memcached-fix-accept-new-conns-race.patch

gistfile1.diff

--- memcached-1.4.5/memcached.c	2010-04-04 04:51:29.000000000 +0900
+++ memcached-1.4.5-modified/memcached.c	2010-08-19 02:34:10.000000000 +0900
@@ -111,6 +111,10 @@
 static conn *listen_conn = NULL;
 static struct event_base *main_base;
 
+static pthread_mutex_t allow_new_conns_lock = PTHREAD_MUTEX_INITIALIZER;
+static volatile bool allow_new_conns = true;
+static volatile bool allow_new_conns_cur = true;
+
 enum transmit_result {
     TRANSMIT_COMPLETE,   /** All done writing. */
     TRANSMIT_INCOMPLETE, /** More data remaining to write. */
@@ -508,7 +512,9 @@
 
     MEMCACHED_CONN_RELEASE(c->sfd);
     close(c->sfd);
-    accept_new_conns(true);
+    pthread_mutex_lock(&allow_new_conns_lock);
+    allow_new_conns = true;
+    pthread_mutex_unlock(&allow_new_conns_lock);
     conn_cleanup(c);
 
     /* if the connection has big buffers, just free it */
@@ -3436,7 +3442,9 @@
                 } else if (errno == EMFILE) {
                     if (settings.verbose > 0)
                         fprintf(stderr, "Too many open connections\n");
-                    accept_new_conns(false);
+                    pthread_mutex_lock(&allow_new_conns_lock);
+                    allow_new_conns = false;
+                    pthread_mutex_unlock(&allow_new_conns_lock);
                     stop = true;
                 } else {
                     perror("accept()");
@@ -4033,6 +4041,16 @@
         initialized = true;
     }
 
+    bool do_accept_changed = false;
+    pthread_mutex_lock(&allow_new_conns_lock);
+    if (allow_new_conns != allow_new_conns_cur) {
+        allow_new_conns_cur = allow_new_conns;
+        do_accept_changed = true;
+    }
+    pthread_mutex_unlock(&allow_new_conns_lock);
+    if (do_accept_changed)
+        accept_new_conns(allow_new_conns_cur);
+
     evtimer_set(&clockevent, clock_handler, 0);
     event_base_set(main_base, &clockevent);
     evtimer_add(&clockevent, &t);