X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fovsdb-idl.c;h=94784bdaabfb236e10351da9adbcac983dffa7a8;hb=c3729ee42dc25a8240cee6c0041b7db3e4070414;hp=e1b53f4eb3730de0aaf3ec3f1153722d20847d17;hpb=dcd1dbc5b3088b1729238be752e75e89cbe1fa27;p=openvswitch

diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c
index e1b53f4e..94784bda 100644
--- a/lib/ovsdb-idl.c
+++ b/lib/ovsdb-idl.c
@@ -1108,6 +1108,15 @@ ovsdb_idl_get(const struct ovsdb_idl_row *row,
 
     return ovsdb_idl_read(row, column);
 }
+
+/* Returns false if 'row' was obtained from the IDL, true if it was initialized
+ * to all-zero-bits by some other entity.  If 'row' was set up some other way
+ * then the return value is indeterminate. */
+bool
+ovsdb_idl_row_is_synthetic(const struct ovsdb_idl_row *row)
+{
+    return row->table == NULL;
+}
 
 /* Transactions. */
 
@@ -1420,6 +1429,8 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn)
             } else {
                 struct ovsdb_idl_txn_insert *insert;
 
+                any_updates = true;
+
                 json_object_put(op, "uuid-name",
                                 json_string_create_nocopy(
                                     uuid_name_from_uuid(&row->uuid)));
@@ -1447,13 +1458,22 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn)
                                             ovsdb_datum_to_json(&row->new[idx],
                                                                 &column->type),
                                             txn));
+
+                        /* If anything really changed, consider it an update.
+                         * We can't suppress not-really-changed values earlier
+                         * or transactions would become nonatomic (see the big
+                         * comment inside ovsdb_idl_txn_write()). */
+                        if (!any_updates && row->old &&
+                            !ovsdb_datum_equals(&row->old[idx], &row->new[idx],
+                                                &column->type)) {
+                            any_updates = true;
+                        }
                     }
                 }
             }
 
             if (!row->old || !shash_is_empty(json_object(row_json))) {
                 json_array_add(operations, op);
-                any_updates = true;
             } else {
                 json_destroy(op);
             }
@@ -1642,7 +1662,10 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_,
      *
      * 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. */
+     * different value in that column since we read it.  (But if a whole
+     * transaction only does writes of existing values, without making any real
+     * changes, we will drop the whole transaction later in
+     * ovsdb_idl_txn_commit().) */
     if (row->table->modes[column_idx] == OVSDB_IDL_MONITOR
         && ovsdb_datum_equals(ovsdb_idl_read(row, column),
                               datum, &column->type)) {