Reland "[heap] Fine-grained JSArrayBuffer tracking"

src/heap/array-buffer-tracker.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/array-buffer-tracker.h"
+#include "src/heap/array-buffer-tracker-inl.h"
 #include "src/heap/heap.h"
 #include "src/isolate.h"
+#include "src/objects-inl.h"
 #include "src/objects.h"
-#include "src/objects-inl.h"
 #include "src/v8.h"
 
 namespace v8 {
 namespace internal {
 
-ArrayBufferTracker::~ArrayBufferTracker() {
-  Isolate* isolate = heap()->isolate();
+LocalArrayBufferTracker::~LocalArrayBufferTracker() {
   size_t freed_memory = 0;
-  for (auto& buffer : live_array_buffers_) {
-    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
-    freed_memory += buffer.second;
+  for (auto& buffer : live_) {
+    heap_->isolate()->array_buffer_allocator()->Free(buffer.second.first,
+                                                     buffer.second.second);
+    freed_memory += buffer.second.second;
   }
-  for (auto& buffer : live_array_buffers_for_scavenge_) {
-    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
-    freed_memory += buffer.second;
+  if (freed_memory > 0) {
+    heap_->update_amount_of_external_allocated_freed_memory(
+        static_cast<intptr_t>(freed_memory));
   }
-  live_array_buffers_.clear();
-  live_array_buffers_for_scavenge_.clear();
-  not_yet_discovered_array_buffers_.clear();
-  not_yet_discovered_array_buffers_for_scavenge_.clear();
+  live_.clear();
+  not_yet_discovered_.clear();
+}
 
+void LocalArrayBufferTracker::Add(Key key, const Value& value) {
+  live_[key] = value;
+  not_yet_discovered_[key] = value;
+}
+
+void LocalArrayBufferTracker::AddLive(Key key, const Value& value) {
+  DCHECK_EQ(not_yet_discovered_.count(key), 0);
+  live_[key] = value;
+}
+
+void LocalArrayBufferTracker::MarkLive(Key key) {
+  DCHECK_EQ(live_.count(key), 1);
+  not_yet_discovered_.erase(key);
+}
+
+LocalArrayBufferTracker::Value LocalArrayBufferTracker::Remove(Key key) {
+  DCHECK_EQ(live_.count(key), 1);
+  Value value = live_[key];
+  live_.erase(key);
+  not_yet_discovered_.erase(key);
+  return value;
+}
+
+void LocalArrayBufferTracker::FreeDead() {
+  size_t freed_memory = 0;
+  for (TrackingMap::iterator it = not_yet_discovered_.begin();
+       it != not_yet_discovered_.end();) {
+    heap_->isolate()->array_buffer_allocator()->Free(it->second.first,
+                                                     it->second.second);
+    freed_memory += it->second.second;
+    live_.erase(it->first);
+    not_yet_discovered_.erase(it++);
+  }
   if (freed_memory > 0) {
-    heap()->update_amount_of_external_allocated_memory(
-        -static_cast<int64_t>(freed_memory));
+    heap_->update_amount_of_external_allocated_freed_memory(
+        static_cast<intptr_t>(freed_memory));
+  }
+  started_ = false;
+}
+
+void LocalArrayBufferTracker::Reset() {
+  if (!started_) {
+    not_yet_discovered_ = live_;
+    started_ = true;
   }
 }
 
+bool LocalArrayBufferTracker::IsEmpty() {
+  return live_.empty() && not_yet_discovered_.empty();
+}
 
-void ArrayBufferTracker::RegisterNew(JSArrayBuffer* buffer) {
+void ArrayBufferTracker::RegisterNew(Heap* heap, JSArrayBuffer* buffer) {
   void* data = buffer->backing_store();
   if (!data) return;
 
-  bool in_new_space = heap()->InNewSpace(buffer);
-  size_t length = NumberToSize(heap()->isolate(), buffer->byte_length());
-  if (in_new_space) {
-    live_array_buffers_for_scavenge_[data] = length;
-  } else {
-    live_array_buffers_[data] = length;
+  size_t length = NumberToSize(heap->isolate(), buffer->byte_length());
+  Page* page = Page::FromAddress(buffer->address());
+  LocalArrayBufferTracker* tracker =
+      page->local_tracker<Page::kCreateIfNotPresent>();
+  DCHECK_NOT_NULL(tracker);
+  {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    if (Marking::IsBlack(Marking::MarkBitFrom(buffer))) {
+      tracker->AddLive(buffer, std::make_pair(data, length));
+    } else {
+      tracker->Add(buffer, std::make_pair(data, length));
+    }
   }
-
   // We may go over the limit of externally allocated memory here. We call the
   // api function to trigger a GC in this case.
-  reinterpret_cast<v8::Isolate*>(heap()->isolate())
+  reinterpret_cast<v8::Isolate*>(heap->isolate())
       ->AdjustAmountOfExternalAllocatedMemory(length);
 }
 
-
-void ArrayBufferTracker::Unregister(JSArrayBuffer* buffer) {
+void ArrayBufferTracker::Unregister(Heap* heap, JSArrayBuffer* buffer) {
   void* data = buffer->backing_store();
   if (!data) return;
 
-  bool in_new_space = heap()->InNewSpace(buffer);
-  std::map<void*, size_t>* live_buffers =
-      in_new_space ? &live_array_buffers_for_scavenge_ : &live_array_buffers_;
-  std::map<void*, size_t>* not_yet_discovered_buffers =
-      in_new_space ? &not_yet_discovered_array_buffers_for_scavenge_
-                   : &not_yet_discovered_array_buffers_;
-
-  DCHECK(live_buffers->count(data) > 0);
-
-  size_t length = (*live_buffers)[data];
-  live_buffers->erase(data);
-  not_yet_discovered_buffers->erase(data);
-
-  heap()->update_amount_of_external_allocated_memory(
-      -static_cast<int64_t>(length));
+  Page* page = Page::FromAddress(buffer->address());
+  LocalArrayBufferTracker* tracker = page->local_tracker<Page::kDontCreate>();
+  DCHECK_NOT_NULL(tracker);
+  size_t length = 0;
+  {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    length = tracker->Remove(buffer).second;
+  }
+  heap->update_amount_of_external_allocated_memory(
+      -static_cast<intptr_t>(length));
 }
 
+void ArrayBufferTracker::FreeDeadInNewSpace(Heap* heap) {
+  NewSpacePageIterator from_it(heap->new_space()->FromSpaceStart(),
+                               heap->new_space()->FromSpaceEnd());
+  while (from_it.has_next()) {
+    ScanAndFreeDeadArrayBuffers<LocalArrayBufferTracker::kForwardingPointer>(
+        from_it.next());
+  }
+  heap->account_amount_of_external_allocated_freed_memory();
+}
 
-void ArrayBufferTracker::MarkLive(JSArrayBuffer* buffer) {
-  base::LockGuard<base::Mutex> guard(&mutex_);
+void ArrayBufferTracker::ResetTrackersInOldSpace(Heap* heap) {
+  heap->old_space()->ForAllPages([](Page* p) {
+    LocalArrayBufferTracker* tracker = p->local_tracker<Page::kDontCreate>();
+    if (tracker != nullptr) {
+      tracker->Reset();
+      if (tracker->IsEmpty()) {
+        p->ReleaseLocalTracker();
+      }
+    }
+  });
+}
+
+void ArrayBufferTracker::MarkLive(Heap* heap, JSArrayBuffer* buffer) {
+  if (buffer->is_external()) return;
   void* data = buffer->backing_store();
+  if (data == nullptr) return;
+  if (data == heap->undefined_value()) return;
 
-  // ArrayBuffer might be in the middle of being constructed.
-  if (data == heap()->undefined_value()) return;
-  if (heap()->InNewSpace(buffer)) {
-    not_yet_discovered_array_buffers_for_scavenge_.erase(data);
+  Page* page = Page::FromAddress(buffer->address());
+  LocalArrayBufferTracker* tracker =
+      page->local_tracker<Page::kCreateIfNotPresent>();
+  DCHECK_NOT_NULL(tracker);
+  if (tracker->IsTracked(buffer)) {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    tracker->MarkLive((buffer));
   } else {
-    not_yet_discovered_array_buffers_.erase(data);
+    RegisterNew(heap, buffer);
   }
 }
 
-
-void ArrayBufferTracker::FreeDead(bool from_scavenge) {
-  size_t freed_memory = 0;
-  Isolate* isolate = heap()->isolate();
-  for (auto& buffer : not_yet_discovered_array_buffers_for_scavenge_) {
-    isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
-    freed_memory += buffer.second;
-    live_array_buffers_for_scavenge_.erase(buffer.first);
+void ArrayBufferTracker::FreeDead(Page* page) {
+  // Only called from the sweeper, which already holds the page lock.
+  LocalArrayBufferTracker* tracker = page->local_tracker<Page::kDontCreate>();
+  if (tracker != nullptr) {
+    tracker->FreeDead();
   }
-
-  if (!from_scavenge) {
-    for (auto& buffer : not_yet_discovered_array_buffers_) {
-      isolate->array_buffer_allocator()->Free(buffer.first, buffer.second);
-      freed_memory += buffer.second;
-      live_array_buffers_.erase(buffer.first);
-    }
-  }
-
-  not_yet_discovered_array_buffers_for_scavenge_ =
-      live_array_buffers_for_scavenge_;
-  if (!from_scavenge) not_yet_discovered_array_buffers_ = live_array_buffers_;
-
-  // Do not call through the api as this code is triggered while doing a GC.
-  heap()->update_amount_of_external_allocated_memory(
-      -static_cast<int64_t>(freed_memory));
 }
 
-
-void ArrayBufferTracker::PrepareDiscoveryInNewSpace() {
-  not_yet_discovered_array_buffers_for_scavenge_ =
-      live_array_buffers_for_scavenge_;
+template <LocalArrayBufferTracker::LivenessIndicator liveness_indicator>
+void ArrayBufferTracker::ScanAndFreeDeadArrayBuffers(Page* page) {
+  LocalArrayBufferTracker* tracker = page->local_tracker<Page::kDontCreate>();
+  if (tracker != nullptr) {
+    base::LockGuard<base::Mutex> guard(page->mutex());
+    tracker->ScanAndFreeDead<liveness_indicator>();
+  }
 }
 
-
-void ArrayBufferTracker::Promote(JSArrayBuffer* buffer) {
-  base::LockGuard<base::Mutex> guard(&mutex_);
-
-  if (buffer->is_external()) return;
-  void* data = buffer->backing_store();
-  if (!data) return;
-  // ArrayBuffer might be in the middle of being constructed.
-  if (data == heap()->undefined_value()) return;
-  DCHECK(live_array_buffers_for_scavenge_.count(data) > 0);
-  live_array_buffers_[data] = live_array_buffers_for_scavenge_[data];
-  live_array_buffers_for_scavenge_.erase(data);
-  not_yet_discovered_array_buffers_for_scavenge_.erase(data);
-}
+template void ArrayBufferTracker::ScanAndFreeDeadArrayBuffers<
+    LocalArrayBufferTracker::LivenessIndicator::kForwardingPointer>(Page* page);
+template void ArrayBufferTracker::ScanAndFreeDeadArrayBuffers<
+    LocalArrayBufferTracker::LivenessIndicator::kMarkBit>(Page* page);
+template void ArrayBufferTracker::ScanAndFreeDeadArrayBuffers<
+    LocalArrayBufferTracker::LivenessIndicator::kForwardingPointerOrMarkBit>(
+    Page* page);
 
 }  // namespace internal
 }  // namespace v8