/*
** Return true if it desirable to avoid allocating a new page cache
** entry.
**
** If memory was allocated specifically to the page cache using
** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then
** it is desirable to avoid allocating a new page cache entry because
** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient
** for all page cache needs and we should not need to spill the
** allocation onto the heap.
**
** Or, the heap is used for all page cache memory but the heap is
** under memory pressure, then again it is desirable to avoid
** allocating a new page cache entry in order to avoid stressing
** the heap even further.
*/
static int pcache1UnderMemoryPressure(PCache1 *pCache){
if( pcache1.nSlot && (pCache->szPage+pCache->szExtra)<=pcache1.szSlot ){
return pcache1.bUnderPressure;
}else{
return sqlite3HeapNearlyFull();
}
}
/*
** Return true if it desirable to avoid allocating a new page cache
** entry.
**
** If memory was allocated specifically to the page cache using
** SQLITE_CONFIG_PAGECACHE but that memory has all been used, then
** it is desirable to avoid allocating a new page cache entry because
** presumably SQLITE_CONFIG_PAGECACHE was suppose to be sufficient
** for all page cache needs and we should not need to spill the
** allocation onto the heap.
**
** Or, the heap is used for all page cache memory put the heap is
** under memory pressure, then again it is desirable to avoid
** allocating a new page cache entry in order to avoid stressing
** the heap even further.
*/
static int pcache1UnderMemoryPressure(PCache1 *pCache){
assert( sqlite3_mutex_held(pcache1.mutex) );
if( pcache1.nSlot && pCache->szPage<=pcache1.szSlot ){
return pcache1.nFreeSlot<pcache1.nReserve;
}else{
return sqlite3HeapNearlyFull();
}
}
/*
** Add a record to the sorter.
*/
SQLITE_PRIVATE int sqlite3VdbeSorterWrite(
sqlite3 *db, /* Database handle */
const VdbeCursor *pCsr, /* Sorter cursor */
Mem *pVal /* Memory cell containing record */
){
VdbeSorter *pSorter = pCsr->pSorter;
int rc = SQLITE_OK; /* Return Code */
SorterRecord *pNew; /* New list element */
assert( pSorter );
pSorter->nInMemory += sqlite3VarintLen(pVal->n) + pVal->n;
pNew = (SorterRecord *)sqlite3DbMallocRaw(db, pVal->n + sizeof(SorterRecord));
if( pNew==0 ){
rc = SQLITE_NOMEM;
}else{
pNew->pVal = (void *)&pNew[1];
memcpy(pNew->pVal, pVal->z, pVal->n);
pNew->nVal = pVal->n;
pNew->pNext = pSorter->pRecord;
pSorter->pRecord = pNew;
}
/* See if the contents of the sorter should now be written out. They
** are written out when either of the following are true:
**
** * The total memory allocated for the in-memory list is greater
** than (page-size * cache-size), or
**
** * The total memory allocated for the in-memory list is greater
** than (page-size * 10) and sqlite3HeapNearlyFull() returns true.
*/
if( rc==SQLITE_OK && pSorter->mxPmaSize>0 && (
(pSorter->nInMemory>pSorter->mxPmaSize)
|| (pSorter->nInMemory>pSorter->mnPmaSize && sqlite3HeapNearlyFull())
)){
#ifdef SQLITE_DEBUG
i64 nExpect = pSorter->iWriteOff
+ sqlite3VarintLen(pSorter->nInMemory)
+ pSorter->nInMemory;
#endif
rc = vdbeSorterListToPMA(db, pCsr);
pSorter->nInMemory = 0;
assert( rc!=SQLITE_OK || (nExpect==pSorter->iWriteOff) );
}
return rc;
}
