add a cmd_flush stat

shouldn't add much lock contention for just this.
I want to add this one stat (mayb a few more?) since it's happened more than
once that folks think memcached is broken when a cron or something is calling
'flush_all' once a minute.

memcached.c

@@ -159,7 +159,7 @@ static rel_time_t realtime(const time_t exptime) {
 
 static void stats_init(void) {
     stats.curr_items = stats.total_items = stats.curr_conns = stats.total_conns = stats.conn_structs = 0;
-    stats.evictions = 0;
+    stats.get_cmds = stats.set_cmds = stats.get_hits = stats.get_misses = stats.evictions = 0;
     stats.curr_bytes = 0;
 
     /* make the time we started always be 2 seconds before we really
@@ -2209,6 +2209,7 @@ static char *server_stats(uint32_t (*add_stats)(char *buf, const char *key,
     APPEND_STAT("connection_structures", "%u", stats.conn_structs);
     APPEND_STAT("cmd_get", "%llu", (unsigned long long)thread_stats.get_cmds);
     APPEND_STAT("cmd_set", "%llu", (unsigned long long)slab_stats.set_cmds);
+    APPEND_STAT("cmd_flush", "%llu", (unsigned long long)thread_stats.flush_cmds);
     APPEND_STAT("get_hits", "%llu", (unsigned long long)slab_stats.get_hits);
     APPEND_STAT("get_misses", "%llu", (unsigned long long)thread_stats.get_misses);
     APPEND_STAT("delete_misses", "%llu", (unsigned long long)thread_stats.delete_misses);
@@ -2223,6 +2224,7 @@ static char *server_stats(uint32_t (*add_stats)(char *buf, const char *key,
     APPEND_STAT("bytes_read", "%llu", (unsigned long long)thread_stats.bytes_read);
     APPEND_STAT("bytes_written", "%llu", (unsigned long long)thread_stats.bytes_written);
     APPEND_STAT("limit_maxbytes", "%llu", (unsigned long long)settings.maxbytes);
+    APPEND_STAT("bytes_written", "%llu", (unsigned long long)thread_stats.bytes_written);
     APPEND_STAT("threads", "%d", settings.num_threads);
 
     if(*buflen > 0 && (buf = malloc(*buflen)) == NULL) {
@@ -2916,6 +2918,10 @@ static void process_command(conn *c, char *command) {
 
         set_noreply_maybe(c, tokens, ntokens);
 
+        STATS_LOCK();
+        c->thread->stats.flush_cmds++;
+        STATS_UNLOCK();
+
         if(ntokens == (c->noreply ? 3 : 2)) {
             settings.oldest_live = current_time - 1;
             item_flush_expired();

memcached.h

@@ -91,6 +91,7 @@ struct thread_stats {
     uint64_t          cas_misses;
     uint64_t          bytes_read;
     uint64_t          bytes_written;
+    uint64_t          flush_cmds;
     struct slab_stats slab_stats[MAX_NUMBER_OF_SLAB_CLASSES];
 };
 
@@ -102,6 +103,10 @@ struct stats {
     unsigned int  curr_conns;
     unsigned int  total_conns;
     unsigned int  conn_structs;
+    uint64_t      get_cmds;
+    uint64_t      set_cmds;
+    uint64_t      get_hits;
+    uint64_t      get_misses;
     uint64_t      evictions;
 };
 

t/stats.t

@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 
 use strict;
-use Test::More tests => 89;
+use Test::More tests => 91;
 use FindBin qw($Bin);
 use lib "$Bin/lib";
 use MemcachedTest;
@@ -25,6 +25,7 @@ my $sock = $server->sock;
 ## STAT curr_connections 1
 ## STAT total_connections 2
 ## STAT connection_structures 2
+## STAT cmd_flush 0
 ## STAT cmd_get 0
 ## STAT cmd_set 0
 ## STAT get_hits 0
@@ -46,10 +47,12 @@ my $sock = $server->sock;
 my $stats = mem_stats($sock);
 
 # Test number of keys
-is(scalar(keys(%$stats)), 31, "31 stats values");
+is(scalar(keys(%$stats)), 32, "32 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)) {
+foreach my $key (qw(curr_items total_items bytes cmd_get cmd_set get_hits evictions get_misses
+                 bytes_written delete_hits delete_misses incr_hits incr_misses decr_hits
+                 decr_misses)) {
     is($stats->{$key}, 0, "initial $key is zero");
 }
 
@@ -171,3 +174,9 @@ is(0, $stats->{'cas_misses'});
 is(0, $stats->{'cas_hits'});
 is(0, $stats->{'cas_badval'});
 is(0, $stats->{'evictions'});
+
+print $sock "flush_all\r\n";
+is(scalar <$sock>, "OK\r\n", "flushed");
+
+my $stats = mem_stats($sock);
+is($stats->{cmd_flush}, 1, "after one flush cmd_flush is 1");

thread.c

@@ -476,6 +476,7 @@ void threadlocal_stats_reset(void) {
         threads[ii].stats.cas_misses = 0;
         threads[ii].stats.bytes_read = 0;
         threads[ii].stats.bytes_written = 0;
+        threads[ii].stats.flush_cmds = 0;
 
         for(sid = 0; sid < MAX_NUMBER_OF_SLAB_CLASSES; sid++) {
             threads[ii].stats.slab_stats[sid].set_cmds = 0;
@@ -502,6 +503,7 @@ void threadlocal_stats_aggregate(struct thread_stats *stats) {
     stats->cas_misses = 0;
     stats->bytes_written = 0;
     stats->bytes_read = 0;
+    stats->flush_cmds = 0;
 
     memset(stats->slab_stats, 0,
            sizeof(struct slab_stats) * MAX_NUMBER_OF_SLAB_CLASSES);
@@ -517,6 +519,7 @@ void threadlocal_stats_aggregate(struct thread_stats *stats) {
         stats->cas_misses += threads[ii].stats.cas_misses;
         stats->bytes_read += threads[ii].stats.bytes_read;
         stats->bytes_written += threads[ii].stats.bytes_written;
+        stats->flush_cmds += threads[ii].stats.flush_cmds;
 
         for (sid = 0; sid < MAX_NUMBER_OF_SLAB_CLASSES; sid++) {
             stats->slab_stats[sid].set_cmds +=