stasis-aries-wal/src/lladd/operations/nestedTopActions.c

/*---
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---*/
/**********************************************
 * $Id$
 * 
 * Decrements the given reference by one
 *********************************************/
#include <lladd/transactional.h>
#include <lladd/common.h>
#include <lladd/operations/nestedTopActions.h>
#include <lladd/logger/logger2.h>
#include "../logger/logWriter.h"
#include <pbl/pbl.h>
#include <string.h>
#include <malloc.h>
#include <pthread.h>
#include <assert.h>
/** @todo Remove extern declaration of transactional_2_mutex from nestedTopActions.c */
extern pthread_mutex_t transactional_2_mutex;


/*#include <lladd/bufferManager.h>*/

extern TransactionLog XactionTable[];

pblHashTable_t * nestedTopActions = NULL;
/** @todo this really should be set somewhere globally. */

void initNestedTopActions() {
  nestedTopActions = pblHtCreate();
}
/** @todo TbeginNestedTopAction's API might not be quite right.  
    Are there cases where we need to pass a recordid in?

    @return a handle that must be passed into TendNestedTopAction
*/
void * TbeginNestedTopAction(int xid, int op, const byte * dat, int datSize) {
  recordid rid = NULLRID;
  
  rid.page = datSize;
  LogEntry * e = LogUpdate(&XactionTable[xid % MAX_TRANSACTIONS], NULL, rid, op, dat);
  DEBUG("Begin Nested Top Action e->LSN: %ld\n", e->LSN);
  lsn_t * prevLSN = malloc(sizeof(lsn_t));
  *prevLSN = e->LSN;
  pthread_mutex_lock(&transactional_2_mutex);
  void * ret = pblHtLookup(nestedTopActions, &xid, sizeof(int));
  if(ret) { 
    pblHtRemove(nestedTopActions, &xid, sizeof(int));
  }
  pblHtInsert(nestedTopActions, &xid, sizeof(int), prevLSN);
  pthread_mutex_unlock(&transactional_2_mutex);
  free(e);
  return ret;
}

/** 
    Call this function at the end of a nested top action.

    @return the lsn of the CLR.  Most users (everyone?) will ignore this.

    @todo LogCLR()'s API is useless.  Make it private, and implement a better 
    public version. (Then rewrite TendNestedTopAction) 
*/
lsn_t TendNestedTopAction(int xid, void * handle) {
  
  pthread_mutex_lock(&transactional_2_mutex);
  
  lsn_t * prevLSN = pblHtLookup(nestedTopActions, &xid, sizeof(int));
  pblHtRemove(nestedTopActions, &xid, sizeof(int));
  if(handle) {
    pblHtInsert(nestedTopActions, &xid, sizeof(int), handle);
  }
  // This action wasn't really undone -- This is a nested top action!
  lsn_t undoneLSN = XactionTable[xid % MAX_TRANSACTIONS].prevLSN; 
  recordid undoneRID = NULLRID;  // Not correct, but this field is unused anyway. ;)
  
  // Write a CLR.
  LogEntry * e = allocCLRLogEntry(-1, xid, undoneLSN, undoneRID, *prevLSN);
  writeLogEntry(e);
  
  // Ensure that the next action in this transaction points to the CLR. 
  XactionTable[xid % MAX_TRANSACTIONS].prevLSN = e->LSN;
  
  DEBUG("NestedTopAction CLR %d, LSN: %ld type: %ld (undoing: %ld, next to undo: %ld)\n", e->xid, 
	 (long int)e->LSN, (long int)e->type, (long int)undone->LSN, (long int)undone->prevLSN);

  lsn_t ret = e->LSN;
  free(e);
  free(prevLSN);
  pthread_mutex_unlock(&transactional_2_mutex);
  
  return ret;
}