s4:dsdb Add a shortcut sequence number for schema reloads

This uses the ldb sequence number, in a hope to detect an unchanged
schema quicker.

Andrew Bartlett

2 files changed, 81 insertions, 14 deletions

diff --git a/source4/dsdb/samdb/ldb_modules/schema_load.c b/source4/dsdb/samdb/ldb_modules/schema_load.c
index 5dd8fb78c9..d13b339f60 100644
--- a/source4/dsdb/samdb/ldb_modules/schema_load.c
+++ b/source4/dsdb/samdb/ldb_modules/schema_load.c
@@ -42,6 +42,14 @@ struct dsdb_schema *dsdb_schema_refresh(struct ldb_module *module, struct dsdb_s
 {
 	uint64_t current_usn;
 	int ret;
+	struct ldb_result *res;
+	struct ldb_request *treq;
+	struct ldb_seqnum_request *tseq;
+	struct ldb_seqnum_result *tseqr;
+	struct dsdb_control_current_partition *ctrl;
+	struct ldb_context *ldb = ldb_module_get_ctx(module);
+	struct dsdb_schema *new_schema;
+	
 	struct schema_load_private_data *private_data = talloc_get_type(ldb_module_get_private(module), struct schema_load_private_data);
 	if (!private_data) {
 		/* We can't refresh until the init function has run */
@@ -53,22 +61,79 @@ struct dsdb_schema *dsdb_schema_refresh(struct ldb_module *module, struct dsdb_s
 		return schema;
 	}
 
+	res = talloc_zero(schema, struct ldb_result);
+	if (res == NULL) {
+		return NULL;
+	}
+	tseq = talloc_zero(res, struct ldb_seqnum_request);
+	if (tseq == NULL) {
+		talloc_free(res);
+		return NULL;
+	}
+	tseq->type = LDB_SEQ_HIGHEST_SEQ;
+	
+	ret = ldb_build_extended_req(&treq, ldb_module_get_ctx(module), res,
+				     LDB_EXTENDED_SEQUENCE_NUMBER,
+				     tseq,
+				     NULL,
+				     res,
+				     ldb_extended_default_callback,
+				     NULL);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(res);
+		return NULL;
+	}
+	
+	ctrl = talloc(treq, struct dsdb_control_current_partition);
+	if (!ctrl) {
+		talloc_free(res);
+		return NULL;
+	}
+	ctrl->version = DSDB_CONTROL_CURRENT_PARTITION_VERSION;
+	ctrl->dn = schema->base_dn;
+	
+	ret = ldb_request_add_control(treq,
+				      DSDB_CONTROL_CURRENT_PARTITION_OID,
+				      false, ctrl);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(res);
+		return NULL;
+	}
+	
+	ret = ldb_next_request(module, treq);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(res);
+		return NULL;
+	}
+	ret = ldb_wait(treq->handle, LDB_WAIT_ALL);
+	if (ret != LDB_SUCCESS) {
+		talloc_free(res);
+		return NULL;
+	}
+	tseqr = talloc_get_type(res->extended->data,
+				struct ldb_seqnum_result);
+	if (tseqr->seq_num == schema->reload_seq_number) {
+		talloc_free(res);
+		return schema;
+	}
+
+	schema->reload_seq_number = tseqr->seq_num;
+	talloc_free(res);
+		
 	ret = dsdb_module_load_partition_usn(module, schema->base_dn, &current_usn, NULL);
-	if (ret == LDB_SUCCESS && current_usn != schema->loaded_usn) {
-		struct ldb_context *ldb = ldb_module_get_ctx(module);
-		struct dsdb_schema *new_schema;
-
-		ret = dsdb_schema_from_db(module, schema->base_dn, current_usn, &new_schema);
-		if (ret != LDB_SUCCESS) {
-			return schema;
-		}
-
-		if (is_global_schema) {
-			dsdb_make_schema_global(ldb, new_schema);
-		}
-		return new_schema;
+	if (ret != LDB_SUCCESS || current_usn == schema->loaded_usn) {
+		return schema;
+	}
+
+	ret = dsdb_schema_from_db(module, schema->base_dn, current_usn, &new_schema);
+	if (ret != LDB_SUCCESS) {
+		return schema;
+	}
+	
+	if (is_global_schema) {
+		dsdb_make_schema_global(ldb, new_schema);
 	}
-	return schema;
+	return new_schema;
 }
 
 
diff --git a/source4/dsdb/schema/schema.h b/source4/dsdb/schema/schema.h
index b5334c7313..7283744f7d 100644
--- a/source4/dsdb/schema/schema.h
+++ b/source4/dsdb/schema/schema.h
@@ -213,6 +213,8 @@ struct dsdb_schema {
 	struct ldb_module *loaded_from_module;
 	struct dsdb_schema *(*refresh_fn)(struct ldb_module *module, struct dsdb_schema *schema, bool is_global_schema);
 	bool refresh_in_progress;
+	/* an 'opaque' sequence number that the reload function may also wish to use */
+	uint64_t reload_seq_number;
 };
 
 enum dsdb_attr_list_query {