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git.ipfire.org Git - thirdparty/squid.git/blob - src/StoreSwapLogData.h
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2 * Copyright (C) 1996-2016 The Squid Software Foundation and contributors
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.
9 #ifndef SQUID_STORESWAPLOGDATA_H
10 #define SQUID_STORESWAPLOGDATA_H
13 \defgroup FileFormatSwapStateAPI swap.state File Structure
15 \section ImplementationNotes Implementation Notes
17 * When writing an object to disk, we must first write the meta data.
18 * This is done with a couple of functions. First, storeSwapMetaPack()
19 * takes a StoreEntry as a parameter and returns a tlv linked
20 * list. Second, storeSwapMetaPack() converts the tlv list
21 * into a character buffer that we can write.
23 \note MemObject has a MemObject::swap_hdr_sz.
24 * This value is the size of that character buffer; the size of the
25 * swap file meta data. The StoreEntry has a member
26 * StoreEntry::swap_file_sz that represents the size of the disk file.
27 * Thus, the size of the object "content" is
28 \code StoreEntry->swap_file_sz - MemObject->swap_hdr_sz; \endcode
29 \note The swap file content includes the HTTP reply headers and the HTTP reply body (if any).
32 * When reading a swap file, there is a similar process to extract
33 * the swap meta data. First, storeSwapMetaUnpack() converts a
34 * character buffer into a tlv linked list. It also tells us
35 * the value for MemObject->swap_hdr_sz.
39 #include "mem/forward.h"
40 #include "store/forward.h"
42 /// maintains a 24-bit checksum over integer fields
46 SwapChecksum24() { raw
[0] = raw
[1] = raw
[2] = 0; }
48 bool operator ==(const SwapChecksum24
&o
) const {
49 return raw
[0] == o
.raw
[0] && raw
[1] == o
.raw
[1] && raw
[2] == o
.raw
[2];
52 bool operator !=(const SwapChecksum24
&o
) const {
56 /// compute and store checksum based on three 32bit integers
57 void set(uint32_t f1
, uint32_t f2
, uint32_t f3
);
59 /// compute and store checksum based on int32_t and uint64_t integers
60 void set(int32_t f1
, uint64_t f2
);
62 // printing for debugging
63 std::ostream
&print(std::ostream
&os
) const;
66 uint8_t raw
[3]; // designed to follow "op" members, in pading space
70 operator <<(std::ostream
&os
, const SwapChecksum24
&sum
)
76 \ingroup FielFormatSwapStateAPI
79 * Defines the structure of a binary swap.state file entry for UFS stores.
80 * TODO: Move to fs/ufs
82 \note StoreSwapLogData entries are written in native machine byte order
83 * They are not necessarily portable across architectures.
85 class StoreSwapLogData
87 MEMPROXY_CLASS(StoreSwapLogData
);
90 /// type to use for storing time-related members; must be signed
91 typedef int64_t SwappedTime
;
95 /// consistency self-check: whether the data appears to make sense
98 /// call this before storing the log entry
102 * Either SWAP_LOG_ADD when an object is added to the disk storage,
103 * or SWAP_LOG_DEL when an object is deleted.
108 * Fingerprint to weed out bogus/corrupted swap.state entries.
110 SwapChecksum24 checksum
; // follows "op" because compiler will pad anyway
113 * The 32-bit file number which maps to a pathname.
114 * Only the low 24-bits are relevant. The high 8-bits are
115 * used as an index to an array of storage directories, and
116 * are set at run time because the order of storage directories
117 * may change over time.
122 * A Unix time value that represents the time when
123 * the origin server generated this response. If the response
124 * has a valid Date: header, this timestamp corresponds
125 * to that time. Otherwise, it is set to the Squid process time
126 * when the response is read (as soon as the end of headers are found).
128 SwappedTime timestamp
;
131 * The last time that a client requested this object.
136 * The value of the response's Expires: header, if any.
137 * If the response does not have an Expires: header, this
139 * If the response has an invalid (unparseable)
140 * Expires: header, it is also set to -1. There are some cases
141 * where Squid sets expires to -2. This happens for the
142 * internal "netdb" object and for FTP URL responses.
147 * The value of the response's Last-modified: header, if any.
148 * This is set to -1 if there is no Last-modified: header,
149 * or if it is unparseable.
154 * This is the number of bytes that the object occupies on
155 * disk. It includes the Squid "swap file header".
157 uint64_t swap_file_sz
;
160 * The number of times that this object has been accessed (referenced).
161 * Since its a 16-bit quantity, it is susceptible to overflow
162 * if a single object is accessed 65,536 times before being replaced.
167 * A copy of the StoreEntry flags field. Used as a sanity
168 * check when rebuilding the cache at startup. Objects that
169 * have the KEY_PRIVATE flag set are not added back to the cache.
174 * The 128-bit MD5 hash for this object.
176 unsigned char key
[SQUID_MD5_DIGEST_LENGTH
];
179 /// \ingroup FileFormatSwapStateAPI
180 /// Swap log starts with this binary structure.
181 class StoreSwapLogHeader
184 // sets default values for this Squid version; loaded values may differ
185 StoreSwapLogHeader();
187 /// consistency self-check: whether the data appears to make sense
190 /// number of bytes after the log header before the first log entry
191 size_t gapSize() const;
194 SwapChecksum24 checksum
; // follows "op" because compiler will pad anyway
199 #endif /* SQUID_STORESWAPLOGDATA_H */