From: Florian Forster <octo@huhu.verplant.org>
Date: Wed, 9 Dec 2009 15:30:10 +0000 (+0100)
Subject: hashed match: Use a different (larger) prime number.
X-Git-Tag: collectd-4.9.0~14
X-Git-Url: https://git.octo.it/?a=commitdiff_plain;h=bc9f312c67c0a76f1de0ceaea53c874fb8773cc8;p=collectd.git

hashed match: Use a different (larger) prime number.

The previous prime number, 251, did not distribute good enough into
three groups.
---

diff --git a/src/match_hashed.c b/src/match_hashed.c
index 062a7a72..4d533050 100644
--- a/src/match_hashed.c
+++ b/src/match_hashed.c
@@ -158,8 +158,8 @@ static int mh_match (const data_set_t __attribute__((unused)) *ds, /* {{{ */
 
   for (host_ptr = vl->host; *host_ptr != 0; host_ptr++)
   {
-    /* 251 is the largest prime smaller than 256. */
-    hash_val = (hash_val * 251) + ((uint32_t) *host_ptr);
+    /* 2184401929 is some appropriately sized prime number. */
+    hash_val = (hash_val * 2184401929) + ((uint32_t) *host_ptr);
   }
   DEBUG ("hashed match: host = %s; hash_val = %"PRIu32";", vl->host, hash_val);