+
/*
- * $Id: carp.cc,v 1.5 1998/08/13 21:14:39 wessels Exp $
+ * $Id$
*
* DEBUG: section 39 Cache Array Routing Protocol
- * AUTHOR: Eric Stern
+ * AUTHOR: Henrik Nordstrom
+ * BASED ON: carp.c by Eric Stern and draft-vinod-carp-v1-03.txt
*
- * SQUID Internet Object Cache http://squid.nlanr.net/Squid/
+ * SQUID Web Proxy Cache http://www.squid-cache.org/
* ----------------------------------------------------------
*
- * Squid is the result of efforts by numerous individuals from the
- * Internet community. Development is led by Duane Wessels of the
- * National Laboratory for Applied Network Research and funded by the
- * National Science Foundation. Squid is Copyrighted (C) 1998 by
- * Duane Wessels and the University of California San Diego. Please
- * see the COPYRIGHT file for full details. Squid incorporates
- * software developed and/or copyrighted by other sources. Please see
- * the CREDITS file for full details.
+ * Squid is the result of efforts by numerous individuals from
+ * the Internet community; see the CONTRIBUTORS file for full
+ * details. Many organizations have provided support for Squid's
+ * development; see the SPONSORS file for full details. Squid is
+ * Copyrighted (C) 2001 by the Regents of the University of
+ * California; see the COPYRIGHT file for full details. Squid
+ * incorporates software developed and/or copyrighted by other
+ * sources; see the CREDITS file for full details.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
- *
+ *
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
- *
+ *
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
*/
#include "squid.h"
+#include "CacheManager.h"
+#include "Store.h"
+
+#define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n))))
+
+static int n_carp_peers = 0;
+static peer **carp_peers = NULL;
+static OBJH carpCachemgr;
+
+static int
+peerSortWeight(const void *a, const void *b)
+{
+ const peer *const *p1 = (const peer *const *)a;
+ const peer *const *p2 = (const peer *const *)b;
+ return (*p1)->weight - (*p2)->weight;
+}
-#if USE_CARP
+static void
+carpRegisterWithCacheManager(void)
+{
+ CacheManager::GetInstance()->
+ registerAction("carp", "CARP information", carpCachemgr, 0, 1);
+}
void
carpInit(void)
{
- /* calculate load factors */
- int K = 0;
- float a = 0.0;
- float X;
- float Xn;
- float n;
+ int W = 0;
+ int K;
int k;
+ double P_last, X_last, Xn;
peer *p;
+ peer **P;
+ char *t;
+ /* Clean up */
+
+ for (k = 0; k < n_carp_peers; k++) {
+ cbdataReferenceDone(carp_peers[k]);
+ }
+
+ safe_free(carp_peers);
+ n_carp_peers = 0;
+
+ /* initialize cache manager before we have a chance to leave the execution path */
+ carpRegisterWithCacheManager();
+
+ /* find out which peers we have */
+
for (p = Config.peers; p; p = p->next) {
- a += p->carp.load_factor;
- K++;
+ if (!p->options.carp)
+ continue;
+
+ assert(p->type == PEER_PARENT);
+
+ if (p->weight == 0)
+ continue;
+
+ n_carp_peers++;
+
+ W += p->weight;
+ }
+
+ if (n_carp_peers == 0)
+ return;
+
+ carp_peers = (peer **)xcalloc(n_carp_peers, sizeof(*carp_peers));
+
+ /* Build a list of the found peers and calculate hashes and load factors */
+ for (P = carp_peers, p = Config.peers; p; p = p->next) {
+ if (!p->options.carp)
+ continue;
+
+ if (p->weight == 0)
+ continue;
+
+ /* calculate this peers hash */
+ p->carp.hash = 0;
+
+ for (t = p->name; *t != 0; t++)
+ p->carp.hash += ROTATE_LEFT(p->carp.hash, 19) + (unsigned int) *t;
+
+ p->carp.hash += p->carp.hash * 0x62531965;
+
+ p->carp.hash = ROTATE_LEFT(p->carp.hash, 21);
+
+ /* and load factor */
+ p->carp.load_factor = ((double) p->weight) / (double) W;
+
+ if (floor(p->carp.load_factor * 1000.0) == 0.0)
+ p->carp.load_factor = 0.0;
+
+ /* add it to our list of peers */
+ *P++ = cbdataReference(p);
}
- if (a == 0.0)
- /* CARP load factors not configured */
- return;
- /*
- * sum of carp-load-factor's for all cache_peer's in squid.conf
- * must equal 1.0
+
+ /* Sort our list on weight */
+ qsort(carp_peers, n_carp_peers, sizeof(*carp_peers), peerSortWeight);
+
+ /* Calculate the load factor multipliers X_k
+ *
+ * X_1 = pow ((K*p_1), (1/K))
+ * X_k = ([K-k+1] * [P_k - P_{k-1}])/(X_1 * X_2 * ... * X_{k-1})
+ * X_k += pow ((X_{k-1}, {K-k+1})
+ * X_k = pow (X_k, {1/(K-k+1)})
+ * simplified to have X_1 part of the loop
*/
- assert(a == 1.0);
- k = 1;
- n = 0;
- Xn = 0;
- for (p = Config.peers; p; p = p->next) {
- X = pow(K * p->carp.load_factor, 1 / K);
- if (Xn == 0)
- Xn = X;
- else
- Xn *= X;
- p->carp.load_multiplier = ((K - k + 1) * (p->carp.load_factor - n)) / Xn
- ;
- k++;
- n = p->carp.load_factor;
+ K = n_carp_peers;
+
+ P_last = 0.0; /* Empty P_0 */
+
+ Xn = 1.0; /* Empty starting point of X_1 * X_2 * ... * X_{x-1} */
+
+ X_last = 0.0; /* Empty X_0, nullifies the first pow statement */
+
+ for (k = 1; k <= K; k++) {
+ double Kk1 = (double) (K - k + 1);
+ p = carp_peers[k - 1];
+ p->carp.load_multiplier = (Kk1 * (p->carp.load_factor - P_last)) / Xn;
+ p->carp.load_multiplier += pow(X_last, Kk1);
+ p->carp.load_multiplier = pow(p->carp.load_multiplier, 1.0 / Kk1);
+ Xn *= p->carp.load_multiplier;
+ X_last = p->carp.load_multiplier;
+ P_last = p->carp.load_factor;
}
}
peer *
-carpSelectParent(request_t * request)
+carpSelectParent(HttpRequest * request)
{
+ int k;
const char *c;
peer *p = NULL;
peer *tp;
- unsigned long url_hash = 0;
- unsigned long combined_hash;
- unsigned long high_score = 0;
- const char *url = urlCanonical(request);
- /* calculate url hash */
- debug(39, 2) ("carpSelectParent: CARP Calculating hash for %s\n", url);
- for (c = url; *c != 0; c++)
- url_hash += (url_hash << 19) + *c;
+ unsigned int user_hash = 0;
+ unsigned int combined_hash;
+ double score;
+ double high_score = 0;
+ const char *key = NULL;
+
+ if (n_carp_peers == 0)
+ return NULL;
+
+ key = urlCanonical(request);
+
+ /* calculate hash key */
+ debugs(39, 2, "carpSelectParent: Calculating hash for " << key);
+
+ for (c = key; *c != 0; c++)
+ user_hash += ROTATE_LEFT(user_hash, 19) + *c;
+
/* select peer */
- for (tp = Config.peers; tp; tp = tp->next) {
- if (p->carp.load_factor == 0.0)
- continue;
- assert(p->type == PEER_PARENT);
- combined_hash = (url_hash ^ tp->carp.hash);
- combined_hash += combined_hash * 0x62531965;
- combined_hash = combined_hash << 21;
- combined_hash = combined_hash * tp->carp.load_multiplier;
- debug(39, 3) ("carpSelectParent: %s combined_hash %d\n",
- tp->host, combined_hash);
- if ((combined_hash > high_score) && neighborUp(tp)) {
- p = tp;
- high_score = combined_hash;
- }
+ for (k = 0; k < n_carp_peers; k++) {
+ tp = carp_peers[k];
+ combined_hash = (user_hash ^ tp->carp.hash);
+ combined_hash += combined_hash * 0x62531965;
+ combined_hash = ROTATE_LEFT(combined_hash, 21);
+ score = combined_hash * tp->carp.load_multiplier;
+ debugs(39, 3, "carpSelectParent: " << tp->name << " combined_hash " << combined_hash <<
+ " score " << std::setprecision(0) << score);
+
+ if ((score > high_score) && peerHTTPOkay(tp, request)) {
+ p = tp;
+ high_score = score;
+ }
}
+
if (p)
- debug(39, 3) ("carpSelectParent: selected CARP %s\n", p->host);
+ debugs(39, 2, "carpSelectParent: selected " << p->name);
+
return p;
}
-#endif
+
+static void
+carpCachemgr(StoreEntry * sentry)
+{
+ peer *p;
+ int sumfetches = 0;
+ storeAppendPrintf(sentry, "%24s %10s %10s %10s %10s\n",
+ "Hostname",
+ "Hash",
+ "Multiplier",
+ "Factor",
+ "Actual");
+
+ for (p = Config.peers; p; p = p->next)
+ sumfetches += p->stats.fetches;
+
+ for (p = Config.peers; p; p = p->next) {
+ storeAppendPrintf(sentry, "%24s %10x %10f %10f %10f\n",
+ p->name, p->carp.hash,
+ p->carp.load_multiplier,
+ p->carp.load_factor,
+ sumfetches ? (double) p->stats.fetches / sumfetches : -1.0);
+ }
+}
projects / thirdparty / squid.git / blobdiff