]>
git.ipfire.org Git - thirdparty/squid.git/blob - src/carp.cc
3 * $Id: carp.cc,v 1.18 2002/04/13 16:24:50 hno Exp $
5 * DEBUG: section 39 Cache Array Routing Protocol
6 * AUTHOR: Henrik Nordstrom
7 * BASED ON: carp.c by Eric Stern and draft-vinod-carp-v1-03.txt
9 * SQUID Web Proxy Cache http://www.squid-cache.org/
10 * ----------------------------------------------------------
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21 * This program is free software; you can redistribute it and/or modify
22 * it under the terms of the GNU General Public License as published by
23 * the Free Software Foundation; either version 2 of the License, or
24 * (at your option) any later version.
26 * This program is distributed in the hope that it will be useful,
27 * but WITHOUT ANY WARRANTY; without even the implied warranty of
28 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
29 * GNU General Public License for more details.
31 * You should have received a copy of the GNU General Public License
32 * along with this program; if not, write to the Free Software
33 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
41 #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
43 static int n_carp_peers
= 0;
44 static peer
**carp_peers
= NULL
;
45 static OBJH carpCachemgr
;
48 peerSortWeight(const void *a
, const void *b
)
50 const peer
*const *p1
= a
, *const *p2
= b
;
51 return (*p1
)->weight
- (*p2
)->weight
;
60 double P_last
, X_last
, Xn
;
65 for (k
= 0; k
< n_carp_peers
; k
++) {
66 cbdataUnlock(carp_peers
[k
]);
68 safe_free(carp_peers
);
70 /* find out which peers we have */
71 for (p
= Config
.peers
; p
; p
= p
->next
) {
74 assert(p
->type
== PEER_PARENT
);
80 if (n_carp_peers
== 0)
82 carp_peers
= xcalloc(n_carp_peers
, sizeof(*carp_peers
));
83 /* Build a list of the found peers and calculate hashes and load factors */
84 for (P
= carp_peers
, p
= Config
.peers
; p
; p
= p
->next
) {
89 /* calculate this peers hash */
91 for (t
= p
->host
; *t
!= 0; t
++)
92 p
->carp
.hash
+= ROTATE_LEFT(p
->carp
.hash
, 19) + (unsigned int) *t
;
93 p
->carp
.hash
+= p
->carp
.hash
* 0x62531965;
94 p
->carp
.hash
= ROTATE_LEFT(p
->carp
.hash
, 21);
96 p
->carp
.load_factor
= ((double) p
->weight
) / (double) W
;
97 if (floor(p
->carp
.load_factor
* 1000.0) == 0.0)
98 p
->carp
.load_factor
= 0.0;
99 /* add it to our list of peers */
103 /* Sort our list on weight */
104 qsort(carp_peers
, n_carp_peers
, sizeof(*carp_peers
), peerSortWeight
);
105 /* Calculate the load factor multipliers X_k
107 * X_1 = pow ((K*p_1), (1/K))
108 * X_k = ([K-k+1] * [P_k - P_{k-1}])/(X_1 * X_2 * ... * X_{k-1})
109 * X_k += pow ((X_{k-1}, {K-k+1})
110 * X_k = pow (X_k, {1/(K-k+1)})
111 * simplified to have X_1 part of the loop
114 P_last
= 0.0; /* Empty P_0 */
115 Xn
= 1.0; /* Empty starting point of X_1 * X_2 * ... * X_{x-1} */
116 X_last
= 0.0; /* Empty X_0, nullifies the first pow statement */
117 for (k
= 1; k
<= K
; k
++) {
118 double Kk1
= (double) (K
- k
+ 1);
119 p
= carp_peers
[k
- 1];
120 p
->carp
.load_multiplier
= (Kk1
* (p
->carp
.load_factor
- P_last
)) / Xn
;
121 p
->carp
.load_multiplier
+= pow(X_last
, Kk1
);
122 p
->carp
.load_multiplier
= pow(p
->carp
.load_multiplier
, 1.0 / Kk1
);
123 Xn
*= p
->carp
.load_multiplier
;
124 X_last
= p
->carp
.load_multiplier
;
125 P_last
= p
->carp
.load_factor
;
127 cachemgrRegister("carp", "CARP information", carpCachemgr
, 0, 1);
131 carpSelectParent(request_t
* request
)
137 unsigned int user_hash
= 0;
138 unsigned int combined_hash
;
140 double high_score
= 0;
141 const char *key
= NULL
;
143 if (n_carp_peers
== 0)
146 key
= urlCanonical(request
);
148 /* calculate hash key */
149 debug(39, 2) ("carpSelectParent: Calculating hash for %s\n", key
);
150 for (c
= key
; *c
!= 0; c
++)
151 user_hash
+= ROTATE_LEFT(user_hash
, 19) + *c
;
153 for (k
= 0; k
< n_carp_peers
; k
++) {
155 combined_hash
= (user_hash
^ tp
->carp
.hash
);
156 combined_hash
+= combined_hash
* 0x62531965;
157 combined_hash
= ROTATE_LEFT(combined_hash
, 21);
158 score
= combined_hash
* tp
->carp
.load_multiplier
;
159 debug(39, 3) ("carpSelectParent: %s combined_hash %u score %.0f\n",
160 tp
->host
, combined_hash
, score
);
161 if ((score
> high_score
) && peerHTTPOkay(tp
, request
)) {
167 debug(39, 2) ("carpSelectParent: selected %s\n", p
->host
);
172 carpCachemgr(StoreEntry
* sentry
)
176 storeAppendPrintf(sentry
, "%24s %10s %10s %10s %10s\n",
182 for (p
= Config
.peers
; p
; p
= p
->next
)
183 sumfetches
+= p
->stats
.fetches
;
184 for (p
= Config
.peers
; p
; p
= p
->next
) {
185 storeAppendPrintf(sentry
, "%24s %10x %10f %10f %10f\n",
186 p
->host
, p
->carp
.hash
,
187 p
->carp
.load_multiplier
,
189 sumfetches
? (double) p
->stats
.fetches
/ sumfetches
: -1.0);