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

[gerrit-no-reply at lists.osmocom.org]

>From Holger Freyther <holger at 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 at 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



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)

-- 
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Gerrit-MessageType: merged
Gerrit-Change-Id: Ia9c2aa86f96b88ad8a710d0a23879ce219bc82dc
Gerrit-PatchSet: 2
Gerrit-Project: openbsc
Gerrit-Branch: master
Gerrit-Owner: Vadim Yanitskiy <axilirator at gmail.com>
Gerrit-Reviewer: Holger Freyther <holger at freyther.de>
Gerrit-Reviewer: Jenkins Builder
Gerrit-Reviewer: Vadim Yanitskiy <axilirator at gmail.com>