stasis-aries-wal/lladd/operations/prepare.h

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/**
 * @file
 * Prepare pseudo-operation
 *
 * Tprepare() uses the operation interface to abstract away log handling.
 * It would be nice if the logger API could be simplified by having
 * more of its functionality handled this way.
 *
 Implementation notes:
 
 - Just a Tupdate, with a log flush as its operationsTable[]
 function.
 
 - After recovery, all of the xacts pages will have been 'stolen',
 (if recovery flushes dirty pages)
 
 - Recovery function needs to distinguish between actions before and
 after the last Tprepare log entry.  This is handle by a guard on
 the logHandle's iterator, but could be generalized in the future
 (to support savepoints, for example) Right now, recovery uses a
 guarded iterator, transUndo() does not.
 
 @todo Test Tprepare()

 *
 * @ingroup OPERATIONS
 *
 * $Id$
 * 
 *
 */

#ifndef __PREPARE_H__
#define __PREPARE_H__

#include <lladd/operations.h>
#include <lladd/logger/logEntry.h>

extern recordid prepare_bogus_rec;
/** 
    Prepare transaction for commit.  Currently, a transaction may be
    prepared multiple times.  Once Tprepare() returns, the caller is
    guaranteed that the current transaction will resume exactly where
    it was when Tprepare() was called.

    @todo Tprepare() shouldn't take a record or buffer as arguments... 

    @param xid Transaction id.
    @param rec must be a valid record id.  any valid recordid will do.  This parameter will be removed eventually.
    @param dat unused.
*/
#define Tprepare(xid, rec) Tupdate(xid, rec, 0, OPERATION_PREPARE)

Operation getPrepare();

/**
   Recovery's undo phase uses this logHandle iterator guard to implement Tprepare().
*/
int prepareGuard(LogEntry * e, void * state);
void * getPrepareGuardState();
int prepareAction(void * state);
#endif