X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=ovsdb%2Fjsonrpc-server.c;h=0cc8bdf9fa717bc32a4b28c6fba43d1272f99392;hb=e0edde6fee279cdbbf3c179f5f50adaf0c7c7f1e;hp=18f59c50233458386e087abd4094f42c49388275;hpb=31d0b6c9420fdd960d4e58475c8089b1f52f3494;p=sliver-openvswitch.git

diff --git a/ovsdb/jsonrpc-server.c b/ovsdb/jsonrpc-server.c
index 18f59c502..0cc8bdf9f 100644
--- a/ovsdb/jsonrpc-server.c
+++ b/ovsdb/jsonrpc-server.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009, 2010 Nicira Networks
+/* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -22,6 +22,7 @@
 
 #include "bitmap.h"
 #include "column.h"
+#include "dynamic-string.h"
 #include "json.h"
 #include "jsonrpc.h"
 #include "ovsdb-error.h"
@@ -29,20 +30,21 @@
 #include "ovsdb.h"
 #include "reconnect.h"
 #include "row.h"
+#include "server.h"
 #include "stream.h"
 #include "table.h"
 #include "timeval.h"
 #include "transaction.h"
 #include "trigger.h"
-
-#define THIS_MODULE VLM_ovsdb_jsonrpc_server
 #include "vlog.h"
 
+VLOG_DEFINE_THIS_MODULE(ovsdb_jsonrpc_server);
+
 struct ovsdb_jsonrpc_remote;
 struct ovsdb_jsonrpc_session;
 
 /* Message rate-limiting. */
-struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
+static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
 
 /* Sessions. */
 static struct ovsdb_jsonrpc_session *ovsdb_jsonrpc_session_create(
@@ -51,6 +53,13 @@ static void ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *);
 static void ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *);
 static void ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *);
 static void ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *);
+static void ovsdb_jsonrpc_session_set_all_options(
+    struct ovsdb_jsonrpc_remote *, const struct ovsdb_jsonrpc_options *);
+static bool ovsdb_jsonrpc_session_get_status(
+    const struct ovsdb_jsonrpc_remote *,
+    struct ovsdb_jsonrpc_remote_status *);
+static void ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *);
 
 /* Triggers. */
 static void ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *,
@@ -74,7 +83,7 @@ static void ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *);
 /* JSON-RPC database server. */
 
 struct ovsdb_jsonrpc_server {
-    struct ovsdb *db;
+    struct ovsdb_server up;
     unsigned int n_sessions, max_sessions;
     struct shash remotes;      /* Contains "struct ovsdb_jsonrpc_remote *"s. */
 };
@@ -88,15 +97,17 @@ struct ovsdb_jsonrpc_remote {
     struct list sessions;       /* List of "struct ovsdb_jsonrpc_session"s. */
 };
 
-static void ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *,
-                                            const char *name);
+static struct ovsdb_jsonrpc_remote *ovsdb_jsonrpc_server_add_remote(
+    struct ovsdb_jsonrpc_server *, const char *name,
+    const struct ovsdb_jsonrpc_options *options
+);
 static void ovsdb_jsonrpc_server_del_remote(struct shash_node *);
 
 struct ovsdb_jsonrpc_server *
 ovsdb_jsonrpc_server_create(struct ovsdb *db)
 {
     struct ovsdb_jsonrpc_server *server = xzalloc(sizeof *server);
-    server->db = db;
+    ovsdb_server_init(&server->up, db);
     server->max_sessions = 64;
     shash_init(&server->remotes);
     return server;
@@ -111,11 +122,23 @@ ovsdb_jsonrpc_server_destroy(struct ovsdb_jsonrpc_server *svr)
         ovsdb_jsonrpc_server_del_remote(node);
     }
     shash_destroy(&svr->remotes);
+    ovsdb_server_destroy(&svr->up);
     free(svr);
 }
 
-/* Sets 'svr''s current set of remotes to the names in 'new_remotes'.  The data
- * values in 'new_remotes' are ignored.
+struct ovsdb_jsonrpc_options *
+ovsdb_jsonrpc_default_options(const char *target)
+{
+    struct ovsdb_jsonrpc_options *options = xzalloc(sizeof *options);
+    options->max_backoff = RECONNECT_DEFAULT_MAX_BACKOFF;
+    options->probe_interval = (stream_or_pstream_needs_probes(target)
+                               ? RECONNECT_DEFAULT_PROBE_INTERVAL
+                               : 0);
+    return options;
+}
+
+/* Sets 'svr''s current set of remotes to the names in 'new_remotes', with
+ * options in the struct ovsdb_jsonrpc_options supplied as the data values.
  *
  * A remote is an active or passive stream connection method, e.g. "pssl:" or
  * "tcp:1.2.3.4". */
@@ -127,28 +150,39 @@ ovsdb_jsonrpc_server_set_remotes(struct ovsdb_jsonrpc_server *svr,
 
     SHASH_FOR_EACH_SAFE (node, next, &svr->remotes) {
         if (!shash_find(new_remotes, node->name)) {
+            VLOG_INFO("%s: remote deconfigured", node->name);
             ovsdb_jsonrpc_server_del_remote(node);
         }
     }
     SHASH_FOR_EACH (node, new_remotes) {
-        if (!shash_find(&svr->remotes, node->name)) {
-            ovsdb_jsonrpc_server_add_remote(svr, node->name);
+        const struct ovsdb_jsonrpc_options *options = node->data;
+        struct ovsdb_jsonrpc_remote *remote;
+
+        remote = shash_find_data(&svr->remotes, node->name);
+        if (!remote) {
+            remote = ovsdb_jsonrpc_server_add_remote(svr, node->name, options);
+            if (!remote) {
+                continue;
+            }
         }
+
+        ovsdb_jsonrpc_session_set_all_options(remote, options);
     }
 }
 
-static void
+static struct ovsdb_jsonrpc_remote *
 ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
-                                const char *name)
+                                const char *name,
+                                const struct ovsdb_jsonrpc_options *options)
 {
     struct ovsdb_jsonrpc_remote *remote;
     struct pstream *listener;
     int error;
 
-    error = jsonrpc_pstream_open(name, &listener);
+    error = jsonrpc_pstream_open(name, &listener, options->dscp);
     if (error && error != EAFNOSUPPORT) {
         VLOG_ERR_RL(&rl, "%s: listen failed: %s", name, strerror(error));
-        return;
+        return NULL;
     }
 
     remote = xmalloc(sizeof *remote);
@@ -160,6 +194,7 @@ ovsdb_jsonrpc_server_add_remote(struct ovsdb_jsonrpc_server *svr,
     if (!listener) {
         ovsdb_jsonrpc_session_create(remote, jsonrpc_session_open(name));
     }
+    return remote;
 }
 
 static void
@@ -173,6 +208,34 @@ ovsdb_jsonrpc_server_del_remote(struct shash_node *node)
     free(remote);
 }
 
+/* Stores status information for the remote named 'target', which should have
+ * been configured on 'svr' with a call to ovsdb_jsonrpc_server_set_remotes(),
+ * into '*status'.  On success returns true, on failure (if 'svr' doesn't have
+ * a remote named 'target' or if that remote is an inbound remote that has no
+ * active connections) returns false.  On failure, 'status' will be zeroed.
+ */
+bool
+ovsdb_jsonrpc_server_get_remote_status(
+    const struct ovsdb_jsonrpc_server *svr, const char *target,
+    struct ovsdb_jsonrpc_remote_status *status)
+{
+    const struct ovsdb_jsonrpc_remote *remote;
+
+    memset(status, 0, sizeof *status);
+
+    remote = shash_find_data(&svr->remotes, target);
+    return remote && ovsdb_jsonrpc_session_get_status(remote, status);
+}
+
+void
+ovsdb_jsonrpc_server_free_remote_status(
+    struct ovsdb_jsonrpc_remote_status *status)
+{
+    free(status->locks_held);
+    free(status->locks_waiting);
+    free(status->locks_lost);
+}
+
 /* Forces all of the JSON-RPC sessions managed by 'svr' to disconnect and
  * reconnect. */
 void
@@ -234,12 +297,12 @@ ovsdb_jsonrpc_server_wait(struct ovsdb_jsonrpc_server *svr)
 /* JSON-RPC database server session. */
 
 struct ovsdb_jsonrpc_session {
-    struct ovsdb_jsonrpc_remote *remote;
     struct list node;           /* Element in remote's sessions list. */
+    struct ovsdb_session up;
+    struct ovsdb_jsonrpc_remote *remote;
 
     /* Triggers. */
     struct hmap triggers;       /* Hmap of "struct ovsdb_jsonrpc_trigger"s. */
-    struct list completions;    /* Completed triggers. */
 
     /* Monitors. */
     struct hmap monitors;       /* Hmap of "struct ovsdb_jsonrpc_monitor"s. */
@@ -252,6 +315,8 @@ struct ovsdb_jsonrpc_session {
 static void ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *);
 static int ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *);
 static void ovsdb_jsonrpc_session_wait(struct ovsdb_jsonrpc_session *);
+static void ovsdb_jsonrpc_session_set_options(
+    struct ovsdb_jsonrpc_session *, const struct ovsdb_jsonrpc_options *);
 static void ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *,
                                              struct jsonrpc_msg *);
 static void ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *,
@@ -264,11 +329,11 @@ ovsdb_jsonrpc_session_create(struct ovsdb_jsonrpc_remote *remote,
     struct ovsdb_jsonrpc_session *s;
 
     s = xzalloc(sizeof *s);
+    ovsdb_session_init(&s->up, remote->server->up.db);
     s->remote = remote;
     list_push_back(&remote->sessions, &s->node);
     hmap_init(&s->triggers);
     hmap_init(&s->monitors);
-    list_init(&s->completions);
     s->js = js;
     s->js_seqno = jsonrpc_session_get_seqno(js);
 
@@ -281,9 +346,12 @@ static void
 ovsdb_jsonrpc_session_close(struct ovsdb_jsonrpc_session *s)
 {
     ovsdb_jsonrpc_monitor_remove_all(s);
+    ovsdb_jsonrpc_session_unlock_all(s);
     jsonrpc_session_close(s->js);
     list_remove(&s->node);
+    ovsdb_session_destroy(&s->up);
     s->remote->server->n_sessions--;
+    ovsdb_session_destroy(&s->up);
     free(s);
 }
 
@@ -295,6 +363,7 @@ ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
         s->js_seqno = jsonrpc_session_get_seqno(s->js);
         ovsdb_jsonrpc_trigger_complete_all(s);
         ovsdb_jsonrpc_monitor_remove_all(s);
+        ovsdb_jsonrpc_session_unlock_all(s);
     }
 
     ovsdb_jsonrpc_trigger_complete_done(s);
@@ -318,13 +387,21 @@ ovsdb_jsonrpc_session_run(struct ovsdb_jsonrpc_session *s)
     return jsonrpc_session_is_alive(s->js) ? 0 : ETIMEDOUT;
 }
 
+static void
+ovsdb_jsonrpc_session_set_options(struct ovsdb_jsonrpc_session *session,
+                                  const struct ovsdb_jsonrpc_options *options)
+{
+    jsonrpc_session_set_max_backoff(session->js, options->max_backoff);
+    jsonrpc_session_set_probe_interval(session->js, options->probe_interval);
+    jsonrpc_session_set_dscp(session->js, options->dscp);
+}
+
 static void
 ovsdb_jsonrpc_session_run_all(struct ovsdb_jsonrpc_remote *remote)
 {
     struct ovsdb_jsonrpc_session *s, *next;
 
-    LIST_FOR_EACH_SAFE (s, next, struct ovsdb_jsonrpc_session, node,
-                        &remote->sessions) {
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
         int error = ovsdb_jsonrpc_session_run(s);
         if (error) {
             ovsdb_jsonrpc_session_close(s);
@@ -346,7 +423,7 @@ ovsdb_jsonrpc_session_wait_all(struct ovsdb_jsonrpc_remote *remote)
 {
     struct ovsdb_jsonrpc_session *s;
 
-    LIST_FOR_EACH (s, struct ovsdb_jsonrpc_session, node, &remote->sessions) {
+    LIST_FOR_EACH (s, node, &remote->sessions) {
         ovsdb_jsonrpc_session_wait(s);
     }
 }
@@ -356,8 +433,7 @@ ovsdb_jsonrpc_session_close_all(struct ovsdb_jsonrpc_remote *remote)
 {
     struct ovsdb_jsonrpc_session *s, *next;
 
-    LIST_FOR_EACH_SAFE (s, next, struct ovsdb_jsonrpc_session, node,
-                        &remote->sessions) {
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
         ovsdb_jsonrpc_session_close(s);
     }
 }
@@ -369,8 +445,7 @@ ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
 {
     struct ovsdb_jsonrpc_session *s, *next;
 
-    LIST_FOR_EACH_SAFE (s, next, struct ovsdb_jsonrpc_session, node,
-                        &remote->sessions) {
+    LIST_FOR_EACH_SAFE (s, next, node, &remote->sessions) {
         jsonrpc_session_force_reconnect(s->js);
         if (!jsonrpc_session_is_alive(s->js)) {
             ovsdb_jsonrpc_session_close(s);
@@ -378,10 +453,73 @@ ovsdb_jsonrpc_session_reconnect_all(struct ovsdb_jsonrpc_remote *remote)
     }
 }
 
+/* Sets the options for all of the JSON-RPC sessions managed by 'remote' to
+ * 'options'. */
+static void
+ovsdb_jsonrpc_session_set_all_options(
+    struct ovsdb_jsonrpc_remote *remote,
+    const struct ovsdb_jsonrpc_options *options)
+{
+    struct ovsdb_jsonrpc_session *s;
+
+    LIST_FOR_EACH (s, node, &remote->sessions) {
+        ovsdb_jsonrpc_session_set_options(s, options);
+    }
+}
+
+static bool
+ovsdb_jsonrpc_session_get_status(const struct ovsdb_jsonrpc_remote *remote,
+                                 struct ovsdb_jsonrpc_remote_status *status)
+{
+    const struct ovsdb_jsonrpc_session *s;
+    const struct jsonrpc_session *js;
+    struct ovsdb_lock_waiter *waiter;
+    struct reconnect_stats rstats;
+    struct ds locks_held, locks_waiting, locks_lost;
+
+    if (list_is_empty(&remote->sessions)) {
+        return false;
+    }
+    s = CONTAINER_OF(remote->sessions.next, struct ovsdb_jsonrpc_session, node);
+    js = s->js;
+
+    status->is_connected = jsonrpc_session_is_connected(js);
+    status->last_error = jsonrpc_session_get_status(js);
+
+    jsonrpc_session_get_reconnect_stats(js, &rstats);
+    status->state = rstats.state;
+    status->sec_since_connect = rstats.msec_since_connect == UINT_MAX
+        ? UINT_MAX : rstats.msec_since_connect / 1000;
+    status->sec_since_disconnect = rstats.msec_since_disconnect == UINT_MAX
+        ? UINT_MAX : rstats.msec_since_disconnect / 1000;
+
+    ds_init(&locks_held);
+    ds_init(&locks_waiting);
+    ds_init(&locks_lost);
+    HMAP_FOR_EACH (waiter, session_node, &s->up.waiters) {
+        struct ds *string;
+
+        string = (ovsdb_lock_waiter_is_owner(waiter) ? &locks_held
+                  : waiter->mode == OVSDB_LOCK_WAIT ? &locks_waiting
+                  : &locks_lost);
+        if (string->length) {
+            ds_put_char(string, ' ');
+        }
+        ds_put_cstr(string, waiter->lock_name);
+    }
+    status->locks_held = ds_steal_cstr(&locks_held);
+    status->locks_waiting = ds_steal_cstr(&locks_waiting);
+    status->locks_lost = ds_steal_cstr(&locks_lost);
+
+    status->n_connections = list_size(&remote->sessions);
+
+    return true;
+}
+
 static const char *
 get_db_name(const struct ovsdb_jsonrpc_session *s)
 {
-    return s->remote->server->db->schema->name;
+    return s->remote->server->up.db->schema->name;
 }
 
 static struct jsonrpc_msg *
@@ -420,6 +558,144 @@ error:
     return reply;
 }
 
+static struct ovsdb_error *
+ovsdb_jsonrpc_session_parse_lock_name(const struct jsonrpc_msg *request,
+                                      const char **lock_namep)
+{
+    const struct json_array *params;
+
+    params = json_array(request->params);
+    if (params->n != 1 || params->elems[0]->type != JSON_STRING ||
+        !ovsdb_parser_is_id(json_string(params->elems[0]))) {
+        *lock_namep = NULL;
+        return ovsdb_syntax_error(request->params, NULL,
+                                  "%s request params must be <id>",
+                                  request->method);
+    }
+
+    *lock_namep = json_string(params->elems[0]);
+    return NULL;
+}
+
+static void
+ovsdb_jsonrpc_session_notify(struct ovsdb_session *session,
+                             const char *lock_name,
+                             const char *method)
+{
+    struct ovsdb_jsonrpc_session *s;
+    struct json *params;
+
+    s = CONTAINER_OF(session, struct ovsdb_jsonrpc_session, up);
+    params = json_array_create_1(json_string_create(lock_name));
+    jsonrpc_session_send(s->js, jsonrpc_create_notify(method, params));
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_session_lock(struct ovsdb_jsonrpc_session *s,
+                           struct jsonrpc_msg *request,
+                           enum ovsdb_lock_mode mode)
+{
+    struct ovsdb_lock_waiter *waiter;
+    struct jsonrpc_msg *reply;
+    struct ovsdb_error *error;
+    struct ovsdb_session *victim;
+    const char *lock_name;
+    struct json *result;
+
+    error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
+    if (error) {
+        goto error;
+    }
+
+    /* Report error if this session has issued a "lock" or "steal" without a
+     * matching "unlock" for this lock. */
+    waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
+    if (waiter) {
+        error = ovsdb_syntax_error(
+            request->params, NULL,
+            "must issue \"unlock\" before new \"%s\"", request->method);
+        goto error;
+    }
+
+    /* Get the lock, add us as a waiter. */
+    waiter = ovsdb_server_lock(&s->remote->server->up, &s->up, lock_name, mode,
+                               &victim);
+    if (victim) {
+        ovsdb_jsonrpc_session_notify(victim, lock_name, "stolen");
+    }
+
+    result = json_object_create();
+    json_object_put(result, "locked",
+                    json_boolean_create(ovsdb_lock_waiter_is_owner(waiter)));
+
+    return jsonrpc_create_reply(result, request->id);
+
+error:
+    reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
+    ovsdb_error_destroy(error);
+    return reply;
+}
+
+static void
+ovsdb_jsonrpc_session_unlock_all(struct ovsdb_jsonrpc_session *s)
+{
+    struct ovsdb_lock_waiter *waiter, *next;
+
+    HMAP_FOR_EACH_SAFE (waiter, next, session_node, &s->up.waiters) {
+        ovsdb_jsonrpc_session_unlock__(waiter);
+    }
+}
+
+static void
+ovsdb_jsonrpc_session_unlock__(struct ovsdb_lock_waiter *waiter)
+{
+    struct ovsdb_lock *lock = waiter->lock;
+
+    if (lock) {
+        struct ovsdb_session *new_owner = ovsdb_lock_waiter_remove(waiter);
+        if (new_owner) {
+            ovsdb_jsonrpc_session_notify(new_owner, lock->name, "locked");
+        } else {
+            /* ovsdb_server_lock() might have freed 'lock'. */
+        }
+    }
+
+    ovsdb_lock_waiter_destroy(waiter);
+}
+
+static struct jsonrpc_msg *
+ovsdb_jsonrpc_session_unlock(struct ovsdb_jsonrpc_session *s,
+                             struct jsonrpc_msg *request)
+{
+    struct ovsdb_lock_waiter *waiter;
+    struct jsonrpc_msg *reply;
+    struct ovsdb_error *error;
+    const char *lock_name;
+
+    error = ovsdb_jsonrpc_session_parse_lock_name(request, &lock_name);
+    if (error) {
+        goto error;
+    }
+
+    /* Report error if this session has not issued a "lock" or "steal" for this
+     * lock. */
+    waiter = ovsdb_session_get_lock_waiter(&s->up, lock_name);
+    if (!waiter) {
+        error = ovsdb_syntax_error(
+            request->params, NULL, "\"unlock\" without \"lock\" or \"steal\"");
+        goto error;
+    }
+
+    ovsdb_jsonrpc_session_unlock__(waiter);
+
+    return jsonrpc_create_reply(json_object_create(), request->id);
+
+error:
+    reply = jsonrpc_create_reply(ovsdb_error_to_json(error), request->id);
+    ovsdb_error_destroy(error);
+    return reply;
+}
+
 static struct jsonrpc_msg *
 execute_transaction(struct ovsdb_jsonrpc_session *s,
                     struct jsonrpc_msg *request)
@@ -455,13 +731,19 @@ ovsdb_jsonrpc_session_got_request(struct ovsdb_jsonrpc_session *s,
         reply = ovsdb_jsonrpc_check_db_name(s, request);
         if (!reply) {
             reply = jsonrpc_create_reply(
-                ovsdb_schema_to_json(s->remote->server->db->schema),
+                ovsdb_schema_to_json(s->remote->server->up.db->schema),
                 request->id);
         }
     } else if (!strcmp(request->method, "list_dbs")) {
         reply = jsonrpc_create_reply(
             json_array_create_1(json_string_create(get_db_name(s))),
             request->id);
+    } else if (!strcmp(request->method, "lock")) {
+        reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_WAIT);
+    } else if (!strcmp(request->method, "steal")) {
+        reply = ovsdb_jsonrpc_session_lock(s, request, OVSDB_LOCK_STEAL);
+    } else if (!strcmp(request->method, "unlock")) {
+        reply = ovsdb_jsonrpc_session_unlock(s, request);
     } else if (!strcmp(request->method, "echo")) {
         reply = jsonrpc_create_reply(json_clone(request->params), request->id);
     } else {
@@ -507,7 +789,6 @@ ovsdb_jsonrpc_session_got_notify(struct ovsdb_jsonrpc_session *s,
 
 struct ovsdb_jsonrpc_trigger {
     struct ovsdb_trigger trigger;
-    struct ovsdb_jsonrpc_session *session;
     struct hmap_node hmap_node; /* In session's "triggers" hmap. */
     struct json *id;
 };
@@ -535,10 +816,7 @@ ovsdb_jsonrpc_trigger_create(struct ovsdb_jsonrpc_session *s,
 
     /* Insert into trigger table. */
     t = xmalloc(sizeof *t);
-    ovsdb_trigger_init(s->remote->server->db,
-                       &t->trigger, params, &s->completions,
-                       time_msec());
-    t->session = s;
+    ovsdb_trigger_init(&s->up, &t->trigger, params, time_msec());
     t->id = id;
     hmap_insert(&s->triggers, &t->hmap_node, hash);
 
@@ -554,8 +832,7 @@ ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 {
     struct ovsdb_jsonrpc_trigger *t;
 
-    HMAP_FOR_EACH_WITH_HASH (t, struct ovsdb_jsonrpc_trigger, hmap_node, hash,
-                             &s->triggers) {
+    HMAP_FOR_EACH_WITH_HASH (t, hmap_node, hash, &s->triggers) {
         if (json_equal(t->id, id)) {
             return t;
         }
@@ -567,7 +844,9 @@ ovsdb_jsonrpc_trigger_find(struct ovsdb_jsonrpc_session *s,
 static void
 ovsdb_jsonrpc_trigger_complete(struct ovsdb_jsonrpc_trigger *t)
 {
-    struct ovsdb_jsonrpc_session *s = t->session;
+    struct ovsdb_jsonrpc_session *s;
+
+    s = CONTAINER_OF(t->trigger.session, struct ovsdb_jsonrpc_session, up);
 
     if (jsonrpc_session_is_connected(s->js)) {
         struct jsonrpc_msg *reply;
@@ -593,8 +872,7 @@ static void
 ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 {
     struct ovsdb_jsonrpc_trigger *t, *next;
-    HMAP_FOR_EACH_SAFE (t, next, struct ovsdb_jsonrpc_trigger, hmap_node,
-                        &s->triggers) {
+    HMAP_FOR_EACH_SAFE (t, next, hmap_node, &s->triggers) {
         ovsdb_jsonrpc_trigger_complete(t);
     }
 }
@@ -602,9 +880,9 @@ ovsdb_jsonrpc_trigger_complete_all(struct ovsdb_jsonrpc_session *s)
 static void
 ovsdb_jsonrpc_trigger_complete_done(struct ovsdb_jsonrpc_session *s)
 {
-    while (!list_is_empty(&s->completions)) {
+    while (!list_is_empty(&s->up.completions)) {
         struct ovsdb_jsonrpc_trigger *t
-            = CONTAINER_OF(s->completions.next,
+            = CONTAINER_OF(s->up.completions.next,
                            struct ovsdb_jsonrpc_trigger, trigger.node);
         ovsdb_jsonrpc_trigger_complete(t);
     }
@@ -619,12 +897,26 @@ enum ovsdb_jsonrpc_monitor_selection {
     OJMS_MODIFY = 1 << 3        /* Modified rows. */
 };
 
+/* A particular column being monitored. */
+struct ovsdb_jsonrpc_monitor_column {
+    const struct ovsdb_column *column;
+    enum ovsdb_jsonrpc_monitor_selection select;
+};
+
+/* A particular table being monitored. */
 struct ovsdb_jsonrpc_monitor_table {
     const struct ovsdb_table *table;
+
+    /* This is the union (bitwise-OR) of the 'select' values in all of the
+     * members of 'columns' below. */
     enum ovsdb_jsonrpc_monitor_selection select;
-    struct ovsdb_column_set columns;
+
+    /* Columns being monitored. */
+    struct ovsdb_jsonrpc_monitor_column *columns;
+    size_t n_columns;
 };
 
+/* A collection of tables being monitored. */
 struct ovsdb_jsonrpc_monitor {
     struct ovsdb_replica replica;
     struct ovsdb_jsonrpc_session *session;
@@ -657,8 +949,7 @@ ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
 {
     struct ovsdb_jsonrpc_monitor *m;
 
-    HMAP_FOR_EACH_WITH_HASH (m, struct ovsdb_jsonrpc_monitor, node,
-                             json_hash(monitor_id, 0), &s->monitors) {
+    HMAP_FOR_EACH_WITH_HASH (m, node, json_hash(monitor_id, 0), &s->monitors) {
         if (json_equal(m->monitor_id, monitor_id)) {
             return m;
         }
@@ -667,6 +958,118 @@ ovsdb_jsonrpc_monitor_find(struct ovsdb_jsonrpc_session *s,
     return NULL;
 }
 
+static void
+ovsdb_jsonrpc_add_monitor_column(struct ovsdb_jsonrpc_monitor_table *mt,
+                                 const struct ovsdb_column *column,
+                                 enum ovsdb_jsonrpc_monitor_selection select,
+                                 size_t *allocated_columns)
+{
+    struct ovsdb_jsonrpc_monitor_column *c;
+
+    if (mt->n_columns >= *allocated_columns) {
+        mt->columns = x2nrealloc(mt->columns, allocated_columns,
+                                 sizeof *mt->columns);
+    }
+
+    c = &mt->columns[mt->n_columns++];
+    c->column = column;
+    c->select = select;
+}
+
+static int
+compare_ovsdb_jsonrpc_monitor_column(const void *a_, const void *b_)
+{
+    const struct ovsdb_jsonrpc_monitor_column *a = a_;
+    const struct ovsdb_jsonrpc_monitor_column *b = b_;
+
+    return a->column < b->column ? -1 : a->column > b->column;
+}
+
+static struct ovsdb_error * WARN_UNUSED_RESULT
+ovsdb_jsonrpc_parse_monitor_request(struct ovsdb_jsonrpc_monitor_table *mt,
+                                    const struct json *monitor_request,
+                                    size_t *allocated_columns)
+{
+    const struct ovsdb_table_schema *ts = mt->table->schema;
+    enum ovsdb_jsonrpc_monitor_selection select;
+    const struct json *columns, *select_json;
+    struct ovsdb_parser parser;
+    struct ovsdb_error *error;
+
+    ovsdb_parser_init(&parser, monitor_request, "table %s", ts->name);
+    columns = ovsdb_parser_member(&parser, "columns", OP_ARRAY | OP_OPTIONAL);
+    select_json = ovsdb_parser_member(&parser, "select",
+                                      OP_OBJECT | OP_OPTIONAL);
+    error = ovsdb_parser_finish(&parser);
+    if (error) {
+        return error;
+    }
+
+    if (select_json) {
+        select = 0;
+        ovsdb_parser_init(&parser, select_json, "table %s select", ts->name);
+        if (parse_bool(&parser, "initial", true)) {
+            select |= OJMS_INITIAL;
+        }
+        if (parse_bool(&parser, "insert", true)) {
+            select |= OJMS_INSERT;
+        }
+        if (parse_bool(&parser, "delete", true)) {
+            select |= OJMS_DELETE;
+        }
+        if (parse_bool(&parser, "modify", true)) {
+            select |= OJMS_MODIFY;
+        }
+        error = ovsdb_parser_finish(&parser);
+        if (error) {
+            return error;
+        }
+    } else {
+        select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
+    }
+    mt->select |= select;
+
+    if (columns) {
+        size_t i;
+
+        if (columns->type != JSON_ARRAY) {
+            return ovsdb_syntax_error(columns, NULL,
+                                      "array of column names expected");
+        }
+
+        for (i = 0; i < columns->u.array.n; i++) {
+            const struct ovsdb_column *column;
+            const char *s;
+
+            if (columns->u.array.elems[i]->type != JSON_STRING) {
+                return ovsdb_syntax_error(columns, NULL,
+                                          "array of column names expected");
+            }
+
+            s = columns->u.array.elems[i]->u.string;
+            column = shash_find_data(&mt->table->schema->columns, s);
+            if (!column) {
+                return ovsdb_syntax_error(columns, NULL, "%s is not a valid "
+                                          "column name", s);
+            }
+            ovsdb_jsonrpc_add_monitor_column(mt, column, select,
+                                             allocated_columns);
+        }
+    } else {
+        struct shash_node *node;
+
+        SHASH_FOR_EACH (node, &ts->columns) {
+            const struct ovsdb_column *column = node->data;
+            if (column->index != OVSDB_COL_UUID) {
+                ovsdb_jsonrpc_add_monitor_column(mt, column, select,
+                                                 allocated_columns);
+            }
+        }
+    }
+
+    return NULL;
+}
+
 static struct json *
 ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
                              struct json *params)
@@ -696,7 +1099,7 @@ ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
 
     m = xzalloc(sizeof *m);
     ovsdb_replica_init(&m->replica, &ovsdb_jsonrpc_replica_class);
-    ovsdb_add_replica(s->remote->server->db, &m->replica);
+    ovsdb_add_replica(s->remote->server->up.db, &m->replica);
     m->session = s;
     hmap_insert(&s->monitors, &m->node, json_hash(monitor_id, 0));
     m->monitor_id = json_clone(monitor_id);
@@ -705,10 +1108,11 @@ ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
     SHASH_FOR_EACH (node, json_object(monitor_requests)) {
         const struct ovsdb_table *table;
         struct ovsdb_jsonrpc_monitor_table *mt;
-        const struct json *columns_json, *select_json;
-        struct ovsdb_parser parser;
+        size_t allocated_columns;
+        const struct json *mr_value;
+        size_t i;
 
-        table = ovsdb_get_table(s->remote->server->db, node->name);
+        table = ovsdb_get_table(s->remote->server->up.db, node->name);
         if (!table) {
             error = ovsdb_syntax_error(NULL, NULL,
                                        "no table named %s", node->name);
@@ -717,55 +1121,37 @@ ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
 
         mt = xzalloc(sizeof *mt);
         mt->table = table;
-        mt->select = OJMS_INITIAL | OJMS_INSERT | OJMS_DELETE | OJMS_MODIFY;
-        ovsdb_column_set_init(&mt->columns);
         shash_add(&m->tables, table->schema->name, mt);
 
-        ovsdb_parser_init(&parser, node->data, "table %s", node->name);
-        columns_json = ovsdb_parser_member(&parser, "columns",
-                                           OP_ARRAY | OP_OPTIONAL);
-        select_json = ovsdb_parser_member(&parser, "select",
-                                          OP_OBJECT | OP_OPTIONAL);
-        error = ovsdb_parser_finish(&parser);
-        if (error) {
-            goto error;
-        }
-
-        if (columns_json) {
-            error = ovsdb_column_set_from_json(columns_json, table,
-                                               &mt->columns);
-            if (error) {
-                goto error;
+        /* Parse columns. */
+        mr_value = node->data;
+        allocated_columns = 0;
+        if (mr_value->type == JSON_ARRAY) {
+            const struct json_array *array = &mr_value->u.array;
+
+            for (i = 0; i < array->n; i++) {
+                error = ovsdb_jsonrpc_parse_monitor_request(
+                    mt, array->elems[i], &allocated_columns);
+                if (error) {
+                    goto error;
+                }
             }
         } else {
-            struct shash_node *node;
-
-            SHASH_FOR_EACH (node, &table->schema->columns) {
-                const struct ovsdb_column *column = node->data;
-                if (column->index != OVSDB_COL_UUID) {
-                    ovsdb_column_set_add(&mt->columns, column);
-                }
+            error = ovsdb_jsonrpc_parse_monitor_request(
+                mt, mr_value, &allocated_columns);
+            if (error) {
+                goto error;
             }
         }
 
-        if (select_json) {
-            mt->select = 0;
-            ovsdb_parser_init(&parser, select_json, "table %s select",
-                              table->schema->name);
-            if (parse_bool(&parser, "initial", true)) {
-                mt->select |= OJMS_INITIAL;
-            }
-            if (parse_bool(&parser, "insert", true)) {
-                mt->select |= OJMS_INSERT;
-            }
-            if (parse_bool(&parser, "delete", true)) {
-                mt->select |= OJMS_DELETE;
-            }
-            if (parse_bool(&parser, "modify", true)) {
-                mt->select |= OJMS_MODIFY;
-            }
-            error = ovsdb_parser_finish(&parser);
-            if (error) {
+        /* Check for duplicate columns. */
+        qsort(mt->columns, mt->n_columns, sizeof *mt->columns,
+              compare_ovsdb_jsonrpc_monitor_column);
+        for (i = 1; i < mt->n_columns; i++) {
+            if (mt->columns[i].column == mt->columns[i - 1].column) {
+                error = ovsdb_syntax_error(mr_value, NULL, "column %s "
+                                           "mentioned more than once",
+                                           mt->columns[i].column->name);
                 goto error;
             }
         }
@@ -775,7 +1161,7 @@ ovsdb_jsonrpc_monitor_create(struct ovsdb_jsonrpc_session *s,
 
 error:
     if (m) {
-        ovsdb_remove_replica(s->remote->server->db, &m->replica);
+        ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
     }
 
     json = ovsdb_error_to_json(error);
@@ -799,7 +1185,7 @@ ovsdb_jsonrpc_monitor_cancel(struct ovsdb_jsonrpc_session *s,
             return jsonrpc_create_error(json_string_create("unknown monitor"),
                                         request_id);
         } else {
-            ovsdb_remove_replica(s->remote->server->db, &m->replica);
+            ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
             return jsonrpc_create_reply(json_object_create(), request_id);
         }
     }
@@ -810,9 +1196,8 @@ ovsdb_jsonrpc_monitor_remove_all(struct ovsdb_jsonrpc_session *s)
 {
     struct ovsdb_jsonrpc_monitor *m, *next;
 
-    HMAP_FOR_EACH_SAFE (m, next,
-                        struct ovsdb_jsonrpc_monitor, node, &s->monitors) {
-        ovsdb_remove_replica(s->remote->server->db, &m->replica);
+    HMAP_FOR_EACH_SAFE (m, next, node, &s->monitors) {
+        ovsdb_remove_replica(s->remote->server->up.db, &m->replica);
     }
 }
 
@@ -833,6 +1218,24 @@ struct ovsdb_jsonrpc_monitor_aux {
     struct json *table_json;    /* JSON for table's transaction. */
 };
 
+static bool
+any_reportable_change(const struct ovsdb_jsonrpc_monitor_table *mt,
+                      const unsigned long int *changed)
+{
+    size_t i;
+
+    for (i = 0; i < mt->n_columns; i++) {
+        const struct ovsdb_jsonrpc_monitor_column *c = &mt->columns[i];
+        unsigned int idx = c->column->index;
+
+        if (c->select & OJMS_MODIFY && bitmap_is_set(changed, idx)) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 static bool
 ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
                                 const struct ovsdb_row *new,
@@ -846,7 +1249,6 @@ ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
     struct json *old_json, *new_json;
     struct json *row_json;
     char uuid[UUID_LEN + 1];
-    int n_changed;
     size_t i;
 
     if (!aux->mt || table != aux->mt->table) {
@@ -869,40 +1271,41 @@ ovsdb_jsonrpc_monitor_change_cb(const struct ovsdb_row *old,
         return true;
     }
 
+    if (type == OJMS_MODIFY && !any_reportable_change(aux->mt, changed)) {
+        /* Nothing of interest changed. */
+        return true;
+    }
+
     old_json = new_json = NULL;
-    n_changed = 0;
-    for (i = 0; i < aux->mt->columns.n_columns; i++) {
-        const struct ovsdb_column *column = aux->mt->columns.columns[i];
-        unsigned int idx = column->index;
-        bool column_changed = false;
-
-        if (type == OJMS_MODIFY) {
-            column_changed = bitmap_is_set(changed, idx);
-            n_changed += column_changed;
-        }
-        if (column_changed || type == OJMS_DELETE) {
-            if (!old_json) {
-                old_json = json_object_create();
-            }
+    if (type & (OJMS_DELETE | OJMS_MODIFY)) {
+        old_json = json_object_create();
+    }
+    if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
+        new_json = json_object_create();
+    }
+    for (i = 0; i < aux->mt->n_columns; i++) {
+        const struct ovsdb_jsonrpc_monitor_column *c = &aux->mt->columns[i];
+        const struct ovsdb_column *column = c->column;
+        unsigned int idx = c->column->index;
+
+        if (!(type & c->select)) {
+            /* We don't care about this type of change for this particular
+             * column (but we will care about it for some other column). */
+            continue;
+        }
+
+        if ((type == OJMS_MODIFY && bitmap_is_set(changed, idx))
+            || type == OJMS_DELETE) {
             json_object_put(old_json, column->name,
                             ovsdb_datum_to_json(&old->fields[idx],
                                                 &column->type));
         }
         if (type & (OJMS_INITIAL | OJMS_INSERT | OJMS_MODIFY)) {
-            if (!new_json) {
-                new_json = json_object_create();
-            }
             json_object_put(new_json, column->name,
                             ovsdb_datum_to_json(&new->fields[idx],
                                                 &column->type));
         }
     }
-    if ((type == OJMS_MODIFY && !n_changed) || (!old_json && !new_json)) {
-        /* No reportable changes. */
-        json_destroy(old_json);
-        json_destroy(new_json);
-        return true;
-    }
 
     /* Create JSON object for transaction overall. */
     if (!aux->json) {
@@ -981,8 +1384,7 @@ ovsdb_jsonrpc_monitor_get_initial(const struct ovsdb_jsonrpc_monitor *m)
         if (mt->select & OJMS_INITIAL) {
             struct ovsdb_row *row;
 
-            HMAP_FOR_EACH (row, struct ovsdb_row, hmap_node,
-                           &mt->table->rows) {
+            HMAP_FOR_EACH (row, hmap_node, &mt->table->rows) {
                 ovsdb_jsonrpc_monitor_change_cb(NULL, row, NULL, &aux);
             }
         }
@@ -999,7 +1401,7 @@ ovsdb_jsonrpc_monitor_destroy(struct ovsdb_replica *replica)
     json_destroy(m->monitor_id);
     SHASH_FOR_EACH (node, &m->tables) {
         struct ovsdb_jsonrpc_monitor_table *mt = node->data;
-        ovsdb_column_set_destroy(&mt->columns);
+        free(mt->columns);
         free(mt);
     }
     shash_destroy(&m->tables);