+
+static void
+ovsdb_idl_set_mode(struct ovsdb_idl *idl,
+ const struct ovsdb_idl_column *column,
+ enum ovsdb_idl_mode mode)
+{
+ size_t i;
+
+ for (i = 0; i < idl->class->n_tables; i++) {
+ const struct ovsdb_idl_table *table = &idl->tables[i];
+ const struct ovsdb_idl_table_class *tc = table->class;
+
+ if (column >= tc->columns && column < &tc->columns[tc->n_columns]) {
+ unsigned char *modep = &table->modes[column - tc->columns];
+ assert(*modep == OVSDB_IDL_MODE_RW || *modep == mode);
+ *modep = mode;
+ return;
+ }
+ }
+
+ NOT_REACHED();
+}
+
+/* By default, 'idl' replicates all of the columns in the remote database, and
+ * ovsdb_idl_run() returns true upon a change to any column in the database.
+ * Call this function to avoid alerting ovsdb_idl_run()'s caller upon changes
+ * to 'column'.
+ *
+ * This is useful for columns that a client treats as "write-only", that is, it
+ * updates them but doesn't want to get alerted about its own updates. It also
+ * won't be alerted about other clients' updates, so this is suitable only for
+ * use by a client that "owns" a particular column.
+ *
+ * The client must be careful not to retain pointers to data in 'column' across
+ * calls to ovsdb_idl_run(), even when that function returns false, because
+ * the client is not alerted to changes.
+ *
+ * This function should be called after ovsdb_idl_create(), but before the
+ * first call to ovsdb_idl_run(). For any given column, this function may be
+ * called or ovsdb_idl_omit() may be called, but not both. */
+void
+ovsdb_idl_set_write_only(struct ovsdb_idl *idl,
+ const struct ovsdb_idl_column *column)
+{
+ ovsdb_idl_set_mode(idl, column, OVSDB_IDL_MODE_WO);
+}
+
+/* By default, 'idl' replicates all of the columns in the remote database.
+ * Call this function to omit replicating 'column'. This saves CPU time and
+ * bandwidth to the database.
+ *
+ * This function should be called after ovsdb_idl_create(), but before the
+ * first call to ovsdb_idl_run(). For any given column, this function may be
+ * called or ovsdb_idl_set_write_only() may be called, but not both. */
+void
+ovsdb_idl_omit(struct ovsdb_idl *idl, const struct ovsdb_idl_column *column)
+{
+ ovsdb_idl_set_mode(idl, column, OVSDB_IDL_MODE_NONE);
+}