stasis-aries-wal/stasis/logger/logger2.h
2008-09-12 23:08:41 +00:00

196 lines
6.1 KiB
C

/*---
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authorized uses. Modifications to this software may be copyrighted by
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provided that the new terms are clearly indicated on the first page of
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FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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GOVERNMENT USE: If you are acquiring this software on behalf of the
U.S. government, the Government shall have only "Restricted Rights" in
the software and related documentation as defined in the Federal
Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2). If you are
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software shall be classified as "Commercial Computer Software" and the
Government shall have only "Restricted Rights" as defined in Clause
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---*/
/**
* @file
*
* Interface to Stasis' log file.
*
* @ingroup LOGGING_DISCIPLINE
*
* $Id$
*
*/
#ifndef __LOGGER2_H__
#define __LOGGER2_H__
#include <stasis/operations.h>
/**
A callback function that allows logHandle's iterator to stop
returning log entries depending on the context in which it was
called.
*/
typedef int (guard_fcn_t)(const LogEntry *, void *);
typedef struct {
/** The LSN of the log entry that we would return if next is called. */
lsn_t next_offset;
/** The LSN of the log entry that we would return if previous is called. */
lsn_t prev_offset;
guard_fcn_t * guard;
void * guard_state;
} LogHandle;
/**
Contains the state needed by the logging layer to perform
operations on a transaction.
*/
typedef struct {
int xid;
lsn_t prevLSN;
lsn_t recLSN;
} TransactionLog;
/**
This is the log implementation that is being used.
Before Stasis is intialized it will be set to a default value.
It may be changed before Tinit() is called by assigning to it.
The default can be overridden at compile time by defining
USE_LOGGER.
(eg: gcc ... -DUSE_LOGGER=LOG_TO_FOO)
@see constants.h for a list of recognized log implementations.
(The constants are named LOG_TO_*)
*/
extern int loggerType;
int LogInit(int logType);
int LogDeinit();
void LogForce(lsn_t lsn);
/**
@param lsn The first lsn that will be available after truncation.
*/
void LogTruncate(lsn_t lsn);
/** This function is guaranteed to return the LSN of the most recent
log entry that has not been flushed to disk. (If the entire log
is flushed, this function returns the LSN of the entry that will
be allocated the next time the log is appended to. */
lsn_t LogFlushedLSN();
/** Returns the LSN of the first entry of the log, or the LSN of the
next to be allocated if the log is empty) */
lsn_t LogTruncationPoint();
/** Read a log entry, given its LSN.
@param lsn The lsn of the log entry to be read.
*/
const LogEntry * LogReadLSN(lsn_t lsn);
/**
Given a log entry, return the LSN of the next entry.
*/
lsn_t LogNextEntry(const LogEntry * e);
/**
Inform the logging layer that a new transaction has begun, and
obtain a handle.
*/
TransactionLog LogTransBegin(int xid);
/**
Write a transaction COMMIT to the log tail. Blocks until the commit
record is stable.
@return The lsn of the commit log entry.
*/
lsn_t LogTransCommit(TransactionLog * l);
/**
Write a transaction ABORT to the log tail.
@return The lsn of the abort log entry.
*/
lsn_t LogTransAbort(TransactionLog * l);
/**
LogUpdate writes an UPDATELOG log record to the log tail. It also interprets
its operation argument to the extent necessary for allocating and laying out
the log entry. Finally, it updates the state of the parameter l.
*/
LogEntry * LogUpdate(TransactionLog * l, Page * p, recordid rid, int operation,
const byte * args);
/**
Any LogEntry that is returned by a function in logger2.h or
logHandle.h should be freed using this function.
@param e The log entry to be freed. (The "const" here is a hack
that allows LogReadLSN to return a const *.
*/
void FreeLogEntry(const LogEntry * e);
/**
Write a compensation log record. These records are used to allow
for efficient recovery, and possibly for log truncation. They
record the completion of undo operations, amongst other things.
@return the lsn of the CLR entry that was written to the log.
(Needed so that the lsn slot of the page in question can be
updated.)
*/
lsn_t LogCLR(const LogEntry * e);
lsn_t LogDummyCLR(int xid, lsn_t prevLSN);
/**
Write a end transaction record @see XEND
@todo Implement LogEnd
*/
void LogEnd (TransactionLog * l);
/**
Needed by sizeofLogEntry
*/
long LoggerSizeOfInternalLogEntry(const LogEntry * e);
/**
For internal use only... This would be static, but it is called by
the test cases.
*/
void LogWrite(LogEntry * e);
#endif