/*---
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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
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---*/

/**
 * @file
 *
 * New version of logger.  Based on logger.h
 * 
 * $Id$
 * 
 */


#ifndef __LOGGER2_H__
#define __LOGGER2_H__

#include <lladd/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 last log entry returned.*/
  /*  lsn_t       file_offset; */ /* Unneeded? */
  /** 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;
  LogHandle lh;
} TransactionLog;

#define LOG_TO_FILE   0
#define LOG_TO_MEMORY 1

extern int loggerType;

int  LogInit(int logType);

int  LogDeinit();


void LogForce(lsn_t lsn);
void LogTruncate(lsn_t lsn);
lsn_t LogFlushedLSN();


lsn_t LogTruncationPoint();

const LogEntry * LogReadLSN(lsn_t lsn);

/**
   Inform the logging layer that a new transaction has begun.
   Currently a no-op.
*/
TransactionLog LogTransBegin(int xid);

/**
  Write a transaction COMMIT to the log tail, then flush the log tail immediately to disk

  @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 UPDATE log record to the log tail
*/
LogEntry * LogUpdate(TransactionLog * l, Page * p, recordid rid, int operation, const byte * args);

/**
   Whenever a LogEntry is returned by a function that is defined by
   logger2.h or logHandle.h, the caller should eventually call this
   function to release any resources held by that entry.
*/
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 (LogEntry * undone);
lsn_t LogCLR(int xid, lsn_t LSN, recordid rid, lsn_t prevLSN);

/**
   Write a end transaction record @see XEND

   @todo Implement LogEnd
*/
void LogEnd (TransactionLog * l);

/** 
  (For internal use only..)
*/
void genericLogWrite(LogEntry * e);

#endif