375     }
 376 }
 377 \f
 378 /* JSON-RPC database server session. */
 379
 380 struct ovsdb_jsonrpc_session {
 381     struct ovs_list node;       /* Element in remote's sessions list. */
 382     struct ovsdb_session up;
 383     struct ovsdb_jsonrpc_remote *remote;
 384
 385     /* Triggers. */
 386     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
 387
 388     /* Monitors. */
 389     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
 390
 391     /* Network connectivity. */
 392     struct jsonrpc_session *js;  /* JSON-RPC session. */
 393     unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
 394 };
 395
 396 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 397 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 398 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
 399 static void ovsdb_jsonrpc_session_get_memory_usage(
 400     const struct ovsdb_jsonrpc_session *, struct simap *usage);
 401 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
 402                                              struct jsonrpc_msg *);
 403 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
 404                                              struct jsonrpc_msg *);
 405
 406 static struct ovsdb_jsonrpc_session *
 407 ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
 408                              struct jsonrpc_session *js)
 409 {
 410     struct ovsdb_jsonrpc_session *s;
 411
 412     s = xzalloc(sizeof *s);
 413     ovsdb_session_init(&s->up, &remote->server->up);
 414     s->remote = remote;
 415     list_push_back(&remote->sessions, &s->node);
 416     hmap_init(&s->triggers);
 417     hmap_init(&s->monitors);
 418     s->js = js;
 419     s->js_seqno = jsonrpc_session_get_seqno(js);
 420
 421     remote->server->n_sessions++;
 422
 423     return s;
 424 }
 425
 426 static void
 427 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 428 {
 429     ovsdb_jsonrpc_monitor_remove_all(s);
 430     ovsdb_jsonrpc_session_unlock_all(s);
 431     ovsdb_jsonrpc_trigger_complete_all(s);
 432
 433     hmap_destroy(&s->monitors);
 434     hmap_destroy(&s->triggers);
 435
 436     jsonrpc_session_close(s->js);
 437     list_remove(&s->node);
 438     s->remote->server->n_sessions--;
 439     ovsdb_session_destroy(&s->up);
 440     free(s);
 441 }
 442
 443 static int
 444 ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
 445 {
 446     jsonrpc_session_run(s->js);
 447     if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
 448         s->js_seqno = jsonrpc_session_get_seqno(s->js);
 449         ovsdb_jsonrpc_trigger_complete_all(s);
 450         ovsdb_jsonrpc_monitor_remove_all(s);
 451         ovsdb_jsonrpc_session_unlock_all(s);
 452     }
 453
 454     ovsdb_jsonrpc_trigger_complete_done(s);
 455
 456     if (!jsonrpc_session_get_backlog(s->js)) {
 457         struct jsonrpc_msg *msg;
 458
 459         ovsdb_jsonrpc_monitor_flush_all(s);
 460
 461         msg = jsonrpc_session_recv(s->js);
 462         if (msg) {
 463             if (msg->type == JSONRPC_REQUEST) {
 464                 ovsdb_jsonrpc_session_got_request(s, msg);
 465             } else if (msg->type == JSONRPC_NOTIFY) {
 466                 ovsdb_jsonrpc_session_got_notify(s, msg);
 467             } else {
 468                 VLOG_WARN("%s: received unexpected %s message",
 469                           jsonrpc_session_get_name(s->js),
 470                           jsonrpc_msg_type_to_string(msg->type));
 471                 jsonrpc_session_force_reconnect(s->js);
 472                 jsonrpc_msg_destroy(msg);
 473             }
 474         }
 475     }
 476     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 477 }
 478
 479 static void
 480 ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
 481                                   const struct ovsdb_jsonrpc_options *options)
 482 {
 483     jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
 484     jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
 485     jsonrpc_session_set_dscp(session->js, options->dscp);
 486 }
 487
 488 static void
 489 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 490 {
 491     struct ovsdb_jsonrpc_session *s, *next;
 492
 493     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 494         int error = ovsdb_jsonrpc_session_run(s);
 495         if (error) {
 496             ovsdb_jsonrpc_session_close(s);
 497         }
 498     }
 499 }
 500
 501 static void
 502 ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
 503 {
 504     jsonrpc_session_wait(s->js);
 505     if (!jsonrpc_session_get_backlog(s->js)) {
 506         if (ovsdb_jsonrpc_monitor_needs_flush(s)) {
 507             poll_immediate_wake();
 508         } else {
 509             jsonrpc_session_recv_wait(s->js);
 510         }
 511     }
 512 }
 513
 514 static void
 515 ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 516 {
 517     struct ovsdb_jsonrpc_session *s;
 518
 519     LIST_FOR_EACH (s, node, &remote->sessions) {
 520         ovsdb_jsonrpc_session_wait(s);
 521     }
 522 }
 523
 524 static void
 525 ovsdb_jsonrpc_session_get_memory_usage(const struct ovsdb_jsonrpc_session *s,
 526                                        struct simap *usage)
 527 {
 528     simap_increase(usage, "triggers", hmap_count(&s->triggers));
 529     simap_increase(usage, "backlog", jsonrpc_session_get_backlog(s->js));
 530 }
 531
 532 static void
 533 ovsdb_jsonrpc_session_get_memory_usage_all(
 534     const struct ovsdb_jsonrpc_remote *remote,
 535     struct simap *usage)
 536 {
 537     struct ovsdb_jsonrpc_session *s;
 538
 539     LIST_FOR_EACH (s, node, &remote->sessions) {
 540         ovsdb_jsonrpc_session_get_memory_usage(s, usage);
 541     }
 542 }
 543
 544 static void
 545 ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 546 {
 547     struct ovsdb_jsonrpc_session *s, *next;
 548
 549     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 550         ovsdb_jsonrpc_session_close(s);
 551     }
 552 }
 553
 554 /* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
 555  * reconnect. */
 556 static void
 557 ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 558 {
 559     struct ovsdb_jsonrpc_session *s, *next;
 560
 561     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 562         jsonrpc_session_force_reconnect(s->js);
 563         if (!jsonrpc_session_is_alive(s->js)) {
 564             ovsdb_jsonrpc_session_close(s);
 565         }
 566     }
 567 }
 568
 569 /* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
 570  * 'options'.
 571  *
 572  * (The dscp value can't be changed directly; the caller must instead close and
 573  * re-open the session.) */
 574 static void
 575 ovsdb_jsonrpc_session_set_all_options(
 576     struct ovsdb_jsonrpc_remote *remote,
 577     const struct ovsdb_jsonrpc_options *options)
 578 {
 579     struct ovsdb_jsonrpc_session *s;
 580
 581     LIST_FOR_EACH (s, node, &remote->sessions) {
 582         ovsdb_jsonrpc_session_set_options(s, options);
 583     }
 584 }
 585
 586 static bool
 587 ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
 588                                  struct ovsdb_jsonrpc_remote_status *status)
 589 {
 590     const struct ovsdb_jsonrpc_session *s;
 591     const struct jsonrpc_session *js;
 592     struct ovsdb_lock_waiter *waiter;
 593     struct reconnect_stats rstats;
 594     struct ds locks_held, locks_waiting, locks_lost;
 595
 596     status->bound_port = (remote->listener
 597                           ? pstream_get_bound_port(remote->listener)
 598                           : htons(0));
 599
 600     if (list_is_empty(&remote->sessions)) {
 601         return false;
 602     }
 603     s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
 604     js = s->js;
 605
 606     status->is_connected = jsonrpc_session_is_connected(js);
 607     status->last_error = jsonrpc_session_get_status(js);
 608
 609     jsonrpc_session_get_reconnect_stats(js, &rstats);
 610     status->state = rstats.state;
 611     status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
 612         ? UINT_MAX : rstats.msec_since_connect / 1000;
 613     status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
 614         ? UINT_MAX : rstats.msec_since_disconnect / 1000;
 615
 616     ds_init(&locks_held);
 617     ds_init(&locks_waiting);
 618     ds_init(&locks_lost);
 619     HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
 620         struct ds *string;
 621
 622         string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
 623                   : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
 624                   : &locks_lost);
 625         if (string->length) {
 626             ds_put_char(string, ' ');
 627         }
 628         ds_put_cstr(string, waiter->lock_name);
 629     }
 630     status->locks_held = ds_steal_cstr(&locks_held);
 631     status->locks_waiting = ds_steal_cstr(&locks_waiting);
 632     status->locks_lost = ds_steal_cstr(&locks_lost);
 633
 634     status->n_connections = list_size(&remote->sessions);
 635
 636     return true;
 637 }
 638
 639 /* Examines 'request' to determine the database to which it relates, and then
 640  * searches 's' to find that database:
 641  *
 642  *    - If successful, returns the database and sets '*replyp' to NULL.
 643  *
 644  *    - If no such database exists, returns NULL and sets '*replyp' to an
 645  *      appropriate JSON-RPC error reply, owned by the caller. */
 646 static struct ovsdb *
 647 ovsdb_jsonrpc_lookup_db(const struct ovsdb_jsonrpc_session *s,
 648                         const struct jsonrpc_msg *request,
 649                         struct jsonrpc_msg **replyp)
 650 {
 651     struct json_array *params;
 652     struct ovsdb_error *error;
 653     const char *db_name;
 654     struct ovsdb *db;
 655
 656     params = json_array(request->params);
 657     if (!params->n || params->elems[0]->type != JSON_STRING) {
 658         error = ovsdb_syntax_error(
 659             request->params, NULL,
 660             "%s request params must begin with <db-name>", request->method);
 661         goto error;
 662     }
 663
 664     db_name = params->elems[0]->u.string;
 665     db = shash_find_data(&s->up.server->dbs, db_name);
 666     if (!db) {
 667         error = ovsdb_syntax_error(
 668             request->params, "unknown database",
 669             "%s request specifies unknown database %s",
 670             request->method, db_name);
 671         goto error;
 672     }
 673
 674     *replyp = NULL;
 675     return db;
 676
 677 error:
 678     *replyp = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 679     ovsdb_error_destroy(error);
 680     return NULL;
 681 }
 682
 683 static struct ovsdb_error *
 684 ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
 685                                       const char **lock_namep)
 686 {
 687     const struct json_array *params;
 688
 689     params = json_array(request->params);
 690     if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
 691         !ovsdb_parser_is_id(json_string(params->elems[0]))) {
 692         *lock_namep = NULL;
 693         return ovsdb_syntax_error(request->params, NULL,
 694                                   "%s request params must be <id>",
 695                                   request->method);
 696     }
 697
 698     *lock_namep = json_string(params->elems[0]);
 699     return NULL;
 700 }
 701
 702 static void
 703 ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
 704                              const char *lock_name,
 705                              const char *method)
 706 {
 707     struct ovsdb_jsonrpc_session *s;
 708     struct json *params;
 709
 710     s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
 711     params = json_array_create_1(json_string_create(lock_name));
 712     ovsdb_jsonrpc_session_send(s, jsonrpc_create_notify(method, params));
 713 }
 714
 715 static struct jsonrpc_msg *
 716 ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
 717                            struct jsonrpc_msg *request,
 718                            enum ovsdb_lock_mode mode)
 719 {
 720     struct ovsdb_lock_waiter *waiter;
 721     struct jsonrpc_msg *reply;
 722     struct ovsdb_error *error;
 723     struct ovsdb_session *victim;
 724     const char *lock_name;
 725     struct json *result;
 726
 727     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 728     if (error) {
 729         goto error;
 730     }
 731
 732     /* Report error if this session has issued a "lock" or "steal" without a
 733      * matching "unlock" for this lock. */
 734     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 735     if (waiter) {
 736         error = ovsdb_syntax_error(
 737             request->params, NULL,
 738             "must issue \"unlock\" before new \"%s\"", request->method);
 739         goto error;
 740     }
 741
 742     /* Get the lock, add us as a waiter. */
 743     waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
 744                                &victim);
 745     if (victim) {
 746         ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
 747     }
 748
 749     result = json_object_create();
 750     json_object_put(result, "locked",
 751                     json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
 752
 753     return jsonrpc_create_reply(result, request->id);
 754
 755 error:
 756     reply = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 757     ovsdb_error_destroy(error);
 758     return reply;
 759 }
 760
 761 static void
 762 ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
 763 {
 764     struct ovsdb_lock_waiter *waiter, *next;
 765
 766     HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
 767         ovsdb_jsonrpc_session_unlock__(waiter);
 768     }
 769 }
 770
 771 static void
 772 ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
 773 {
 774     struct ovsdb_lock *lock = waiter->lock;
 775
 776     if (lock) {
 777         struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
 778         if (new_owner) {
 779             ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
 780         } else {
 781             /* ovsdb_server_lock() might have freed 'lock'. */
 782         }
 783     }
 784
 785     ovsdb_lock_waiter_destroy(waiter);
 786 }
 787
 788 static struct jsonrpc_msg *
 789 ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
 790                              struct jsonrpc_msg *request)
 791 {
 792     struct ovsdb_lock_waiter *waiter;
 793     struct jsonrpc_msg *reply;
 794     struct ovsdb_error *error;
 795     const char *lock_name;
 796
 797     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 798     if (error) {
 799         goto error;
 800     }
 801
 802     /* Report error if this session has not issued a "lock" or "steal" for this
 803      * lock. */
 804     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 805     if (!waiter) {
 806         error = ovsdb_syntax_error(
 807             request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
 808         goto error;
 809     }
 810
 811     ovsdb_jsonrpc_session_unlock__(waiter);
 812
 813     return jsonrpc_create_reply(json_object_create(), request->id);
 814
 815 error:
 816     reply = jsonrpc_create_error(ovsdb_error_to_json(error), request->id);
 817     ovsdb_error_destroy(error);
 818     return reply;
 819 }
 820
 821 static struct jsonrpc_msg *
 822 execute_transaction(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 823                     struct jsonrpc_msg *request)
 824 {
 825     ovsdb_jsonrpc_trigger_create(s, db, request->id, request->params);
 826     request->id = NULL;
 827     request->params = NULL;
 828     jsonrpc_msg_destroy(request);
 829     return NULL;
 830 }
 831
 832 static void
 833 ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
 834                                   struct jsonrpc_msg *request)
 835 {
 836     struct jsonrpc_msg *reply;
 837
 838     if (!strcmp(request->method, "transact")) {
 839         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 840         if (!reply) {
 841             reply = execute_transaction(s, db, request);
 842         }
 843     } else if (!strcmp(request->method, "monitor") ||
 844                (monitor2_enable__ && !strcmp(request->method, "monitor2"))) {
 845         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 846         if (!reply) {
 847             int l = strlen(request->method) - strlen("monitor");
 848             enum ovsdb_monitor_version version = l ? OVSDB_MONITOR_V2
 849                                                    : OVSDB_MONITOR_V1;
 850             reply = ovsdb_jsonrpc_monitor_create(s, db, request->params,
 851                                                  version, 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     enum ovsdb_monitor_version version;
1043 };
1044
1045 static struct ovsdb_jsonrpc_monitor *
1046 ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
1047                            const struct json *monitor_id)
1048 {
1049     struct ovsdb_jsonrpc_monitor *m;
1050
1051     HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
1052         if (json_equal(m->monitor_id, monitor_id)) {
1053             return m;
1054         }
1055     }
1056
1057     return NULL;
1058 }
1059
1060 static bool
1061 parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
1062 {
1063     const struct json *json;
1064
1065     json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
1066     return json ? json_boolean(json) : default_value;
1067 }
1068
1069 static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
1070 ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_monitor *dbmon,
1071                                     const struct ovsdb_table *table,
1072                                     const struct json *monitor_request,
1073                                     size_t *allocated_columns)
1074 {
1075     const struct ovsdb_table_schema *ts = table->schema;
1076     enum ovsdb_monitor_selection select;
1077     const struct json *columns, *select_json;
1078     struct ovsdb_parser parser;
1079     struct ovsdb_error *error;
1080
1081     ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
1082     columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
1083     select_json = ovsdb_parser_member(&parser, "select",
1084                                       OP_OBJECT | OP_OPTIONAL);
1085     error = ovsdb_parser_finish(&parser);
1086     if (error) {
1087         return error;
1088     }
1089
1090     if (select_json) {
1091         select = 0;
1092         ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
1093         if (parse_bool(&parser, "initial", true)) {
1094             select |= OJMS_INITIAL;
1095         }
1096         if (parse_bool(&parser, "insert", true)) {
1097             select |= OJMS_INSERT;
1098         }
1099         if (parse_bool(&parser, "delete", true)) {
1100             select |= OJMS_DELETE;
1101         }
1102         if (parse_bool(&parser, "modify", true)) {
1103             select |= OJMS_MODIFY;
1104         }
1105         error = ovsdb_parser_finish(&parser);
1106         if (error) {
1107             return error;
1108         }
1109     } else {
1110         select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
1111     }
1112
1113     ovsdb_monitor_table_add_select(dbmon, table, select);
1114     if (columns) {
1115         size_t i;
1116
1117         if (columns->type != JSON_ARRAY) {
1118             return ovsdb_syntax_error(columns, NULL,
1119                                       "array of column names expected");
1120         }
1121
1122         for (i = 0; i < columns->u.array.n; i++) {
1123             const struct ovsdb_column *column;
1124             const char *s;
1125
1126             if (columns->u.array.elems[i]->type != JSON_STRING) {
1127                 return ovsdb_syntax_error(columns, NULL,
1128                                           "array of column names expected");
1129             }
1130
1131             s = columns->u.array.elems[i]->u.string;
1132             column = shash_find_data(&table->schema->columns, s);
1133             if (!column) {
1134                 return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
1135                                           "column name", s);
1136             }
1137             ovsdb_monitor_add_column(dbmon, table, column, select,
1138                                      allocated_columns);
1139         }
1140     } else {
1141         struct shash_node *node;
1142
1143         SHASH_FOR_EACH (node, &ts->columns) {
1144             const struct ovsdb_column *column = node->data;
1145             if (column->index != OVSDB_COL_UUID) {
1146                 ovsdb_monitor_add_column(dbmon, table, column, select,
1147                                          allocated_columns);
1148             }
1149         }
1150     }
1151
1152     return NULL;
1153 }
1154
1155 static struct jsonrpc_msg *
1156 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
1157                              struct json *params,
1158                              enum ovsdb_monitor_version version,
1159                              const struct json *request_id)
1160 {
1161     struct ovsdb_jsonrpc_monitor *m = NULL;
1162     struct ovsdb_monitor *dbmon = NULL;
1163     struct json *monitor_id, *monitor_requests;
1164     struct ovsdb_error *error = NULL;
1165     struct shash_node *node;
1166     struct json *json;
1167
1168     if (json_array(params)->n != 3) {
1169         error = ovsdb_syntax_error(params, NULL, "invalid parameters");
1170         goto error;
1171     }
1172     monitor_id = params->u.array.elems[1];
1173     monitor_requests = params->u.array.elems[2];
1174     if (monitor_requests->type != JSON_OBJECT) {
1175         error = ovsdb_syntax_error(monitor_requests, NULL,
1176                                    "monitor-requests must be object");
1177         goto error;
1178     }
1179
1180     if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
1181         error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
1182         goto error;
1183     }
1184
1185     m = xzalloc(sizeof *m);
1186     m->session = s;
1187     m->db = db;
1188     m->dbmon = ovsdb_monitor_create(db, m);
1189     m->unflushed = 0;
1190     m->version = version;
1191     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
1192     m->monitor_id = json_clone(monitor_id);
1193
1194     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
1195         const struct ovsdb_table *table;
1196         const char *column_name;
1197         size_t allocated_columns;
1198         const struct json *mr_value;
1199         size_t i;
1200
1201         table = ovsdb_get_table(m->db, node->name);
1202         if (!table) {
1203             error = ovsdb_syntax_error(NULL, NULL,
1204                                        "no table named %s", node->name);
1205             goto error;
1206         }
1207
1208         ovsdb_monitor_add_table(m->dbmon, table);
1209
1210         /* Parse columns. */
1211         mr_value = node->data;
1212         allocated_columns = 0;
1213         if (mr_value->type == JSON_ARRAY) {
1214             const struct json_array *array = &mr_value->u.array;
1215
1216             for (i = 0; i < array->n; i++) {
1217                 error = ovsdb_jsonrpc_parse_monitor_request(
1218                     m->dbmon, table, array->elems[i], &allocated_columns);
1219                 if (error) {
1220                     goto error;
1221                 }
1222             }
1223         } else {
1224             error = ovsdb_jsonrpc_parse_monitor_request(
1225                 m->dbmon, table, mr_value, &allocated_columns);
1226             if (error) {
1227                 goto error;
1228             }
1229         }
1230
1231         column_name = ovsdb_monitor_table_check_duplicates(m->dbmon, table);
1232
1233         if (column_name) {
1234             error = ovsdb_syntax_error(mr_value, NULL, "column %s "
1235                                        "mentioned more than once",
1236                                         column_name);
1237             goto error;
1238         }
1239     }
1240
1241     dbmon = ovsdb_monitor_add(m->dbmon);
1242     if (dbmon != m->dbmon) {
1243         /* Found an exisiting dbmon, reuse the current one. */
1244         ovsdb_monitor_remove_jsonrpc_monitor(m->dbmon, m);
1245         ovsdb_monitor_add_jsonrpc_monitor(dbmon, m);
1246         m->dbmon = dbmon;
1247     }
1248
1249     ovsdb_monitor_get_initial(m->dbmon);
1250     json = ovsdb_jsonrpc_monitor_compose_update(m, true);
1251     json = json ? json : json_object_create();
1252     return jsonrpc_create_reply(json, request_id);
1253
1254 error:
1255     if (m) {
1256         ovsdb_jsonrpc_monitor_destroy(m);
1257     }
1258
1259     json = ovsdb_error_to_json(error);
1260     ovsdb_error_destroy(error);
1261     return jsonrpc_create_error(json, request_id);
1262 }
1263
1264 static struct jsonrpc_msg *
1265 ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
1266                              struct json_array *params,
1267                              const struct json *request_id)
1268 {
1269     if (params->n != 1) {
1270         return jsonrpc_create_error(json_string_create("invalid parameters"),
1271                                     request_id);
1272     } else {
1273         struct ovsdb_jsonrpc_monitor *m;
1274
1275         m = ovsdb_jsonrpc_monitor_find(s, params->elems[0]);
1276         if (!m) {
1277             return jsonrpc_create_error(json_string_create("unknown monitor"),
1278                                         request_id);
1279         } else {
1280             ovsdb_jsonrpc_monitor_destroy(m);
1281             return jsonrpc_create_reply(json_object_create(), request_id);
1282         }
1283     }
1284 }
1285
1286 static void
1287 ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
1288 {
1289     struct ovsdb_jsonrpc_monitor *m, *next;
1290
1291     HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
1292         ovsdb_jsonrpc_monitor_destroy(m);
1293     }
1294 }
1295
1296 static struct json *
1297 ovsdb_jsonrpc_monitor_compose_update(struct ovsdb_jsonrpc_monitor *m,
1298                                      bool initial)
1299 {
1300     return ovsdb_monitor_get_update(m->dbmon, initial, &m->unflushed,
1301                                     m->version);
1302 }
1303
1304 static bool
1305 ovsdb_jsonrpc_monitor_needs_flush(struct ovsdb_jsonrpc_session *s)
1306 {
1307     struct ovsdb_jsonrpc_monitor *m;
1308
1309     HMAP_FOR_EACH (m, node, &s->monitors) {
1310         if (ovsdb_monitor_needs_flush(m->dbmon, m->unflushed)) {
1311             return true;
1312         }
1313     }
1314
1315     return false;
1316 }
1317
1318 void
1319 ovsdb_jsonrpc_monitor_destroy(struct ovsdb_jsonrpc_monitor *m)
1320 {
1321     json_destroy(m->monitor_id);
1322     hmap_remove(&m->session->monitors, &m->node);
1323     ovsdb_monitor_remove_jsonrpc_monitor(m->dbmon, m);
1324     free(m);
1325 }
1326
1327 static struct jsonrpc_msg *
1328 ovsdb_jsonrpc_create_notify(const struct ovsdb_jsonrpc_monitor *m,
1329                             struct json *params)
1330 {
1331     const char *method;
1332
1333     switch(m->version) {
1334     case OVSDB_MONITOR_V1:
1335         method = "update";
1336         break;
1337     case OVSDB_MONITOR_V2:
1338         method = "update2";
1339         break;
1340     case OVSDB_MONITOR_VERSION_MAX:
1341     default:
1342         OVS_NOT_REACHED();
1343     }
1344
1345     return jsonrpc_create_notify(method, params);
1346 }
1347
1348 static void
1349 ovsdb_jsonrpc_monitor_flush_all(struct ovsdb_jsonrpc_session *s)
1350 {
1351     struct ovsdb_jsonrpc_monitor *m;
1352
1353     HMAP_FOR_EACH (m, node, &s->monitors) {
1354         struct json *json;
1355
1356         json = ovsdb_jsonrpc_monitor_compose_update(m, false);
1357         if (json) {
1358             struct jsonrpc_msg *msg;
1359             struct json *params;
1360
1361             params = json_array_create_2(json_clone(m->monitor_id), json);
1362             msg = ovsdb_jsonrpc_create_notify(m, params);
1363             jsonrpc_session_send(s->js, msg);
1364         }
1365     }
1366 }
1367
1368 void
1369 ovsdb_jsonrpc_disable_monitor2(void)
1370 {
1371     /* Once disabled, it is not possible to re-enable it. */
1372     monitor2_enable__ = false;
1373 }