cluster/tier: Adding compaction option for metadata databases

Problem: As metadata in the database fills up, querying the database
take a long time. As a result, tier migration slows down.  To
counteract this, we added a way to enable the compaction methods of
the underlying database. The goal is to reduce the size of the
underlying file by eliminating database fragmentation.

NOTE: There is currently a bug where sometimes a brick will
attempt to activate compaction. This happens even compaction is already
turned on.

The cause is narrowed down to the compact_mode_switch flipping its value.

Changes: libglusterfs/src/gfdb - Added a gfdb function to compact the
underlying database, compact_db() This is a no-op if the database has
no such option.

- Added a compaction function for SQLite3 that does the following

1) Changes the auto_vacuum pragma of the database
2) Compacts the database according to the type of compaction requested

- Compaction type can be changed by changing the macro
  GF_SQL_COMPACT_DEF to one of the 4 compaction types in
  gfdb_sqlite3.h

  It is currently set to GF_SQL_COMPACT_INCR, or incremental
  vacuuming.

xlators/cluster/dht/src - Added the following command-line option to
enable SQLite3 compaction.

gluster volume set <vol-name> tier-compact <off|on>

- Added the following command-line option to change the frequency the
  hot and cold tier are ordered to compact.

gluster volume set <vol-name> tier-hot-compact-frequency <int>
gluster volume set <vol-name> tier-cold-compact-frequency <int>

- tier daemon periodically sends the (new)
  GFDB_IPC_CTR_SET_COMPACT_PRAGMA IPC to the CTR xlator. The IPC
  triggers compaction of the database.

  The inputs are both gf_boolean_t.

  IPC Input:

  compact_active: Is compaction currently on for the db.
  compact_mode_switched: Did we flip the compaction switch recently?

  IPC Output:

  0 if the compaction succeeds.
  Non-zero otherwise.

xlators/features/changetimerecorder/src/ - When the CTR gets the
compaction IPC, it launches a thread that will perform the
compaction. The IPC ends after the thread is launched. To avoid extra
allocations, the parameters are passed using static variables.

Change-Id: I5e1433becb9eeff2afe8dcb4a5798977bf5ba0dd
Signed-off-by: Diogenes Nunez <dnunez@redhat.com>
Reviewed-on: http://review.gluster.org/15031
Reviewed-by: Milind Changire <mchangir@redhat.com>
Reviewed-by: Dan Lambright <dlambrig@redhat.com>
Tested-by: Dan Lambright <dlambrig@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Smoke: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 24 insertions, 7 deletions

diff --git a/xlators/cluster/dht/src/dht-common.h b/xlators/cluster/dht/src/dht-common.h
index 3717a68273c..da1bcb6a4a1 100644
--- a/xlators/cluster/dht/src/dht-common.h
+++ b/xlators/cluster/dht/src/dht-common.h
@@ -310,7 +310,7 @@ typedef struct dht_local dht_local_t;
 /* du - disk-usage */
 struct dht_du {
         double   avail_percent;
-	double   avail_inodes;
+        double   avail_inodes;
         uint64_t avail_space;
         uint32_t log;
         uint32_t chunks;
@@ -325,10 +325,10 @@ enum gf_defrag_type {
         GF_DEFRAG_CMD_START_FORCE = 1 + 4,
         GF_DEFRAG_CMD_START_TIER = 1 + 5,
         GF_DEFRAG_CMD_STATUS_TIER = 1 + 6,
-	GF_DEFRAG_CMD_START_DETACH_TIER = 1 + 7,
-	GF_DEFRAG_CMD_STOP_DETACH_TIER = 1 + 8,
-	GF_DEFRAG_CMD_PAUSE_TIER = 1 + 9,
-	GF_DEFRAG_CMD_RESUME_TIER = 1 + 10,
+        GF_DEFRAG_CMD_START_DETACH_TIER = 1 + 7,
+        GF_DEFRAG_CMD_STOP_DETACH_TIER = 1 + 8,
+        GF_DEFRAG_CMD_PAUSE_TIER = 1 + 9,
+        GF_DEFRAG_CMD_RESUME_TIER = 1 + 10,
 };
 typedef enum gf_defrag_type gf_defrag_type;
 
@@ -398,9 +398,26 @@ typedef struct gf_tier_conf {
         uint64_t                     max_migrate_bytes;
         int                          max_migrate_files;
         tier_mode_t                  mode;
+        /* These flags are only used for tier-compact */
+        gf_boolean_t                 compact_active;
+        /* These 3 flags are set to true when the client changes the */
+        /* compaction mode on the command line. */
+        /* When they are set, the daemon will trigger compaction as */
+        /* soon as possible to activate or deactivate compaction. */
+        /* If in the middle of a compaction, then the switches take */
+        /* effect on the next compaction, not the current one. */
+        /* If the user switches it off, we want to avoid needless */
+        /* compactions. */
+        /* If the user switches it on, they want to compact as soon */
+        /* as possible. */
+        gf_boolean_t                 compact_mode_switched;
+        gf_boolean_t                 compact_mode_switched_hot;
+        gf_boolean_t                 compact_mode_switched_cold;
         int                          tier_max_promote_size;
         int                          tier_promote_frequency;
         int                          tier_demote_frequency;
+        int                          tier_compact_hot_frequency;
+        int                          tier_compact_cold_frequency;
         uint64_t                     st_last_promoted_size;
         uint64_t                     st_last_demoted_size;
         tier_pause_state_t           pause_state;
@@ -1023,9 +1040,9 @@ int32_t dht_setattr (call_frame_t  *frame, xlator_t *this, loc_t *loc,
 int32_t dht_fsetattr (call_frame_t *frame, xlator_t *this, fd_t *fd,
                       struct iatt  *stbuf, int32_t valid, dict_t *xdata);
 int32_t dht_fallocate(call_frame_t *frame, xlator_t *this, fd_t *fd,
-		      int32_t mode, off_t offset, size_t len, dict_t *xdata);
+                      int32_t mode, off_t offset, size_t len, dict_t *xdata);
 int32_t dht_discard(call_frame_t *frame, xlator_t *this, fd_t *fd,
-		    off_t offset, size_t len, dict_t *xdata);
+                    off_t offset, size_t len, dict_t *xdata);
 int32_t dht_zerofill(call_frame_t *frame, xlator_t *this, fd_t *fd,
                     off_t offset, off_t len, dict_t *xdata);
 int32_t dht_ipc (call_frame_t *frame, xlator_t *this, int32_t op,