Update CAS on non-replace incr/decr.

This fixes a problem reported as bug 15 where incr and decr do not
change CAS values when they aren't completely replacing the item
(which is the typical case).

http://code.google.com/p/memcached/issues/detail?id=15

4 files changed, 32 insertions, 2 deletions

diff --git a/items.c b/items.c
index 8c69384..79e93cf 100644
--- a/items.c
+++ b/items.c
@@ -17,7 +17,6 @@
 /* Forward Declarations */
 static void item_link_q(item *it);
 static void item_unlink_q(item *it);
-static uint64_t get_cas_id(void);
 
 /*
  * We only reposition items in the LRU queue if they haven't been repositioned
diff --git a/items.h b/items.h
index 660cc8a..0c680a2 100644
--- a/items.h
+++ b/items.h
@@ -1,5 +1,7 @@
 /* See items.c */
 void item_init(void);
+uint64_t get_cas_id(void);
+
 /*@null@*/
 item *do_item_alloc(char *key, const size_t nkey, const int flags, const rel_time_t exptime, const int nbytes);
 void item_free(item *it);
diff --git a/memcached.c b/memcached.c
index 508f04d..a5fc781 100644
--- a/memcached.c
+++ b/memcached.c
@@ -2633,6 +2633,10 @@ char *do_add_delta(conn *c, item *it, const bool incr, const int64_t delta, char
         item_replace(it, new_it);
         do_item_remove(new_it);       /* release our reference */
     } else { /* replace in-place */
+        /* When changing the value without replacing the item, we
+           need to update the CAS on the existing item. */
+        ITEM_set_cas(it, (settings.use_cas) ? get_cas_id() : 0);
+
         memcpy(ITEM_data(it), buf, res);
         memset(ITEM_data(it) + res, ' ', it->nbytes - res - 2);
     }
diff --git a/t/cas.t b/t/cas.t
index 9208c1e..a84fdd9 100644
--- a/t/cas.t
+++ b/t/cas.t
@@ -1,7 +1,7 @@
 #!/usr/bin/perl
 
 use strict;
-use Test::More tests => 30;
+use Test::More tests => 39;
 use FindBin qw($Bin);
 use lib "$Bin/lib";
 use MemcachedTest;
@@ -115,3 +115,28 @@ ok( ( $res1 eq "STORED\r\n" && $res2 eq "EXISTS\r\n") ||
     ( $res1 eq "EXISTS\r\n" && $res2 eq "STORED\r\n"),
     "cas on same item from two sockets");
 
+### bug 15: http://code.google.com/p/memcached/issues/detail?id=15
+
+# set foo
+print $sock "set bug15 0 0 1\r\n0\r\n";
+is(scalar <$sock>, "STORED\r\n", "stored 0");
+
+# Check out the first gets.
+print $sock "gets bug15\r\n";
+ok(scalar <$sock> =~ /VALUE bug15 0 1 (\d+)\r\n/, "gets bug15 regexp success");
+my $bug15_cas = $1;
+is(scalar <$sock>, "0\r\n", "gets bug15 data is 0");
+is(scalar <$sock>, "END\r\n","gets bug15 END");
+
+# Increment
+print $sock "incr bug15 1\r\n";
+is(scalar <$sock>, "1\r\n", "incr worked");
+
+# Validate a changed CAS
+print $sock "gets bug15\r\n";
+ok(scalar <$sock> =~ /VALUE bug15 0 1 (\d+)\r\n/, "gets bug15 regexp success");
+my $next_bug15_cas = $1;
+is(scalar <$sock>, "1\r\n", "gets bug15 data is 0");
+is(scalar <$sock>, "END\r\n","gets bug15 END");
+
+ok($bug15_cas != $next_bug15_cas, "CAS changed");