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

/*---
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---*/
/**********************************************
 * $Id$
 * 
 * sets the given reference to dat
 **********************************************/

#include <lladd/operations.h>
#include "../page.h"
#include <string.h>
#include <assert.h>
static int operate(int xid, Page *p,  lsn_t lsn, recordid rid, const void *dat) {
	writeRecord(xid, p, lsn, rid, dat);
	return 0;
}
typedef struct {
  int offset;
  int realRecordLength;
} set_range_t;

static int operateRange(int xid, Page * p, lsn_t lsn, recordid rid, const void * dat)  {
  int diffLength = rid.size - sizeof(set_range_t);
  assert(! (diffLength % 2));
  diffLength /= 2;
  const set_range_t * range = dat;
  rid.size = range->realRecordLength;

  byte * data = (byte*)(range + 1);
  byte * tmp = malloc(rid.size);

  readRecord(xid, p, rid, tmp);
  memcpy(tmp+range->offset, data, diffLength);
  writeRecord(xid, p, lsn, rid, tmp);

  free(tmp);
  return 0;
}

static int deOperateRange(int xid, Page * p, lsn_t lsn, recordid rid, const void * dat)  {
  int diffLength = rid.size - sizeof(set_range_t);
  assert(! (diffLength % 2));
  diffLength /= 2;
  
  const set_range_t * range = dat;
  rid.size = range->realRecordLength;

  byte * data = (byte*)(range + 1);
  data += diffLength;
  byte * tmp = malloc(rid.size);

  readRecord(xid, p, rid, tmp);
  memcpy(tmp+range->offset, data, diffLength);
  writeRecord(xid, p, lsn, rid, tmp);

  free(tmp);
  return 0;
}
void TsetRange(int xid, recordid rid, int offset, int length, const void * dat) {

  set_range_t * range = malloc(sizeof(set_range_t) + 2 * length);
  byte * record = malloc(rid.size);
  
  range->offset = offset;
  range->realRecordLength = rid.size;

  // Copy new value into log structure
  memcpy(range + 1, dat, length);
  
  Page * p = loadPage(rid.page);
  // No further locking is necessary here; readRecord protects the 
  // page layout, but attempts at concurrent modification have undefined 
  // results.  (See page.c)
  readRecord(xid, p, rid, record);

  // Copy old value into log structure 
  memcpy((byte*)(range + 1) + length, record+offset, length);
  
  // Pass size of range into Tupdate via the recordid.
  rid.size = sizeof(set_range_t) + 2 * length;
  Tupdate(xid, rid, range, OPERATION_SET_RANGE);

  releasePage(p);
  free(record);
  free(range);
  
}

Operation getSet() { 
	Operation o = {
		OPERATION_SET, /* id */
		SIZEOF_RECORD, /* use the size of the record as size of arg */
		NO_INVERSE, 
		&operate /* Function */
	};
	return o;
}

Operation getSetRange() {
	Operation o = {
		OPERATION_SET_RANGE,
		SIZEOF_RECORD,
		OPERATION_SET_RANGE_INVERSE,
		&operateRange
	};
	return o;
}

Operation getSetRangeInverse() {
	Operation o = {
		OPERATION_SET_RANGE_INVERSE,
		SIZEOF_RECORD,
		OPERATION_SET_RANGE,
		&deOperateRange
	};
	return o;
}