Change in openbsc[master]: db.c: implemented incremental migration
diff mbox

Message ID 20160515193119.4F0D01C96D@lists.osmocom.org
State New
Headers show

Commit Message

gerrit-no-reply@lists.osmocom.org May 15, 2016, 7:31 p.m. UTC
From Holger Freyther <holger@freyther.de>:

Holger Freyther has submitted this change and it was merged.

Change subject: db.c: implemented incremental migration
......................................................................


db.c: implemented incremental migration

In the past, normal migration was possible only if the actual
schema version differed from the version used in DB by 1. For
example, if DB uses an old version 3 and you need to use it
with the code written for version 5, the check_db_revision()
will convert it to 4 and DB will still use incompatible schema
version during Osmo-NITB running time. After next run it will
be converted to version 5.

This patch replaces a set of 'else-if' checks by a 'switch'
without 'break' statements between 'case' labels (waterfall).
It makes you able to migrate from current version to the
latest despite any difference between them.

Change-Id: Ia9c2aa86f96b88ad8a710d0a23879ce219bc82dc
Reviewed-on: https://gerrit.osmocom.org/62
Tested-by: Jenkins Builder
Reviewed-by: Holger Freyther <holger@freyther.de>
---
M openbsc/src/libmsc/db.c
1 file changed, 35 insertions(+), 18 deletions(-)

Approvals:
  Jenkins Builder: Verified
  Holger Freyther: Looks good to me, approved

Patch
diff mbox

diff --git a/openbsc/src/libmsc/db.c b/openbsc/src/libmsc/db.c
index e5017ae..b3235bb 100644
--- a/openbsc/src/libmsc/db.c
+++ b/openbsc/src/libmsc/db.c
@@ -374,9 +374,13 @@ 
 {
 	dbi_result result;
 	const char *rev_s;
+	int db_rev = 0;
 
+	/* Make a query */
 	result = dbi_conn_query(conn,
-				"SELECT value FROM Meta WHERE key='revision'");
+		"SELECT value FROM Meta "
+		"WHERE key = 'revision'");
+
 	if (!result)
 		return -EINVAL;
 
@@ -384,33 +388,46 @@ 
 		dbi_result_free(result);
 		return -EINVAL;
 	}
+
+	/* Fetch the DB schema revision */
 	rev_s = dbi_result_get_string(result, "value");
 	if (!rev_s) {
 		dbi_result_free(result);
 		return -EINVAL;
 	}
-	if (!strcmp(rev_s, "2")) {
-		if (update_db_revision_2()) {
-			LOGP(DDB, LOGL_FATAL, "Failed to update database from schema revision '%s'.\n", rev_s);
-			dbi_result_free(result);
-			return -EINVAL;
-		}
-	} else if (!strcmp(rev_s, "3")) {
-		if (update_db_revision_3()) {
-			LOGP(DDB, LOGL_FATAL, "Failed to update database from schema revision '%s'.\n", rev_s);
-			dbi_result_free(result);
-			return -EINVAL;
-		}
-	} else if (!strcmp(rev_s, SCHEMA_REVISION)) {
-		/* everything is fine */
-	} else {
-		LOGP(DDB, LOGL_FATAL, "Invalid database schema revision '%s'.\n", rev_s);
+
+	if (!strcmp(rev_s, SCHEMA_REVISION)) {
+		/* Everything is fine */
 		dbi_result_free(result);
+		return 0;
+	}
+
+	db_rev = atoi(rev_s);
+	dbi_result_free(result);
+
+	/* Incremental migration waterfall */
+	switch (db_rev) {
+	case 2:
+		if (update_db_revision_2())
+			goto error;
+	case 3:
+		if (update_db_revision_3())
+			goto error;
+
+	/* The end of waterfall */
+	break;
+	default:
+		LOGP(DDB, LOGL_FATAL,
+			"Invalid database schema revision '%d'.\n", db_rev);
 		return -EINVAL;
 	}
 
-	dbi_result_free(result);
 	return 0;
+
+error:
+	LOGP(DDB, LOGL_FATAL, "Failed to update database "
+		"from schema revision '%d'.\n", db_rev);
+	return -EINVAL;
 }
 
 static int db_configure(void)