Added CAS stats.

CAS stats break down into three different types:

 * CAS misses (non-existent key)
 * CAS hits (key + CAS ID match)
 * CAS badval (key + CAS ID mismatch)

hits and bad-val are slab-specific stats.  Specifically, they are
both based on the slab ID of the original item (the one being
replaced).

5 files changed, 95 insertions, 2 deletions

diff --git a/memcached.c b/memcached.c
index 18d2078..f209446 100644
--- a/memcached.c
+++ b/memcached.c
@@ -1868,12 +1868,25 @@ enum store_item_type do_store_item(item *it, int comm, conn *c) {
         if(old_it == NULL) {
             // LRU expired
             stored = NOT_FOUND;
+            pthread_mutex_lock(&c->thread->stats.mutex);
+            c->thread->stats.cas_misses++;
+            pthread_mutex_unlock(&c->thread->stats.mutex);
         }
         else if (ITEM_get_cas(it) == ITEM_get_cas(old_it)) {
             // cas validates
+            // it and old_it may belong to different classes.
+            // I'm updating the stats for the one that's getting pushed out
+            pthread_mutex_lock(&c->thread->stats.mutex);
+            c->thread->stats.slab_stats[old_it->slabs_clsid].cas_hits++;
+            pthread_mutex_unlock(&c->thread->stats.mutex);
+
             item_replace(old_it, it);
             stored = STORED;
         } else {
+            pthread_mutex_lock(&c->thread->stats.mutex);
+            c->thread->stats.slab_stats[old_it->slabs_clsid].cas_badval++;
+            pthread_mutex_unlock(&c->thread->stats.mutex);
+
             if(settings.verbose > 1) {
                 fprintf(stderr, "CAS:  failure: expected %llu, got %llu\n",
                         (unsigned long long)ITEM_get_cas(old_it),
@@ -2211,6 +2224,24 @@ static char *server_stats(uint32_t (*add_stats)(char *buf, const char *key,
     pos += nbytes;
     *buflen += nbytes;
 
+    vlen = sprintf(val, "%llu", (unsigned long long)thread_stats.cas_misses);
+    nbytes = add_stats(pos, "cas_misses", strlen("cas_misses"), val, vlen,
+                       (void *)c);
+    pos += nbytes;
+    *buflen += nbytes;
+
+    vlen = sprintf(val, "%llu", (unsigned long long)slab_stats.cas_hits);
+    nbytes = add_stats(pos, "cas_hits", strlen("cas_hits"), val, vlen,
+                       (void *)c);
+    pos += nbytes;
+    *buflen += nbytes;
+
+    vlen = sprintf(val, "%llu", (unsigned long long)slab_stats.cas_badval);
+    nbytes = add_stats(pos, "cas_badval", strlen("cas_badval"), val, vlen,
+                       (void *)c);
+    pos += nbytes;
+    *buflen += nbytes;
+
     vlen = sprintf(val, "%llu", (unsigned long long)thread_stats.bytes_read);
     nbytes = add_stats(pos, "bytes_read", strlen("bytes_read"), val, vlen,
                        (void *)c);
diff --git a/memcached.h b/memcached.h
index 8ccf980..59039ff 100644
--- a/memcached.h
+++ b/memcached.h
@@ -71,6 +71,8 @@ struct slab_stats {
     uint64_t  set_cmds;
     uint64_t  get_hits;
     uint64_t  delete_hits;
+    uint64_t  cas_hits;
+    uint64_t  cas_badval;
     uint64_t  incr_hits;
     uint64_t  decr_hits;
 };
@@ -82,6 +84,7 @@ struct thread_stats {
     uint64_t          delete_misses;
     uint64_t          incr_misses;
     uint64_t          decr_misses;
+    uint64_t          cas_misses;
     uint64_t          bytes_read;
     uint64_t          bytes_written;
     struct slab_stats slab_stats[MAX_NUMBER_OF_SLAB_CLASSES];
diff --git a/slabs.c b/slabs.c
index 2c3bde2..b28fc68 100644
--- a/slabs.c
+++ b/slabs.c
@@ -476,6 +476,20 @@ static char *do_slabs_stats(uint32_t (*add_stats)(char *buf, const char *key,
             linelen += nbytes;
             bufcurr += nbytes;
 
+            sprintf(key, "%d:cas_hits", i);
+            sprintf(val, "%llu",
+                    (unsigned long long)thread_stats.slab_stats[i].cas_hits);
+            nbytes = add_stats(bufcurr, key, strlen(key), val, strlen(val), c);
+            linelen += nbytes;
+            bufcurr += nbytes;
+
+            sprintf(key, "%d:cas_badval", i);
+            sprintf(val, "%llu",
+                    (unsigned long long)thread_stats.slab_stats[i].cas_badval);
+            nbytes = add_stats(bufcurr, key, strlen(key), val, strlen(val), c);
+            linelen += nbytes;
+            bufcurr += nbytes;
+
             total++;
         }
     }
diff --git a/t/stats.t b/t/stats.t
index cdbfa1a..e5d3af8 100755
--- a/t/stats.t
+++ b/t/stats.t
@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 
 use strict;
-use Test::More tests => 51;
+use Test::More tests => 70;
 use FindBin qw($Bin);
 use lib "$Bin/lib";
 use MemcachedTest;
@@ -35,6 +35,9 @@ my $sock = $server->sock;
 ## STAT incr_hits 2
 ## STAT decr_misses 1
 ## STAT decr_hits 1
+## STAT cas_misses 0
+## STAT cas_hits 0
+## STAT cas_badval 0
 ## STAT evictions 0
 ## STAT bytes_read 7
 ## STAT bytes_written 0
@@ -43,7 +46,7 @@ my $sock = $server->sock;
 my $stats = mem_stats($sock);
 
 # Test number of keys
-is(scalar(keys(%$stats)), 28, "28 stats values");
+is(scalar(keys(%$stats)), 31, "31 stats values");
 
 # Test initial state
 foreach my $key (qw(curr_items total_items bytes cmd_get cmd_set get_hits evictions get_misses bytes_written delete_hits delete_misses incr_hits incr_misses decr_hits decr_misses)) {
@@ -110,4 +113,36 @@ print $sock "decr n 1\r\n";
 is(scalar <$sock>, "2\r\n", "decr works");
 check_incr_stats(1, 1, 1, 1);
 
+# cas stats
 
+sub check_cas_stats {
+    my ($ch, $cm, $cb) = @_;
+    my $stats = mem_stats($sock);
+
+    is($stats->{cas_hits}, $ch);
+    is($stats->{cas_misses}, $cm);
+    is($stats->{cas_badval}, $cb);
+}
+
+check_cas_stats(0, 0, 0);
+
+print $sock "cas c 0 0 1 99999999\r\nz\r\n";
+is(scalar <$sock>, "NOT_FOUND\r\n", "missed cas");
+check_cas_stats(0, 1, 0);
+
+print $sock "set c 0 0 1\r\nx\r\n";
+is(scalar <$sock>, "STORED\r\n", "stored c");
+my ($id, $v) = mem_gets($sock, 'c');
+is('x', $v, 'got the expected value');
+
+print $sock "cas c 0 0 1 99999999\r\nz\r\n";
+is(scalar <$sock>, "EXISTS\r\n", "missed cas");
+check_cas_stats(0, 1, 1);
+my ($newid, $v) = mem_gets($sock, 'c');
+is('x', $v, 'got the expected value');
+
+print $sock "cas c 0 0 1 $id\r\nz\r\n";
+is(scalar <$sock>, "STORED\r\n", "good cas");
+check_cas_stats(1, 1, 1);
+my ($newid, $v) = mem_gets($sock, 'c');
+is('z', $v, 'got the expected value');
diff --git a/thread.c b/thread.c
index 8ff5a59..611a9ed 100644
--- a/thread.c
+++ b/thread.c
@@ -562,6 +562,7 @@ void threadlocal_stats_aggregate(struct thread_stats *stats) {
     stats->delete_misses = 0;
     stats->incr_misses = 0;
     stats->decr_misses = 0;
+    stats->cas_misses = 0;
     stats->bytes_written = 0;
     stats->bytes_read = 0;
 
@@ -576,6 +577,7 @@ void threadlocal_stats_aggregate(struct thread_stats *stats) {
         stats->delete_misses += threads[ii].stats.delete_misses;
         stats->decr_misses += threads[ii].stats.decr_misses;
         stats->incr_misses += threads[ii].stats.incr_misses;
+        stats->cas_misses += threads[ii].stats.cas_misses;
         stats->bytes_read += threads[ii].stats.bytes_read;
         stats->bytes_written += threads[ii].stats.bytes_written;
 
@@ -590,6 +592,10 @@ void threadlocal_stats_aggregate(struct thread_stats *stats) {
                 threads[ii].stats.slab_stats[sid].decr_hits;
             stats->slab_stats[sid].incr_hits +=
                 threads[ii].stats.slab_stats[sid].incr_hits;
+            stats->slab_stats[sid].cas_hits +=
+                threads[ii].stats.slab_stats[sid].cas_hits;
+            stats->slab_stats[sid].cas_badval +=
+                threads[ii].stats.slab_stats[sid].cas_badval;
         }
 
         pthread_mutex_unlock(&threads[ii].stats.mutex);
@@ -604,6 +610,8 @@ void slab_stats_aggregate(struct thread_stats *stats, struct slab_stats *out) {
     out->delete_hits = 0;
     out->incr_hits = 0;
     out->decr_hits = 0;
+    out->cas_hits = 0;
+    out->cas_badval = 0;
 
     for (sid = 0; sid < MAX_NUMBER_OF_SLAB_CLASSES; sid++) {
         out->set_cmds += stats->slab_stats[sid].set_cmds;
@@ -611,6 +619,8 @@ void slab_stats_aggregate(struct thread_stats *stats, struct slab_stats *out) {
         out->delete_hits += stats->slab_stats[sid].delete_hits;
         out->decr_hits += stats->slab_stats[sid].decr_hits;
         out->incr_hits += stats->slab_stats[sid].incr_hits;
+        out->cas_hits += stats->slab_stats[sid].cas_hits;
+        out->cas_badval += stats->slab_stats[sid].cas_badval;
     }
 }