tier/ctr: Solution for db locks for tier migrator and ctr using sqlite version less than 3.7 i.e rhel 6.7

Problem: On RHEL 6.7, we have sqlite version 3.6.2 which doesnt support
WAL journaling mode, as this journaling mode is only available in sqlite 3.7 and above.
As a result we cannot have to progreses concurrently accessing sqlite, without
running into db locks! Well WAL is also need for performace on CTR side.

Solution: This solution is to use CTR db connection for doing queries when WAL mode is
absent. i,e tier migrator will send sync_op ipc calls to CTR, which in turn will
do the query and create/update the query file suggested by tier migrator.

Pending: Well this solution will stop the db locks but the performance is still an issue for CTR.
We are developing an in-Memory Transaction Log (iMeTaL) which will help boost the CTR
performance by doing in memory udpates on the IO path and later flush the updates to
the db in a batch/segment flush.

Change-Id: Ie3149643ded159234b5cc6aa6cf93b9022c2f124
BUG: 1240577
Signed-off-by: Joseph Fernandes <josferna@redhat.com>
Signed-off-by: Dan Lambright <dlambrig@redhat.com>
Signed-off-by: Joseph Fernandes <josferna@redhat.com>
Reviewed-on: http://review.gluster.org/12191
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Luis Pabon <lpabon@redhat.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/libglusterfs/src/gfdb/gfdb_sqlite3.h b/libglusterfs/src/gfdb/gfdb_sqlite3.h
index 7bcba5a54bd..2051d75fd8e 100644
--- a/libglusterfs/src/gfdb/gfdb_sqlite3.h
+++ b/libglusterfs/src/gfdb/gfdb_sqlite3.h
@@ -281,6 +281,34 @@ int gf_sqlite3_find_recently_changed_files_freq (void *db_conn,
 
 int gf_sqlite3_clear_files_heat (void *db_conn);
 
+/* Function to extract version of sqlite db
+ * Input:
+ * void *db_conn        : Sqlite connection
+ * char **version  : the version is extracted as a string and will be stored in
+ *                   this variable. The freeing of the memory should be done by
+ *                   the caller.
+ * Return:
+ *      On success return the lenght of the version string that is
+ *      extracted.
+ *      On failure return -1
+ * */
+int gf_sqlite3_version (void *db_conn, char **version);
+
+/* Function to extract PRAGMA or setting from sqlite db
+ * Input:
+ * void *db_conn        : Sqlite connection
+ * char *pragma_key     : PRAGMA or setting to be extracted
+ * char **pragma_value  : the value of the PRAGMA or setting that is
+ *                        extracted. This function will allocate memory
+ *                        to pragma_value. The caller should free the memory
+ * Return:
+ *      On success return the lenght of the pragma/setting value that is
+ *      extracted.
+ *      On failure return -1
+ * */
+int gf_sqlite3_pragma (void *db_conn, char *pragma_key, char **pragma_value);
+
 void gf_sqlite3_fill_db_operations (gfdb_db_operations_t  *gfdb_db_ops);
 
+
 #endif