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Overview
| Comment: | Performance improvement in sqlite3VdbeMemShallowCopy() for the common case where the receiver does not require prior resource deallocation. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
d718ea36dce8cf1684c8bcda457fee87 |
| User & Date: | drh 2015-06-17 23:28:03 |
Context
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2015-06-18
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| 12:37 | Add #ifdefs to some features speedtest1.c so that it compiles with older versions of SQLite, going back to version 3.5.1. check-in: f50dd154 user: drh tags: trunk | |
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2015-06-17
| ||
| 23:28 | Performance improvement in sqlite3VdbeMemShallowCopy() for the common case where the receiver does not require prior resource deallocation. check-in: d718ea36 user: drh tags: trunk | |
| 18:57 | Improve spacing and comment style for the shell. No changes to code. check-in: 5b547da0 user: mistachkin tags: trunk | |
Changes
Changes to src/vdbemem.c.
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/*
** Make an shallow copy of pFrom into pTo. Prior contents of
** pTo are freed. The pFrom->z field is not duplicated. If
** pFrom->z is used, then pTo->z points to the same thing as pFrom->z
** and flags gets srcType (either MEM_Ephem or MEM_Static).
*/
void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){
assert( (pFrom->flags & MEM_RowSet)==0 );
assert( pTo->db==pFrom->db );
if( VdbeMemDynamic(pTo) ) vdbeMemClearExternAndSetNull(pTo);
memcpy(pTo, pFrom, MEMCELLSIZE);
if( (pFrom->flags&MEM_Static)==0 ){
pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem);
assert( srcType==MEM_Ephem || srcType==MEM_Static );
pTo->flags |= srcType;
}
}
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/* ** Make an shallow copy of pFrom into pTo. Prior contents of ** pTo are freed. The pFrom->z field is not duplicated. If ** pFrom->z is used, then pTo->z points to the same thing as pFrom->z ** and flags gets srcType (either MEM_Ephem or MEM_Static). */ static SQLITE_NOINLINE void vdbeClrCopy(Mem *pTo, const Mem *pFrom, int eType){ vdbeMemClearExternAndSetNull(pTo); assert( !VdbeMemDynamic(pTo) ); sqlite3VdbeMemShallowCopy(pTo, pFrom, eType); } void sqlite3VdbeMemShallowCopy(Mem *pTo, const Mem *pFrom, int srcType){ assert( (pFrom->flags & MEM_RowSet)==0 ); assert( pTo->db==pFrom->db ); if( VdbeMemDynamic(pTo) ){ vdbeClrCopy(pTo,pFrom,srcType); return; } memcpy(pTo, pFrom, MEMCELLSIZE); if( (pFrom->flags&MEM_Static)==0 ){ pTo->flags &= ~(MEM_Dyn|MEM_Static|MEM_Ephem); assert( srcType==MEM_Ephem || srcType==MEM_Static ); pTo->flags |= srcType; } } |