/*
** Free an outstanding memory allocation.
*/
static void memsys5FreeUnsafe(void *pOld){
u32 size, iLogsize;
int iBlock;
/* Set iBlock to the index of the block pointed to by pOld in
** the array of mem5.szAtom byte blocks pointed to by mem5.zPool.
*/
iBlock = (int)(((u8 *)pOld-mem5.zPool)/mem5.szAtom);
/* Check that the pointer pOld points to a valid, non-free block. */
assert( iBlock>=0 && iBlock<mem5.nBlock );
assert( ((u8 *)pOld-mem5.zPool)%mem5.szAtom==0 );
assert( (mem5.aCtrl[iBlock] & CTRL_FREE)==0 );
iLogsize = mem5.aCtrl[iBlock] & CTRL_LOGSIZE;
size = 1<<iLogsize;
assert( iBlock+size-1<(u32)mem5.nBlock );
mem5.aCtrl[iBlock] |= CTRL_FREE;
mem5.aCtrl[iBlock+size-1] |= CTRL_FREE;
assert( mem5.currentCount>0 );
assert( mem5.currentOut>=(size*mem5.szAtom) );
mem5.currentCount--;
mem5.currentOut -= size*mem5.szAtom;
assert( mem5.currentOut>0 || mem5.currentCount==0 );
assert( mem5.currentCount>0 || mem5.currentOut==0 );
mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
while( ALWAYS(iLogsize<LOGMAX) ){
int iBuddy;
if( (iBlock>>iLogsize) & 1 ){
iBuddy = iBlock - size;
}else{
iBuddy = iBlock + size;
}
assert( iBuddy>=0 );
if( (iBuddy+(1<<iLogsize))>mem5.nBlock ) break;
if( mem5.aCtrl[iBuddy]!=(CTRL_FREE | iLogsize) ) break;
memsys5Unlink(iBuddy, iLogsize);
iLogsize++;
if( iBuddy<iBlock ){
mem5.aCtrl[iBuddy] = CTRL_FREE | iLogsize;
mem5.aCtrl[iBlock] = 0;
iBlock = iBuddy;
}else{
mem5.aCtrl[iBlock] = CTRL_FREE | iLogsize;
mem5.aCtrl[iBuddy] = 0;
}
size *= 2;
}
/*
** Find the first entry on the freelist iLogsize. Unlink that
** entry and return its index.
*/
static int memsys5UnlinkFirst(int iLogsize){
int i;
int iFirst;
assert( iLogsize>=0 && iLogsize<=LOGMAX );
i = iFirst = mem5.aiFreelist[iLogsize];
assert( iFirst>=0 );
while( i>0 ){
if( i<iFirst ) iFirst = i;
i = MEM5LINK(i)->next;
}
memsys5Unlink(iFirst, iLogsize);
return iFirst;
}
/*
** Return a block of memory of at least nBytes in size.
** Return NULL if unable. Return NULL if nBytes==0.
**
** The caller guarantees that nByte is positive.
**
** The caller has obtained a mutex prior to invoking this
** routine so there is never any chance that two or more
** threads can be in this routine at the same time.
*/
static void *memsys5MallocUnsafe(int nByte){
int i; /* Index of a mem5.aPool[] slot */
int iBin; /* Index into mem5.aiFreelist[] */
int iFullSz; /* Size of allocation rounded up to power of 2 */
int iLogsize; /* Log2 of iFullSz/POW2_MIN */
/* nByte must be a positive */
assert( nByte>0 );
/* Keep track of the maximum allocation request. Even unfulfilled
** requests are counted */
if( (u32)nByte>mem5.maxRequest ){
mem5.maxRequest = nByte;
}
/* Abort if the requested allocation size is larger than the largest
** power of two that we can represent using 32-bit signed integers.
*/
if( nByte > 0x40000000 ){
return 0;
}
/* Round nByte up to the next valid power of two */
for(iFullSz=mem5.szAtom, iLogsize=0; iFullSz<nByte; iFullSz *= 2, iLogsize++){}
/* Make sure mem5.aiFreelist[iLogsize] contains at least one free
** block. If not, then split a block of the next larger power of
** two in order to create a new free block of size iLogsize.
*/
for(iBin=iLogsize; iBin<=LOGMAX && mem5.aiFreelist[iBin]<0; iBin++){}
if( iBin>LOGMAX ){
testcase( sqlite3GlobalConfig.xLog!=0 );
sqlite3_log(SQLITE_NOMEM, "failed to allocate %u bytes", nByte);
return 0;
}
i = mem5.aiFreelist[iBin];
memsys5Unlink(i, iBin);
while( iBin>iLogsize ){
int newSize;
iBin--;
newSize = 1 << iBin;
mem5.aCtrl[i+newSize] = CTRL_FREE | iBin;
memsys5Link(i+newSize, iBin);
}
mem5.aCtrl[i] = iLogsize;
/* Update allocator performance statistics. */
mem5.nAlloc++;
mem5.totalAlloc += iFullSz;
mem5.totalExcess += iFullSz - nByte;
mem5.currentCount++;
mem5.currentOut += iFullSz;
if( mem5.maxCount<mem5.currentCount ) mem5.maxCount = mem5.currentCount;
if( mem5.maxOut<mem5.currentOut ) mem5.maxOut = mem5.currentOut;
#ifdef SQLITE_DEBUG
/* Make sure the allocated memory does not assume that it is set to zero
** or retains a value from a previous allocation */
memset(&mem5.zPool[i*mem5.szAtom], 0xAA, iFullSz);
#endif
/* Return a pointer to the allocated memory. */
return (void*)&mem5.zPool[i*mem5.szAtom];
}
