/*---
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associated with the software unless explicitly disclaimed in
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The authors hereby grant permission to use, copy, modify, distribute,
and license this software and its documentation for any purpose,
provided that existing copyright notices are retained in all copies
and that this notice is included verbatim in any distributions. No
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authorized uses. Modifications to this software may be copyrighted by
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FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
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POSSIBILITY OF SUCH DAMAGE.

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INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND
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THE AUTHORS AND DISTRIBUTORS HAVE NO OBLIGATION TO PROVIDE
MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.

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
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acquiring the software on behalf of the Department of Defense, the
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
 * 
 * New version of logstreamer; designed to work with logEntry, and has
 * a simplified API.
 *
 * logstreamer is the implementation of writing the log tail
 * It must be bufferred -- in that when something is written to the log tail it
 * is not immediately written to disk, but rather just to memory. But
 * logstreamer must be able to force flush to disk, which will be done when a
 * commit log entry is written to the log tail
 * 
 * Note: using the stdio FILEs for this, and by default it is "fully" buffered.
 * The log tail may be flushed to disk without an explicit call to fflush (when
 * the program terminates, the file closes), but this is acceptable because it
 * never hurts to have more flushes to disk, as long as it doesn't hurt
 * performance.
 *
 * @todo Everything in this file cores on failure (no error handling yet)
 * @todo All of the logWriter calls should be reentrant.
 *
 * $Id$
 * 
 */

#ifndef __LOGWRITER_H__
#define __LOGWRITER_H__

#include "logEntry.h"
#include <lladd/constants.h>
#include <lladd/common.h>

BEGIN_C_DECLS
/**
  start a new log stream by opening the log file for reading

  returns 0 on success, or an error code define above

*/
int openLogWriter();

/**
   
  @param e Pointer to a log entry.  After the call, e->LSN will be set appropriately.

  returns 0 on success, or an error code defined above
*/
int writeLogEntry(LogEntry * e);

/*
  flush the entire log (tail) that is currently in memory to disk
*/
void syncLog();

/*
  Close the log stream
*/
void closeLogWriter();

/*
  Get the current position of the stream (in terms of bytes)
*/
/*long getFilePos();*/

/*
  Actually deletes the log file that may have been written to disk! Danger!!
  Only use after calling closeLogStream AND you are sure there are no active (or
  future active) transactions!
*/
void deleteLogWriter();

/*
 * Returns the current position of the stream no matter where it is
 */
/*long streamPos();*/

/*
 * Returns the position of the stream if it were to read.
 */
/*long writeStreamPos();*/

/*
 *   readLog reads a line from the log puts it in a string
 *
 *   This was made static because it exports state that the interface
 *   should be hiding.  (To use this function, the user must make
 *   assumptions regarding the value of the FILE's current offset.)
 *
 *     returns the number of bytes read and put into buffer
 *     */
/*int readLog(byte **buffer);*/
/* LogEntry * readLogEntry(); */

/*
 *   seek to a position in the log file and read it into the buffer
 *
 *     returns the number of bytes read and put into buffer
 *     */

/*int seekAndReadLog(long pos, byte **buffer);*/

LogEntry * readLSNEntry(lsn_t LSN);

/*  lsn_t nextLSN();  */

/*
 *   tell the current position in the log file
 *   */
/*long readPos ();

void seekInLog(long pos);*/

END_C_DECLS

#endif /* __LLADD_LOGGER_LOGWRITER_H */