md-cache: Add cache hit and miss counters

These counters can be accessed either by .meta interface
or statedump.

From meta: cat on the private file in md-cache directory.
Eg: cat /mnt/glusterfs/0/.meta/graphs/active/patchy-md-cache/private
[performance/md-cache.patchy-md-cache]
stat_hit_count = 2
stat_miss_count = 8
xattr_hit_count = 4
xattr_miss_count = 3
nameless_lookup_count = 1
negative_lookup_count = 0
stat_invalidations_recieved = 1
xattr_invalidations_recieved = 1

Change-Id: Ib62a8822f263a9f75858b15832d0119fbe382629
BUG: 1211863
Signed-off-by: Poornima G <pgurusid@redhat.com>
Reviewed-on: http://review.gluster.org/15185
Smoke: Gluster Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/libglusterfs/src/globals.h b/libglusterfs/src/globals.h
index e6cb593c238..50734ecc2d8 100644
--- a/libglusterfs/src/globals.h
+++ b/libglusterfs/src/globals.h
@@ -80,6 +80,23 @@
 #define THIS (*__glusterfs_this_location())
 #define DECLARE_OLD_THIS        xlator_t *old_THIS = THIS
 
+/*
+ * a more comprehensive feature test is shown at
+ * http://lists.iptel.org/pipermail/semsdev/2010-October/005075.html
+ * this is sufficient for RHEL5 i386 builds
+ */
+#if (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 1)) && !defined(__i386__)
+# define INCREMENT_ATOMIC(lk, op) __sync_add_and_fetch(&op, 1)
+# define DECREMENT_ATOMIC(lk, op) __sync_sub_and_fetch(&op, 1)
+#else
+/* These are only here for old gcc, e.g. on RHEL5 i386.
+ * We're not ever going to use this in an if stmt,
+ * but let's be pedantically correct for style points */
+# define INCREMENT_ATOMIC(lk, op) do { LOCK (&lk); ++op; UNLOCK (&lk); } while (0)
+/* this is a gcc 'statement expression', it works with llvm/clang too */
+# define DECREMENT_ATOMIC(lk, op) ({ LOCK (&lk); --op; UNLOCK (&lk); op; })
+#endif
+
 xlator_t **__glusterfs_this_location (void);
 xlator_t *glusterfs_this_get (void);
 int glusterfs_this_set (xlator_t *);