ovsdb/jsonrpc-server.c

   1 /* Copyright (c) 2009, 2010, 2011, 2012, 2013, 2014 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     /* The OVSDB protocol doesn't have a way to notify a client that a
 131      * database has been added.  If some client tried to use the database
 132      * that we're adding and failed, then forcing it to reconnect seems like
 133      * a reasonable way to make it try again.
 134      *
 135      * If this is too big of a hammer in practice, we could be more selective,
 136      * e.g. disconnect only connections that actually tried to use a database
 137      * with 'db''s name. */
 138     ovsdb_jsonrpc_server_reconnect(svr);
 139
 140     return ovsdb_server_add_db(&svr->up, db);
 141 }
 142
 143 /* Removes 'db' from the set of databases served out by 'svr'.  Returns
 144  * true if successful, false if there is no database associated with 'db'. */
 145 bool
 146 ovsdb_jsonrpc_server_remove_db(struct ovsdb_jsonrpc_server *svr,
 147                                struct ovsdb *db)
 148 {
 149     /* There might be pointers to 'db' from 'svr', such as monitors or
 150      * outstanding transactions.  Disconnect all JSON-RPC connections to avoid
 151      * accesses to freed memory.
 152      *
 153      * If this is too big of a hammer in practice, we could be more selective,
 154      * e.g. disconnect only connections that actually reference 'db'. */
 155     ovsdb_jsonrpc_server_reconnect(svr);
 156
 157     return ovsdb_server_remove_db(&svr->up, db);
 158 }
 159
 160 void
 161 ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
 162 {
 163     struct shash_node *node, *next;
 164
 165     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 166         ovsdb_jsonrpc_server_del_remote(node);
 167     }
 168     shash_destroy(&svr->remotes);
 169     ovsdb_server_destroy(&svr->up);
 170     free(svr);
 171 }
 172
 173 struct ovsdb_jsonrpc_options *
 174 ovsdb_jsonrpc_default_options(const char *target)
 175 {
 176     struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
 177     options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
 178     options->probe_interval = (stream_or_pstream_needs_probes(target)
 179                                ? RECONNECT_DEFAULT_PROBE_INTERVAL
 180                                : 0);
 181     return options;
 182 }
 183
 184 /* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
 185  * options in the struct ovsdb_jsonrpc_options supplied as the data values.
 186  *
 187  * A remote is an active or passive stream connection method, e.g. "pssl:" or
 188  * "tcp:1.2.3.4". */
 189 void
 190 ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 191                                  const struct shash *new_remotes)
 192 {
 193     struct shash_node *node, *next;
 194
 195     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
 196         if (!shash_find(new_remotes, node->name)) {
 197             VLOG_INFO("%s: remote deconfigured", node->name);
 198             ovsdb_jsonrpc_server_del_remote(node);
 199         }
 200     }
 201     SHASH_FOR_EACH (node, new_remotes) {
 202         const struct ovsdb_jsonrpc_options *options = node->data;
 203         struct ovsdb_jsonrpc_remote *remote;
 204
 205         remote = shash_find_data(&svr->remotes, node->name);
 206         if (!remote) {
 207             remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
 208             if (!remote) {
 209                 continue;
 210             }
 211         }
 212
 213         ovsdb_jsonrpc_session_set_all_options(remote, options);
 214     }
 215 }
 216
 217 static struct ovsdb_jsonrpc_remote *
 218 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
 219                                 const char *name,
 220                                 const struct ovsdb_jsonrpc_options *options)
 221 {
 222     struct ovsdb_jsonrpc_remote *remote;
 223     struct pstream *listener;
 224     int error;
 225
 226     error = jsonrpc_pstream_open(name, &listener, options->dscp);
 227     if (error && error != EAFNOSUPPORT) {
 228         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, ovs_strerror(error));
 229         return NULL;
 230     }
 231
 232     remote = xmalloc(sizeof *remote);
 233     remote->server = svr;
 234     remote->listener = listener;
 235     list_init(&remote->sessions);
 236     remote->dscp = options->dscp;
 237     shash_add(&svr->remotes, name, remote);
 238
 239     if (!listener) {
 240         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name, true));
 241     }
 242     return remote;
 243 }
 244
 245 static void
 246 ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
 247 {
 248     struct ovsdb_jsonrpc_remote *remote = node->data;
 249
 250     ovsdb_jsonrpc_session_close_all(remote);
 251     pstream_close(remote->listener);
 252     shash_delete(&remote->server->remotes, node);
 253     free(remote);
 254 }
 255
 256 /* Stores status information for the remote named 'target', which should have
 257  * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
 258  * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
 259  * a remote named 'target' or if that remote is an inbound remote that has no
 260  * active connections) returns false.  On failure, 'status' will be zeroed.
 261  */
 262 bool
 263 ovsdb_jsonrpc_server_get_remote_status(
 264     const struct ovsdb_jsonrpc_server *svr, const char *target,
 265     struct ovsdb_jsonrpc_remote_status *status)
 266 {
 267     const struct ovsdb_jsonrpc_remote *remote;
 268
 269     memset(status, 0, sizeof *status);
 270
 271     remote = shash_find_data(&svr->remotes, target);
 272     return remote && ovsdb_jsonrpc_session_get_status(remote, status);
 273 }
 274
 275 void
 276 ovsdb_jsonrpc_server_free_remote_status(
 277     struct ovsdb_jsonrpc_remote_status *status)
 278 {
 279     free(status->locks_held);
 280     free(status->locks_waiting);
 281     free(status->locks_lost);
 282 }
 283
 284 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
 285  * reconnect. */
 286 void
 287 ovsdb_jsonrpc_server_reconnect(struct ovsdb_jsonrpc_server *svr)
 288 {
 289     struct shash_node *node;
 290
 291     SHASH_FOR_EACH (node, &svr->remotes) {
 292         struct ovsdb_jsonrpc_remote *remote = node->data;
 293
 294         ovsdb_jsonrpc_session_reconnect_all(remote);
 295     }
 296 }
 297
 298 void
 299 ovsdb_jsonrpc_server_run(struct ovsdb_jsonrpc_server *svr)
 300 {
 301     struct shash_node *node;
 302
 303     SHASH_FOR_EACH (node, &svr->remotes) {
 304         struct ovsdb_jsonrpc_remote *remote = node->data;
 305
 306         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 307             struct stream *stream;
 308             int error;
 309
 310             error = pstream_accept(remote->listener, &stream);
 311             if (!error) {
 312                 struct jsonrpc_session *js;
 313                 js = jsonrpc_session_open_unreliably(jsonrpc_open(stream),
 314                                                      remote->dscp);
 315                 ovsdb_jsonrpc_session_create(remote, js);
 316             } else if (error != EAGAIN) {
 317                 VLOG_WARN_RL(&rl, "%s: accept failed: %s",
 318                              pstream_get_name(remote->listener),
 319                              ovs_strerror(error));
 320             }
 321         }
 322
 323         ovsdb_jsonrpc_session_run_all(remote);
 324     }
 325 }
 326
 327 void
 328 ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 329 {
 330     struct shash_node *node;
 331
 332     SHASH_FOR_EACH (node, &svr->remotes) {
 333         struct ovsdb_jsonrpc_remote *remote = node->data;
 334
 335         if (remote->listener && svr->n_sessions < svr->max_sessions) {
 336             pstream_wait(remote->listener);
 337         }
 338
 339         ovsdb_jsonrpc_session_wait_all(remote);
 340     }
 341 }
 342
 343 /* Adds some memory usage statistics for 'svr' into 'usage', for use with
 344  * memory_report(). */
 345 void
 346 ovsdb_jsonrpc_server_get_memory_usage(const struct ovsdb_jsonrpc_server *svr,
 347                                       struct simap *usage)
 348 {
 349     struct shash_node *node;
 350
 351     simap_increase(usage, "sessions", svr->n_sessions);
 352     SHASH_FOR_EACH (node, &svr->remotes) {
 353         struct ovsdb_jsonrpc_remote *remote = node->data;
 354
 355         ovsdb_jsonrpc_session_get_memory_usage_all(remote, usage);
 356     }
 357 }
 358 \f
 359 /* JSON-RPC database server session. */
 360
 361 struct ovsdb_jsonrpc_session {
 362     struct list node;           /* Element in remote's sessions list. */
 363     struct ovsdb_session up;
 364     struct ovsdb_jsonrpc_remote *remote;
 365
 366     /* Triggers. */
 367     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
 368
 369     /* Monitors. */
 370     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
 371
 372     /* Network connectivity. */
 373     struct jsonrpc_session *js;  /* JSON-RPC session. */
 374     unsigned int js_seqno;       /* Last jsonrpc_session_get_seqno() value. */
 375 };
 376
 377 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 378 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 379 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
 380 static void ovsdb_jsonrpc_session_get_memory_usage(
 381     const struct ovsdb_jsonrpc_session *, struct simap *usage);
 382 static void ovsdb_jsonrpc_session_set_options(
 383     struct ovsdb_jsonrpc_session *, const struct ovsdb_jsonrpc_options *);
 384 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
 385                                              struct jsonrpc_msg *);
 386 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
 387                                              struct jsonrpc_msg *);
 388
 389 static struct ovsdb_jsonrpc_session *
 390 ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
 391                              struct jsonrpc_session *js)
 392 {
 393     struct ovsdb_jsonrpc_session *s;
 394
 395     s = xzalloc(sizeof *s);
 396     ovsdb_session_init(&s->up, &remote->server->up);
 397     s->remote = remote;
 398     list_push_back(&remote->sessions, &s->node);
 399     hmap_init(&s->triggers);
 400     hmap_init(&s->monitors);
 401     s->js = js;
 402     s->js_seqno = jsonrpc_session_get_seqno(js);
 403
 404     remote->server->n_sessions++;
 405
 406     return s;
 407 }
 408
 409 static void
 410 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 411 {
 412     ovsdb_jsonrpc_monitor_remove_all(s);
 413     ovsdb_jsonrpc_session_unlock_all(s);
 414     ovsdb_jsonrpc_trigger_complete_all(s);
 415
 416     hmap_destroy(&s->monitors);
 417     hmap_destroy(&s->triggers);
 418
 419     jsonrpc_session_close(s->js);
 420     list_remove(&s->node);
 421     s->remote->server->n_sessions--;
 422     ovsdb_session_destroy(&s->up);
 423     free(s);
 424 }
 425
 426 static int
 427 ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
 428 {
 429     jsonrpc_session_run(s->js);
 430     if (s->js_seqno != jsonrpc_session_get_seqno(s->js)) {
 431         s->js_seqno = jsonrpc_session_get_seqno(s->js);
 432         ovsdb_jsonrpc_trigger_complete_all(s);
 433         ovsdb_jsonrpc_monitor_remove_all(s);
 434         ovsdb_jsonrpc_session_unlock_all(s);
 435     }
 436
 437     ovsdb_jsonrpc_trigger_complete_done(s);
 438
 439     if (!jsonrpc_session_get_backlog(s->js)) {
 440         struct jsonrpc_msg *msg = jsonrpc_session_recv(s->js);
 441         if (msg) {
 442             if (msg->type == JSONRPC_REQUEST) {
 443                 ovsdb_jsonrpc_session_got_request(s, msg);
 444             } else if (msg->type == JSONRPC_NOTIFY) {
 445                 ovsdb_jsonrpc_session_got_notify(s, msg);
 446             } else {
 447                 VLOG_WARN("%s: received unexpected %s message",
 448                           jsonrpc_session_get_name(s->js),
 449                           jsonrpc_msg_type_to_string(msg->type));
 450                 jsonrpc_session_force_reconnect(s->js);
 451                 jsonrpc_msg_destroy(msg);
 452             }
 453         }
 454     }
 455     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 456 }
 457
 458 static void
 459 ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
 460                                   const struct ovsdb_jsonrpc_options *options)
 461 {
 462     jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
 463     jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
 464     jsonrpc_session_set_dscp(session->js, options->dscp);
 465 }
 466
 467 static void
 468 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 469 {
 470     struct ovsdb_jsonrpc_session *s, *next;
 471
 472     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 473         int error = ovsdb_jsonrpc_session_run(s);
 474         if (error) {
 475             ovsdb_jsonrpc_session_close(s);
 476         }
 477     }
 478 }
 479
 480 static void
 481 ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *s)
 482 {
 483     jsonrpc_session_wait(s->js);
 484     if (!jsonrpc_session_get_backlog(s->js)) {
 485         jsonrpc_session_recv_wait(s->js);
 486     }
 487 }
 488
 489 static void
 490 ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 491 {
 492     struct ovsdb_jsonrpc_session *s;
 493
 494     LIST_FOR_EACH (s, node, &remote->sessions) {
 495         ovsdb_jsonrpc_session_wait(s);
 496     }
 497 }
 498
 499 static void
 500 ovsdb_jsonrpc_session_get_memory_usage(const struct ovsdb_jsonrpc_session *s,
 501                                        struct simap *usage)
 502 {
 503     simap_increase(usage, "triggers", hmap_count(&s->triggers));
 504     simap_increase(usage, "monitors", hmap_count(&s->monitors));
 505     simap_increase(usage, "backlog", jsonrpc_session_get_backlog(s->js));
 506 }
 507
 508 static void
 509 ovsdb_jsonrpc_session_get_memory_usage_all(
 510     const struct ovsdb_jsonrpc_remote *remote,
 511     struct simap *usage)
 512 {
 513     struct ovsdb_jsonrpc_session *s;
 514
 515     LIST_FOR_EACH (s, node, &remote->sessions) {
 516         ovsdb_jsonrpc_session_get_memory_usage(s, usage);
 517     }
 518 }
 519
 520 static void
 521 ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 522 {
 523     struct ovsdb_jsonrpc_session *s, *next;
 524
 525     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 526         ovsdb_jsonrpc_session_close(s);
 527     }
 528 }
 529
 530 /* Forces all of the JSON-RPC sessions managed by 'remote' to disconnect and
 531  * reconnect. */
 532 static void
 533 ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 534 {
 535     struct ovsdb_jsonrpc_session *s, *next;
 536
 537     LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
 538         jsonrpc_session_force_reconnect(s->js);
 539         if (!jsonrpc_session_is_alive(s->js)) {
 540             ovsdb_jsonrpc_session_close(s);
 541         }
 542     }
 543 }
 544
 545 /* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
 546  * 'options'. */
 547 static void
 548 ovsdb_jsonrpc_session_set_all_options(
 549     struct ovsdb_jsonrpc_remote *remote,
 550     const struct ovsdb_jsonrpc_options *options)
 551 {
 552     struct ovsdb_jsonrpc_session *s;
 553
 554     if (remote->listener) {
 555         int error;
 556
 557         error = pstream_set_dscp(remote->listener, options->dscp);
 558         if (error) {
 559             VLOG_ERR("%s: set_dscp failed %s",
 560                      pstream_get_name(remote->listener), ovs_strerror(error));
 561         } else {
 562             remote->dscp = options->dscp;
 563         }
 564         /*
 565          * XXX race window between setting dscp to listening socket
 566          * and accepting socket. Accepted socket may have old dscp value.
 567          * Ignore this race window for now.
 568          */
 569     }
 570     LIST_FOR_EACH (s, node, &remote->sessions) {
 571         ovsdb_jsonrpc_session_set_options(s, options);
 572     }
 573 }
 574
 575 static bool
 576 ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
 577                                  struct ovsdb_jsonrpc_remote_status *status)
 578 {
 579     const struct ovsdb_jsonrpc_session *s;
 580     const struct jsonrpc_session *js;
 581     struct ovsdb_lock_waiter *waiter;
 582     struct reconnect_stats rstats;
 583     struct ds locks_held, locks_waiting, locks_lost;
 584
 585     status->bound_port = (remote->listener
 586                           ? pstream_get_bound_port(remote->listener)
 587                           : htons(0));
 588
 589     if (list_is_empty(&remote->sessions)) {
 590         return false;
 591     }
 592     s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
 593     js = s->js;
 594
 595     status->is_connected = jsonrpc_session_is_connected(js);
 596     status->last_error = jsonrpc_session_get_status(js);
 597
 598     jsonrpc_session_get_reconnect_stats(js, &rstats);
 599     status->state = rstats.state;
 600     status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
 601         ? UINT_MAX : rstats.msec_since_connect / 1000;
 602     status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
 603         ? UINT_MAX : rstats.msec_since_disconnect / 1000;
 604
 605     ds_init(&locks_held);
 606     ds_init(&locks_waiting);
 607     ds_init(&locks_lost);
 608     HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
 609         struct ds *string;
 610
 611         string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
 612                   : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
 613                   : &locks_lost);
 614         if (string->length) {
 615             ds_put_char(string, ' ');
 616         }
 617         ds_put_cstr(string, waiter->lock_name);
 618     }
 619     status->locks_held = ds_steal_cstr(&locks_held);
 620     status->locks_waiting = ds_steal_cstr(&locks_waiting);
 621     status->locks_lost = ds_steal_cstr(&locks_lost);
 622
 623     status->n_connections = list_size(&remote->sessions);
 624
 625     return true;
 626 }
 627
 628 /* Examines 'request' to determine the database to which it relates, and then
 629  * searches 's' to find that database:
 630  *
 631  *    - If successful, returns the database and sets '*replyp' to NULL.
 632  *
 633  *    - If no such database exists, returns NULL and sets '*replyp' to an
 634  *      appropriate JSON-RPC error reply, owned by the caller. */
 635 static struct ovsdb *
 636 ovsdb_jsonrpc_lookup_db(const struct ovsdb_jsonrpc_session *s,
 637                         const struct jsonrpc_msg *request,
 638                         struct jsonrpc_msg **replyp)
 639 {
 640     struct json_array *params;
 641     struct ovsdb_error *error;
 642     const char *db_name;
 643     struct ovsdb *db;
 644
 645     params = json_array(request->params);
 646     if (!params->n || params->elems[0]->type != JSON_STRING) {
 647         error = ovsdb_syntax_error(
 648             request->params, NULL,
 649             "%s request params must begin with <db-name>", request->method);
 650         goto error;
 651     }
 652
 653     db_name = params->elems[0]->u.string;
 654     db = shash_find_data(&s->up.server->dbs, db_name);
 655     if (!db) {
 656         error = ovsdb_syntax_error(
 657             request->params, "unknown database",
 658             "%s request specifies unknown database %s",
 659             request->method, db_name);
 660         goto error;
 661     }
 662
 663     *replyp = NULL;
 664     return db;
 665
 666 error:
 667     *replyp = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 668     ovsdb_error_destroy(error);
 669     return NULL;
 670 }
 671
 672 static struct ovsdb_error *
 673 ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
 674                                       const char **lock_namep)
 675 {
 676     const struct json_array *params;
 677
 678     params = json_array(request->params);
 679     if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
 680         !ovsdb_parser_is_id(json_string(params->elems[0]))) {
 681         *lock_namep = NULL;
 682         return ovsdb_syntax_error(request->params, NULL,
 683                                   "%s request params must be <id>",
 684                                   request->method);
 685     }
 686
 687     *lock_namep = json_string(params->elems[0]);
 688     return NULL;
 689 }
 690
 691 static void
 692 ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
 693                              const char *lock_name,
 694                              const char *method)
 695 {
 696     struct ovsdb_jsonrpc_session *s;
 697     struct json *params;
 698
 699     s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
 700     params = json_array_create_1(json_string_create(lock_name));
 701     jsonrpc_session_send(s->js, jsonrpc_create_notify(method, params));
 702 }
 703
 704 static struct jsonrpc_msg *
 705 ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
 706                            struct jsonrpc_msg *request,
 707                            enum ovsdb_lock_mode mode)
 708 {
 709     struct ovsdb_lock_waiter *waiter;
 710     struct jsonrpc_msg *reply;
 711     struct ovsdb_error *error;
 712     struct ovsdb_session *victim;
 713     const char *lock_name;
 714     struct json *result;
 715
 716     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 717     if (error) {
 718         goto error;
 719     }
 720
 721     /* Report error if this session has issued a "lock" or "steal" without a
 722      * matching "unlock" for this lock. */
 723     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 724     if (waiter) {
 725         error = ovsdb_syntax_error(
 726             request->params, NULL,
 727             "must issue \"unlock\" before new \"%s\"", request->method);
 728         goto error;
 729     }
 730
 731     /* Get the lock, add us as a waiter. */
 732     waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
 733                                &victim);
 734     if (victim) {
 735         ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
 736     }
 737
 738     result = json_object_create();
 739     json_object_put(result, "locked",
 740                     json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
 741
 742     return jsonrpc_create_reply(result, request->id);
 743
 744 error:
 745     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 746     ovsdb_error_destroy(error);
 747     return reply;
 748 }
 749
 750 static void
 751 ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
 752 {
 753     struct ovsdb_lock_waiter *waiter, *next;
 754
 755     HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
 756         ovsdb_jsonrpc_session_unlock__(waiter);
 757     }
 758 }
 759
 760 static void
 761 ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
 762 {
 763     struct ovsdb_lock *lock = waiter->lock;
 764
 765     if (lock) {
 766         struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
 767         if (new_owner) {
 768             ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
 769         } else {
 770             /* ovsdb_server_lock() might have freed 'lock'. */
 771         }
 772     }
 773
 774     ovsdb_lock_waiter_destroy(waiter);
 775 }
 776
 777 static struct jsonrpc_msg *
 778 ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
 779                              struct jsonrpc_msg *request)
 780 {
 781     struct ovsdb_lock_waiter *waiter;
 782     struct jsonrpc_msg *reply;
 783     struct ovsdb_error *error;
 784     const char *lock_name;
 785
 786     error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
 787     if (error) {
 788         goto error;
 789     }
 790
 791     /* Report error if this session has not issued a "lock" or "steal" for this
 792      * lock. */
 793     waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
 794     if (!waiter) {
 795         error = ovsdb_syntax_error(
 796             request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
 797         goto error;
 798     }
 799
 800     ovsdb_jsonrpc_session_unlock__(waiter);
 801
 802     return jsonrpc_create_reply(json_object_create(), request->id);
 803
 804 error:
 805     reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
 806     ovsdb_error_destroy(error);
 807     return reply;
 808 }
 809
 810 static struct jsonrpc_msg *
 811 execute_transaction(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 812                     struct jsonrpc_msg *request)
 813 {
 814     ovsdb_jsonrpc_trigger_create(s, db, request->id, request->params);
 815     request->id = NULL;
 816     request->params = NULL;
 817     jsonrpc_msg_destroy(request);
 818     return NULL;
 819 }
 820
 821 static void
 822 ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
 823                                   struct jsonrpc_msg *request)
 824 {
 825     struct jsonrpc_msg *reply;
 826
 827     if (!strcmp(request->method, "transact")) {
 828         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 829         if (!reply) {
 830             reply = execute_transaction(s, db, request);
 831         }
 832     } else if (!strcmp(request->method, "monitor")) {
 833         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 834         if (!reply) {
 835             reply = jsonrpc_create_reply(
 836                 ovsdb_jsonrpc_monitor_create(s, db, request->params),
 837                 request->id);
 838         }
 839     } else if (!strcmp(request->method, "monitor_cancel")) {
 840         reply = ovsdb_jsonrpc_monitor_cancel(s, json_array(request->params),
 841                                              request->id);
 842     } else if (!strcmp(request->method, "get_schema")) {
 843         struct ovsdb *db = ovsdb_jsonrpc_lookup_db(s, request, &reply);
 844         if (!reply) {
 845             reply = jsonrpc_create_reply(ovsdb_schema_to_json(db->schema),
 846                                          request->id);
 847         }
 848     } else if (!strcmp(request->method, "list_dbs")) {
 849         size_t n_dbs = shash_count(&s->up.server->dbs);
 850         struct shash_node *node;
 851         struct json **dbs;
 852         size_t i;
 853
 854         dbs = xmalloc(n_dbs * sizeof *dbs);
 855         i = 0;
 856         SHASH_FOR_EACH (node, &s->up.server->dbs) {
 857             dbs[i++] = json_string_create(node->name);
 858         }
 859         reply = jsonrpc_create_reply(json_array_create(dbs, n_dbs),
 860                                      request->id);
 861     } else if (!strcmp(request->method, "lock")) {
 862         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
 863     } else if (!strcmp(request->method, "steal")) {
 864         reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
 865     } else if (!strcmp(request->method, "unlock")) {
 866         reply = ovsdb_jsonrpc_session_unlock(s, request);
 867     } else if (!strcmp(request->method, "echo")) {
 868         reply = jsonrpc_create_reply(json_clone(request->params), request->id);
 869     } else {
 870         reply = jsonrpc_create_error(json_string_create("unknown method"),
 871                                      request->id);
 872     }
 873
 874     if (reply) {
 875         jsonrpc_msg_destroy(request);
 876         jsonrpc_session_send(s->js, reply);
 877     }
 878 }
 879
 880 static void
 881 execute_cancel(struct ovsdb_jsonrpc_session *s, struct jsonrpc_msg *request)
 882 {
 883     if (json_array(request->params)->n == 1) {
 884         struct ovsdb_jsonrpc_trigger *t;
 885         struct json *id;
 886
 887         id = request->params->u.array.elems[0];
 888         t = ovsdb_jsonrpc_trigger_find(s, id, json_hash(id, 0));
 889         if (t) {
 890             ovsdb_jsonrpc_trigger_complete(t);
 891         }
 892     }
 893 }
 894
 895 static void
 896 ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
 897                                  struct jsonrpc_msg *request)
 898 {
 899     if (!strcmp(request->method, "cancel")) {
 900         execute_cancel(s, request);
 901     }
 902     jsonrpc_msg_destroy(request);
 903 }
 904 \f
 905 /* JSON-RPC database server triggers.
 906  *
 907  * (Every transaction is treated as a trigger even if it doesn't actually have
 908  * any "wait" operations.) */
 909
 910 struct ovsdb_jsonrpc_trigger {
 911     struct ovsdb_trigger trigger;
 912     struct hmap_node hmap_node; /* In session's "triggers" hmap. */
 913     struct json *id;
 914 };
 915
 916 static void
 917 ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
 918                              struct json *id, struct json *params)
 919 {
 920     struct ovsdb_jsonrpc_trigger *t;
 921     size_t hash;
 922
 923     /* Check for duplicate ID. */
 924     hash = json_hash(id, 0);
 925     t = ovsdb_jsonrpc_trigger_find(s, id, hash);
 926     if (t) {
 927         struct jsonrpc_msg *msg;
 928
 929         msg = jsonrpc_create_error(json_string_create("duplicate request ID"),
 930                                    id);
 931         jsonrpc_session_send(s->js, msg);
 932         json_destroy(id);
 933         json_destroy(params);
 934         return;
 935     }
 936
 937     /* Insert into trigger table. */
 938     t = xmalloc(sizeof *t);
 939     ovsdb_trigger_init(&s->up, db, &t->trigger, params, time_msec());
 940     t->id = id;
 941     hmap_insert(&s->triggers, &t->hmap_node, hash);
 942
 943     /* Complete early if possible. */
 944     if (ovsdb_trigger_is_complete(&t->trigger)) {
 945         ovsdb_jsonrpc_trigger_complete(t);
 946     }
 947 }
 948
 949 static struct ovsdb_jsonrpc_trigger *
 950 ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 951                            const struct json *id, size_t hash)
 952 {
 953     struct ovsdb_jsonrpc_trigger *t;
 954
 955     HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
 956         if (json_equal(t->id, id)) {
 957             return t;
 958         }
 959     }
 960
 961     return NULL;
 962 }
 963
 964 static void
 965 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 966 {
 967     struct ovsdb_jsonrpc_session *s;
 968
 969     s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
 970
 971     if (jsonrpc_session_is_connected(s->js)) {
 972         struct jsonrpc_msg *reply;
 973         struct json *result;
 974
 975         result = ovsdb_trigger_steal_result(&t->trigger);
 976         if (result) {
 977             reply = jsonrpc_create_reply(result, t->id);
 978         } else {
 979             reply = jsonrpc_create_error(json_string_create("canceled"),
 980                                          t->id);
 981         }
 982         jsonrpc_session_send(s->js, reply);
 983     }
 984
 985     json_destroy(t->id);
 986     ovsdb_trigger_destroy(&t->trigger);
 987     hmap_remove(&s->triggers, &t->hmap_node);
 988     free(t);
 989 }
 990
 991 static void
 992 ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 993 {
 994     struct ovsdb_jsonrpc_trigger *t, *next;
 995     HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
 996         ovsdb_jsonrpc_trigger_complete(t);
 997     }
 998 }
 999
1000 static void
1001 ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
1002 {
1003     while (!list_is_empty(&s->up.completions)) {
1004         struct ovsdb_jsonrpc_trigger *t
1005             = CONTAINER_OF(s->up.completions.next,
1006                            struct ovsdb_jsonrpc_trigger, trigger.node);
1007         ovsdb_jsonrpc_trigger_complete(t);
1008     }
1009 }
1010 \f
1011 /* JSON-RPC database table monitors. */
1012
1013 enum ovsdb_jsonrpc_monitor_selection {
1014     OJMS_INITIAL = 1 << 0,      /* All rows when monitor is created. */
1015     OJMS_INSERT = 1 << 1,       /* New rows. */
1016     OJMS_DELETE = 1 << 2,       /* Deleted rows. */
1017     OJMS_MODIFY = 1 << 3        /* Modified rows. */
1018 };
1019
1020 /* A particular column being monitored. */
1021 struct ovsdb_jsonrpc_monitor_column {
1022     const struct ovsdb_column *column;
1023     enum ovsdb_jsonrpc_monitor_selection select;
1024 };
1025
1026 /* A row that has changed in a monitored table. */
1027 struct ovsdb_jsonrpc_monitor_row {
1028     struct hmap_node hmap_node; /* In ovsdb_jsonrpc_monitor_table.changes. */
1029     struct uuid uuid;           /* UUID of row that changed. */
1030     struct ovsdb_datum *old;    /* Old data, NULL for an inserted row. */
1031     struct ovsdb_datum *new;    /* New data, NULL for a deleted row. */
1032 };
1033
1034 /* A particular table being monitored. */
1035 struct ovsdb_jsonrpc_monitor_table {
1036     const struct ovsdb_table *table;
1037
1038     /* This is the union (bitwise-OR) of the 'select' values in all of the
1039      * members of 'columns' below. */
1040     enum ovsdb_jsonrpc_monitor_selection select;
1041
1042     /* Columns being monitored. */
1043     struct ovsdb_jsonrpc_monitor_column *columns;
1044     size_t n_columns;
1045
1046     /* Contains 'struct ovsdb_jsonrpc_monitor_row's for rows that have been
1047      * updated but not yet flushed to the jsonrpc connection. */
1048     struct hmap changes;
1049 };
1050
1051 /* A collection of tables being monitored. */
1052 struct ovsdb_jsonrpc_monitor {
1053     struct ovsdb_replica replica;
1054     struct ovsdb_jsonrpc_session *session;
1055     struct ovsdb *db;
1056     struct hmap_node node;      /* In ovsdb_jsonrpc_session's "monitors". */
1057
1058     struct json *monitor_id;
1059     struct shash tables;     /* Holds "struct ovsdb_jsonrpc_monitor_table"s. */
1060 };
1061
1062 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class;
1063
1064 struct ovsdb_jsonrpc_monitor *ovsdb_jsonrpc_monitor_find(
1065     struct ovsdb_jsonrpc_session *, const struct json *monitor_id);
1066 static void ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *);
1067 static struct json *ovsdb_jsonrpc_monitor_get_initial(
1068     const struct ovsdb_jsonrpc_monitor *);
1069
1070 static bool
1071 parse_bool(struct ovsdb_parser *parser, const char *name, bool default_value)
1072 {
1073     const struct json *json;
1074
1075     json = ovsdb_parser_member(parser, name, OP_BOOLEAN | OP_OPTIONAL);
1076     return json ? json_boolean(json) : default_value;
1077 }
1078
1079 struct ovsdb_jsonrpc_monitor *
1080 ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
1081                            const struct json *monitor_id)
1082 {
1083     struct ovsdb_jsonrpc_monitor *m;
1084
1085     HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
1086         if (json_equal(m->monitor_id, monitor_id)) {
1087             return m;
1088         }
1089     }
1090
1091     return NULL;
1092 }
1093
1094 static void
1095 ovsdb_jsonrpc_add_monitor_column(struct ovsdb_jsonrpc_monitor_table *mt,
1096                                  const struct ovsdb_column *column,
1097                                  enum ovsdb_jsonrpc_monitor_selection select,
1098                                  size_t *allocated_columns)
1099 {
1100     struct ovsdb_jsonrpc_monitor_column *c;
1101
1102     if (mt->n_columns >= *allocated_columns) {
1103         mt->columns = x2nrealloc(mt->columns, allocated_columns,
1104                                  sizeof *mt->columns);
1105     }
1106
1107     c = &mt->columns[mt->n_columns++];
1108     c->column = column;
1109     c->select = select;
1110 }
1111
1112 static int
1113 compare_ovsdb_jsonrpc_monitor_column(const void *a_, const void *b_)
1114 {
1115     const struct ovsdb_jsonrpc_monitor_column *a = a_;
1116     const struct ovsdb_jsonrpc_monitor_column *b = b_;
1117
1118     return a->column < b->column ? -1 : a->column > b->column;
1119 }
1120
1121 static struct ovsdb_error * WARN_UNUSED_RESULT
1122 ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_jsonrpc_monitor_table *mt,
1123                                     const struct json *monitor_request,
1124                                     size_t *allocated_columns)
1125 {
1126     const struct ovsdb_table_schema *ts = mt->table->schema;
1127     enum ovsdb_jsonrpc_monitor_selection select;
1128     const struct json *columns, *select_json;
1129     struct ovsdb_parser parser;
1130     struct ovsdb_error *error;
1131
1132     ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
1133     columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
1134     select_json = ovsdb_parser_member(&parser, "select",
1135                                       OP_OBJECT | OP_OPTIONAL);
1136     error = ovsdb_parser_finish(&parser);
1137     if (error) {
1138         return error;
1139     }
1140
1141     if (select_json) {
1142         select = 0;
1143         ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
1144         if (parse_bool(&parser, "initial", true)) {
1145             select |= OJMS_INITIAL;
1146         }
1147         if (parse_bool(&parser, "insert", true)) {
1148             select |= OJMS_INSERT;
1149         }
1150         if (parse_bool(&parser, "delete", true)) {
1151             select |= OJMS_DELETE;
1152         }
1153         if (parse_bool(&parser, "modify", true)) {
1154             select |= OJMS_MODIFY;
1155         }
1156         error = ovsdb_parser_finish(&parser);
1157         if (error) {
1158             return error;
1159         }
1160     } else {
1161         select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
1162     }
1163     mt->select |= select;
1164
1165     if (columns) {
1166         size_t i;
1167
1168         if (columns->type != JSON_ARRAY) {
1169             return ovsdb_syntax_error(columns, NULL,
1170                                       "array of column names expected");
1171         }
1172
1173         for (i = 0; i < columns->u.array.n; i++) {
1174             const struct ovsdb_column *column;
1175             const char *s;
1176
1177             if (columns->u.array.elems[i]->type != JSON_STRING) {
1178                 return ovsdb_syntax_error(columns, NULL,
1179                                           "array of column names expected");
1180             }
1181
1182             s = columns->u.array.elems[i]->u.string;
1183             column = shash_find_data(&mt->table->schema->columns, s);
1184             if (!column) {
1185                 return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
1186                                           "column name", s);
1187             }
1188             ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1189                                              allocated_columns);
1190         }
1191     } else {
1192         struct shash_node *node;
1193
1194         SHASH_FOR_EACH (node, &ts->columns) {
1195             const struct ovsdb_column *column = node->data;
1196             if (column->index != OVSDB_COL_UUID) {
1197                 ovsdb_jsonrpc_add_monitor_column(mt, column, select,
1198                                                  allocated_columns);
1199             }
1200         }
1201     }
1202
1203     return NULL;
1204 }
1205
1206 static struct json *
1207 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s, struct ovsdb *db,
1208                              struct json *params)
1209 {
1210     struct ovsdb_jsonrpc_monitor *m = NULL;
1211     struct json *monitor_id, *monitor_requests;
1212     struct ovsdb_error *error = NULL;
1213     struct shash_node *node;
1214     struct json *json;
1215
1216     if (json_array(params)->n != 3) {
1217         error = ovsdb_syntax_error(params, NULL, "invalid parameters");
1218         goto error;
1219     }
1220     monitor_id = params->u.array.elems[1];
1221     monitor_requests = params->u.array.elems[2];
1222     if (monitor_requests->type != JSON_OBJECT) {
1223         error = ovsdb_syntax_error(monitor_requests, NULL,
1224                                    "monitor-requests must be object");
1225         goto error;
1226     }
1227
1228     if (ovsdb_jsonrpc_monitor_find(s, monitor_id)) {
1229         error = ovsdb_syntax_error(monitor_id, NULL, "duplicate monitor ID");
1230         goto error;
1231     }
1232
1233     m = xzalloc(sizeof *m);
1234     ovsdb_replica_init(&m->replica, &ovsdb_jsonrpc_replica_class);
1235     ovsdb_add_replica(db, &m->replica);
1236     m->session = s;
1237     m->db = db;
1238     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
1239     m->monitor_id = json_clone(monitor_id);
1240     shash_init(&m->tables);
1241
1242     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
1243         const struct ovsdb_table *table;
1244         struct ovsdb_jsonrpc_monitor_table *mt;
1245         size_t allocated_columns;
1246         const struct json *mr_value;
1247         size_t i;
1248
1249         table = ovsdb_get_table(m->db, node->name);
1250         if (!table) {
1251             error = ovsdb_syntax_error(NULL, NULL,
1252                                        "no table named %s", node->name);
1253             goto error;
1254         }
1255
1256         mt = xzalloc(sizeof *mt);
1257         mt->table = table;
1258         hmap_init(&mt->changes);
1259         shash_add(&m->tables, table->schema->name, mt);
1260
1261         /* Parse columns. */
1262         mr_value = node->data;
1263         allocated_columns = 0;
1264         if (mr_value->type == JSON_ARRAY) {
1265             const struct json_array *array = &mr_value->u.array;
1266
1267             for (i = 0; i < array->n; i++) {
1268                 error = ovsdb_jsonrpc_parse_monitor_request(
1269                     mt, array->elems[i], &allocated_columns);
1270                 if (error) {
1271                     goto error;
1272                 }
1273             }
1274         } else {
1275             error = ovsdb_jsonrpc_parse_monitor_request(
1276                 mt, mr_value, &allocated_columns);
1277             if (error) {
1278                 goto error;
1279             }
1280         }
1281
1282         /* Check for duplicate columns. */
1283         qsort(mt->columns, mt->n_columns, sizeof *mt->columns,
1284               compare_ovsdb_jsonrpc_monitor_column);
1285         for (i = 1; i < mt->n_columns; i++) {
1286             if (mt->columns[i].column == mt->columns[i - 1].column) {
1287                 error = ovsdb_syntax_error(mr_value, NULL, "column %s "
1288                                            "mentioned more than once",
1289                                            mt->columns[i].column->name);
1290                 goto error;
1291             }
1292         }
1293     }
1294
1295     return ovsdb_jsonrpc_monitor_get_initial(m);
1296
1297 error:
1298     if (m) {
1299         ovsdb_remove_replica(m->db, &m->replica);
1300     }
1301
1302     json = ovsdb_error_to_json(error);
1303     ovsdb_error_destroy(error);
1304     return json;
1305 }
1306
1307 static struct jsonrpc_msg *
1308 ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
1309                              struct json_array *params,
1310                              const struct json *request_id)
1311 {
1312     if (params->n != 1) {
1313         return jsonrpc_create_error(json_string_create("invalid parameters"),
1314                                     request_id);
1315     } else {
1316         struct ovsdb_jsonrpc_monitor *m;
1317
1318         m = ovsdb_jsonrpc_monitor_find(s, params->elems[0]);
1319         if (!m) {
1320             return jsonrpc_create_error(json_string_create("unknown monitor"),
1321                                         request_id);
1322         } else {
1323             ovsdb_remove_replica(m->db, &m->replica);
1324             return jsonrpc_create_reply(json_object_create(), request_id);
1325         }
1326     }
1327 }
1328
1329 static void
1330 ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
1331 {
1332     struct ovsdb_jsonrpc_monitor *m, *next;
1333
1334     HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
1335         ovsdb_remove_replica(m->db, &m->replica);
1336     }
1337 }
1338
1339 static struct ovsdb_jsonrpc_monitor *
1340 ovsdb_jsonrpc_monitor_cast(struct ovsdb_replica *replica)
1341 {
1342     ovs_assert(replica->class == &ovsdb_jsonrpc_replica_class);
1343     return CONTAINER_OF(replica, struct ovsdb_jsonrpc_monitor, replica);
1344 }
1345
1346 struct ovsdb_jsonrpc_monitor_aux {
1347     const struct ovsdb_jsonrpc_monitor *monitor;
1348     struct ovsdb_jsonrpc_monitor_table *mt;
1349 };
1350
1351 /* Finds and returns the ovsdb_jsonrpc_monitor_row in 'mt->changes' for the
1352  * given 'uuid', or NULL if there is no such row. */
1353 static struct ovsdb_jsonrpc_monitor_row *
1354 ovsdb_jsonrpc_monitor_row_find(const struct ovsdb_jsonrpc_monitor_table *mt,
1355                                const struct uuid *uuid)
1356 {
1357     struct ovsdb_jsonrpc_monitor_row *row;
1358
1359     HMAP_FOR_EACH_WITH_HASH (row, hmap_node, uuid_hash(uuid), &mt->changes) {
1360         if (uuid_equals(uuid, &row->uuid)) {
1361             return row;
1362         }
1363     }
1364     return NULL;
1365 }
1366
1367 /* Allocates an array of 'mt->n_columns' ovsdb_datums and initializes them as
1368  * copies of the data in 'row' drawn from the columns represented by
1369  * mt->columns[].  Returns the array.
1370  *
1371  * If 'row' is NULL, returns NULL. */
1372 static struct ovsdb_datum *
1373 clone_monitor_row_data(const struct ovsdb_jsonrpc_monitor_table *mt,
1374                        const struct ovsdb_row *row)
1375 {
1376     struct ovsdb_datum *data;
1377     size_t i;
1378
1379     if (!row) {
1380         return NULL;
1381     }
1382
1383     data = xmalloc(mt->n_columns * sizeof *data);
1384     for (i = 0; i < mt->n_columns; i++) {
1385         const struct ovsdb_column *c = mt->columns[i].column;
1386         const struct ovsdb_datum *src = &row->fields[c->index];
1387         struct ovsdb_datum *dst = &data[i];
1388         const struct ovsdb_type *type = &c->type;
1389
1390         ovsdb_datum_clone(dst, src, type);
1391     }
1392     return data;
1393 }
1394
1395 /* Replaces the mt->n_columns ovsdb_datums in row[] by copies of the data from
1396  * in 'row' drawn from the columns represented by mt->columns[]. */
1397 static void
1398 update_monitor_row_data(const struct ovsdb_jsonrpc_monitor_table *mt,
1399                         const struct ovsdb_row *row,
1400                         struct ovsdb_datum *data)
1401 {
1402     size_t i;
1403
1404     for (i = 0; i < mt->n_columns; i++) {
1405         const struct ovsdb_column *c = mt->columns[i].column;
1406         const struct ovsdb_datum *src = &row->fields[c->index];
1407         struct ovsdb_datum *dst = &data[i];
1408         const struct ovsdb_type *type = &c->type;
1409
1410         if (!ovsdb_datum_equals(src, dst, type)) {
1411             ovsdb_datum_destroy(dst, type);
1412             ovsdb_datum_clone(dst, src, type);
1413         }
1414     }
1415 }
1416
1417 /* Frees all of the mt->n_columns ovsdb_datums in data[], using the types taken
1418  * from mt->columns[], plus 'data' itself. */
1419 static void
1420 free_monitor_row_data(const struct ovsdb_jsonrpc_monitor_table *mt,
1421                       struct ovsdb_datum *data)
1422 {
1423     if (data) {
1424         size_t i;
1425
1426         for (i = 0; i < mt->n_columns; i++) {
1427             const struct ovsdb_column *c = mt->columns[i].column;
1428
1429             ovsdb_datum_destroy(&data[i], &c->type);
1430         }
1431         free(data);
1432     }
1433 }
1434
1435 /* Frees 'row', which must have been created from 'mt'. */
1436 static void
1437 ovsdb_jsonrpc_monitor_row_destroy(const struct ovsdb_jsonrpc_monitor_table *mt,
1438                                   struct ovsdb_jsonrpc_monitor_row *row)
1439 {
1440     if (row) {
1441         free_monitor_row_data(mt, row->old);
1442         free_monitor_row_data(mt, row->new);
1443         free(row);
1444     }
1445 }
1446
1447 static bool
1448 ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
1449                                 const struct ovsdb_row *new,
1450                                 const unsigned long int *changed OVS_UNUSED,
1451                                 void *aux_)
1452 {
1453     struct ovsdb_jsonrpc_monitor_aux *aux = aux_;
1454     const struct ovsdb_jsonrpc_monitor *m = aux->monitor;
1455     struct ovsdb_table *table = new ? new->table : old->table;
1456     const struct uuid *uuid = ovsdb_row_get_uuid(new ? new : old);
1457     struct ovsdb_jsonrpc_monitor_row *change;
1458     struct ovsdb_jsonrpc_monitor_table *mt;
1459
1460     if (!aux->mt || table != aux->mt->table) {
1461         aux->mt = shash_find_data(&m->tables, table->schema->name);
1462         if (!aux->mt) {
1463             /* We don't care about rows in this table at all.  Tell the caller
1464              * to skip it.  */
1465             return false;
1466         }
1467     }
1468     mt = aux->mt;
1469
1470     change = ovsdb_jsonrpc_monitor_row_find(mt, uuid);
1471     if (!change) {
1472         change = xmalloc(sizeof *change);
1473         hmap_insert(&mt->changes, &change->hmap_node, uuid_hash(uuid));
1474         change->uuid = *uuid;
1475         change->old = clone_monitor_row_data(mt, old);
1476         change->new = clone_monitor_row_data(mt, new);
1477     } else {
1478         if (new) {
1479             update_monitor_row_data(mt, new, change->new);
1480         } else {
1481             free_monitor_row_data(mt, change->new);
1482             change->new = NULL;
1483
1484             if (!change->old) {
1485                 /* This row was added then deleted.  Forget about it. */
1486                 hmap_remove(&mt->changes, &change->hmap_node);
1487                 free(change);
1488             }
1489         }
1490     }
1491     return true;
1492 }
1493
1494 /* Returns JSON for a <row-update> (as described in ovsdb/SPECS) for 'row'
1495  * within 'mt', or NULL if no row update should be sent.
1496  *
1497  * The caller should specify 'initial' as true if the returned JSON is going to
1498  * be used as part of the initial reply to a "monitor" request, false if it is
1499  * going to be used as part of an "update" notification.
1500  *
1501  * 'changed' must be a scratch buffer for internal use that is at least
1502  * bitmap_n_bytes(mt->n_columns) bytes long. */
1503 static struct json *
1504 ovsdb_jsonrpc_monitor_compose_row_update(
1505     const struct ovsdb_jsonrpc_monitor_table *mt,
1506     const struct ovsdb_jsonrpc_monitor_row *row,
1507     bool initial, unsigned long int *changed)
1508 {
1509     enum ovsdb_jsonrpc_monitor_selection type;
1510     struct json *old_json, *new_json;
1511     struct json *row_json;
1512     size_t i;
1513
1514     type = (initial ? OJMS_INITIAL
1515             : !row->old ? OJMS_INSERT
1516             : !row->new ? OJMS_DELETE
1517             : OJMS_MODIFY);
1518     if (!(mt->select & type)) {
1519         return NULL;
1520     }
1521
1522     if (type == OJMS_MODIFY) {
1523         size_t n_changes;
1524
1525         n_changes = 0;
1526         memset(changed, 0, bitmap_n_bytes(mt->n_columns));
1527         for (i = 0; i < mt->n_columns; i++) {
1528             const struct ovsdb_column *c = mt->columns[i].column;
1529             if (!ovsdb_datum_equals(&row->old[i], &row->new[i], &c->type)) {
1530                 bitmap_set1(changed, i);
1531                 n_changes++;
1532             }
1533         }
1534         if (!n_changes) {
1535             /* No actual changes: presumably a row changed and then
1536              * changed back later. */
1537             return NULL;
1538         }
1539     }
1540
1541     row_json = json_object_create();
1542     old_json = new_json = NULL;
1543     if (type & (OJMS_DELETE | OJMS_MODIFY)) {
1544         old_json = json_object_create();
1545         json_object_put(row_json, "old", old_json);
1546     }
1547     if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1548         new_json = json_object_create();
1549         json_object_put(row_json, "new", new_json);
1550     }
1551     for (i = 0; i < mt->n_columns; i++) {
1552         const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
1553
1554         if (!(type & c->select)) {
1555             /* We don't care about this type of change for this
1556              * particular column (but we will care about it for some
1557              * other column). */
1558             continue;
1559         }
1560
1561         if ((type == OJMS_MODIFY && bitmap_is_set(changed, i))
1562             || type == OJMS_DELETE) {
1563             json_object_put(old_json, c->column->name,
1564                             ovsdb_datum_to_json(&row->old[i],
1565                                                 &c->column->type));
1566         }
1567         if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
1568             json_object_put(new_json, c->column->name,
1569                             ovsdb_datum_to_json(&row->new[i],
1570                                                 &c->column->type));
1571         }
1572     }
1573
1574     return row_json;
1575 }
1576
1577 /* Constructs and returns JSON for a <table-updates> object (as described in
1578  * ovsdb/SPECS) for all the outstanding changes within 'monitor', and deletes
1579  * all the outstanding changes from 'monitor'.  Returns NULL if no update needs
1580  * to be sent.
1581  *
1582  * The caller should specify 'initial' as true if the returned JSON is going to
1583  * be used as part of the initial reply to a "monitor" request, false if it is
1584  * going to be used as part of an "update" notification. */
1585 static struct json *
1586 ovsdb_jsonrpc_monitor_compose_table_update(
1587     const struct ovsdb_jsonrpc_monitor *monitor, bool initial)
1588 {
1589     struct shash_node *node;
1590     unsigned long int *changed;
1591     struct json *json;
1592     size_t max_columns;
1593
1594     max_columns = 0;
1595     SHASH_FOR_EACH (node, &monitor->tables) {
1596         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1597
1598         max_columns = MAX(max_columns, mt->n_columns);
1599     }
1600     changed = xmalloc(bitmap_n_bytes(max_columns));
1601
1602     json = NULL;
1603     SHASH_FOR_EACH (node, &monitor->tables) {
1604         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1605         struct ovsdb_jsonrpc_monitor_row *row, *next;
1606         struct json *table_json = NULL;
1607
1608         HMAP_FOR_EACH_SAFE (row, next, hmap_node, &mt->changes) {
1609             struct json *row_json;
1610
1611             row_json = ovsdb_jsonrpc_monitor_compose_row_update(
1612                 mt, row, initial, changed);
1613             if (row_json) {
1614                 char uuid[UUID_LEN + 1];
1615
1616                 /* Create JSON object for transaction overall. */
1617                 if (!json) {
1618                     json = json_object_create();
1619                 }
1620
1621                 /* Create JSON object for transaction on this table. */
1622                 if (!table_json) {
1623                     table_json = json_object_create();
1624                     json_object_put(json, mt->table->schema->name, table_json);
1625                 }
1626
1627                 /* Add JSON row to JSON table. */
1628                 snprintf(uuid, sizeof uuid, UUID_FMT, UUID_ARGS(&row->uuid));
1629                 json_object_put(table_json, uuid, row_json);
1630             }
1631
1632             hmap_remove(&mt->changes, &row->hmap_node);
1633             ovsdb_jsonrpc_monitor_row_destroy(mt, row);
1634         }
1635     }
1636
1637     free(changed);
1638
1639     return json;
1640 }
1641
1642 static void
1643 ovsdb_jsonrpc_monitor_init_aux(struct ovsdb_jsonrpc_monitor_aux *aux,
1644                                const struct ovsdb_jsonrpc_monitor *m)
1645 {
1646     aux->monitor = m;
1647     aux->mt = NULL;
1648 }
1649
1650 static struct ovsdb_error *
1651 ovsdb_jsonrpc_monitor_commit(struct ovsdb_replica *replica,
1652                              const struct ovsdb_txn *txn,
1653                              bool durable OVS_UNUSED)
1654 {
1655     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1656     struct ovsdb_jsonrpc_monitor_aux aux;
1657     struct json *json;
1658
1659     ovsdb_jsonrpc_monitor_init_aux(&aux, m);
1660     ovsdb_txn_for_each_change(txn, ovsdb_jsonrpc_monitor_change_cb, &aux);
1661     json = ovsdb_jsonrpc_monitor_compose_table_update(m, false);
1662     if (json) {
1663         struct jsonrpc_msg *msg;
1664         struct json *params;
1665
1666         params = json_array_create_2(json_clone(aux.monitor->monitor_id),
1667                                      json);
1668         msg = jsonrpc_create_notify("update", params);
1669         jsonrpc_session_send(aux.monitor->session->js, msg);
1670     }
1671
1672     return NULL;
1673 }
1674
1675 static struct json *
1676 ovsdb_jsonrpc_monitor_get_initial(const struct ovsdb_jsonrpc_monitor *m)
1677 {
1678     struct ovsdb_jsonrpc_monitor_aux aux;
1679     struct shash_node *node;
1680     struct json *json;
1681
1682     ovsdb_jsonrpc_monitor_init_aux(&aux, m);
1683     SHASH_FOR_EACH (node, &m->tables) {
1684         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1685
1686         if (mt->select & OJMS_INITIAL) {
1687             struct ovsdb_row *row;
1688
1689             HMAP_FOR_EACH (row, hmap_node, &mt->table->rows) {
1690                 ovsdb_jsonrpc_monitor_change_cb(NULL, row, NULL, &aux);
1691             }
1692         }
1693     }
1694     json = ovsdb_jsonrpc_monitor_compose_table_update(m, true);
1695     return json ? json : json_object_create();
1696 }
1697
1698 static void
1699 ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *replica)
1700 {
1701     struct ovsdb_jsonrpc_monitor *m = ovsdb_jsonrpc_monitor_cast(replica);
1702     struct shash_node *node;
1703
1704     json_destroy(m->monitor_id);
1705     SHASH_FOR_EACH (node, &m->tables) {
1706         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
1707         struct ovsdb_jsonrpc_monitor_row *row, *next;
1708
1709         HMAP_FOR_EACH_SAFE (row, next, hmap_node, &mt->changes) {
1710             hmap_remove(&mt->changes, &row->hmap_node);
1711             ovsdb_jsonrpc_monitor_row_destroy(mt, row);
1712         }
1713         hmap_destroy(&mt->changes);
1714
1715         free(mt->columns);
1716         free(mt);
1717     }
1718     shash_destroy(&m->tables);
1719     hmap_remove(&m->session->monitors, &m->node);
1720     free(m);
1721 }
1722
1723 static const struct ovsdb_replica_class ovsdb_jsonrpc_replica_class = {
1724     ovsdb_jsonrpc_monitor_commit,
1725     ovsdb_jsonrpc_monitor_destroy
1726 };