Mercurial > hg > nginx-quic
annotate src/core/ngx_murmurhash.c @ 4621:c90801720a0c
Upstream: smooth weighted round-robin balancing.
For edge case weights like { 5, 1, 1 } we now produce { a, a, b, a, c, a, a }
sequence instead of { c, b, a, a, a, a, a } produced previously.
Algorithm is as follows: on each peer selection we increase current_weight
of each eligible peer by its weight, select peer with greatest current_weight
and reduce its current_weight by total number of weight points distributed
among peers.
In case of { 5, 1, 1 } weights this gives the following sequence of
current_weight's:
a b c
0 0 0 (initial state)
5 1 1 (a selected)
-2 1 1
3 2 2 (a selected)
-4 2 2
1 3 3 (b selected)
1 -4 3
6 -3 4 (a selected)
-1 -3 4
4 -2 5 (c selected)
4 -2 -2
9 -1 -1 (a selected)
2 -1 -1
7 0 0 (a selected)
0 0 0
To preserve weight reduction in case of failures the effective_weight
variable was introduced, which usually matches peer's weight, but is
reduced temporarily on peer failures.
This change also fixes loop with backup servers and proxy_next_upstream
http_404 (ticket #47), and skipping alive upstreams in some cases if there
are multiple dead ones (ticket #64).
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Mon, 14 May 2012 09:57:20 +0000 |
parents | 203eb026ec07 |
children | f38647c651a8 |
rev | line source |
---|---|
3891 | 1 |
2 /* | |
3 * Copyright (C) Austin Appleby | |
4 */ | |
5 | |
6 | |
7 #include <ngx_config.h> | |
8 #include <ngx_core.h> | |
9 | |
10 | |
11 uint32_t | |
12 ngx_murmur_hash2(u_char *data, size_t len) | |
13 { | |
14 uint32_t h, k; | |
15 | |
16 h = 0 ^ len; | |
17 | |
18 while (len >= 4) { | |
19 k = data[0]; | |
20 k |= data[1] << 8; | |
21 k |= data[2] << 16; | |
22 k |= data[3] << 24; | |
23 | |
24 k *= 0x5bd1e995; | |
25 k ^= k >> 24; | |
26 k *= 0x5bd1e995; | |
27 | |
28 h *= 0x5bd1e995; | |
29 h ^= k; | |
30 | |
31 data += 4; | |
32 len -= 4; | |
33 } | |
34 | |
35 switch (len) { | |
36 case 3: | |
37 h ^= data[2] << 16; | |
38 case 2: | |
39 h ^= data[1] << 8; | |
40 case 1: | |
41 h ^= data[0]; | |
42 h *= 0x5bd1e995; | |
43 } | |
44 | |
45 h ^= h >> 13; | |
46 h *= 0x5bd1e995; | |
47 h ^= h >> 15; | |
48 | |
49 return h; | |
50 } |