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git.ipfire.org Git - thirdparty/squid.git/blob - src/StoreSwapLogData.h
4 * SQUID Web Proxy Cache http://www.squid-cache.org/
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16 * This program is free software; you can redistribute it and/or modify
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22 * but WITHOUT ANY WARRANTY; without even the implied warranty of
23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
24 * GNU General Public License for more details.
26 * You should have received a copy of the GNU General Public License
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30 * Copyright (c) 2003, Robert Collins <robertc@squid-cache.org>
33 #ifndef SQUID_STORESWAPLOGDATA_H
34 #define SQUID_STORESWAPLOGDATA_H
37 \defgroup FileFormatSwapStateAPI swap.state File Structure
39 \section ImplementationNotes Implementation Notes
41 * When writing an object to disk, we must first write the meta data.
42 * This is done with a couple of functions. First, storeSwapMetaPack()
43 * takes a StoreEntry as a parameter and returns a tlv linked
44 * list. Second, storeSwapMetaPack() converts the tlv list
45 * into a character buffer that we can write.
47 \note MemObject has a MemObject::swap_hdr_sz.
48 * This value is the size of that character buffer; the size of the
49 * swap file meta data. The StoreEntry has a member
50 * StoreEntry::swap_file_sz that represents the size of the disk file.
51 * Thus, the size of the object "content" is
52 \code StoreEntry->swap_file_sz - MemObject->swap_hdr_sz; \endcode
53 \note The swap file content includes the HTTP reply headers and the HTTP reply body (if any).
56 * When reading a swap file, there is a similar process to extract
57 * the swap meta data. First, storeSwapMetaUnpack() converts a
58 * character buffer into a tlv linked list. It also tells us
59 * the value for MemObject->swap_hdr_sz.
66 /// maintains a 24-bit checksum over integer fields
70 SwapChecksum24() { raw
[0] = raw
[1] = raw
[2] = 0; }
72 bool operator ==(const SwapChecksum24
&o
) const {
73 return raw
[0] == o
.raw
[0] && raw
[1] == o
.raw
[1] && raw
[2] == o
.raw
[2];
76 bool operator !=(const SwapChecksum24
&o
) const {
80 /// compute and store checksum based on three 32bit integers
81 void set(uint32_t f1
, uint32_t f2
, uint32_t f3
);
83 /// compute and store checksum based on int32_t and uint64_t integers
84 void set(int32_t f1
, uint64_t f2
);
86 // printing for debugging
87 std::ostream
&print(std::ostream
&os
) const;
90 uint8_t raw
[3]; // designed to follow "op" members, in pading space
94 operator <<(std::ostream
&os
, const SwapChecksum24
&sum
)
100 \ingroup FielFormatSwapStateAPI
103 * Defines the structure of a binary swap.state file entry for UFS stores.
104 * TODO: Move to fs/ufs (and remove from COSS).
106 \note StoreSwapLogData entries are written in native machine byte order
107 * They are not necessarily portable across architectures.
109 class StoreSwapLogData
113 MEMPROXY_CLASS(StoreSwapLogData
);
115 /// type to use for storing time-related members; must be signed
116 typedef int64_t SwappedTime
;
120 /// consistency self-check: whether the data appears to make sense
123 /// call this before storing the log entry
127 * Either SWAP_LOG_ADD when an object is added to the disk storage,
128 * or SWAP_LOG_DEL when an object is deleted.
133 * Fingerprint to weed out bogus/corrupted swap.state entries.
135 SwapChecksum24 checksum
; // follows "op" because compiler will pad anyway
138 * The 32-bit file number which maps to a pathname.
139 * Only the low 24-bits are relevant. The high 8-bits are
140 * used as an index to an array of storage directories, and
141 * are set at run time because the order of storage directories
142 * may change over time.
147 * A Unix time value that represents the time when
148 * the origin server generated this response. If the response
149 * has a valid Date: header, this timestamp corresponds
150 * to that time. Otherwise, it is set to the Squid process time
151 * when the response is read (as soon as the end of headers are found).
153 SwappedTime timestamp
;
156 * The last time that a client requested this object.
157 * Strictly speaking, this time is set whenever the StoreEntry
158 * is locked (via storeLockObject()).
163 * The value of the response's Expires: header, if any.
164 * If the response does not have an Expires: header, this
166 * If the response has an invalid (unparseable)
167 * Expires: header, it is also set to -1. There are some cases
168 * where Squid sets expires to -2. This happens for the
169 * internal "netdb" object and for FTP URL responses.
174 * The value of the response's Last-modified: header, if any.
175 * This is set to -1 if there is no Last-modified: header,
176 * or if it is unparseable.
181 * This is the number of bytes that the object occupies on
182 * disk. It includes the Squid "swap file header".
184 uint64_t swap_file_sz
;
187 * The number of times that this object has been accessed (referenced).
188 * Since its a 16-bit quantity, it is susceptible to overflow
189 * if a single object is accessed 65,536 times before being replaced.
194 * A copy of the StoreEntry flags field. Used as a sanity
195 * check when rebuilding the cache at startup. Objects that
196 * have the KEY_PRIVATE flag set are not added back to the cache.
201 * The 128-bit MD5 hash for this object.
203 unsigned char key
[SQUID_MD5_DIGEST_LENGTH
];
206 MEMPROXY_CLASS_INLINE(StoreSwapLogData
);
208 /// \ingroup FileFormatSwapStateAPI
209 /// Swap log starts with this binary structure.
210 class StoreSwapLogHeader
213 // sets default values for this Squid version; loaded values may differ
214 StoreSwapLogHeader();
216 /// consistency self-check: whether the data appears to make sense
219 /// number of bytes after the log header before the first log entry
220 size_t gapSize() const;
223 SwapChecksum24 checksum
; // follows "op" because compiler will pad anyway
229 #endif /* SQUID_STORESWAPLOGDATA_H */