v8::internal::StoreBufferRebuilder Class Reference

#include <heap.h>

Collaboration diagram for v8::internal::StoreBufferRebuilder:

Public Member Functions
	StoreBufferRebuilder (StoreBuffer *store_buffer)
void	Callback (MemoryChunk *page, StoreBufferEvent event)

Private Attributes
StoreBuffer *	store_buffer_
Object ***	start_of_current_page_
MemoryChunk *	current_page_

Detailed Description

Definition at line 349 of file heap.h.

Constructor & Destructor Documentation

StoreBufferRebuilder()

v8::internal::StoreBufferRebuilder::StoreBufferRebuilder ( StoreBuffer *  store_buffer )

inlineexplicit

Definition at line 351 of file heap.h.

      : store_buffer_(store_buffer) {}

Member Function Documentation

Callback()

void v8::internal::StoreBufferRebuilder::Callback	(	MemoryChunk *	page,
		StoreBufferEvent	event
	)

Definition at line 1315 of file heap.cc.

                                                                             {
  if (event == kStoreBufferStartScanningPagesEvent) {
    start_of_current_page_ = NULL;
    current_page_ = NULL;
  } else if (event == kStoreBufferScanningPageEvent) {
    if (current_page_ != NULL) {
      // If this page already overflowed the store buffer during this iteration.
      if (current_page_->scan_on_scavenge()) {
        // Then we should wipe out the entries that have been added for it.
        store_buffer_->SetTop(start_of_current_page_);
      } else if (store_buffer_->Top() - start_of_current_page_ >=
                 (store_buffer_->Limit() - store_buffer_->Top()) >> 2) {
        // Did we find too many pointers in the previous page?  The heuristic is
        // that no page can take more then 1/5 the remaining slots in the store
        // buffer.
        current_page_->set_scan_on_scavenge(true);
        store_buffer_->SetTop(start_of_current_page_);
      } else {
        // In this case the page we scanned took a reasonable number of slots in
        // the store buffer.  It has now been rehabilitated and is no longer
        // marked scan_on_scavenge.
        DCHECK(!current_page_->scan_on_scavenge());
      }
    }
    start_of_current_page_ = store_buffer_->Top();
    current_page_ = page;
  } else if (event == kStoreBufferFullEvent) {
    // The current page overflowed the store buffer again.  Wipe out its entries
    // in the store buffer and mark it scan-on-scavenge again.  This may happen
    // several times while scanning.
    if (current_page_ == NULL) {
      // Store Buffer overflowed while scanning promoted objects.  These are not
      // in any particular page, though they are likely to be clustered by the
      // allocation routines.
      store_buffer_->EnsureSpace(StoreBuffer::kStoreBufferSize / 2);
    } else {
      // Store Buffer overflowed while scanning a particular old space page for
      // pointers to new space.
      DCHECK(current_page_ == page);
      DCHECK(page != NULL);
      current_page_->set_scan_on_scavenge(true);
      DCHECK(start_of_current_page_ != store_buffer_->Top());
      store_buffer_->SetTop(start_of_current_page_);
    }
  } else {
    UNREACHABLE();
  }
}

References current_page_, DCHECK, v8::internal::StoreBuffer::EnsureSpace(), v8::internal::kStoreBufferFullEvent, v8::internal::kStoreBufferScanningPageEvent, v8::internal::StoreBuffer::kStoreBufferSize, v8::internal::kStoreBufferStartScanningPagesEvent, v8::internal::StoreBuffer::Limit(), NULL, v8::internal::MemoryChunk::scan_on_scavenge(), v8::internal::MemoryChunk::set_scan_on_scavenge(), v8::internal::StoreBuffer::SetTop(), start_of_current_page_, store_buffer_, v8::internal::StoreBuffer::Top(), and UNREACHABLE.

Referenced by v8::internal::Heap::ScavengeStoreBufferCallback().

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Member Data Documentation

current_page_

MemoryChunk* v8::internal::StoreBufferRebuilder::current_page_

private

Definition at line 365 of file heap.h.

Referenced by Callback().

start_of_current_page_

Object*** v8::internal::StoreBufferRebuilder::start_of_current_page_

private

Definition at line 363 of file heap.h.

Referenced by Callback().

store_buffer_

StoreBuffer* v8::internal::StoreBufferRebuilder::store_buffer_

private

Definition at line 357 of file heap.h.

Referenced by Callback().

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The documentation for this class was generated from the following files:

• /mnt/V8SourceCode/src/heap/heap.h
• /mnt/V8SourceCode/src/heap/heap.cc