ovsdb-server: Log database transactions for user requested tables.

Add a new command, 'ovsdb-server/tlog-set DB:TABLE on|off', which
allows the user to enable/disable transaction logging for specific
databases and tables.

By default, logging is disabled.  Once enabled, logs are generated
with level INFO and are also rate limited.

If used with care, this command can be useful in analyzing production
deployment performance issues, allowing the user to pin point
bottlenecks without the need to enable wider debug logs, e.g., jsonrpc.

A command to inspect the logging state is also added:
'ovsdb-server/tlog-list'.

Signed-off-by: Dumitru Ceara <dceara@redhat.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>

NEWS

@@ -14,6 +14,9 @@ Post-v2.17.0
    - OVSDB:
      * 'relay' service model now supports transaction history, i.e. honors the
        'last-txn-id' field in 'monitor_cond_since' requests from clients.
+     * New unixctl command 'ovsdb-server/tlog-set DB:TABLE on|off".
+       If turned on, ovsdb-server will log (at level INFO and rate limited)
+       all operations that are committed to table TABLE in the DB database.
    - OVSDB-IDL:
      * New monitor mode flag, OVSDB_IDL_WRITE_CHANGED_ONLY, allowing
        applications to relax atomicity requirements when dealing with

ovsdb/ovsdb-server.1.in

@@ -273,6 +273,13 @@ again (with \fBovsdb\-server/add\-db\fR).
 Outputs a list of the currently configured databases added either through
 the command line or through the \fBovsdb\-server/add\-db\fR command.
 .
+.IP "\fBovsdb\-server/tlog\-set \fIdatabase\fR:\fItable\fR \fIon\fR|\fIoff\fR"
+Enables or disables logging of all operations executed on the specified
+database and table.  Logs are generated at INFO level and are rate limtied.
+.
+.IP "\fBovsdb\-server/tlog\-list"
+Displays the logging state for all currently configured databases and tables.
+.
 .SS "Active-Backup Commands"
 .PP
 These commands query and update the role of \fBovsdb\-server\fR within

ovsdb/ovsdb-server.c

@@ -116,6 +116,8 @@ static unixctl_cb_func ovsdb_server_list_remotes;
 static unixctl_cb_func ovsdb_server_add_database;
 static unixctl_cb_func ovsdb_server_remove_database;
 static unixctl_cb_func ovsdb_server_list_databases;
+static unixctl_cb_func ovsdb_server_tlog_set;
+static unixctl_cb_func ovsdb_server_tlog_list;
 
 static void read_db(struct server_config *, struct db *);
 static struct ovsdb_error *open_db(struct server_config *,
@@ -444,6 +446,10 @@ main(int argc, char *argv[])
                              ovsdb_server_remove_database, &server_config);
     unixctl_command_register("ovsdb-server/list-dbs", "", 0, 0,
                              ovsdb_server_list_databases, &all_dbs);
+    unixctl_command_register("ovsdb-server/tlog-set", "DB:TABLE on|off",
+                             2, 2, ovsdb_server_tlog_set, &all_dbs);
+    unixctl_command_register("ovsdb-server/tlog-list", "",
+                             0, 0, ovsdb_server_tlog_list, &all_dbs);
     unixctl_command_register("ovsdb-server/perf-counters-show", "", 0, 0,
                              ovsdb_server_perf_counters_show, NULL);
     unixctl_command_register("ovsdb-server/perf-counters-clear", "", 0, 0,
@@ -1774,6 +1780,87 @@ ovsdb_server_list_databases(struct unixctl_conn *conn, int argc OVS_UNUSED,
     ds_destroy(&s);
 }
 
+static void
+ovsdb_server_tlog_set(struct unixctl_conn *conn, int argc OVS_UNUSED,
+                      const char *argv[], void *all_dbs_)
+{
+    struct shash *all_dbs = all_dbs_;
+    const char *name_ = argv[1];
+    const char *command = argv[2];
+    bool log;
+
+    if (!strcasecmp(command, "on")) {
+        log = true;
+    } else if (!strcasecmp(command, "off")) {
+        log = false;
+    } else {
+        unixctl_command_reply_error(conn, "invalid command argument");
+        return;
+    }
+
+    char *name = xstrdup(name_);
+    char *save_ptr = NULL;
+
+    const char *db_name = strtok_r(name, ":", &save_ptr); /* "DB" */
+    const char *tbl_name = strtok_r(NULL, ":", &save_ptr); /* "TABLE" */
+    if (!db_name || !tbl_name || strtok_r(NULL, ":", &save_ptr)) {
+        unixctl_command_reply_error(conn, "invalid DB:TABLE argument");
+        goto out;
+    }
+
+    struct db *db = shash_find_data(all_dbs, db_name);
+    if (!db) {
+        unixctl_command_reply_error(conn, "no such database");
+        goto out;
+    }
+
+    struct ovsdb_table *table = ovsdb_get_table(db->db, tbl_name);
+    if (!table) {
+        unixctl_command_reply_error(conn, "no such table");
+        goto out;
+    }
+
+    ovsdb_table_logging_enable(table, log);
+    unixctl_command_reply(conn, NULL);
+out:
+    free(name);
+}
+
+static void
+ovsdb_server_tlog_list(struct unixctl_conn *conn, int argc OVS_UNUSED,
+                       const char *argv[] OVS_UNUSED, void *all_dbs_)
+{
+    const struct shash_node **db_nodes;
+    struct ds s = DS_EMPTY_INITIALIZER;
+    struct shash *all_dbs = all_dbs_;
+
+    ds_put_cstr(&s, "database        table                       logging\n");
+    ds_put_cstr(&s, "--------        -----                       -------\n");
+
+    db_nodes = shash_sort(all_dbs);
+    for (size_t i = 0; i < shash_count(all_dbs); i++) {
+        const struct shash_node *db_node = db_nodes[i];
+        struct db *db = db_node->data;
+        if (db->db) {
+            const struct shash_node **tbl_nodes = shash_sort(&db->db->tables);
+
+            ds_put_format(&s, "%-16s \n", db_node->name);
+            for (size_t j = 0; j < shash_count(&db->db->tables); j++) {
+                const char *logging_enabled =
+                    ovsdb_table_is_logging_enabled(tbl_nodes[j]->data)
+                    ? "ON" : "OFF";
+                ds_put_format(&s, "                %-27s %s\n",
+                              tbl_nodes[j]->name, logging_enabled);
+            }
+            free(tbl_nodes);
+        }
+    }
+    free(db_nodes);
+
+    unixctl_command_reply(conn, ds_cstr(&s));
+    ds_destroy(&s);
+}
+
 static void
 ovsdb_server_get_sync_status(struct unixctl_conn *conn, int argc OVS_UNUSED,
                              const char *argv[] OVS_UNUSED, void *config_)

ovsdb/row.c

@@ -343,6 +343,23 @@ ovsdb_row_to_json(const struct ovsdb_row *row,
     }
     return json;
 }
+
+void
+ovsdb_row_to_string(const struct ovsdb_row *row, struct ds *out)
+{
+    struct shash_node *node;
+
+    SHASH_FOR_EACH (node, &row->table->schema->columns) {
+        const struct ovsdb_column *column = node->data;
+
+        ds_put_format(out, "%s:", column->name);
+        ovsdb_datum_to_string(&row->fields[column->index], &column->type, out);
+        ds_put_char(out, ',');
+    }
+    if (shash_count(&row->table->schema->columns)) {
+        ds_chomp(out, ',');
+    }
+}
 
 void
 ovsdb_row_set_init(struct ovsdb_row_set *set)

ovsdb/row.h

@@ -117,6 +117,7 @@ struct ovsdb_error *ovsdb_row_from_json(struct ovsdb_row *,
     OVS_WARN_UNUSED_RESULT;
 struct json *ovsdb_row_to_json(const struct ovsdb_row *,
                                const struct ovsdb_column_set *include);
+void ovsdb_row_to_string(const struct ovsdb_row *, struct ds *);
 
 static inline const struct uuid *
 ovsdb_row_get_uuid(const struct ovsdb_row *row)

ovsdb/table.c

@@ -301,10 +301,23 @@ ovsdb_table_create(struct ovsdb_table_schema *ts)
         hmap_init(&table->indexes[i]);
     }
     hmap_init(&table->rows);
+    table->log = false;
 
     return table;
 }
 
+void
+ovsdb_table_logging_enable(struct ovsdb_table *table, bool enabled)
+{
+    table->log = enabled;
+}
+
+bool
+ovsdb_table_is_logging_enabled(struct ovsdb_table *table)
+{
+    return table->log;
+}
+
 void
 ovsdb_table_destroy(struct ovsdb_table *table)
 {

ovsdb/table.h

@@ -63,10 +63,14 @@ struct ovsdb_table {
      * ovsdb_row"s.  Each of the hmap_nodes in indexes[i] are at index 'i' at
      * the end of struct ovsdb_row, following the 'fields' member. */
     struct hmap *indexes;
+
+    bool log; /* True if logging is enabled for this table. */
 };
 
 struct ovsdb_table *ovsdb_table_create(struct ovsdb_table_schema *);
 void ovsdb_table_destroy(struct ovsdb_table *);
+void ovsdb_table_logging_enable(struct ovsdb_table *, bool);
+bool ovsdb_table_is_logging_enabled(struct ovsdb_table *table);
 
 const struct ovsdb_row *ovsdb_table_get_row(const struct ovsdb_table *,
                                             const struct uuid *);

ovsdb/transaction.c

@@ -29,6 +29,7 @@
 #include "openvswitch/vlog.h"
 #include "ovsdb-error.h"
 #include "ovsdb.h"
+#include "ovs-thread.h"
 #include "row.h"
 #include "storage.h"
 #include "table.h"
@@ -102,6 +103,7 @@ struct ovsdb_txn_row {
 static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
 delete_garbage_row(struct ovsdb_txn *txn, struct ovsdb_txn_row *r);
 static void ovsdb_txn_row_prefree(struct ovsdb_txn_row *);
+static void ovsdb_txn_row_log(const struct ovsdb_txn_row *);
 static struct ovsdb_error * OVS_WARN_UNUSED_RESULT
 for_each_txn_row(struct ovsdb_txn *txn,
                       struct ovsdb_error *(*)(struct ovsdb_txn *,
@@ -111,6 +113,11 @@ for_each_txn_row(struct ovsdb_txn *txn,
  * processed.  */
 static unsigned int serial;
 
+/* Used by ovsdb_txn_row_log() to avoid reallocating dynamic strings
+ * every time a row operation is logged.
+ */
+DEFINE_STATIC_PER_THREAD_DATA(struct ds, row_log_str, DS_EMPTY_INITIALIZER);
+
 struct ovsdb_txn *
 ovsdb_txn_create(struct ovsdb *db)
 {
@@ -471,6 +478,41 @@ update_ref_counts(struct ovsdb_txn *txn)
     return for_each_txn_row(txn, check_ref_count);
 }
 
+static void
+ovsdb_txn_row_log(const struct ovsdb_txn_row *txn_row)
+{
+    static struct vlog_rate_limit rl_row_log = VLOG_RATE_LIMIT_INIT(30, 60);
+
+    if (!txn_row->table->log) {
+        return;
+    }
+
+    size_t n_columns = shash_count(&txn_row->table->schema->columns);
+    struct ovsdb_row *log_row;
+    const char *op = NULL;
+
+    if (!txn_row->old && txn_row->new) {
+        log_row = txn_row->new;
+        op = "inserted";
+    } else if (txn_row->old && txn_row->new
+               && !bitmap_is_all_zeros(txn_row->changed, n_columns)) {
+        log_row = txn_row->new;
+        op = "updated";
+    } else if (txn_row->old && !txn_row->new) {
+        log_row = txn_row->old;
+        op = "deleted";
+    }
+
+    if (op && !VLOG_DROP_INFO(&rl_row_log)) {
+        struct ds *ds = row_log_str_get();
+        ds_clear(ds);
+        ds_put_format(ds, "table:%s,op:%s,", txn_row->table->schema->name,
+                      op);
+        ovsdb_row_to_string(log_row, ds);
+        VLOG_INFO("%s", ds_cstr(ds));
+    }
+}
+
 static struct ovsdb_error *
 ovsdb_txn_row_commit(struct ovsdb_txn *txn OVS_UNUSED,
                      struct ovsdb_txn_row *txn_row)
@@ -494,6 +536,7 @@ ovsdb_txn_row_commit(struct ovsdb_txn *txn OVS_UNUSED,
         }
     }
 
+    ovsdb_txn_row_log(txn_row);
     ovsdb_txn_row_prefree(txn_row);
     if (txn_row->new) {
         txn_row->new->n_refs = txn_row->n_refs;