IncrementalSweeper.cpp [plain text]
#include "config.h"
#include "IncrementalSweeper.h"
#include "DeferGC.h"
#include "HeapInlines.h"
#include "MarkedBlock.h"
#include "VM.h"
namespace JSC {
static constexpr Seconds sweepTimeSlice = 10_ms;
static constexpr double sweepTimeTotal = .10;
static constexpr double sweepTimeMultiplier = 1.0 / sweepTimeTotal;
void IncrementalSweeper::scheduleTimer()
{
setTimeUntilFire(sweepTimeSlice * sweepTimeMultiplier);
}
IncrementalSweeper::IncrementalSweeper(Heap* heap)
: Base(heap->vm())
, m_currentDirectory(nullptr)
{
}
void IncrementalSweeper::doWork(VM& vm)
{
doSweep(vm, MonotonicTime::now());
}
void IncrementalSweeper::doSweep(VM& vm, MonotonicTime sweepBeginTime)
{
while (sweepNextBlock(vm)) {
Seconds elapsedTime = MonotonicTime::now() - sweepBeginTime;
if (elapsedTime < sweepTimeSlice)
continue;
scheduleTimer();
return;
}
if (m_shouldFreeFastMallocMemoryAfterSweeping) {
WTF::releaseFastMallocFreeMemory();
m_shouldFreeFastMallocMemoryAfterSweeping = false;
}
cancelTimer();
}
bool IncrementalSweeper::sweepNextBlock(VM& vm)
{
vm.heap.stopIfNecessary();
MarkedBlock::Handle* block = nullptr;
for (; m_currentDirectory; m_currentDirectory = m_currentDirectory->nextDirectory()) {
block = m_currentDirectory->findBlockToSweep();
if (block)
break;
}
if (block) {
DeferGCForAWhile deferGC(vm.heap);
block->sweep(nullptr);
vm.heap.objectSpace().freeOrShrinkBlock(block);
return true;
}
return vm.heap.sweepNextLogicallyEmptyWeakBlock();
}
void IncrementalSweeper::startSweeping(Heap& heap)
{
scheduleTimer();
m_currentDirectory = heap.objectSpace().firstDirectory();
}
void IncrementalSweeper::stopSweeping()
{
m_currentDirectory = nullptr;
cancelTimer();
}
}