stasis-aries-wal/stasis/logger/logWriter.h

/*---
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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 logWriter is optimized for forward operation, scanning backwards 
 *       (as in abort()) is very slow.  Perhaps we should maintian a 
 *       'write behind' buffer?
 *
 * $Id$
 * 
 */

#ifndef __LOGWRITER_H__
#define __LOGWRITER_H__

#include <stasis/common.h>
#include <stasis/logger/logger2.h>
#include <stasis/logger/logEntry.h>

BEGIN_C_DECLS
/**
   Start a new log stream by opening the log file for reading.  This
   is stasis's default log implementation, and uses safe writes to
   perform truncation.

   @return NULL on error
*/
stasis_log_t* openLogWriter(const char * filename,
                            int filemode,
                            int fileperm);

/**
  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!

  @todo This only exists because the tests use it...once the logfile
        name isn't hardcoded, remove this function.
*/
void deleteLogWriter();

END_C_DECLS

#endif /* __LLADD_LOGGER_LOGWRITER_H */