+#if USE_BACKGROUND_THREAD_TO_SCAVENGE_MEMORY
+
+#if !HAVE(DISPATCH_H)
+
+void TCMalloc_PageHeap::initializeScavenger()
+{
+ pthread_mutex_init(&m_scavengeMutex, 0);
+ pthread_cond_init(&m_scavengeCondition, 0);
+ m_scavengeThreadActive = true;
+ pthread_t thread;
+ pthread_create(&thread, 0, runScavengerThread, this);
+}
+
+void* TCMalloc_PageHeap::runScavengerThread(void* context)
+{
+ static_cast<TCMalloc_PageHeap*>(context)->scavengerThread();
+#if COMPILER(MSVC)
+ // Without this, Visual Studio will complain that this method does not return a value.
+ return 0;
+#endif
+}
+
+ALWAYS_INLINE void TCMalloc_PageHeap::signalScavenger()
+{
+ if (!m_scavengeThreadActive && shouldScavenge())
+ pthread_cond_signal(&m_scavengeCondition);
+}
+
+#else // !HAVE(DISPATCH_H)
+
+void TCMalloc_PageHeap::initializeScavenger()
+{
+ m_scavengeQueue = dispatch_queue_create("com.apple.JavaScriptCore.FastMallocSavenger", NULL);
+ m_scavengeTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, m_scavengeQueue);
+ dispatch_time_t startTime = dispatch_time(DISPATCH_TIME_NOW, kScavengeDelayInSeconds * NSEC_PER_SEC);
+ dispatch_source_set_timer(m_scavengeTimer, startTime, kScavengeDelayInSeconds * NSEC_PER_SEC, 1000 * NSEC_PER_USEC);
+ dispatch_source_set_event_handler(m_scavengeTimer, ^{ periodicScavenge(); });
+ m_scavengingScheduled = false;
+}
+
+ALWAYS_INLINE void TCMalloc_PageHeap::signalScavenger()
+{
+ if (!m_scavengingScheduled && shouldScavenge()) {
+ m_scavengingScheduled = true;
+ dispatch_resume(m_scavengeTimer);
+ }
+}
+
+#endif
+
+void TCMalloc_PageHeap::scavenge()
+{
+ size_t pagesToRelease = min_free_committed_pages_since_last_scavenge_ * kScavengePercentage;
+ size_t targetPageCount = std::max<size_t>(kMinimumFreeCommittedPageCount, free_committed_pages_ - pagesToRelease);
+
+ while (free_committed_pages_ > targetPageCount) {
+ for (int i = kMaxPages; i > 0 && free_committed_pages_ >= targetPageCount; i--) {
+ SpanList* slist = (static_cast<size_t>(i) == kMaxPages) ? &large_ : &free_[i];
+ // If the span size is bigger than kMinSpanListsWithSpans pages return all the spans in the list, else return all but 1 span.
+ // Return only 50% of a spanlist at a time so spans of size 1 are not the only ones left.
+ size_t numSpansToReturn = (i > kMinSpanListsWithSpans) ? DLL_Length(&slist->normal) : static_cast<size_t>(.5 * DLL_Length(&slist->normal));
+ for (int j = 0; static_cast<size_t>(j) < numSpansToReturn && !DLL_IsEmpty(&slist->normal) && free_committed_pages_ > targetPageCount; j++) {
+ Span* s = slist->normal.prev;
+ DLL_Remove(s);
+ ASSERT(!s->decommitted);
+ if (!s->decommitted) {
+ TCMalloc_SystemRelease(reinterpret_cast<void*>(s->start << kPageShift),
+ static_cast<size_t>(s->length << kPageShift));
+ ASSERT(free_committed_pages_ >= s->length);
+ free_committed_pages_ -= s->length;
+ s->decommitted = true;
+ }
+ DLL_Prepend(&slist->returned, s);
+ }
+ }
+ }
+
+ min_free_committed_pages_since_last_scavenge_ = free_committed_pages_;
+}
+
+ALWAYS_INLINE bool TCMalloc_PageHeap::shouldScavenge() const
+{
+ return free_committed_pages_ > kMinimumFreeCommittedPageCount;
+}
+
+#endif // USE_BACKGROUND_THREAD_TO_SCAVENGE_MEMORY
+
projects / apple / javascriptcore.git / blobdiff