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MEDIUM: backend: add the crc32 hash algorithm for load balancing

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Since we have it available, let's make it usable for load balancing,
it comes at no cost except 3 lines of documentation.
This commit is contained in:
Willy Tarreau 2015-01-20 19:44:50 +01:00
parent 8059977d3e
commit 324f07f6dd
4 changed files with 15 additions and 2 deletions
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5
doc/configuration.txt
View File

@ -2794,6 +2794,11 @@ hash-type <method> <function> <modifier>
data such as a source IP address or a visitor identifier in a URL
parameter.
crc32 this is the most common CRC32 implementation as used in Ethernet,
gzip, PNG, etc. It is slower than the other ones but may provide
a better distribution or less predictable results especially when
used on strings.
<modifier> indicates an optional method applied after hashing the key :
avalanche This directive indicates that the result from the hash

1
include/types/backend.h
View File

@ -115,6 +115,7 @@
#define BE_LB_HFCN_SDBM 0x000000 /* sdbm hash */
#define BE_LB_HFCN_DJB2 0x400000 /* djb2 hash */
#define BE_LB_HFCN_WT6 0x800000 /* wt6 hash */
#define BE_LB_HFCN_CRC32 0xC00000 /* crc32 hash */
#define BE_LB_HASH_FUNC 0xC00000 /* get/clear hash function */

3
src/backend.c
View File

@ -75,6 +75,9 @@ static unsigned int gen_hash(const struct proxy* px, const char* key, unsigned l
case BE_LB_HFCN_WT6:
hash = hash_wt6(key, len);
break;
case BE_LB_HFCN_CRC32:
hash = hash_crc32(key, len);
break;
case BE_LB_HFCN_SDBM:
/* this is the default hash function */
default:

8
src/cfgparse.c
View File

@ -4835,11 +4835,15 @@ stats_error_parsing:
}
else if (!strcmp(args[2], "djb2")) {
curproxy->lbprm.algo |= BE_LB_HFCN_DJB2;
} else if (!strcmp(args[2], "wt6")) {
}
else if (!strcmp(args[2], "wt6")) {
curproxy->lbprm.algo |= BE_LB_HFCN_WT6;
}
else if (!strcmp(args[2], "crc32")) {
curproxy->lbprm.algo |= BE_LB_HFCN_CRC32;
}
else {
Alert("parsing [%s:%d] : '%s' only supports 'sdbm', 'djb2' or 'wt6' hash functions.\n", file, linenum, args[0]);
Alert("parsing [%s:%d] : '%s' only supports 'sdbm', 'djb2', 'crc32', or 'wt6' hash functions.\n", file, linenum, args[0]);
err_code |= ERR_ALERT | ERR_FATAL;
goto out;
}