ovsdb-idl: Fix atomicity of writes that don't change a column's value.

[sliver-openvswitch.git] / lib / ovsdb-idl.c

diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
index 448f9c9..911d7b8 100644 (file)
--- a/lib/ovsdb-idl.c
+++ b/lib/ovsdb-idl.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2009, 2010 Nicira Networks.
+/* Copyright (c) 2009, 2010, 2011 Nicira Networks.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -282,7 +282,7 @@ ovsdb_idl_run(struct ovsdb_idl *idl)
     assert(!idl->txn);
     jsonrpc_session_run(idl->session);
     for (i = 0; jsonrpc_session_is_connected(idl->session) && i < 50; i++) {
-        struct jsonrpc_msg *msg, *reply;
+        struct jsonrpc_msg *msg;
         unsigned int seqno;
 
         seqno = jsonrpc_session_get_seqno(idl->session);
@@ -298,7 +298,6 @@ ovsdb_idl_run(struct ovsdb_idl *idl)
             break;
         }
 
-        reply = NULL;
         if (msg->type == JSONRPC_NOTIFY
                    && !strcmp(msg->method, "update")
                    && msg->params->type == JSON_ARRAY
@@ -313,8 +312,7 @@ ovsdb_idl_run(struct ovsdb_idl *idl)
             idl->monitor_request_id = NULL;
             ovsdb_idl_clear(idl);
             ovsdb_idl_parse_update(idl, msg->result);
-        } else if (msg->type == JSONRPC_REPLY
-                   && msg->id && msg->id->type == JSON_STRING
+        } else if (msg->type == JSONRPC_REPLY && msg->id->type == JSON_STRING
                    && !strcmp(msg->id->u.string, "echo")) {
             /* It's a reply to our echo request.  Ignore it. */
         } else if ((msg->type == JSONRPC_ERROR
@@ -329,9 +327,6 @@ ovsdb_idl_run(struct ovsdb_idl *idl)
                      jsonrpc_session_get_name(idl->session),
                      jsonrpc_msg_type_to_string(msg->type));
         }
-        if (reply) {
-            jsonrpc_session_send(idl->session, reply);
-        }
         jsonrpc_msg_destroy(msg);
     }
 
@@ -1441,9 +1436,7 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn)
                                                         &class->columns[idx];
 
                     if (row->old
-                        ? !ovsdb_datum_equals(&row->old[idx], &row->new[idx],
-                                              &column->type)
-                        : !ovsdb_datum_is_default(&row->new[idx],
+                        || !ovsdb_datum_is_default(&row->new[idx],
                                                   &column->type)) {
                         json_object_put(row_json, column->name,
                                         substitute_uuids(
@@ -1638,6 +1631,21 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_,
     assert(row->old == NULL ||
            row->table->modes[column_idx] & OVSDB_IDL_MONITOR);
 
+    /* If this is a write-only column and the datum being written is the same
+     * as the one already there, just skip the update entirely.  This is worth
+     * optimizing because we have a lot of columns that get periodically
+     * refreshed into the database but don't actually change that often.
+     *
+     * We don't do this for read/write columns because that would break
+     * atomicity of transactions--some other client might have written a
+     * different value in that column since we read it. */
+    if (row->table->modes[column_idx] == OVSDB_IDL_MONITOR
+        && ovsdb_datum_equals(ovsdb_idl_read(row, column),
+                              datum, &column->type)) {
+        ovsdb_datum_destroy(datum, &column->type);
+        return;
+    }
+
     if (hmap_node_is_null(&row->txn_node)) {
         hmap_insert(&row->table->idl->txn->txn_rows, &row->txn_node,
                     uuid_hash(&row->uuid));
@@ -1693,6 +1701,8 @@ ovsdb_idl_txn_verify(const struct ovsdb_idl_row *row_,
     size_t column_idx = column - class->columns;
 
     assert(row->new != NULL);
+    assert(row->old == NULL ||
+           row->table->modes[column_idx] & OVSDB_IDL_MONITOR);
     if (!row->old
         || (row->written && bitmap_is_set(row->written, column_idx))) {
         return;