]>
git.ipfire.org Git - thirdparty/squid.git/blob - src/carp.cc
1b552f98422d21a891edc74371e0c877e0ab68c2
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 * ----------------------------------------------------------
12 * Squid is the result of efforts by numerous individuals from
13 * the Internet community; see the CONTRIBUTORS file for full
14 * details. Many organizations have provided support for Squid's
15 * development; see the SPONSORS file for full details. Squid is
16 * Copyrighted (C) 2001 by the Regents of the University of
17 * California; see the COPYRIGHT file for full details. Squid
18 * incorporates software developed and/or copyrighted by other
19 * sources; see the CREDITS file for full details.
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.
38 #include "HttpRequest.h"
39 #include "mgr/Registration.h"
41 #include "URLScheme.h"
43 #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
45 static int n_carp_peers
= 0;
46 static peer
**carp_peers
= NULL
;
47 static OBJH carpCachemgr
;
50 peerSortWeight(const void *a
, const void *b
)
52 const peer
*const *p1
= (const peer
*const *)a
;
53 const peer
*const *p2
= (const peer
*const *)b
;
54 return (*p1
)->weight
- (*p2
)->weight
;
58 carpRegisterWithCacheManager(void)
60 Mgr::RegisterAction("carp", "CARP information", carpCachemgr
, 0, 1);
69 double P_last
, X_last
, Xn
;
75 for (k
= 0; k
< n_carp_peers
; k
++) {
76 cbdataReferenceDone(carp_peers
[k
]);
79 safe_free(carp_peers
);
82 /* initialize cache manager before we have a chance to leave the execution path */
83 carpRegisterWithCacheManager();
85 /* find out which peers we have */
87 for (p
= Config
.peers
; p
; p
= p
->next
) {
91 assert(p
->type
== PEER_PARENT
);
101 if (n_carp_peers
== 0)
104 carp_peers
= (peer
**)xcalloc(n_carp_peers
, sizeof(*carp_peers
));
106 /* Build a list of the found peers and calculate hashes and load factors */
107 for (P
= carp_peers
, p
= Config
.peers
; p
; p
= p
->next
) {
108 if (!p
->options
.carp
)
114 /* calculate this peers hash */
117 for (t
= p
->name
; *t
!= 0; t
++)
118 p
->carp
.hash
+= ROTATE_LEFT(p
->carp
.hash
, 19) + (unsigned int) *t
;
120 p
->carp
.hash
+= p
->carp
.hash
* 0x62531965;
122 p
->carp
.hash
= ROTATE_LEFT(p
->carp
.hash
, 21);
124 /* and load factor */
125 p
->carp
.load_factor
= ((double) p
->weight
) / (double) W
;
127 if (floor(p
->carp
.load_factor
* 1000.0) == 0.0)
128 p
->carp
.load_factor
= 0.0;
130 /* add it to our list of peers */
131 *P
++ = cbdataReference(p
);
134 /* Sort our list on weight */
135 qsort(carp_peers
, n_carp_peers
, sizeof(*carp_peers
), peerSortWeight
);
137 /* Calculate the load factor multipliers X_k
139 * X_1 = pow ((K*p_1), (1/K))
140 * X_k = ([K-k+1] * [P_k - P_{k-1}])/(X_1 * X_2 * ... * X_{k-1})
141 * X_k += pow ((X_{k-1}, {K-k+1})
142 * X_k = pow (X_k, {1/(K-k+1)})
143 * simplified to have X_1 part of the loop
147 P_last
= 0.0; /* Empty P_0 */
149 Xn
= 1.0; /* Empty starting point of X_1 * X_2 * ... * X_{x-1} */
151 X_last
= 0.0; /* Empty X_0, nullifies the first pow statement */
153 for (k
= 1; k
<= K
; k
++) {
154 double Kk1
= (double) (K
- k
+ 1);
155 p
= carp_peers
[k
- 1];
156 p
->carp
.load_multiplier
= (Kk1
* (p
->carp
.load_factor
- P_last
)) / Xn
;
157 p
->carp
.load_multiplier
+= pow(X_last
, Kk1
);
158 p
->carp
.load_multiplier
= pow(p
->carp
.load_multiplier
, 1.0 / Kk1
);
159 Xn
*= p
->carp
.load_multiplier
;
160 X_last
= p
->carp
.load_multiplier
;
161 P_last
= p
->carp
.load_factor
;
166 carpSelectParent(HttpRequest
* request
)
171 unsigned int user_hash
= 0;
172 unsigned int combined_hash
;
174 double high_score
= 0;
176 if (n_carp_peers
== 0)
179 /* calculate hash key */
180 debugs(39, 2, "carpSelectParent: Calculating hash for " << urlCanonical(request
));
183 for (k
= 0; k
< n_carp_peers
; k
++) {
186 if (tp
->options
.carp_key
.set
) {
187 //this code follows urlCanonical's pattern.
188 // corner cases should use the canonical URL
189 if (tp
->options
.carp_key
.scheme
) {
190 // temporary, until bug 1961 URL handling is fixed.
191 const URLScheme sch
= request
->protocol
;
192 key
.append(sch
.const_str());
193 if (key
.size()) //if the scheme is not empty
196 if (tp
->options
.carp_key
.host
) {
197 key
.append(request
->GetHost());
199 if (tp
->options
.carp_key
.port
) {
200 static char portbuf
[7];
201 snprintf(portbuf
,7,":%d", request
->port
);
204 if (tp
->options
.carp_key
.path
) {
205 String::size_type pos
;
206 if ((pos
=request
->urlpath
.find('?'))!=String::npos
)
207 key
.append(request
->urlpath
.substr(0,pos
));
209 key
.append(request
->urlpath
);
211 if (tp
->options
.carp_key
.params
) {
212 String::size_type pos
;
213 if ((pos
=request
->urlpath
.find('?'))!=String::npos
)
214 key
.append(request
->urlpath
.substr(pos
,request
->urlpath
.size()));
217 // if the url-based key is empty, e.g. because the user is
218 // asking to balance on the path but the request doesn't supply any,
219 // then fall back to canonical URL
222 key
=urlCanonical(request
);
224 for (const char *c
= key
.rawBuf(), *e
=key
.rawBuf()+key
.size(); c
< e
; c
++)
225 user_hash
+= ROTATE_LEFT(user_hash
, 19) + *c
;
226 combined_hash
= (user_hash
^ tp
->carp
.hash
);
227 combined_hash
+= combined_hash
* 0x62531965;
228 combined_hash
= ROTATE_LEFT(combined_hash
, 21);
229 score
= combined_hash
* tp
->carp
.load_multiplier
;
230 debugs(39, 3, "carpSelectParent: key=" << key
<< " name=" << tp
->name
<< " combined_hash=" << combined_hash
<<
231 " score=" << std::setprecision(0) << score
);
233 if ((score
> high_score
) && peerHTTPOkay(tp
, request
)) {
240 debugs(39, 2, "carpSelectParent: selected " << p
->name
);
246 carpCachemgr(StoreEntry
* sentry
)
250 storeAppendPrintf(sentry
, "%24s %10s %10s %10s %10s\n",
257 for (p
= Config
.peers
; p
; p
= p
->next
)
258 sumfetches
+= p
->stats
.fetches
;
260 for (p
= Config
.peers
; p
; p
= p
->next
) {
261 storeAppendPrintf(sentry
, "%24s %10x %10f %10f %10f\n",
262 p
->name
, p
->carp
.hash
,
263 p
->carp
.load_multiplier
,
265 sumfetches
? (double) p
->stats
.fetches
/ sumfetches
: -1.0);