void Heap::allocateSmallBumpRanges(std::lock_guard<StaticMutex>& lock, size_t sizeClass, BumpAllocator& allocator, BumpRangeCache& rangeCache)
{
BASSERT(!rangeCache.size());
SmallPage* page = allocateSmallPage(lock, sizeClass);
SmallLine* lines = page->begin();
// Due to overlap from the previous line, the last line in the page may not be able to fit any objects.
size_t end = SmallPage::lineCount;
if (!m_smallLineMetadata[sizeClass][SmallPage::lineCount - 1].objectCount)
--end;
// Find a free line.
for (size_t lineNumber = 0; lineNumber < end; ++lineNumber) {
if (lines[lineNumber].refCount(lock))
continue;
// In a fragmented page, some free ranges might not fit in the cache.
if (rangeCache.size() == rangeCache.capacity()) {
m_smallPagesWithFreeLines[sizeClass].push(page);
return;
}
LineMetadata& lineMetadata = m_smallLineMetadata[sizeClass][lineNumber];
char* begin = lines[lineNumber].begin() + lineMetadata.startOffset;
unsigned short objectCount = lineMetadata.objectCount;
lines[lineNumber].ref(lock, lineMetadata.objectCount);
page->ref(lock);
// Merge with subsequent free lines.
while (++lineNumber < end) {
if (lines[lineNumber].refCount(lock))
break;
LineMetadata& lineMetadata = m_smallLineMetadata[sizeClass][lineNumber];
objectCount += lineMetadata.objectCount;
lines[lineNumber].ref(lock, lineMetadata.objectCount);
page->ref(lock);
}
if (!allocator.canAllocate())
allocator.refill({ begin, objectCount });
else
rangeCache.push({ begin, objectCount });
}
}
SmallLine* Heap::allocateSmallLineSlowCase(std::lock_guard<StaticMutex>& lock, size_t smallSizeClass)
{
m_isAllocatingPages = true;
SmallPage* page = [this]() {
if (m_smallPages.size())
return m_smallPages.pop();
SmallPage* page = m_vmHeap.allocateSmallPage();
vmAllocatePhysicalPages(page->begin()->begin(), vmPageSize);
return page;
}();
SmallLine* line = page->begin();
Vector<SmallLine*>& smallLines = m_smallLines[smallSizeClass];
for (auto it = line + 1; it != page->end(); ++it)
smallLines.push(it);
BASSERT(!line->refCount(lock));
page->setSmallSizeClass(smallSizeClass);
page->ref(lock);
return line;
}