ovsdb/jsonrpc-server.c

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