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>
This commit is contained in:
Vadim Yanitskiy 2016-05-13 15:38:09 +06:00 committed by Holger Freyther
parent 34e2b09278
commit a8d8e93086
1 changed files with 35 additions and 18 deletions

View File

@ -374,9 +374,13 @@ static int check_db_revision(void)
{
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 @@ static int check_db_revision(void)
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)