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6a566b9c | 1 | |
2 | /* | |
262a0e14 | 3 | * $Id$ |
6a566b9c | 4 | * |
5 | * DEBUG: section 20 Storage Manager Heap-based replacement | |
6 | * AUTHOR: John Dilley | |
7 | * | |
2b6662ba | 8 | * SQUID Web Proxy Cache http://www.squid-cache.org/ |
6a566b9c | 9 | * ---------------------------------------------------------- |
10 | * | |
2b6662ba | 11 | * Squid is the result of efforts by numerous individuals from |
12 | * the Internet community; see the CONTRIBUTORS file for full | |
13 | * details. Many organizations have provided support for Squid's | |
14 | * development; see the SPONSORS file for full details. Squid is | |
15 | * Copyrighted (C) 2001 by the Regents of the University of | |
16 | * California; see the COPYRIGHT file for full details. Squid | |
17 | * incorporates software developed and/or copyrighted by other | |
18 | * sources; see the CREDITS file for full details. | |
6a566b9c | 19 | * |
20 | * This program is free software; you can redistribute it and/or modify | |
21 | * it under the terms of the GNU General Public License as published by | |
22 | * the Free Software Foundation; either version 2 of the License, or | |
23 | * (at your option) any later version. | |
26ac0430 | 24 | * |
6a566b9c | 25 | * This program is distributed in the hope that it will be useful, |
26 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
27 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
28 | * GNU General Public License for more details. | |
26ac0430 | 29 | * |
6a566b9c | 30 | * You should have received a copy of the GNU General Public License |
31 | * along with this program; if not, write to the Free Software | |
32 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. | |
33 | * | |
34 | */ | |
35 | ||
36 | /* | |
37 | * The code in this file is Copyrighted (C) 1999 by Hewlett Packard. | |
26ac0430 | 38 | * |
6a566b9c | 39 | * |
40 | * For a description of these cache replacement policies see -- | |
41 | * http://www.hpl.hp.com/techreports/1999/HPL-1999-69.html | |
42 | */ | |
43 | ||
582c2af2 | 44 | #include "squid.h" |
6a566b9c | 45 | #include "heap.h" |
2d72d4fd | 46 | #include "store_heap_replacement.h" |
e6ccf245 | 47 | #include "Store.h" |
528b2c61 | 48 | #include "MemObject.h" |
985c86bc | 49 | #include "SquidTime.h" |
6a566b9c | 50 | |
582c2af2 FC |
51 | #if HAVE_MATH_H |
52 | #include <math.h> | |
53 | #endif | |
54 | ||
6a566b9c | 55 | /* |
56 | * Key generation function to implement the LFU-DA policy (Least | |
57 | * Frequently Used with Dynamic Aging). Similar to classical LFU | |
58 | * but with aging to handle turnover of the popular document set. | |
59 | * Maximizes byte hit rate by keeping more currently popular objects | |
60 | * in cache regardless of size. Achieves lower hit rate than GDS | |
61 | * because there are more large objects in cache (so less room for | |
62 | * smaller popular objects). | |
26ac0430 | 63 | * |
6a566b9c | 64 | * This version implements a tie-breaker based upon recency |
65 | * (e->lastref): for objects that have the same reference count | |
66 | * the most recent object wins (gets a higher key value). | |
67 | * | |
68 | * Note: this does not properly handle when the aging factor | |
69 | * gets so huge that the added value is outside of the | |
70 | * precision of double. However, Squid has to stay up | |
71 | * for quite a extended period of time (number of requests) | |
72 | * for this to become a problem. (estimation is 10^8 cache | |
73 | * turnarounds) | |
74 | */ | |
f0debecb | 75 | heap_key |
b6a7f52c | 76 | HeapKeyGen_StoreEntry_LFUDA(void *entry, double heap_age) |
6a566b9c | 77 | { |
e6ccf245 | 78 | StoreEntry *e = (StoreEntry *)entry; |
6a566b9c | 79 | heap_key key; |
80 | double tie; | |
62e76326 | 81 | |
6a566b9c | 82 | if (e->lastref <= 0) |
62e76326 | 83 | tie = 0.0; |
6a566b9c | 84 | else if (squid_curtime <= e->lastref) |
62e76326 | 85 | tie = 0.0; |
6a566b9c | 86 | else |
62e76326 | 87 | tie = 1.0 - exp((double) (e->lastref - squid_curtime) / 86400.0); |
88 | ||
b6a7f52c | 89 | key = heap_age + (double) e->refcount - tie; |
62e76326 | 90 | |
e4049756 | 91 | debugs(81, 3, "HeapKeyGen_StoreEntry_LFUDA: " << e->getMD5Text() << |
92 | " refcnt=" << e->refcount << " lastref=" << e->lastref << | |
93 | " heap_age=" << heap_age << " tie=" << tie << " -> " << key); | |
62e76326 | 94 | |
6a566b9c | 95 | if (e->mem_obj && e->mem_obj->url) |
bf8fe701 | 96 | debugs(81, 3, "HeapKeyGen_StoreEntry_LFUDA: url=" << e->mem_obj->url); |
62e76326 | 97 | |
be1ed2a4 | 98 | return (double) key; |
6a566b9c | 99 | } |
100 | ||
6a566b9c | 101 | /* |
102 | * Key generation function to implement the GDS-Frequency policy. | |
103 | * Similar to Greedy Dual-Size Hits policy, but adds aging of | |
104 | * documents to prevent pollution. Maximizes object hit rate by | |
105 | * keeping more small, popular objects in cache. Achieves lower | |
106 | * byte hit rate than LFUDA because there are fewer large objects | |
107 | * in cache. | |
26ac0430 | 108 | * |
6a566b9c | 109 | * This version implements a tie-breaker based upon recency |
110 | * (e->lastref): for objects that have the same reference count | |
111 | * the most recent object wins (gets a higher key value). | |
112 | * | |
113 | * Note: this does not properly handle when the aging factor | |
114 | * gets so huge that the added value is outside of the | |
115 | * precision of double. However, Squid has to stay up | |
116 | * for quite a extended period of time (number of requests) | |
117 | * for this to become a problem. (estimation is 10^8 cache | |
118 | * turnarounds) | |
119 | */ | |
f0debecb | 120 | heap_key |
b6a7f52c | 121 | HeapKeyGen_StoreEntry_GDSF(void *entry, double heap_age) |
6a566b9c | 122 | { |
e6ccf245 | 123 | StoreEntry *e = (StoreEntry *)entry; |
6a566b9c | 124 | heap_key key; |
125 | double size = e->swap_file_sz ? (double) e->swap_file_sz : 1.0; | |
126 | double tie = (e->lastref > 1) ? (1.0 / e->lastref) : 1.0; | |
b6a7f52c | 127 | key = heap_age + ((double) e->refcount / size) - tie; |
e4049756 | 128 | debugs(81, 3, "HeapKeyGen_StoreEntry_GDSF: " << e->getMD5Text() << |
129 | " size=" << size << " refcnt=" << e->refcount << " lastref=" << | |
130 | e->lastref << " heap_age=" << heap_age << " tie=" << tie << | |
131 | " -> " << key); | |
62e76326 | 132 | |
6a566b9c | 133 | if (e->mem_obj && e->mem_obj->url) |
bf8fe701 | 134 | debugs(81, 3, "HeapKeyGen_StoreEntry_GDSF: url=" << e->mem_obj->url); |
62e76326 | 135 | |
6a566b9c | 136 | return key; |
137 | } | |
138 | ||
62e76326 | 139 | /* |
6a566b9c | 140 | * Key generation function to implement the LRU policy. Normally |
141 | * one would not do this with a heap -- use the linked list instead. | |
142 | * For testing and performance characterization it was useful. | |
143 | * Don't use it unless you are trying to compare performance among | |
144 | * heap-based replacement policies... | |
145 | */ | |
f0debecb | 146 | heap_key |
b6a7f52c | 147 | HeapKeyGen_StoreEntry_LRU(void *entry, double heap_age) |
6a566b9c | 148 | { |
e6ccf245 | 149 | StoreEntry *e = (StoreEntry *)entry; |
26ac0430 AJ |
150 | debugs(81, 3, "HeapKeyGen_StoreEntry_LRU: " << |
151 | e->getMD5Text() << " heap_age=" << heap_age << | |
152 | " lastref=" << (double) e->lastref ); | |
62e76326 | 153 | |
6a566b9c | 154 | if (e->mem_obj && e->mem_obj->url) |
bf8fe701 | 155 | debugs(81, 3, "HeapKeyGen_StoreEntry_LRU: url=" << e->mem_obj->url); |
62e76326 | 156 | |
6a566b9c | 157 | return (heap_key) e->lastref; |
158 | } |