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1 | /* | |
2 | * Copyright (C) 1996-2021 The Squid Software Foundation and contributors | |
3 | * | |
4 | * Squid software is distributed under GPLv2+ license and includes | |
5 | * contributions from numerous individuals and organizations. | |
6 | * Please see the COPYING and CONTRIBUTORS files for details. | |
7 | */ | |
8 | ||
9 | /* DEBUG: section 39 Cache Array Routing Protocol */ | |
10 | ||
11 | #include "squid.h" | |
12 | #include "CachePeer.h" | |
13 | #include "HttpRequest.h" | |
14 | #include "mgr/Registration.h" | |
15 | #include "neighbors.h" | |
16 | #include "PeerSelectState.h" | |
17 | #include "SquidConfig.h" | |
18 | #include "Store.h" | |
19 | ||
20 | #include <cmath> | |
21 | ||
22 | #define ROTATE_LEFT(x, n) (((x) << (n)) | ((x) >> (32-(n)))) | |
23 | ||
24 | static int n_carp_peers = 0; | |
25 | static CachePeer **carp_peers = NULL; | |
26 | static OBJH carpCachemgr; | |
27 | ||
28 | static int | |
29 | peerSortWeight(const void *a, const void *b) | |
30 | { | |
31 | const CachePeer *const *p1 = (const CachePeer *const *)a; | |
32 | const CachePeer *const *p2 = (const CachePeer *const *)b; | |
33 | return (*p1)->weight - (*p2)->weight; | |
34 | } | |
35 | ||
36 | static void | |
37 | carpRegisterWithCacheManager(void) | |
38 | { | |
39 | Mgr::RegisterAction("carp", "CARP information", carpCachemgr, 0, 1); | |
40 | } | |
41 | ||
42 | void | |
43 | carpInit(void) | |
44 | { | |
45 | int W = 0; | |
46 | int K; | |
47 | int k; | |
48 | double P_last, X_last, Xn; | |
49 | CachePeer *p; | |
50 | CachePeer **P; | |
51 | char *t; | |
52 | /* Clean up */ | |
53 | ||
54 | for (k = 0; k < n_carp_peers; ++k) { | |
55 | cbdataReferenceDone(carp_peers[k]); | |
56 | } | |
57 | ||
58 | safe_free(carp_peers); | |
59 | n_carp_peers = 0; | |
60 | ||
61 | /* initialize cache manager before we have a chance to leave the execution path */ | |
62 | carpRegisterWithCacheManager(); | |
63 | ||
64 | /* find out which peers we have */ | |
65 | ||
66 | for (p = Config.peers; p; p = p->next) { | |
67 | if (!p->options.carp) | |
68 | continue; | |
69 | ||
70 | assert(p->type == PEER_PARENT); | |
71 | ||
72 | if (p->weight == 0) | |
73 | continue; | |
74 | ||
75 | ++n_carp_peers; | |
76 | ||
77 | W += p->weight; | |
78 | } | |
79 | ||
80 | if (n_carp_peers == 0) | |
81 | return; | |
82 | ||
83 | carp_peers = (CachePeer **)xcalloc(n_carp_peers, sizeof(*carp_peers)); | |
84 | ||
85 | /* Build a list of the found peers and calculate hashes and load factors */ | |
86 | for (P = carp_peers, p = Config.peers; p; p = p->next) { | |
87 | if (!p->options.carp) | |
88 | continue; | |
89 | ||
90 | if (p->weight == 0) | |
91 | continue; | |
92 | ||
93 | /* calculate this peers hash */ | |
94 | p->carp.hash = 0; | |
95 | ||
96 | for (t = p->name; *t != 0; ++t) | |
97 | p->carp.hash += ROTATE_LEFT(p->carp.hash, 19) + (unsigned int) *t; | |
98 | ||
99 | p->carp.hash += p->carp.hash * 0x62531965; | |
100 | ||
101 | p->carp.hash = ROTATE_LEFT(p->carp.hash, 21); | |
102 | ||
103 | /* and load factor */ | |
104 | p->carp.load_factor = ((double) p->weight) / (double) W; | |
105 | ||
106 | if (floor(p->carp.load_factor * 1000.0) == 0.0) | |
107 | p->carp.load_factor = 0.0; | |
108 | ||
109 | /* add it to our list of peers */ | |
110 | *P = cbdataReference(p); | |
111 | ++P; | |
112 | } | |
113 | ||
114 | /* Sort our list on weight */ | |
115 | qsort(carp_peers, n_carp_peers, sizeof(*carp_peers), peerSortWeight); | |
116 | ||
117 | /* Calculate the load factor multipliers X_k | |
118 | * | |
119 | * X_1 = pow ((K*p_1), (1/K)) | |
120 | * X_k = ([K-k+1] * [P_k - P_{k-1}])/(X_1 * X_2 * ... * X_{k-1}) | |
121 | * X_k += pow ((X_{k-1}, {K-k+1}) | |
122 | * X_k = pow (X_k, {1/(K-k+1)}) | |
123 | * simplified to have X_1 part of the loop | |
124 | */ | |
125 | K = n_carp_peers; | |
126 | ||
127 | P_last = 0.0; /* Empty P_0 */ | |
128 | ||
129 | Xn = 1.0; /* Empty starting point of X_1 * X_2 * ... * X_{x-1} */ | |
130 | ||
131 | X_last = 0.0; /* Empty X_0, nullifies the first pow statement */ | |
132 | ||
133 | for (k = 1; k <= K; ++k) { | |
134 | double Kk1 = (double) (K - k + 1); | |
135 | p = carp_peers[k - 1]; | |
136 | p->carp.load_multiplier = (Kk1 * (p->carp.load_factor - P_last)) / Xn; | |
137 | p->carp.load_multiplier += pow(X_last, Kk1); | |
138 | p->carp.load_multiplier = pow(p->carp.load_multiplier, 1.0 / Kk1); | |
139 | Xn *= p->carp.load_multiplier; | |
140 | X_last = p->carp.load_multiplier; | |
141 | P_last = p->carp.load_factor; | |
142 | } | |
143 | } | |
144 | ||
145 | CachePeer * | |
146 | carpSelectParent(PeerSelector *ps) | |
147 | { | |
148 | assert(ps); | |
149 | HttpRequest *request = ps->request; | |
150 | ||
151 | int k; | |
152 | CachePeer *p = NULL; | |
153 | CachePeer *tp; | |
154 | unsigned int user_hash = 0; | |
155 | unsigned int combined_hash; | |
156 | double score; | |
157 | double high_score = 0; | |
158 | ||
159 | if (n_carp_peers == 0) | |
160 | return NULL; | |
161 | ||
162 | /* calculate hash key */ | |
163 | debugs(39, 2, "carpSelectParent: Calculating hash for " << request->effectiveRequestUri()); | |
164 | ||
165 | /* select CachePeer */ | |
166 | for (k = 0; k < n_carp_peers; ++k) { | |
167 | SBuf key; | |
168 | tp = carp_peers[k]; | |
169 | if (tp->options.carp_key.set) { | |
170 | // this code follows URI syntax pattern. | |
171 | // corner cases should use the full effective request URI | |
172 | if (tp->options.carp_key.scheme) { | |
173 | key.append(request->url.getScheme().image()); | |
174 | if (key.length()) //if the scheme is not empty | |
175 | key.append("://"); | |
176 | } | |
177 | if (tp->options.carp_key.host) { | |
178 | key.append(request->url.host()); | |
179 | } | |
180 | if (tp->options.carp_key.port) { | |
181 | key.appendf(":%u", request->url.port()); | |
182 | } | |
183 | if (tp->options.carp_key.path) { | |
184 | // XXX: fix when path and query are separate | |
185 | key.append(request->url.path().substr(0,request->url.path().find('?'))); // 0..N | |
186 | } | |
187 | if (tp->options.carp_key.params) { | |
188 | // XXX: fix when path and query are separate | |
189 | SBuf::size_type pos; | |
190 | if ((pos=request->url.path().find('?')) != SBuf::npos) | |
191 | key.append(request->url.path().substr(pos)); // N..npos | |
192 | } | |
193 | } | |
194 | // if the url-based key is empty, e.g. because the user is | |
195 | // asking to balance on the path but the request doesn't supply any, | |
196 | // then fall back to the effective request URI | |
197 | ||
198 | if (key.isEmpty()) | |
199 | key=request->effectiveRequestUri(); | |
200 | ||
201 | for (const char *c = key.rawContent(), *e=key.rawContent()+key.length(); c < e; ++c) | |
202 | user_hash += ROTATE_LEFT(user_hash, 19) + *c; | |
203 | combined_hash = (user_hash ^ tp->carp.hash); | |
204 | combined_hash += combined_hash * 0x62531965; | |
205 | combined_hash = ROTATE_LEFT(combined_hash, 21); | |
206 | score = combined_hash * tp->carp.load_multiplier; | |
207 | debugs(39, 3, "carpSelectParent: key=" << key << " name=" << tp->name << " combined_hash=" << combined_hash << | |
208 | " score=" << std::setprecision(0) << score); | |
209 | ||
210 | if ((score > high_score) && peerHTTPOkay(tp, ps)) { | |
211 | p = tp; | |
212 | high_score = score; | |
213 | } | |
214 | } | |
215 | ||
216 | if (p) | |
217 | debugs(39, 2, "carpSelectParent: selected " << p->name); | |
218 | ||
219 | return p; | |
220 | } | |
221 | ||
222 | static void | |
223 | carpCachemgr(StoreEntry * sentry) | |
224 | { | |
225 | CachePeer *p; | |
226 | int sumfetches = 0; | |
227 | storeAppendPrintf(sentry, "%24s %10s %10s %10s %10s\n", | |
228 | "Hostname", | |
229 | "Hash", | |
230 | "Multiplier", | |
231 | "Factor", | |
232 | "Actual"); | |
233 | ||
234 | for (p = Config.peers; p; p = p->next) | |
235 | sumfetches += p->stats.fetches; | |
236 | ||
237 | for (p = Config.peers; p; p = p->next) { | |
238 | storeAppendPrintf(sentry, "%24s %10x %10f %10f %10f\n", | |
239 | p->name, p->carp.hash, | |
240 | p->carp.load_multiplier, | |
241 | p->carp.load_factor, | |
242 | sumfetches ? (double) p->stats.fetches / sumfetches : -1.0); | |
243 | } | |
244 | } | |
245 |