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Add a function to the session extension invert a changeset.

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FossilOrigin-Name: 75d5dff725dbb66d67d56ad042926f1daae56dbe
This commit is contained in:
dan
2011-03-09 11:17:05 +00:00
parent 4fccf43aae
commit 91ddd5595b
6 changed files with 195 additions and 38 deletions
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108
ext/session/sqlite3session.c
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@ -839,28 +839,34 @@ static int sessionReadRecord(
for(i=0; i<nCol; i++){
int eType = *aRec++;
assert( apOut[i]==0 );
assert( !apOut || apOut[i]==0 );
if( eType ){
apOut[i] = sqlite3ValueNew(0);
if( !apOut[i] ) return SQLITE_NOMEM;
if( apOut ){
apOut[i] = sqlite3ValueNew(0);
if( !apOut[i] ) return SQLITE_NOMEM;
}
if( eType==SQLITE_TEXT || eType==SQLITE_BLOB ){
int nByte;
int enc = (eType==SQLITE_TEXT ? SQLITE_UTF8 : 0);
aRec += sessionVarintGet(aRec, &nByte);
sqlite3ValueSetStr(apOut[i], nByte, aRec, enc, SQLITE_STATIC);
if( apOut ){
sqlite3ValueSetStr(apOut[i], nByte, aRec, enc, SQLITE_STATIC);
}
aRec += nByte;
}
if( eType==SQLITE_INTEGER || eType==SQLITE_FLOAT ){
sqlite3_int64 v = sessionGetI64(aRec);
aRec += 8;
if( eType==SQLITE_INTEGER ){
sqlite3VdbeMemSetInt64(apOut[i], v);
}else{
double d;
memcpy(&d, &i, 8);
sqlite3VdbeMemSetDouble(apOut[i], d);
if( apOut ){
sqlite3_int64 v = sessionGetI64(aRec);
if( eType==SQLITE_INTEGER ){
sqlite3VdbeMemSetInt64(apOut[i], v);
}else{
double d;
memcpy(&d, &i, 8);
sqlite3VdbeMemSetDouble(apOut[i], d);
}
}
aRec += 8;
}
}
}
@ -990,4 +996,82 @@ int sqlite3changeset_finalize(sqlite3_changeset_iter *p){
return rc;
}
/*
** Invert a changeset object.
*/
int sqlite3changeset_invert(
int nChangeset, /* Number of bytes in input */
void *pChangeset, /* Input changeset */
int *pnInverted, /* OUT: Number of bytes in output changeset */
void **ppInverted /* OUT: Inverse of pChangeset */
){
u8 *aOut;
u8 *aIn;
int i;
int nCol = 0;
/* Zero the output variables in case an error occurs. */
*ppInverted = 0;
*pnInverted = 0;
if( nChangeset==0 ) return SQLITE_OK;
aOut = (u8 *)sqlite3_malloc(nChangeset);
if( !aOut ) return SQLITE_NOMEM;
aIn = (u8 *)pChangeset;
i = 0;
while( i<nChangeset ){
u8 eType = aIn[i];
switch( eType ){
case 'T': {
int nByte = 1 + sessionVarintGet(&aIn[i+1], &nCol);
nByte += 1 + strlen((char *)&aIn[i+nByte]);
memcpy(&aOut[i], &aIn[i], nByte);
i += nByte;
break;
}
case SQLITE_INSERT:
case SQLITE_DELETE: {
int nByte;
u8 *aEnd = &aIn[i+1];
sessionReadRecord(&aEnd, nCol, 0);
aOut[i] = (eType==SQLITE_DELETE ? SQLITE_INSERT : SQLITE_DELETE);
nByte = aEnd - &aIn[i+1];
memcpy(&aOut[i+1], &aIn[i+1], nByte);
i += 1 + nByte;
break;
}
case SQLITE_UPDATE: {
int nByte1; /* Size of old.* record in bytes */
int nByte2; /* Size of new.* record in bytes */
u8 *aEnd = &aIn[i+1];
sessionReadRecord(&aEnd, nCol, 0);
nByte1 = aEnd - &aIn[i+1];
sessionReadRecord(&aEnd, nCol, 0);
nByte2 = aEnd - &aIn[i+1] - nByte1;
aOut[i] = SQLITE_UPDATE;
memcpy(&aOut[i+1], &aIn[i+1+nByte1], nByte2);
memcpy(&aOut[i+1+nByte2], &aIn[i+1], nByte1);
i += 1 + nByte1 + nByte2;
break;
}
default:
sqlite3_free(aOut);
return SQLITE_CORRUPT;
}
}
*pnInverted = nChangeset;
*ppInverted = (void *)aOut;
return SQLITE_OK;
}
#endif /* #ifdef SQLITE_ENABLE_SESSION */