From: Erik Dubbelboer <erik@dubbelboer.com>
Date: Wed, 11 Apr 2012 15:04:31 +0000 (+0200)
Subject: added explanation for the magic 511 backlog number
X-Git-Url: https://git.saurik.com/redis.git/commitdiff_plain/b9cd703b5b16e350c0783061ce99c79089bcfc0a

added explanation for the magic 511 backlog number
---

diff --git a/src/anet.c b/src/anet.c
index ba4e6cce..434d945c 100644
--- a/src/anet.c
+++ b/src/anet.c
@@ -262,7 +262,11 @@ static int anetListen(char *err, int s, struct sockaddr *sa, socklen_t len) {
         close(s);
         return ANET_ERR;
     }
-    if (listen(s, 511) == -1) { /* the magic 511 constant is from nginx */
+
+    /* Use a backlog of 512 entries. We pass 511 to the listen() call because
+     * the kernel does: backlogsize = roundup_pow_of_two(backlogsize + 1);
+     * which will thus give us a backlog of 512 entries */
+    if (listen(s, 511) == -1) {
         anetSetError(err, "listen: %s", strerror(errno));
         close(s);
         return ANET_ERR;