inline void* MarkedAllocator::tryAllocateHelper(size_t bytes)
{
// We need a while loop to check the free list because the DelayedReleaseScope
// could cause arbitrary code to execute and exhaust the free list that we
// thought had elements in it.
while (!m_freeList.head) {
DelayedReleaseScope delayedReleaseScope(*m_markedSpace);
if (m_currentBlock) {
ASSERT(m_currentBlock == m_nextBlockToSweep);
m_currentBlock->didConsumeFreeList();
m_nextBlockToSweep = m_currentBlock->next();
}
MarkedBlock* next;
for (MarkedBlock*& block = m_nextBlockToSweep; block; block = next) {
next = block->next();
MarkedBlock::FreeList freeList = block->sweep(MarkedBlock::SweepToFreeList);
if (!freeList.head) {
block->didConsumeEmptyFreeList();
m_blockList.remove(block);
m_blockList.push(block);
if (!m_lastFullBlock)
m_lastFullBlock = block;
continue;
}
if (bytes > block->cellSize()) {
block->stopAllocating(freeList);
continue;
}
m_currentBlock = block;
m_freeList = freeList;
break;
}
if (!m_freeList.head) {
m_currentBlock = 0;
return 0;
}
}
ASSERT(m_freeList.head);
void* head = tryPopFreeList(bytes);
ASSERT(head);
m_markedSpace->didAllocateInBlock(m_currentBlock);
return head;
}
inline void* MarkedAllocator::tryAllocateHelper(size_t bytes)
{
if (m_currentBlock) {
ASSERT(m_currentBlock == m_nextBlockToSweep);
m_currentBlock->didConsumeFreeList();
m_nextBlockToSweep = m_currentBlock->next();
}
MarkedBlock* next;
for (MarkedBlock*& block = m_nextBlockToSweep; block; block = next) {
next = block->next();
MarkedBlock::FreeList freeList = block->sweep(MarkedBlock::SweepToFreeList);
double utilization = ((double)MarkedBlock::blockSize - (double)freeList.bytes) / (double)MarkedBlock::blockSize;
if (utilization >= Options::minMarkedBlockUtilization()) {
ASSERT(freeList.bytes || !freeList.head);
m_blockList.remove(block);
m_retiredBlocks.push(block);
block->didRetireBlock(freeList);
continue;
}
if (bytes > block->cellSize()) {
block->stopAllocating(freeList);
continue;
}
m_currentBlock = block;
m_freeList = freeList;
break;
}
if (!m_freeList.head) {
m_currentBlock = 0;
return 0;
}
ASSERT(m_freeList.head);
void* head = tryPopFreeList(bytes);
ASSERT(head);
m_markedSpace->didAllocateInBlock(m_currentBlock);
return head;
}
inline void* MarkedAllocator::tryAllocate(size_t bytes)
{
ASSERT(!m_heap->isBusy());
m_heap->m_operationInProgress = Allocation;
void* result = tryAllocateHelper(bytes);
// Due to the DelayedReleaseScope in tryAllocateHelper, some other thread might have
// created a new block after we thought we didn't find any free cells.
while (!result && m_currentBlock) {
// A new block was added by another thread so try popping the free list.
result = tryPopFreeList(bytes);
if (result)
break;
// The free list was empty, so call tryAllocateHelper to do the normal sweeping stuff.
result = tryAllocateHelper(bytes);
}
m_heap->m_operationInProgress = NoOperation;
ASSERT(result || !m_currentBlock);
return result;
}
