ovsdb/jsonrpc-server.c

   1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013 Nicira, Inc.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15
  16 #include <config.h>
  17
  18 #include "jsonrpc-server.h"
  19
  20 #include <assert.h>
  21 #include <errno.h>
  22
  23 #include "bitmap.h"
  24 #include "column.h"
  25 #include "dynamic-string.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 "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 "vlog.h"
  41
  42 VLOG_DEFINE_THIS_MODULE(ovsdb_jsonrpc_server);
  43
  44 struct ovsdb_jsonrpc_remote;
  45 struct ovsdb_jsonrpc_session;
  46
  47 /* Message rate-limiting. */
  48 static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
  49
  50 /* Sessions. */
  51 static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
  52     struct ovsdb_jsonrpc_remote *, struct jsonrpc_session *);
  53 static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
  54 static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
  55 static void ovsdb_jsonrpc_session_get_memory_usage_all(
  56     const struct ovsdb_jsonrpc_remote *, struct simap *usage);
  57 static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
  58 static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
  59 static void ovsdb_jsonrpc_session_set_all_options(
  60     struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
  61 static bool ovsdb_jsonrpc_session_get_status(
  62     const struct ovsdb_jsonrpc_remote *,
  63     struct ovsdb_jsonrpc_remote_status *);
  64 static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
  65 static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
  66
  67 /* Triggers. */
  68 static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
  69                                          struct ovsdb *,
  70                                          struct json *id, struct json *params);
  71 static struct ovsdb_jsonrpc_trigger *ovsdb_jsonrpc_trigger_find(
  72     struct ovsdb_jsonrpc_session *, const struct json *id, size_t hash);
  73 static void ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *);
  74 static void ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *);
  75 static void ovsdb_jsonrpc_trigger_complete_done(
  76     struct ovsdb_jsonrpc_session *);
  77
  78 /* Monitors. */
  79 static struct json *ovsdb_jsonrpc_monitor_create(
  80     struct ovsdb_jsonrpc_session *, struct ovsdb *, struct json *params);
  81 static struct jsonrpc_msg *ovsdb_jsonrpc_monitor_cancel(
  82     struct ovsdb_jsonrpc_session *,
  83     struct json_array *params,
  84     const struct json *request_id);
  85 static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
  86 \f
  87 /* JSON-RPC database server. */
  88
  89 struct ovsdb_jsonrpc_server {
  90     struct ovsdb_server up;
  91     unsigned int n_sessions, max_sessions;
  92     struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
  93 };
  94
  95 /* A configured remote.  This is either a passive stream listener plus a list
  96  * of the currently connected sessions, or a list of exactly one active
  97  * session. */
  98 struct ovsdb_jsonrpc_remote {
  99     struct ovsdb_jsonrpc_server *server;
 100     struct pstream *listener;   /* Listener, if passive. */
 101     struct list sessions;       /* List of "struct ovsdb_jsonrpc_session"s. */
 102     uint8_t dscp;
 103 };
 104
 105 static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
 106     struct ovsdb_jsonrpc_server *, const char *name,
 107     const struct ovsdb_jsonrpc_options *options
 108 );
 109 static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 110
 111 /* Creates and returns a new server to provide JSON-RPC access to an OVSDB.
 112  *
 113  * The caller must call ovsdb_jsonrpc_server_add_db() for each database to
 114  * which 'server' should provide access. */
 115 struct ovsdb_jsonrpc_server *
 116 ovsdb_jsonrpc_server_create(void)
 117 {
 118     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
 119     ovsdb_server_init(&server->up);
 120     server->max_sessions = 64;
 121     shash_init(&server->remotes);
 122     return server;
 123 }
 124
 125 /* Adds 'db' to the set of databases served out by 'svr'.  Returns true if
 126  * successful, false if 'db''s name is the same as some database already in
 127  * 'server'. */
 128 bool
 129 ovsdb_jsonrpc_server_add_db(struct ovsdb_jsonrpc_server *svr, struct ovsdb *db)
 130 {
 131     return ovsdb_server_add_db(&svr->up, db);
 132 }
 133
 134 void
 135 ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
 136 {
 137     struct shash_node *node, *next;
 138
 139     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 140         ovsdb_jsonrpc_server_del_remote(node);
 141     }
 142     shash_destroy(&svr->remotes);
 143     ovsdb_server_destroy(&svr->up);
 144     free(svr);
 145 }
 146
 147 struct ovsdb_jsonrpc_options *
 148 ovsdb_jsonrpc_default_options(const char *target)
 149 {
 150     struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
 151     options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
 152     options->probe_interval = (stream_or_pstream_needs_probes(target)
 153                                ? RECONNECT_DEFAULT_PROBE_INTERVAL
 154                                : 0);
 155     return options;
 156 }
 157
 158 /* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
 159  * options in the struct ovsdb_jsonrpc_options supplied as the data values.
 160  *
 161  * A remote is an active or passive stream connection method, e.g. "pssl:" or
 162  * "tcp:1.2.3.4". */
 163 void
 164 ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 165                                  const struct shash *new_remotes)
 166 {
 167     struct shash_node *node, *next;
 168
 169     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 170         if (!shash_find(new_remotes, node->name)) {
 171             VLOG_INFO("%s: remote deconfigured", node->name);
 172             ovsdb_jsonrpc_server_del_remote(node);
 173         }
 174     }
 175     SHASH_FOR_EACH (node, new_remotes) {
 176         const struct ovsdb_jsonrpc_options *options = node->data;
 177         struct ovsdb_jsonrpc_remote *remote;
 178
 179         remote = shash_find_data(&svr->remotes, node->name);
 180         if (!remote) {
 181             remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
 182             if (!remote) {
 183                 continue;
 184             }
 185         }
 186
 187         ovsdb_jsonrpc_session_set_all_options(remote, options);
 188     }
 189 }
 190
 191 static struct ovsdb_jsonrpc_remote *
 192 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
 193                                 const char *name,
 194                                 const struct ovsdb_jsonrpc_options *options)
 195 {
 196     struct ovsdb_jsonrpc_remote *remote;
 197     struct pstream *listener;
 198     int error;
 199
 200     error = jsonrpc_pstream_open(name, &listener, options->dscp);
 201     if (error && error != EAFNOSUPPORT) {
 202         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, strerror(error));
 203         return NULL;
 204     }
 205
 206     remote = xmalloc(sizeof *remote);
 207     remote->server = svr;
 208     remote->listener = listener;
 209     list_init(&remote->sessions);
 210     remote->dscp = options->dscp;
 211     shash_add(&svr->remotes, name, remote);
 212
 213     if (!listener) {
 214         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name));
 215     }
 216     return remote;
 217 }
 218
 219 static void
 220 ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
 221 {
 222     struct ovsdb_jsonrpc_remote *remote = node->data;
 223
 224     ovsdb_jsonrpc_session_close_all(remote);
 225     pstream_close(remote->listener);
 226     shash_delete(&remote->server->remotes, node);
 227     free(remote);
 228 }
 229
 230 /* Stores status information for the remote named 'target', which should have
 231  * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
 232  * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
 233  * a remote named 'target' or if that remote is an inbound remote that has no
 234  * active connections) returns false.  On failure, 'status' will be zeroed.
 235  */
 236 bool
 237 ovsdb_jsonrpc_server_get_remote_status(
 238     const struct ovsdb_jsonrpc_server *svr, const char *target,
 239     struct ovsdb_jsonrpc_remote_status *status)
 240 {
 241     const struct ovsdb_jsonrpc_remote *remote;
 242
 243     memset(status, 0, sizeof *status);
 244
 245     remote = shash_find_data(&svr->remotes, target);
 246     return remote && ovsdb_jsonrpc_session_get_status(remote, status);
 247 }
 248
 249 void
 250 ovsdb_jsonrpc_server_free_remote_status(
 251     struct ovsdb_jsonrpc_remote_status *status)
 252 {
 253     free(status->locks_held);
 254     free(status->locks_waiting);
 255     free(status->locks_lost);
 256 }
 257
 258 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
 259  * reconnect. */
 260 void
 261 ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
 262 {
 263     struct shash_node *node;
 264
 265     SHASH_FOR_EACH (node, &svr->remotes) {
 266         struct ovsdb_jsonrpc_remote *remote = node->data;
 267
 268         ovsdb_jsonrpc_session_reconnect_all(remote);
 269     }
 270 }
 271
 272 void
 273 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 274 {
 275     struct shash_node *node;
 276
 277     SHASH_FOR_EACH (node, &svr->remotes) {
 278         struct ovsdb_jsonrpc_remote *remote = node->data;
 279
 280         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 281             struct stream *stream;
 282             int error;
 283
 284             error = pstream_accept(remote->listener, &stream);
 285             if (!error) {
 286                 struct jsonrpc_session *js;
 287                 js = jsonrpc_session_open_unreliably(jsonrpc_open(stream),
 288                                                      remote->dscp);
 289                 ovsdb_jsonrpc_session_create(remote, js);
 290             } else if (error != EAGAIN) {
 291                 VLOG_WARN_RL(&rl, "%s: accept failed: %s",
 292                              pstream_get_name(remote->listener),
 293                              strerror(error));
 294             }
 295         }
 296
 297         ovsdb_jsonrpc_session_run_all(remote);
 298     }
 299 }
 300
 301 void
 302 ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 303 {
 304     struct shash_node *node;
 305
 306     SHASH_FOR_EACH (node, &svr->remotes) {
 307         struct ovsdb_jsonrpc_remote *remote = node->data;
 308
 309         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 310             pstream_wait(remote->listener);
 311         }
 312
 313         ovsdb_jsonrpc_session_wait_all(remote);
 314     }
 315 }
 316
 317 /* Adds some memory usage statistics for 'svr' into 'usage', for use with
 318  * memory_report(). */
 319 void
 320 ovsdb_jsonrpc_server_get_memory_usage(const struct ovsdb_jsonrpc_server *svr,
 321                                       struct simap *usage)
 322 {
 323     struct shash_node *node;
 324
 325     simap_increase(usage, "sessions", svr->n_sessions);
 326     SHASH_FOR_EACH (node, &svr->remotes) {
 327         struct ovsdb_jsonrpc_remote *remote = node->data;
 328
 329         ovsdb_jsonrpc_session_get_memory_usage_all(remote, usage);
 330     }
 331 }
 332 \f
 333 /* JSON-RPC database server session. */
 334
 335 struct ovsdb_jsonrpc_session {
 336     struct list node;           /* Element in remote's sessions list. */
 337     struct ovsdb_session up;
 338     struct ovsdb_jsonrpc_remote *remote;
 339
 340     /* Triggers. */
 341     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
 342
 343     /* Monitors. */
 344     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
 345
 346     /* Network connectivity. */
 347     struct jsonrpc_session *js;  /* JSON-RPC session. */
 348     unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
 349 };
 350
 351 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 352 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 353 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
 354 static void ovsdb_jsonrpc_session_get_memory_usage(
 355     const struct ovsdb_jsonrpc_session *, struct simap *usage);
 356 static void ovsdb_jsonrpc_session_set_options(
 357     struct ovsdb_jsonrpc_session *, const struct ovsdb_jsonrpc_options *);
 358 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
 359                                              struct jsonrpc_msg *);
 360 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
 361                                              struct jsonrpc_msg *);
 362
 363 static struct ovsdb_jsonrpc_session *
 364 ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
 365                              struct jsonrpc_session *js)
 366 {
 367     struct ovsdb_jsonrpc_session *s;
 368
 369     s = xzalloc(sizeof *s);
 370     ovsdb_session_init(&s->up, &remote->server->up);
 371     s->remote = remote;
 372     list_push_back(&remote->sessions, &s->node);
 373     hmap_init(&s->triggers);
 374     hmap_init(&s->monitors);
 375     s->js = js;
 376     s->js_seqno = jsonrpc_session_get_seqno(js);
 377
 378     remote->server->n_sessions++;
 379
 380     return s;
 381 }
 382
 383 static void
 384 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 385 {
 386     ovsdb_jsonrpc_monitor_remove_all(s);
 387     ovsdb_jsonrpc_session_unlock_all(s);
 388     ovsdb_jsonrpc_trigger_complete_all(s);
 389
 390     hmap_destroy(&s->monitors);
 391     hmap_destroy(&s->triggers);
 392
 393     jsonrpc_session_close(s->js);
 394     list_remove(&s->node);
 395     s->remote->server->n_sessions--;
 396     ovsdb_session_destroy(&s->up);
 397     free(s);
 398 }
 399
 400 static int
 401 ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
 402 {
 403     jsonrpc_session_run(s->js);
 404     if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
 405         s->js_seqno = jsonrpc_session_get_seqno(s->js);
 406         ovsdb_jsonrpc_trigger_complete_all(s);
 407         ovsdb_jsonrpc_monitor_remove_all(s);
 408         ovsdb_jsonrpc_session_unlock_all(s);
 409     }
 410
 411     ovsdb_jsonrpc_trigger_complete_done(s);
 412
 413     if (!jsonrpc_session_get_backlog(s->js)) {
 414         struct jsonrpc_msg *msg = jsonrpc_session_recv(s->js);
 415         if (msg) {
 416             if (msg->type == JSONRPC_REQUEST) {
 417                 ovsdb_jsonrpc_session_got_request(s, msg);
 418             } else if (msg->type == JSONRPC_NOTIFY) {
 419                 ovsdb_jsonrpc_session_got_notify(s, msg);
 420             } else {
 421                 VLOG_WARN("%s: received unexpected %s message",
 422                           jsonrpc_session_get_name(s->js),
 423                           jsonrpc_msg_type_to_string(msg->type));
 424                 jsonrpc_session_force_reconnect(s->js);
 425                 jsonrpc_msg_destroy(msg);
 426             }
 427         }
 428     }
 429     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 430 }
 431
 432 static void
 433 ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
 434                                   const struct ovsdb_jsonrpc_options *options)
 435 {
 436     jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
 437     jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
 438     jsonrpc_session_set_dscp(session->js, options->dscp);
 439 }
 440
 441 static void
 442 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 443 {
 444     struct ovsdb_jsonrpc_session *s, *next;
 445
 446     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 447         int error = ovsdb_jsonrpc_session_run(s);
 448         if (error) {
 449             ovsdb_jsonrpc_session_close(s);
 450         }
 451     }
 452 }
 453
 454 static void
 455 ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
 456 {
 457     jsonrpc_session_wait(s->js);
 458     if (!jsonrpc_session_get_backlog(s->js)) {
 459         jsonrpc_session_recv_wait(s->js);
 460     }
 461 }
 462
 463 static void
 464 ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 465 {
 466     struct ovsdb_jsonrpc_session *s;
 467
 468     LIST_FOR_EACH (s, node, &remote->sessions) {
 469         ovsdb_jsonrpc_session_wait(s);
 470     }
 471 }
 472
 473 static void
 474 ovsdb_jsonrpc_session_get_memory_usage(const struct ovsdb_jsonrpc_session *s,
 475                                        struct simap *usage)
 476 {
 477     simap_increase(usage, "triggers", hmap_count(&s->triggers));
 478     simap_increase(usage, "monitors", hmap_count(&s->monitors));
 479     simap_increase(usage, "backlog", jsonrpc_session_get_backlog(s->js));
 480 }
 481
 482 static void
 483 ovsdb_jsonrpc_session_get_memory_usage_all(
 484     const struct ovsdb_jsonrpc_remote *remote,
 485     struct simap *usage)
 486 {
 487     struct ovsdb_jsonrpc_session *s;
 488
 489     LIST_FOR_EACH (s, node, &remote->sessions) {
 490         ovsdb_jsonrpc_session_get_memory_usage(s, usage);
 491     }
 492 }
 493
 494 static void
 495 ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 496 {
 497     struct ovsdb_jsonrpc_session *s, *next;
 498
 499     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 500         ovsdb_jsonrpc_session_close(s);
 501     }
 502 }
 503
 504 /* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
 505  * reconnect. */
 506 static void
 507 ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 508 {
 509     struct ovsdb_jsonrpc_session *s, *next;
 510
 511     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 512         jsonrpc_session_force_reconnect(s->js);
 513         if (!jsonrpc_session_is_alive(s->js)) {
 514             ovsdb_jsonrpc_session_close(s);
 515         }
 516     }
 517 }
 518
 519 /* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
 520  * 'options'. */
 521 static void
 522 ovsdb_jsonrpc_session_set_all_options(
 523     struct ovsdb_jsonrpc_remote *remote,
 524     const struct ovsdb_jsonrpc_options *options)
 525 {
 526     struct ovsdb_jsonrpc_session *s;
 527
 528     if (remote->listener) {
 529         int error;
 530
 531         error = pstream_set_dscp(remote->listener, options->dscp);
 532         if (error) {
 533             VLOG_ERR("%s: set_dscp failed %s",
 534                      pstream_get_name(remote->listener), strerror(error));
 535         } else {
 536             remote->dscp = options->dscp;
 537         }
 538         /*
 539          * TODO:XXX race window between setting dscp to listening socket
 540          * and accepting socket. Accepted socket may have old dscp value.
 541          * Ignore this race window for now.
 542          */
 543     }
 544     LIST_FOR_EACH (s, node, &remote->sessions) {
 545         ovsdb_jsonrpc_session_set_options(s, options);
 546     }
 547 }
 548
 549 static bool
 550 ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
 551                                  struct ovsdb_jsonrpc_remote_status *status)
 552 {
 553     const struct ovsdb_jsonrpc_session *s;
 554     const struct jsonrpc_session *js;
 555     struct ovsdb_lock_waiter *waiter;
 556     struct reconnect_stats rstats;
 557     struct ds locks_held, locks_waiting, locks_lost;
 558
 559     if (list_is_empty(&remote->sessions)) {
 560         return false;
 561     }
 562     s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
 563     js = s->js;
 564
 565     status->is_connected = jsonrpc_session_is_connected(js);
 566     status->last_error = jsonrpc_session_get_status(js);
 567
 568     jsonrpc_session_get_reconnect_stats(js, &rstats);
 569     status->state = rstats.state;
 570     status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
 571         ? UINT_MAX : rstats.msec_since_connect / 1000;
 572     status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
 573         ? UINT_MAX : rstats.msec_since_disconnect / 1000;
 574
 575     ds_init(&locks_held);
 576     ds_init(&locks_waiting);
 577     ds_init(&locks_lost);
 578     HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
 579         struct ds *string;
 580
 581         string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
 582                   : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
 583                   : &locks_lost);
 584         if (string->length) {
 585             ds_put_char(string, ' ');
 586         }
 587         ds_put_cstr(string, waiter->lock_name);
 588     }
 589     status->locks_held = ds_steal_cstr(&locks_held);
 590     status->locks_waiting = ds_steal_cstr(&locks_waiting);
 591     status->locks_lost = ds_steal_cstr(&locks_lost);
 592
 593     status->n_connections = list_size(&remote->sessions);
 594
 595     return true;
 596 }
 597
 598 /* Examines 'request' to determine the database to which it relates, and then
 599  * searches 's' to find that database:
 600  *
 601  *    - If successful, returns the database and sets '*replyp' to NULL.
 602  *
 603  *    - If no such database exists, returns NULL and sets '*replyp' to an
 604  *      appropriate JSON-RPC error reply, owned by the caller. */
 605 static struct ovsdb *
 606 ovsdb_jsonrpc_lookup_db(const struct ovsdb_jsonrpc_session *s,
 607                         const struct jsonrpc_msg *request,
 608                         struct jsonrpc_msg **replyp)
 609 {
 610     struct json_array *params;
 611     struct ovsdb_error *error;
 612     const char *db_name;
 613     struct ovsdb *db;
 614
 615     params = json_array(request->params);
 616     if (!params->n || params->elems[0]->type != JSON_STRING) {
 617         error = ovsdb_syntax_error(
 618             request->params, NULL,
 619             "%s request params must begin with <db-name>", request->method);
 620         goto error;
 621     }
 622
 623     db_name = params->elems[0]->u.string;
 624     db = shash_find_data(&s->up.server->dbs, db_name);
 625     if (!db) {
 626         error = ovsdb_syntax_error(
 627             request->params, "unknown database",
 628             "%s request specifies unknown database %s",
 629             request->method, db_name);
 630         goto error;
 631     }
 632
 633     *replyp = NULL;
 634     return db;
 635
 636 error:
 637     *replyp = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 638     ovsdb_error_destroy(error);
 639     return NULL;
 640 }
 641
 642 static struct ovsdb_error *
 643 ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
 644                                       const char **lock_namep)
 645 {
 646     const struct json_array *params;
 647
 648     params = json_array(request->params);
 649     if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
 650         !ovsdb_parser_is_id(json_string(params->elems[0]))) {
 651         *lock_namep = NULL;
 652         return ovsdb_syntax_error(request->params, NULL,
 653                                   "%s request params must be <id>",
 654                                   request->method);
 655     }
 656
 657     *lock_namep = json_string(params->elems[0]);
 658     return NULL;
 659 }
 660
 661 static void
 662 ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
 663                              const char *lock_name,
 664                              const char *method)
 665 {
 666     struct ovsdb_jsonrpc_session *s;
 667     struct json *params;
 668
 669     s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
 670     params = json_array_create_1(json_string_create(lock_name));
 671     jsonrpc_session_send(s->js, jsonrpc_create_notify(method, params));
 672 }
 673
 674 static struct jsonrpc_msg *
 675 ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
 676                            struct jsonrpc_msg *request,
 677                            enum ovsdb_lock_mode mode)
 678 {
 679     struct ovsdb_lock_waiter *waiter;
 680     struct jsonrpc_msg *reply;
 681     struct ovsdb_error *error;
 682     struct ovsdb_session *victim;
 683     const char *lock_name;
 684     struct json *result;
 685
 686     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 687     if (error) {
 688         goto error;
 689     }
 690
 691     /* Report error if this session has issued a "lock" or "steal" without a
 692      * matching "unlock" for this lock. */
 693     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 694     if (waiter) {
 695         error = ovsdb_syntax_error(
 696             request->params, NULL,
 697             "must issue \"unlock\" before new \"%s\"", request->method);
 698         goto error;
 699     }
 700
 701     /* Get the lock, add us as a waiter. */
 702     waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
 703                                &victim);
 704     if (victim) {
 705         ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
 706     }
 707
 708     result = json_object_create();
 709     json_object_put(result, "locked",
 710                     json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
 711
 712     return jsonrpc_create_reply(result, request->id);
 713
 714 error:
 715     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 716     ovsdb_error_destroy(error);
 717     return reply;
 718 }
 719
 720 static void
 721 ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
 722 {
 723     struct ovsdb_lock_waiter *waiter, *next;
 724
 725     HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
 726         ovsdb_jsonrpc_session_unlock__(waiter);
 727     }
 728 }
 729
 730 static void
 731 ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
 732 {
 733     struct ovsdb_lock *lock = waiter->lock;
 734
 735     if (lock) {
 736         struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
 737         if (new_owner) {
 738             ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
 739         } else {
 740             /* ovsdb_server_lock() might have freed 'lock'. */
 741         }
 742     }
 743
 744     ovsdb_lock_waiter_destroy(waiter);
 745 }
 746
 747 static struct jsonrpc_msg *
 748 ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
 749                              struct jsonrpc_msg *request)
 750 {
 751     struct ovsdb_lock_waiter *waiter;
 752     struct jsonrpc_msg *reply;
 753     struct ovsdb_error *error;
 754     const char *lock_name;
 755
 756     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 757     if (error) {
 758         goto error;
 759     }
 760
 761     /* Report error if this session has not issued a "lock" or "steal" for this
 762      * lock. */
 763     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 764     if (!waiter) {
 765         error = ovsdb_syntax_error(
 766             request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
 767         goto error;
 768     }
 769
 770     ovsdb_jsonrpc_session_unlock__(waiter);
 771
 772     return jsonrpc_create_reply(json_object_create(), request->id);
 773
 774 error:
 775     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 776     ovsdb_error_destroy(error);
 777     return reply;
 778 }
 779
 780 static struct jsonrpc_msg *
 781 execute_transaction(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 782                     struct jsonrpc_msg *request)
 783 {
 784     ovsdb_jsonrpc_trigger_create(s, db, request->id, request->params);
 785     request->id = NULL;
 786     request->params = NULL;
 787     jsonrpc_msg_destroy(request);
 788     return NULL;
 789 }
 790
 791 static void
 792 ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
 793                                   struct jsonrpc_msg *request)
 794 {
 795     struct jsonrpc_msg *reply;
 796
 797     if (!strcmp(request->method, "transact")) {
 798         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 799         if (!reply) {
 800             reply = execute_transaction(s, db, request);
 801         }
 802     } else if (!strcmp(request->method, "monitor")) {
 803         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 804         if (!reply) {
 805             reply = jsonrpc_create_reply(
 806                 ovsdb_jsonrpc_monitor_create(s, db, request->params),
 807                 request->id);
 808         }
 809     } else if (!strcmp(request->method, "monitor_cancel")) {
 810         reply = ovsdb_jsonrpc_monitor_cancel(s, json_array(request->params),
 811                                              request->id);
 812     } else if (!strcmp(request->method, "get_schema")) {
 813         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 814         if (!reply) {
 815             reply = jsonrpc_create_reply(ovsdb_schema_to_json(db->schema),
 816                                          request->id);
 817         }
 818     } else if (!strcmp(request->method, "list_dbs")) {
 819         size_t n_dbs = shash_count(&s->up.server->dbs);
 820         struct shash_node *node;
 821         struct json **dbs;
 822         size_t i;
 823
 824         dbs = xmalloc(n_dbs * sizeof *dbs);
 825         i = 0;
 826         SHASH_FOR_EACH (node, &s->up.server->dbs) {
 827             dbs[i++] = json_string_create(node->name);
 828         }
 829         reply = jsonrpc_create_reply(json_array_create(dbs, n_dbs),
 830                                      request->id);
 831     } else if (!strcmp(request->method, "lock")) {
 832         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
 833     } else if (!strcmp(request->method, "steal")) {
 834         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
 835     } else if (!strcmp(request->method, "unlock")) {
 836         reply = ovsdb_jsonrpc_session_unlock(s, request);
 837     } else if (!strcmp(request->method, "echo")) {
 838         reply = jsonrpc_create_reply(json_clone(request->params), request->id);
 839     } else {
 840         reply = jsonrpc_create_error(json_string_create("unknown method"),
 841                                      request->id);
 842     }
 843
 844     if (reply) {
 845         jsonrpc_msg_destroy(request);
 846         jsonrpc_session_send(s->js, reply);
 847     }
 848 }
 849
 850 static void
 851 execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
 852 {
 853     if (json_array(request->params)->n == 1) {
 854         struct ovsdb_jsonrpc_trigger *t;
 855         struct json *id;
 856
 857         id = request->params->u.array.elems[0];
 858         t = ovsdb_jsonrpc_trigger_find(s, id, json_hash(id, 0));
 859         if (t) {
 860             ovsdb_jsonrpc_trigger_complete(t);
 861         }
 862     }
 863 }
 864
 865 static void
 866 ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
 867                                  struct jsonrpc_msg *request)
 868 {
 869     if (!strcmp(request->method, "cancel")) {
 870         execute_cancel(s, request);
 871     }
 872     jsonrpc_msg_destroy(request);
 873 }
 874 \f
 875 /* JSON-RPC database server triggers.
 876  *
 877  * (Every transaction is treated as a trigger even if it doesn't actually have
 878  * any "wait" operations.) */
 879
 880 struct ovsdb_jsonrpc_trigger {
 881     struct ovsdb_trigger trigger;
 882     struct hmap_node hmap_node; /* In session's "triggers" hmap. */
 883     struct json *id;
 884 };
 885
 886 static void
 887 ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 888                              struct json *id, struct json *params)
 889 {
 890     struct ovsdb_jsonrpc_trigger *t;
 891     size_t hash;
 892
 893     /* Check for duplicate ID. */
 894     hash = json_hash(id, 0);
 895     t = ovsdb_jsonrpc_trigger_find(s, id, hash);
 896     if (t) {
 897         struct jsonrpc_msg *msg;
 898
 899         msg = jsonrpc_create_error(json_string_create("duplicate request ID"),
 900                                    id);
 901         jsonrpc_session_send(s->js, msg);
 902         json_destroy(id);
 903         json_destroy(params);
 904         return;
 905     }
 906
 907     /* Insert into trigger table. */
 908     t = xmalloc(sizeof *t);
 909     ovsdb_trigger_init(&s->up, db, &t->trigger, params, time_msec());
 910     t->id = id;
 911     hmap_insert(&s->triggers, &t->hmap_node, hash);
 912
 913     /* Complete early if possible. */
 914     if (ovsdb_trigger_is_complete(&t->trigger)) {
 915         ovsdb_jsonrpc_trigger_complete(t);
 916     }
 917 }
 918
 919 static struct ovsdb_jsonrpc_trigger *
 920 ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 921                            const struct json *id, size_t hash)
 922 {
 923     struct ovsdb_jsonrpc_trigger *t;
 924
 925     HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
 926         if (json_equal(t->id, id)) {
 927             return t;
 928         }
 929     }
 930
 931     return NULL;
 932 }
 933
 934 static void
 935 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 936 {
 937     struct ovsdb_jsonrpc_session *s;
 938
 939     s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
 940
 941     if (jsonrpc_session_is_connected(s->js)) {
 942         struct jsonrpc_msg *reply;
 943         struct json *result;
 944
 945         result = ovsdb_trigger_steal_result(&t->trigger);
 946         if (result) {
 947             reply = jsonrpc_create_reply(result, t->id);
 948         } else {
 949             reply = jsonrpc_create_error(json_string_create("canceled"),
 950                                          t->id);
 951         }
 952         jsonrpc_session_send(s->js, reply);
 953     }
 954
 955     json_destroy(t->id);
 956     ovsdb_trigger_destroy(&t->trigger);
 957     hmap_remove(&s->triggers, &t->hmap_node);
 958     free(t);
 959 }
 960
 961 static void
 962 ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 963 {
 964     struct ovsdb_jsonrpc_trigger *t, *next;
 965     HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
 966         ovsdb_jsonrpc_trigger_complete(t);
 967     }
 968 }
 969
 970 static void
 971 ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
 972 {
 973     while (!list_is_empty(&s->up.completions)) {
 974         struct ovsdb_jsonrpc_trigger *t
 975             = CONTAINER_OF(s->up.completions.next,
 976                            struct ovsdb_jsonrpc_trigger, trigger.node);
 977         ovsdb_jsonrpc_trigger_complete(t);
 978     }
 979 }
 980 \f
 981 /* JSON-RPC database table monitors. */
 982
 983 enum ovsdb_jsonrpc_monitor_selection {
 984     OJMS_INITIAL = 1 << 0,      /* All rows when monitor is created. */
 985     OJMS_INSERT = 1 << 1,       /* New rows. */
 986     OJMS_DELETE = 1 << 2,       /* Deleted rows. */
 987     OJMS_MODIFY = 1 << 3        /* Modified rows. */
 988 };
 989
 990 /* A particular column being monitored. */
 991 struct ovsdb_jsonrpc_monitor_column {
 992     const struct ovsdb_column *column;
 993     enum ovsdb_jsonrpc_monitor_selection select;
 994 };
 995
 996 /* A particular table being monitored. */
 997 struct ovsdb_jsonrpc_monitor_table {
 998     const struct ovsdb_table *table;
 999
1000     /* This is the union (bitwise-OR) of the 'select' values in all of the
1001      * members of 'columns' below. */
1002     enum ovsdb_jsonrpc_monitor_selection select;
1003
1004     /* Columns being monitored. */
1005     struct ovsdb_jsonrpc_monitor_column *columns;
1006     size_t n_columns;
1007 };
1008
1009 /* A collection of tables being monitored. */
1010 struct ovsdb_jsonrpc_monitor {
1011     struct ovsdb_replica replica;
1012     struct ovsdb_jsonrpc_session *session;
1013     struct ovsdb *db;
1014     struct hmap_node node;      /* In ovsdb_jsonrpc_session's "monitors". */
1015
1016     struct json *monitor_id;
1017     struct shash tables;     /* Holds "struct ovsdb_jsonrpc_monitor_table"s. */
1018 };
1019
1020 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class;
1021
1022 struct ovsdb_jsonrpc_monitor *ovsdb_jsonrpc_monitor_find(
1023     struct ovsdb_jsonrpc_session *, const struct json *monitor_id);
1024 static void ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *);
1025 static struct json *ovsdb_jsonrpc_monitor_get_initial(
1026     const struct ovsdb_jsonrpc_monitor *);
1027
1028 static bool
1029 parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
1030 {
1031     const struct json *json;
1032
1033     json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
1034     return json ? json_boolean(json) : default_value;
1035 }
1036
1037 struct ovsdb_jsonrpc_monitor *
1038 ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
1039                            const struct json *monitor_id)
1040 {
1041     struct ovsdb_jsonrpc_monitor *m;
1042
1043     HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
1044         if (json_equal(m->monitor_id, monitor_id)) {
1045             return m;
1046         }
1047     }
1048
1049     return NULL;
1050 }
1051
1052 static void
1053 ovsdb_jsonrpc_add_monitor_column(struct ovsdb_jsonrpc_monitor_table *mt,
1054                                  const struct ovsdb_column *column,
1055                                  enum ovsdb_jsonrpc_monitor_selection select,
1056                                  size_t *allocated_columns)
1057 {
1058     struct ovsdb_jsonrpc_monitor_column *c;
1059
1060     if (mt->n_columns >= *allocated_columns) {
1061         mt->columns = x2nrealloc(mt->columns, allocated_columns,
1062                                  sizeof *mt->columns);
1063     }
1064
1065     c = &mt->columns[mt->n_columns++];
1066     c->column = column;
1067     c->select = select;
1068 }
1069
1070 static int
1071 compare_ovsdb_jsonrpc_monitor_column(const void *a_, const void *b_)
1072 {
1073     const struct ovsdb_jsonrpc_monitor_column *a = a_;
1074     const struct ovsdb_jsonrpc_monitor_column *b = b_;
1075
1076     return a->column < b->column ? -1 : a->column > b->column;
1077 }
1078
1079 static struct ovsdb_error * WARN_UNUSED_RESULT
1080 ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_jsonrpc_monitor_table *mt,
1081                                     const struct json *monitor_request,
1082                                     size_t *allocated_columns)
1083 {
1084     const struct ovsdb_table_schema *ts = mt->table->schema;
1085     enum ovsdb_jsonrpc_monitor_selection select;
1086     const struct json *columns, *select_json;
1087     struct ovsdb_parser parser;
1088     struct ovsdb_error *error;
1089
1090     ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
1091     columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
1092     select_json = ovsdb_parser_member(&parser, "select",
1093                                       OP_OBJECT | OP_OPTIONAL);
1094     error = ovsdb_parser_finish(&parser);
1095     if (error) {
1096         return error;
1097     }
1098
1099     if (select_json) {
1100         select = 0;
1101         ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
1102         if (parse_bool(&parser, "initial", true)) {
1103             select |= OJMS_INITIAL;
1104         }
1105         if (parse_bool(&parser, "insert", true)) {
1106             select |= OJMS_INSERT;
1107         }
1108         if (parse_bool(&parser, "delete", true)) {
1109             select |= OJMS_DELETE;
1110         }
1111         if (parse_bool(&parser, "modify", true)) {
1112             select |= OJMS_MODIFY;
1113         }
1114         error = ovsdb_parser_finish(&parser);
1115         if (error) {
1116             return error;
1117         }
1118     } else {
1119         select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
1120     }
1121     mt->select |= select;
1122
1123     if (columns) {
1124         size_t i;
1125
1126         if (columns->type != JSON_ARRAY) {
1127             return ovsdb_syntax_error(columns, NULL,
1128                                       "array of column names expected");
1129         }
1130
1131         for (i = 0; i < columns->u.array.n; i++) {
1132             const struct ovsdb_column *column;
1133             const char *s;
1134
1135             if (columns->u.array.elems[i]->type != JSON_STRING) {
1136                 return ovsdb_syntax_error(columns, NULL,
1137                                           "array of column names expected");
1138             }
1139
1140             s = columns->u.array.elems[i]->u.string;
1141             column = shash_find_data(&mt->table->schema->columns, s);
1142             if (!column) {
1143                 return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
1144                                           "column name", s);
1145             }
1146             ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1147                                              allocated_columns);
1148         }
1149     } else {
1150         struct shash_node *node;
1151
1152         SHASH_FOR_EACH (node, &ts->columns) {
1153             const struct ovsdb_column *column = node->data;
1154             if (column->index != OVSDB_COL_UUID) {
1155                 ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1156                                                  allocated_columns);
1157             }
1158         }
1159     }
1160
1161     return NULL;
1162 }
1163
1164 static struct json *
1165 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
1166                              struct json *params)
1167 {
1168     struct ovsdb_jsonrpc_monitor *m = NULL;
1169     struct json *monitor_id, *monitor_requests;
1170     struct ovsdb_error *error = NULL;
1171     struct shash_node *node;
1172     struct json *json;
1173
1174     if (json_array(params)->n != 3) {
1175         error = ovsdb_syntax_error(params, NULL, "invalid parameters");
1176         goto error;
1177     }
1178     monitor_id = params->u.array.elems[1];
1179     monitor_requests = params->u.array.elems[2];
1180     if (monitor_requests->type != JSON_OBJECT) {
1181         error = ovsdb_syntax_error(monitor_requests, NULL,
1182                                    "monitor-requests must be object");
1183         goto error;
1184     }
1185
1186     if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
1187         error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
1188         goto error;
1189     }
1190
1191     m = xzalloc(sizeof *m);
1192     ovsdb_replica_init(&m->replica, &ovsdb_jsonrpc_replica_class);
1193     ovsdb_add_replica(db, &m->replica);
1194     m->session = s;
1195     m->db = db;
1196     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
1197     m->monitor_id = json_clone(monitor_id);
1198     shash_init(&m->tables);
1199
1200     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
1201         const struct ovsdb_table *table;
1202         struct ovsdb_jsonrpc_monitor_table *mt;
1203         size_t allocated_columns;
1204         const struct json *mr_value;
1205         size_t i;
1206
1207         table = ovsdb_get_table(m->db, node->name);
1208         if (!table) {
1209             error = ovsdb_syntax_error(NULL, NULL,
1210                                        "no table named %s", node->name);
1211             goto error;
1212         }
1213
1214         mt = xzalloc(sizeof *mt);
1215         mt->table = table;
1216         shash_add(&m->tables, table->schema->name, mt);
1217
1218         /* Parse columns. */
1219         mr_value = node->data;
1220         allocated_columns = 0;
1221         if (mr_value->type == JSON_ARRAY) {
1222             const struct json_array *array = &mr_value->u.array;
1223
1224             for (i = 0; i < array->n; i++) {
1225                 error = ovsdb_jsonrpc_parse_monitor_request(
1226                     mt, array->elems[i], &allocated_columns);
1227                 if (error) {
1228                     goto error;
1229                 }
1230             }
1231         } else {
1232             error = ovsdb_jsonrpc_parse_monitor_request(
1233                 mt, mr_value, &allocated_columns);
1234             if (error) {
1235                 goto error;
1236             }
1237         }
1238
1239         /* Check for duplicate columns. */
1240         qsort(mt->columns, mt->n_columns, sizeof *mt->columns,
1241               compare_ovsdb_jsonrpc_monitor_column);
1242         for (i = 1; i < mt->n_columns; i++) {
1243             if (mt->columns[i].column == mt->columns[i - 1].column) {
1244                 error = ovsdb_syntax_error(mr_value, NULL, "column %s "
1245                                            "mentioned more than once",
1246                                            mt->columns[i].column->name);
1247                 goto error;
1248             }
1249         }
1250     }
1251
1252     return ovsdb_jsonrpc_monitor_get_initial(m);
1253
1254 error:
1255     if (m) {
1256         ovsdb_remove_replica(m->db, &m->replica);
1257     }
1258
1259     json = ovsdb_error_to_json(error);
1260     ovsdb_error_destroy(error);
1261     return json;
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_remove_replica(m->db, &m->replica);
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_remove_replica(m->db, &m->replica);
1293     }
1294 }
1295
1296 static struct ovsdb_jsonrpc_monitor *
1297 ovsdb_jsonrpc_monitor_cast(struct ovsdb_replica *replica)
1298 {
1299     assert(replica->class == &ovsdb_jsonrpc_replica_class);
1300     return CONTAINER_OF(replica, struct ovsdb_jsonrpc_monitor, replica);
1301 }
1302
1303 struct ovsdb_jsonrpc_monitor_aux {
1304     bool initial;               /* Sending initial contents of table? */
1305     const struct ovsdb_jsonrpc_monitor *monitor;
1306     struct json *json;          /* JSON for the whole transaction. */
1307
1308     /* Current table.  */
1309     struct ovsdb_jsonrpc_monitor_table *mt;
1310     struct json *table_json;    /* JSON for table's transaction. */
1311 };
1312
1313 static bool
1314 any_reportable_change(const struct ovsdb_jsonrpc_monitor_table *mt,
1315                       const unsigned long int *changed)
1316 {
1317     size_t i;
1318
1319     for (i = 0; i < mt->n_columns; i++) {
1320         const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
1321         unsigned int idx = c->column->index;
1322
1323         if (c->select & OJMS_MODIFY && bitmap_is_set(changed, idx)) {
1324             return true;
1325         }
1326     }
1327
1328     return false;
1329 }
1330
1331 static bool
1332 ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
1333                                 const struct ovsdb_row *new,
1334                                 const unsigned long int *changed,
1335                                 void *aux_)
1336 {
1337     struct ovsdb_jsonrpc_monitor_aux *aux = aux_;
1338     const struct ovsdb_jsonrpc_monitor *m = aux->monitor;
1339     struct ovsdb_table *table = new ? new->table : old->table;
1340     enum ovsdb_jsonrpc_monitor_selection type;
1341     struct json *old_json, *new_json;
1342     struct json *row_json;
1343     char uuid[UUID_LEN + 1];
1344     size_t i;
1345
1346     if (!aux->mt || table != aux->mt->table) {
1347         aux->mt = shash_find_data(&m->tables, table->schema->name);
1348         aux->table_json = NULL;
1349         if (!aux->mt) {
1350             /* We don't care about rows in this table at all.  Tell the caller
1351              * to skip it.  */
1352             return false;
1353         }
1354     }
1355
1356     type = (aux->initial ? OJMS_INITIAL
1357             : !old ? OJMS_INSERT
1358             : !new ? OJMS_DELETE
1359             : OJMS_MODIFY);
1360     if (!(aux->mt->select & type)) {
1361         /* We don't care about this type of change (but do want to be called
1362          * back for changes to other rows in the same table). */
1363         return true;
1364     }
1365
1366     if (type == OJMS_MODIFY && !any_reportable_change(aux->mt, changed)) {
1367         /* Nothing of interest changed. */
1368         return true;
1369     }
1370
1371     old_json = new_json = NULL;
1372     if (type & (OJMS_DELETE | OJMS_MODIFY)) {
1373         old_json = json_object_create();
1374     }
1375     if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1376         new_json = json_object_create();
1377     }
1378     for (i = 0; i < aux->mt->n_columns; i++) {
1379         const struct ovsdb_jsonrpc_monitor_column *c = &aux->mt->columns[i];
1380         const struct ovsdb_column *column = c->column;
1381         unsigned int idx = c->column->index;
1382
1383         if (!(type & c->select)) {
1384             /* We don't care about this type of change for this particular
1385              * column (but we will care about it for some other column). */
1386             continue;
1387         }
1388
1389         if ((type == OJMS_MODIFY && bitmap_is_set(changed, idx))
1390             || type == OJMS_DELETE) {
1391             json_object_put(old_json, column->name,
1392                             ovsdb_datum_to_json(&old->fields[idx],
1393                                                 &column->type));
1394         }
1395         if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1396             json_object_put(new_json, column->name,
1397                             ovsdb_datum_to_json(&new->fields[idx],
1398                                                 &column->type));
1399         }
1400     }
1401
1402     /* Create JSON object for transaction overall. */
1403     if (!aux->json) {
1404         aux->json = json_object_create();
1405     }
1406
1407     /* Create JSON object for transaction on this table. */
1408     if (!aux->table_json) {
1409         aux->table_json = json_object_create();
1410         json_object_put(aux->json, aux->mt->table->schema->name,
1411                         aux->table_json);
1412     }
1413
1414     /* Create JSON object for transaction on this row. */
1415     row_json = json_object_create();
1416     if (old_json) {
1417         json_object_put(row_json, "old", old_json);
1418     }
1419     if (new_json) {
1420         json_object_put(row_json, "new", new_json);
1421     }
1422
1423     /* Add JSON row to JSON table. */
1424     snprintf(uuid, sizeof uuid,
1425              UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
1426     json_object_put(aux->table_json, uuid, row_json);
1427
1428     return true;
1429 }
1430
1431 static void
1432 ovsdb_jsonrpc_monitor_init_aux(struct ovsdb_jsonrpc_monitor_aux *aux,
1433                                const struct ovsdb_jsonrpc_monitor *m,
1434                                bool initial)
1435 {
1436     aux->initial = initial;
1437     aux->monitor = m;
1438     aux->json = NULL;
1439     aux->mt = NULL;
1440     aux->table_json = NULL;
1441 }
1442
1443 static struct ovsdb_error *
1444 ovsdb_jsonrpc_monitor_commit(struct ovsdb_replica *replica,
1445                              const struct ovsdb_txn *txn,
1446                              bool durable OVS_UNUSED)
1447 {
1448     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1449     struct ovsdb_jsonrpc_monitor_aux aux;
1450
1451     ovsdb_jsonrpc_monitor_init_aux(&aux, m, false);
1452     ovsdb_txn_for_each_change(txn, ovsdb_jsonrpc_monitor_change_cb, &aux);
1453     if (aux.json) {
1454         struct jsonrpc_msg *msg;
1455         struct json *params;
1456
1457         params = json_array_create_2(json_clone(aux.monitor->monitor_id),
1458                                      aux.json);
1459         msg = jsonrpc_create_notify("update", params);
1460         jsonrpc_session_send(aux.monitor->session->js, msg);
1461     }
1462
1463     return NULL;
1464 }
1465
1466 static struct json *
1467 ovsdb_jsonrpc_monitor_get_initial(const struct ovsdb_jsonrpc_monitor *m)
1468 {
1469     struct ovsdb_jsonrpc_monitor_aux aux;
1470     struct shash_node *node;
1471
1472     ovsdb_jsonrpc_monitor_init_aux(&aux, m, true);
1473     SHASH_FOR_EACH (node, &m->tables) {
1474         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1475
1476         if (mt->select & OJMS_INITIAL) {
1477             struct ovsdb_row *row;
1478
1479             HMAP_FOR_EACH (row, hmap_node, &mt->table->rows) {
1480                 ovsdb_jsonrpc_monitor_change_cb(NULL, row, NULL, &aux);
1481             }
1482         }
1483     }
1484     return aux.json ? aux.json : json_object_create();
1485 }
1486
1487 static void
1488 ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *replica)
1489 {
1490     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1491     struct shash_node *node;
1492
1493     json_destroy(m->monitor_id);
1494     SHASH_FOR_EACH (node, &m->tables) {
1495         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1496         free(mt->columns);
1497         free(mt);
1498     }
1499     shash_destroy(&m->tables);
1500     hmap_remove(&m->session->monitors, &m->node);
1501     free(m);
1502 }
1503
1504 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class = {
1505     ovsdb_jsonrpc_monitor_commit,
1506     ovsdb_jsonrpc_monitor_destroy
1507 };