/* * $Id$ * * DEBUG: section 39 Peer user hash based selection * AUTHOR: Henrik Nordstrom * BASED ON: carp.cc * * SQUID Web Proxy Cache http://www.squid-cache.org/ * ---------------------------------------------------------- * * 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-old.h" #if USE_AUTH #include "mgr/Registration.h" #include "Store.h" #include "HttpRequest.h" #include "auth/UserRequest.h" #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n)))) static int n_userhash_peers = 0; static peer **userhash_peers = NULL; static OBJH peerUserHashCachemgr; static void peerUserHashRegisterWithCacheManager(void); 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; } void peerUserHashInit(void) { 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_userhash_peers; ++k) { cbdataReferenceDone(userhash_peers[k]); } safe_free(userhash_peers); n_userhash_peers = 0; /* find out which peers we have */ peerUserHashRegisterWithCacheManager(); for (p = Config.peers; p; p = p->next) { if (!p->options.userhash) continue; assert(p->type == PEER_PARENT); if (p->weight == 0) continue; ++n_userhash_peers; W += p->weight; } if (n_userhash_peers == 0) return; userhash_peers = (peer **)xcalloc(n_userhash_peers, sizeof(*userhash_peers)); /* Build a list of the found peers and calculate hashes and load factors */ for (P = userhash_peers, p = Config.peers; p; p = p->next) { if (!p->options.userhash) continue; if (p->weight == 0) continue; /* calculate this peers hash */ p->userhash.hash = 0; for (t = p->name; *t != 0; ++t) p->userhash.hash += ROTATE_LEFT(p->userhash.hash, 19) + (unsigned int) *t; p->userhash.hash += p->userhash.hash * 0x62531965; p->userhash.hash = ROTATE_LEFT(p->userhash.hash, 21); /* and load factor */ p->userhash.load_factor = ((double) p->weight) / (double) W; if (floor(p->userhash.load_factor * 1000.0) == 0.0) p->userhash.load_factor = 0.0; /* add it to our list of peers */ *P++ = cbdataReference(p); } /* Sort our list on weight */ qsort(userhash_peers, n_userhash_peers, sizeof(*userhash_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 */ K = n_userhash_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 = userhash_peers[k - 1]; p->userhash.load_multiplier = (Kk1 * (p->userhash.load_factor - P_last)) / Xn; p->userhash.load_multiplier += pow(X_last, Kk1); p->userhash.load_multiplier = pow(p->userhash.load_multiplier, 1.0 / Kk1); Xn *= p->userhash.load_multiplier; X_last = p->userhash.load_multiplier; P_last = p->userhash.load_factor; } } static void peerUserHashRegisterWithCacheManager(void) { Mgr::RegisterAction("userhash", "peer userhash information", peerUserHashCachemgr, 0, 1); } peer * peerUserHashSelectParent(HttpRequest * request) { int k; const char *c; peer *p = NULL; peer *tp; unsigned int user_hash = 0; unsigned int combined_hash; double score; double high_score = 0; const char *key = NULL; if (n_userhash_peers == 0) return NULL; if (request->auth_user_request != NULL) key = request->auth_user_request->username(); if (!key) return NULL; /* calculate hash key */ debugs(39, 2, "peerUserHashSelectParent: Calculating hash for " << key); for (c = key; *c != 0; ++c) user_hash += ROTATE_LEFT(user_hash, 19) + *c; /* select peer */ for (k = 0; k < n_userhash_peers; ++k) { tp = userhash_peers[k]; combined_hash = (user_hash ^ tp->userhash.hash); combined_hash += combined_hash * 0x62531965; combined_hash = ROTATE_LEFT(combined_hash, 21); score = combined_hash * tp->userhash.load_multiplier; debugs(39, 3, "peerUserHashSelectParent: " << 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) debugs(39, 2, "peerUserHashSelectParent: selected " << p->name); return p; } static void peerUserHashCachemgr(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->userhash.hash, p->userhash.load_multiplier, p->userhash.load_factor, sumfetches ? (double) p->stats.fetches / sumfetches : -1.0); } } #endif /* USE_AUTH */