/* * Copyright (C) 1996-2017 The Squid Software Foundation and contributors * * Squid software is distributed under GPLv2+ license and includes * contributions from numerous individuals and organizations. * Please see the COPYING and CONTRIBUTORS files for details. */ /* DEBUG: section 39 Cache Array Routing Protocol */ #include "squid.h" #include "CachePeer.h" #include "HttpRequest.h" #include "mgr/Registration.h" #include "neighbors.h" #include "SquidConfig.h" #include "Store.h" #include "URL.h" #include #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n)))) static int n_carp_peers = 0; static CachePeer **carp_peers = NULL; static OBJH carpCachemgr; static int peerSortWeight(const void *a, const void *b) { const CachePeer *const *p1 = (const CachePeer *const *)a; const CachePeer *const *p2 = (const CachePeer *const *)b; return (*p1)->weight - (*p2)->weight; } static void carpRegisterWithCacheManager(void) { Mgr::RegisterAction("carp", "CARP information", carpCachemgr, 0, 1); } void carpInit(void) { int W = 0; int K; int k; double P_last, X_last, Xn; CachePeer *p; CachePeer **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) { 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 = (CachePeer **)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); ++P; } /* 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 */ 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; } } CachePeer * carpSelectParent(HttpRequest * request) { int k; CachePeer *p = NULL; CachePeer *tp; unsigned int user_hash = 0; unsigned int combined_hash; double score; double high_score = 0; if (n_carp_peers == 0) return NULL; /* calculate hash key */ debugs(39, 2, "carpSelectParent: Calculating hash for " << urlCanonical(request)); /* select CachePeer */ for (k = 0; k < n_carp_peers; ++k) { SBuf key; tp = carp_peers[k]; if (tp->options.carp_key.set) { //this code follows urlCanonical's pattern. // corner cases should use the canonical URL if (tp->options.carp_key.scheme) { key.append(request->url.getScheme().c_str()); if (key.length()) //if the scheme is not empty key.append("://"); } if (tp->options.carp_key.host) { key.append(request->GetHost()); } if (tp->options.carp_key.port) { static char portbuf[7]; snprintf(portbuf,7,":%d", request->port); key.append(portbuf); } if (tp->options.carp_key.path) { String::size_type pos; if ((pos=request->urlpath.find('?'))!=String::npos) key.append(SBuf(request->urlpath.substr(0,pos))); else key.append(SBuf(request->urlpath)); } if (tp->options.carp_key.params) { String::size_type pos; if ((pos=request->urlpath.find('?'))!=String::npos) key.append(SBuf(request->urlpath.substr(pos,request->urlpath.size()))); } } // if the url-based key is empty, e.g. because the user is // asking to balance on the path but the request doesn't supply any, // then fall back to canonical URL if (key.isEmpty()) key=SBuf(urlCanonical(request)); for (const char *c = key.rawContent(), *e=key.rawContent()+key.length(); c < e; ++c) user_hash += ROTATE_LEFT(user_hash, 19) + *c; 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: key=" << key << " name=" << 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, "carpSelectParent: selected " << p->name); return p; } static void carpCachemgr(StoreEntry * sentry) { CachePeer *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); } }