tier/ctr: Solving DB Lock issue due to write contention from db connections

This is a backport of 12031.

> Problem: The DB on the brick is been accessed by CTR, for write and
> tier migrator, for read and write. The write from tier migrator is reseting
> the heat counters after a cycle. Since we are using sqlite, two connections
> trying to write would cause a db lock contention. As a result CTR used to fail
> to update the db.

> Solution: Using the same db connection of CTR for reseting the heat counters.
> 1) Introducted a new IPC FOP for CTR
> 2) After the query do a ipc syncop to the underlying client xlator associated
>    to the brick.
> 3) CTR in brick will catch the IPC FOP and cleat the heat counters.

> Change-Id: I53306bfc08dcdba479deb4ccc154896521336150
> BUG: 1260730
> Signed-off-by: Joseph Fernandes <josferna@redhat.com>
> Reviewed-on: http://review.gluster.org/12031
> Tested-by: NetBSD Build System <jenkins@build.gluster.org>
> Tested-by: Gluster Build System <jenkins@build.gluster.com>

Signed-off-by: Dan Lambright <dlambrig@redhat.com>

Conflicts:
	xlators/cluster/dht/src/tier.c

Change-Id: I88aa289cdf21e216b42c3d8ccfb4e7e828b43772
BUG: 1262341
Reviewed-on: http://review.gluster.org/12161
Reviewed-by: Joseph Fernandes
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: Dan Lambright <dlambrig@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/libglusterfs/src/gfdb/gfdb_sqlite3.c b/libglusterfs/src/gfdb/gfdb_sqlite3.c
index 27ebef39882..40817af4902 100644
--- a/libglusterfs/src/gfdb/gfdb_sqlite3.c
+++ b/libglusterfs/src/gfdb/gfdb_sqlite3.c
@@ -248,6 +248,8 @@ gf_sqlite3_fill_db_operations(gfdb_db_operations_t  *gfdb_db_ops)
                         gf_sqlite3_find_unchanged_for_time_freq;
         gfdb_db_ops->find_recently_changed_files_freq_op =
                         gf_sqlite3_find_recently_changed_files_freq;
+
+        gfdb_db_ops->clear_files_heat_op = gf_sqlite3_clear_files_heat;
 }
 
 
@@ -1116,3 +1118,26 @@ out:
         sqlite3_finalize(prep_stmt);
         return ret;
 }
+
+
+int
+gf_sqlite3_clear_files_heat (void *db_conn)
+{
+        int ret = -1;
+        gf_sql_connection_t *sql_conn           =       db_conn;
+
+        CHECK_SQL_CONN (sql_conn, out);
+
+        ret = gf_sql_clear_counters (sql_conn);
+        if (ret) {
+                gf_msg (GFDB_STR_SQLITE3, GF_LOG_ERROR, 0,
+                        LG_MSG_CLEAR_COUNTER_FAILED, "Failed clearing "
+                        "files heat!");
+                goto out;
+        }
+
+        ret = 0;
+out:
+        return ret;
+}
+