core: add more information on dictionary usage

when you take the 'statedump', it shows the output like below

-----
[dict]
max-number-of-dict-pairs=13
total-pairs-used=41613
total-dict-used=12629
average-pairs-per-dict=3
------

Updates #220

Change-Id: I71a7eda3a3cd23edf4483234f22f983923bbb081
Signed-off-by: Amar Tumballi <amarts@redhat.com>
Reviewed-on: https://review.gluster.org/4035
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>

5 files changed, 58 insertions, 0 deletions

diff --git a/libglusterfs/src/ctx.c b/libglusterfs/src/ctx.c
index 1c707eb5dfd..1cf1b988590 100644
--- a/libglusterfs/src/ctx.c
+++ b/libglusterfs/src/ctx.c
@@ -49,6 +49,9 @@ glusterfs_ctx_new ()
 		ctx = NULL;
 	}
 
+        GF_ATOMIC_INIT (ctx->stats.max_dict_pairs, 0);
+        GF_ATOMIC_INIT (ctx->stats.total_pairs_used, 0);
+        GF_ATOMIC_INIT (ctx->stats.total_dicts_used, 0);
 out:
 	return ctx;
 }
diff --git a/libglusterfs/src/dict.c b/libglusterfs/src/dict.c
index a92d03a5434..04d627dde39 100644
--- a/libglusterfs/src/dict.c
+++ b/libglusterfs/src/dict.c
@@ -407,6 +407,9 @@ dict_set_lk (dict_t *this, char *key, data_t *value, gf_boolean_t replace)
 
         if (key_free)
                 GF_FREE (key);
+
+        if (this->max_count < this->count)
+                this->max_count = this->count;
         return 0;
 }
 
@@ -575,6 +578,9 @@ dict_destroy (dict_t *this)
 
         data_pair_t *pair = this->members_list;
         data_pair_t *prev = this->members_list;
+        glusterfs_ctx_t *ctx = NULL;
+        uint32_t total_pairs = 0;
+        uint64_t current_max = 0;
 
         LOCK_DESTROY (&this->lock);
 
@@ -585,6 +591,7 @@ dict_destroy (dict_t *this)
                 if (prev != &this->free_pair) {
                         mem_put (prev);
                 }
+                total_pairs++;
                 prev = pair;
         }
 
@@ -595,6 +602,24 @@ dict_destroy (dict_t *this)
         GF_FREE (this->extra_free);
         free (this->extra_stdfree);
 
+        /* update 'ctx->stats.dict.details' using max_count */
+        ctx = THIS->ctx;
+
+        /* NOTE: below logic is not totaly race proof */
+        /* thread0 and thread1 gets current_max as 10 */
+        /* thread0 has 'this->max_count as 11 */
+        /* thread1 has 'this->max_count as 20 */
+        /* thread1 goes ahead and sets the max_dict_pairs to 20 */
+        /* thread0 then goes and sets it to 11 */
+        /* As it is for information purpose only, no functionality will be
+           broken by this, but a point to consider about ATOMIC macros. */
+        current_max = GF_ATOMIC_GET (ctx->stats.max_dict_pairs);
+        if (current_max < this->max_count)
+                GF_ATOMIC_INIT (ctx->stats.max_dict_pairs, this->max_count);
+
+        GF_ATOMIC_ADD (ctx->stats.total_pairs_used, total_pairs);
+        GF_ATOMIC_INC (ctx->stats.total_dicts_used);
+
         if (!this->is_static)
                 mem_put (this);
 
diff --git a/libglusterfs/src/dict.h b/libglusterfs/src/dict.h
index 0ce6ab8e2e3..bdc003ea373 100644
--- a/libglusterfs/src/dict.h
+++ b/libglusterfs/src/dict.h
@@ -91,6 +91,7 @@ struct _dict {
         data_pair_t    *members_internal;
         data_pair_t     free_pair;
         gf_boolean_t    free_pair_in_use;
+        uint32_t        max_count;
 };
 
 typedef gf_boolean_t (*dict_match_t) (dict_t *d, char *k, data_t *v,
diff --git a/libglusterfs/src/glusterfs.h b/libglusterfs/src/glusterfs.h
index 7eaeb0c7dbd..6feefb85e97 100644
--- a/libglusterfs/src/glusterfs.h
+++ b/libglusterfs/src/glusterfs.h
@@ -37,6 +37,7 @@
 #include "lkowner.h"
 #include "compat-uuid.h"
 #include "refcount.h"
+#include "atomic.h"
 
 #define GF_YES 1
 #define GF_NO  0
@@ -522,6 +523,13 @@ struct _glusterfs_ctx {
         struct gf_ctx_tw   *tw; /* refcounted timer_wheel */
 
         gf_lock_t           volfile_lock;
+
+
+        struct {
+                gf_atomic_t max_dict_pairs;
+                gf_atomic_t total_pairs_used;
+                gf_atomic_t total_dicts_used;
+        } stats;
 };
 typedef struct _glusterfs_ctx glusterfs_ctx_t;
 
diff --git a/libglusterfs/src/statedump.c b/libglusterfs/src/statedump.c
index bb8043a869f..697ddc3b7ba 100644
--- a/libglusterfs/src/statedump.c
+++ b/libglusterfs/src/statedump.c
@@ -467,6 +467,23 @@ gf_proc_dump_mempool_info_to_dict (glusterfs_ctx_t *ctx, dict_t *dict)
 void gf_proc_dump_latency_info (xlator_t *xl);
 
 void
+gf_proc_dump_dict_info (glusterfs_ctx_t *ctx)
+{
+        uint64_t total_dicts = 0;
+        uint64_t total_pairs = 0;
+
+        total_dicts = GF_ATOMIC_GET (ctx->stats.total_dicts_used);
+        total_pairs = GF_ATOMIC_GET (ctx->stats.total_pairs_used);
+
+        gf_proc_dump_write ("max-pairs-per-dict", "%u",
+                            GF_ATOMIC_GET (ctx->stats.max_dict_pairs));
+        gf_proc_dump_write ("total-pairs-used", "%lu", total_pairs);
+        gf_proc_dump_write ("total-dicts-used", "%lu", total_dicts);
+        gf_proc_dump_write ("average-pairs-per-dict", "%lu",
+                            (total_pairs / total_dicts));
+}
+
+void
 gf_proc_dump_xlator_info (xlator_t *top)
 {
         xlator_t        *trav = NULL;
@@ -827,6 +844,10 @@ gf_proc_dump_info (int signum, glusterfs_ctx_t *ctx)
         if (GF_PROC_DUMP_IS_OPTION_ENABLED (callpool))
                 gf_proc_dump_pending_frames (ctx->pool);
 
+        /* dictionary stats */
+        gf_proc_dump_add_section ("dict");
+        gf_proc_dump_dict_info (ctx);
+
         if (ctx->master) {
                 gf_proc_dump_add_section ("fuse");
                 gf_proc_dump_xlator_info (ctx->master);