private static PgHdr pcache1Alloc(int nByte)
{
PgHdr p = null;
Debug.Assert(MutexEx.NotHeld(pcache1.grp.mutex));
StatusEx.sqlite3StatusSet(StatusEx.STATUS.PAGECACHE_SIZE, nByte);
if (nByte <= pcache1.szSlot)
{
MutexEx.Enter(pcache1.mutex);
p = pcache1.pFree._PgHdr;
if (p != null)
{
pcache1.pFree = pcache1.pFree.pNext;
pcache1.nFreeSlot--;
pcache1.bUnderPressure = pcache1.nFreeSlot < pcache1.nReserve;
Debug.Assert(pcache1.nFreeSlot >= 0);
StatusEx.sqlite3StatusAdd(StatusEx.STATUS.PAGECACHE_USED, 1);
}
MutexEx.Leave(pcache1.mutex);
}
if (p == null)
{
// Memory is not available in the SQLITE_CONFIG_PAGECACHE pool. Get it from sqlite3Malloc instead.
p = new PgHdr();
{
var sz = nByte;
MutexEx.Enter(pcache1.mutex);
StatusEx.sqlite3StatusAdd(StatusEx.STATUS.PAGECACHE_OVERFLOW, sz);
MutexEx.Leave(pcache1.mutex);
}
SysEx.sqlite3MemdebugSetType(p, SysEx.MEMTYPE.PCACHE);
}
return(p);
}
private static void pcache1Free(ref PgHdr p)
{
if (p == null)
{
return;
}
if (p.CacheAllocated)
{
var pSlot = new PgFreeslot();
MutexEx.Enter(pcache1.mutex);
StatusEx.sqlite3StatusAdd(StatusEx.STATUS.PAGECACHE_USED, -1);
pSlot._PgHdr = p;
pSlot.pNext = pcache1.pFree;
pcache1.pFree = pSlot;
pcache1.nFreeSlot++;
pcache1.bUnderPressure = pcache1.nFreeSlot < pcache1.nReserve;
Debug.Assert(pcache1.nFreeSlot <= pcache1.nSlot);
MutexEx.Leave(pcache1.mutex);
}
else
{
Debug.Assert(SysEx.sqlite3MemdebugHasType(p, SysEx.MEMTYPE.PCACHE));
SysEx.sqlite3MemdebugSetType(p, SysEx.MEMTYPE.HEAP);
var iSize = MallocEx.sqlite3MallocSize(p.Data);
MutexEx.Enter(pcache1.mutex);
StatusEx.sqlite3StatusAdd(StatusEx.STATUS.PAGECACHE_OVERFLOW, -iSize);
MutexEx.Leave(pcache1.mutex);
MallocEx.sqlite3_free(ref p.Data);
}
}
private static int pcache1MemSize(object p)
{
if (p >= pcache1.pStart && p < pcache1.pEnd)
{
return(pcache1.szSlot);
}
else
{
Debug.Assert(SysEx.sqlite3MemdebugHasType(p, SysEx.MEMTYPE.PCACHE));
SysEx.sqlite3MemdebugSetType(p, SysEx.MEMTYPE.HEAP);
var iSize = SysEx.sqlite3MallocSize(p);
SysEx.sqlite3MemdebugSetType(p, SysEx.MEMTYPE.PCACHE);
return(iSize);
}
}