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/*
* SQUID Web Proxy Cache http://www.squid-cache.org/
* ----------------------------------------------------------
*
* Squid is the result of efforts by numerous individuals from
* the Internet community; see the CONTRIBUTORS file for full
* details. Many organizations have provided support for Squid's
* development; see the SPONSORS file for full details. Squid is
* Copyrighted (C) 2001 by the Regents of the University of
* California; see the COPYRIGHT file for full details. Squid
* incorporates software developed and/or copyrighted by other
* sources; see the CREDITS file for full details.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
*
* Copyright (c) 2003, Robert Collins <robertc@squid-cache.org>
*/
#ifndef SQUID_STORESWAPLOGDATA_H
#define SQUID_STORESWAPLOGDATA_H
/**
\defgroup FileFormatSwapStateAPI swap.state File Structure
\ingroup FileSystems
\section ImplementationNotes Implementation Notes
\par
* When writing an object to disk, we must first write the meta data.
* This is done with a couple of functions. First, storeSwapMetaPack()
* takes a StoreEntry as a parameter and returns a tlv linked
* list. Second, storeSwapMetaPack() converts the tlv list
* into a character buffer that we can write.
*
\note MemObject has a MemObject::swap_hdr_sz.
* This value is the size of that character buffer; the size of the
* swap file meta data. The StoreEntry has a member
* StoreEntry::swap_file_sz that represents the size of the disk file.
* Thus, the size of the object "content" is
\code StoreEntry->swap_file_sz - MemObject->swap_hdr_sz; \endcode
\note The swap file content includes the HTTP reply headers and the HTTP reply body (if any).
*
\par
* When reading a swap file, there is a similar process to extract
* the swap meta data. First, storeSwapMetaUnpack() converts a
* character buffer into a tlv linked list. It also tells us
* the value for MemObject->swap_hdr_sz.
*/
#include "md5.h"
#include "MemPool.h"
#include "typedefs.h"
/// maintains a 24-bit checksum over integer fields
class SwapChecksum24
{
public:
SwapChecksum24() { raw[0] = raw[1] = raw[2] = 0; }
bool operator ==(const SwapChecksum24 &o) const {
return raw[0] == o.raw[0] && raw[1] == o.raw[1] && raw[2] == o.raw[2];
}
bool operator !=(const SwapChecksum24 &o) const {
return !(*this == o);
}
/// compute and store checksum based on three 32bit integers
void set(uint32_t f1, uint32_t f2, uint32_t f3);
/// compute and store checksum based on int32_t and uint64_t integers
void set(int32_t f1, uint64_t f2);
// printing for debugging
std::ostream &print(std::ostream &os) const;
private:
uint8_t raw[3]; // designed to follow "op" members, in pading space
};
inline std::ostream &
operator <<(std::ostream &os, const SwapChecksum24 &sum)
{
return sum.print(os);
}
/**
\ingroup FielFormatSwapStateAPI
*
\par
* Defines the structure of a binary swap.state file entry for UFS stores.
* TODO: Move to fs/ufs (and remove from COSS).
*
\note StoreSwapLogData entries are written in native machine byte order
* They are not necessarily portable across architectures.
*/
class StoreSwapLogData
{
public:
MEMPROXY_CLASS(StoreSwapLogData);
/// type to use for storing time-related members; must be signed
typedef int64_t SwappedTime;
StoreSwapLogData();
/// consistency self-check: whether the data appears to make sense
bool sane() const;
/// call this before storing the log entry
void finalize();
/**
* Either SWAP_LOG_ADD when an object is added to the disk storage,
* or SWAP_LOG_DEL when an object is deleted.
*/
uint8_t op;
/**
* Fingerprint to weed out bogus/corrupted swap.state entries.
*/
SwapChecksum24 checksum; // follows "op" because compiler will pad anyway
/**
* The 32-bit file number which maps to a pathname.
* Only the low 24-bits are relevant. The high 8-bits are
* used as an index to an array of storage directories, and
* are set at run time because the order of storage directories
* may change over time.
*/
sfileno swap_filen;
/**
* A Unix time value that represents the time when
* the origin server generated this response. If the response
* has a valid Date: header, this timestamp corresponds
* to that time. Otherwise, it is set to the Squid process time
* when the response is read (as soon as the end of headers are found).
*/
SwappedTime timestamp;
/**
* The last time that a client requested this object.
* Strictly speaking, this time is set whenever the StoreEntry
* is locked (via storeLockObject()).
*/
SwappedTime lastref;
/**
* The value of the response's Expires: header, if any.
* If the response does not have an Expires: header, this
* is set to -1.
* If the response has an invalid (unparseable)
* Expires: header, it is also set to -1. There are some cases
* where Squid sets expires to -2. This happens for the
* internal "netdb" object and for FTP URL responses.
*/
SwappedTime expires;
/**
* The value of the response's Last-modified: header, if any.
* This is set to -1 if there is no Last-modified: header,
* or if it is unparseable.
*/
SwappedTime lastmod;
/**
* This is the number of bytes that the object occupies on
* disk. It includes the Squid "swap file header".
*/
uint64_t swap_file_sz;
/**
* The number of times that this object has been accessed (referenced).
* Since its a 16-bit quantity, it is susceptible to overflow
* if a single object is accessed 65,536 times before being replaced.
*/
uint16_t refcount;
/**
* A copy of the StoreEntry flags field. Used as a sanity
* check when rebuilding the cache at startup. Objects that
* have the KEY_PRIVATE flag set are not added back to the cache.
*/
uint16_t flags;
/**
* The 128-bit MD5 hash for this object.
*/
unsigned char key[SQUID_MD5_DIGEST_LENGTH];
};
MEMPROXY_CLASS_INLINE(StoreSwapLogData);
/// \ingroup FileFormatSwapStateAPI
/// Swap log starts with this binary structure.
class StoreSwapLogHeader
{
public:
// sets default values for this Squid version; loaded values may differ
StoreSwapLogHeader();
/// consistency self-check: whether the data appears to make sense
bool sane() const;
/// number of bytes after the log header before the first log entry
size_t gapSize() const;
uint8_t op;
SwapChecksum24 checksum; // follows "op" because compiler will pad anyway
int32_t version;
int32_t record_size;
};
#endif /* SQUID_STORESWAPLOGDATA_H */
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