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59b2d47f | 1 | /* |
59b2d47f | 2 | * SQUID Web Proxy Cache http://www.squid-cache.org/ |
3 | * ---------------------------------------------------------- | |
4 | * | |
5 | * Squid is the result of efforts by numerous individuals from | |
6 | * the Internet community; see the CONTRIBUTORS file for full | |
7 | * details. Many organizations have provided support for Squid's | |
8 | * development; see the SPONSORS file for full details. Squid is | |
9 | * Copyrighted (C) 2001 by the Regents of the University of | |
10 | * California; see the COPYRIGHT file for full details. Squid | |
11 | * incorporates software developed and/or copyrighted by other | |
12 | * sources; see the CREDITS file for full details. | |
13 | * | |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License as published by | |
16 | * the Free Software Foundation; either version 2 of the License, or | |
17 | * (at your option) any later version. | |
26ac0430 | 18 | * |
59b2d47f | 19 | * This program is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | * GNU General Public License for more details. | |
26ac0430 | 23 | * |
59b2d47f | 24 | * You should have received a copy of the GNU General Public License |
25 | * along with this program; if not, write to the Free Software | |
26 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA. | |
27 | * | |
28 | * Copyright (c) 2003, Robert Collins <robertc@squid-cache.org> | |
29 | */ | |
30 | ||
31 | #ifndef SQUID_STOREFILESYSTEM_H | |
32 | #define SQUID_STOREFILESYSTEM_H | |
33 | ||
59b2d47f | 34 | #include "Array.h" |
35 | ||
946c686b AJ |
36 | /* ****** DOCUMENTATION ***** */ |
37 | ||
4d95a996 AJ |
38 | /** |
39 | \defgroup FileSystems Storage Filesystems | |
26ac0430 | 40 | * |
4d95a996 AJ |
41 | \section Introduction Introduction |
42 | \par | |
43 | * Traditionally, Squid has always used the Unix filesystem (\link UFS UFS\endlink) | |
44 | * to store cache objects on disk. Over the years, the | |
45 | * poor performance of \link UFS UFS\endlink has become very obvious. In most | |
46 | * cases, \link UFS UFS\endlink limits Squid to about 30-50 requests per second. | |
47 | * Our work indicates that the poor performance is mostly | |
48 | * due to the synchronous nature of open() and unlink() | |
49 | * system calls, and perhaps thrashing of inode/buffer caches. | |
26ac0430 | 50 | * |
4d95a996 AJ |
51 | \par |
52 | * We want to try out our own, customized filesystems with Squid. | |
53 | * In order to do that, we need a well-defined interface | |
54 | * for the bits of Squid that access the permanent storage | |
55 | * devices. We also require tighter control of the replacement | |
56 | * policy by each storage module, rather than a single global | |
57 | * replacement policy. | |
26ac0430 | 58 | * |
4d95a996 AJ |
59 | \section BuildStructure Build structure |
60 | \par | |
61 | * The storage types live in \em src/fs/. Each subdirectory corresponds | |
62 | * to the name of the storage type. When a new storage type is implemented | |
a6093a2d | 63 | * configure.ac must be updated to autogenerate a Makefile in |
4d95a996 AJ |
64 | * \em src/fs/foo/ from a Makefile.in file. |
65 | * | |
a6093a2d | 66 | \todo DOCS: add template addition to configure.ac for storage module addition. |
4d95a996 | 67 | \todo DOCS: add template Makefile.am for storage module addition. |
26ac0430 | 68 | * |
4d95a996 AJ |
69 | \par |
70 | * configure will take a list of storage types through the | |
71 | * --enable-store-io parameter. This parameter takes a list of | |
72 | * space seperated storage types. For example, | |
73 | * --enable-store-io="ufs coss" . | |
26ac0430 | 74 | * |
4d95a996 AJ |
75 | \par |
76 | * Each storage type must create an archive file | |
77 | * in \em src/fs/foo/.a . This file is automatically linked into | |
78 | * squid at compile time. | |
26ac0430 | 79 | * |
4d95a996 AJ |
80 | \par |
81 | * Each storage filesystem must inherit from StoreFileSystem and provide | |
82 | * all virtual function hooks for squid to operate with. | |
26ac0430 | 83 | * |
4d95a996 AJ |
84 | \section OperationOfStorageModules Operation of a Storage Module |
85 | \par | |
86 | * Squid understands the concept of multiple diverse storage directories. | |
87 | * Each storage directory provides a caching object store, with object | |
88 | * storage, retrieval, indexing and replacement. | |
26ac0430 | 89 | * |
4d95a996 AJ |
90 | \par |
91 | * Each open object has associated with it a storeIOState object. The | |
92 | * storeIOState object is used to record the state of the current | |
93 | * object. Each storeIOState can have a storage module specific data | |
94 | * structure containing information private to the storage module. | |
26ac0430 | 95 | * |
4d95a996 AJ |
96 | \par |
97 | * Each SwapDir has the concept of a maximum object size. This is used | |
98 | * as a basic hint to the storage layer in first choosing a suitable | |
99 | * SwapDir. The checkobj function is then called for suitable | |
100 | * candidate SwapDirs to find out whether it wants to store a | |
101 | * given StoreEntry. A maxobjsize of -1 means 'any size'. | |
102 | */ | |
62ee09ca | 103 | |
e1f7507e AJ |
104 | class SwapDir; |
105 | ||
4d95a996 AJ |
106 | /** |
107 | \ingroup FileSystems | |
108 | * | |
109 | * The core API for storage modules this class provides all the hooks | |
110 | * squid uses to interact with a filesystem IO module. | |
111 | */ | |
59b2d47f | 112 | class StoreFileSystem |
113 | { | |
114 | ||
115 | public: | |
116 | static void SetupAllFs(); | |
117 | static void FsAdd(StoreFileSystem &); | |
118 | static void FreeAllFs(); | |
119 | static Vector<StoreFileSystem*> const &FileSystems(); | |
120 | typedef Vector<StoreFileSystem*>::iterator iterator; | |
121 | typedef Vector<StoreFileSystem*>::const_iterator const_iterator; | |
e1f7507e | 122 | StoreFileSystem() : initialised(false) {} |
59b2d47f | 123 | |
26ac0430 | 124 | virtual ~StoreFileSystem() {} |
59b2d47f | 125 | |
126 | virtual char const *type () const = 0; | |
127 | virtual SwapDir *createSwapDir() = 0; | |
128 | virtual void done() = 0; | |
129 | virtual void setup() = 0; | |
130 | // Not implemented | |
131 | StoreFileSystem(StoreFileSystem const &); | |
132 | StoreFileSystem &operator=(StoreFileSystem const&); | |
133 | ||
134 | protected: | |
135 | bool initialised; | |
6b7d87bb | 136 | virtual void registerWithCacheManager(void); |
59b2d47f | 137 | |
138 | private: | |
139 | static Vector<StoreFileSystem*> &GetFileSystems(); | |
140 | static Vector<StoreFileSystem*> *_FileSystems; | |
6b7d87bb | 141 | static void RegisterAllFsWithCacheManager(void); |
59b2d47f | 142 | }; |
143 | ||
4d95a996 | 144 | // TODO: Kill this typedef! |
59b2d47f | 145 | typedef StoreFileSystem storefs_entry_t; |
146 | ||
59b2d47f | 147 | #endif /* SQUID_STOREFILESYSTEM_H */ |