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Overview
| Comment: | Recognize the invariant that a Mem object cannot be MEM_Dyn and have a non-zero szMalloc at the same time. Enforce this with assert()s and exploit it in the sqlite3VdbeMemClearAndResize() routine for a performance increase. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
3b21cf2b284048da4b728a5d6ec89e5c |
| User & Date: | drh 2014-09-19 22:30:49 |
Context
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2014-09-19
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| 22:44 | Simplify two conditionals and add testcase() macros to the affinity transform logic in the comparison operators. check-in: 544664ca user: drh tags: trunk | |
| 22:30 | Recognize the invariant that a Mem object cannot be MEM_Dyn and have a non-zero szMalloc at the same time. Enforce this with assert()s and exploit it in the sqlite3VdbeMemClearAndResize() routine for a performance increase. check-in: 3b21cf2b user: drh tags: trunk | |
| 22:01 | Tighten the conditions under which applyNumericAffinity() be called and add assert() statements to prove that it is never called otherwise. check-in: e996ca32 user: drh tags: trunk | |
Changes
Changes to src/vdbemem.c.
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*/
int sqlite3VdbeCheckMemInvariants(Mem *p){
/* If MEM_Dyn is set then Mem.xDel!=0.
** Mem.xDel is might not be initialized if MEM_Dyn is clear.
*/
assert( (p->flags & MEM_Dyn)==0 || p->xDel!=0 );
/* Cannot be both MEM_Int and MEM_Real at the same time */
assert( (p->flags & (MEM_Int|MEM_Real))!=(MEM_Int|MEM_Real) );
/* The szMalloc field holds the correct memory allocation size */
assert( p->szMalloc==0
|| p->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc) );
................................................................................
** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, and MEM_Null
** values are preserved.
**
** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
** if unable to complete the resizing.
*/
int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
if( pMem->szMalloc<szNew || (pMem->flags & MEM_Dyn)!=0 ){
return sqlite3VdbeMemGrow(pMem, szNew, 0);
}
pMem->z = pMem->zMalloc;
pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
return SQLITE_OK;
}
/*
** Make the given Mem object MEM_Dyn. In other words, make it so
** that any TEXT or BLOB content is stored in memory obtained from
** malloc(). In this way, we know that the memory is safe to be
** overwritten or altered.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
int sqlite3VdbeMemMakeWriteable(Mem *pMem){
int f;
assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
assert( (pMem->flags&MEM_RowSet)==0 );
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*/
int sqlite3VdbeCheckMemInvariants(Mem *p){
/* If MEM_Dyn is set then Mem.xDel!=0.
** Mem.xDel is might not be initialized if MEM_Dyn is clear.
*/
assert( (p->flags & MEM_Dyn)==0 || p->xDel!=0 );
/* MEM_Dyn may only be set if Mem.szMalloc==0 */
assert( (p->flags & MEM_Dyn)==0 || p->szMalloc==0 );
/* Cannot be both MEM_Int and MEM_Real at the same time */
assert( (p->flags & (MEM_Int|MEM_Real))!=(MEM_Int|MEM_Real) );
/* The szMalloc field holds the correct memory allocation size */
assert( p->szMalloc==0
|| p->szMalloc==sqlite3DbMallocSize(p->db,p->zMalloc) );
................................................................................
** and MEM_Blob values may be discarded, MEM_Int, MEM_Real, and MEM_Null
** values are preserved.
**
** Return SQLITE_OK on success or an error code (probably SQLITE_NOMEM)
** if unable to complete the resizing.
*/
int sqlite3VdbeMemClearAndResize(Mem *pMem, int szNew){
assert( szNew>=0 );
if( pMem->szMalloc<szNew ){
return sqlite3VdbeMemGrow(pMem, szNew, 0);
}
assert( (pMem->flags & MEM_Dyn)==0 );
pMem->z = pMem->zMalloc;
pMem->flags &= (MEM_Null|MEM_Int|MEM_Real);
return SQLITE_OK;
}
/*
** Change pMem so that its MEM_Str or MEM_Blob value is stored in
** MEM.zMalloc, where it can be safely written.
**
** Return SQLITE_OK on success or SQLITE_NOMEM if malloc fails.
*/
int sqlite3VdbeMemMakeWriteable(Mem *pMem){
int f;
assert( pMem->db==0 || sqlite3_mutex_held(pMem->db->mutex) );
assert( (pMem->flags&MEM_RowSet)==0 );
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