Allocation sampling for paged/lo spaces

src/heap/spaces.h

 // Copyright 2011 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.
 
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/platform/mutex.h"
 #include "src/flags.h"
 #include "src/hashmap.h"
 #include "src/list.h"
 #include "src/objects.h"
 #include "src/utils.h"
 
 namespace v8 {
 namespace internal {
 
 class AllocationInfo;
+class AllocationObserver;
 class CompactionSpace;
 class CompactionSpaceCollection;
 class FreeList;
-class InlineAllocationObserver;
 class Isolate;
 class MemoryAllocator;
 class MemoryChunk;
 class PagedSpace;
 class SemiSpace;
 class SkipList;
 class SlotsBuffer;
 class Space;
 
 // -----------------------------------------------------------------------------
@@ skipping 903 matching lines @@
 
   friend class MemoryAllocator;
 };
 
 
 // ----------------------------------------------------------------------------
 // Space is the abstract superclass for all allocation spaces.
 class Space : public Malloced {
  public:
   Space(Heap* heap, AllocationSpace id, Executability executable)
-      : heap_(heap),
+      : allocation_observers_paused_(false),
+        heap_(heap),
         id_(id),
         executable_(executable),
         committed_(0),
         max_committed_(0) {}
 
   virtual ~Space() {}
 
   Heap* heap() const { return heap_; }
 
   // Does the space need executable memory?
   Executability executable() { return executable_; }
 
   // Identity used in error reporting.
   AllocationSpace identity() { return id_; }
 
+  virtual void AddAllocationObserver(AllocationObserver* observer) {
+    allocation_observers_->Add(observer);
+  }
+
+  virtual void RemoveAllocationObserver(AllocationObserver* observer) {
+    bool removed = allocation_observers_->RemoveElement(observer);
+    static_cast<void>(removed);

[Hannes Payer (out of office), 2016/02/08 10:13:48]

USE(removed);

[mattloring, 2016/02/09 20:20:05]

Done.

+    DCHECK(removed);
+  }
+
+  virtual void PauseAllocationObservers() {
+    allocation_observers_paused_ = true;
+  }
+
+  virtual void ResumeAllocationObservers() {
+    allocation_observers_paused_ = false;
+  }
+
+  void AllocationStep(Address soon_object, int size);
+
   // Return the total amount committed memory for this space, i.e., allocatable
   // memory and page headers.
   virtual intptr_t CommittedMemory() { return committed_; }
 
   virtual intptr_t MaximumCommittedMemory() { return max_committed_; }
 
   // Returns allocated size.
   virtual intptr_t Size() = 0;
 
   // Returns size of objects. Can differ from the allocated size
@@ skipping 26 matching lines @@
       max_committed_ = committed_;
     }
   }
 
   void AccountUncommitted(intptr_t bytes) {
     DCHECK_GE(bytes, 0);
     committed_ -= bytes;
     DCHECK_GE(committed_, 0);
   }
 
+  // When inline allocation stepping is active, either because of incremental
+  // marking or because of idle scavenge, we 'interrupt' inline allocation every

[Hannes Payer (out of office), 2016/02/08 10:13:48]

This list is not complete: allocation statistics gather also interrupts inline
allocation.

[mattloring, 2016/02/09 20:20:05]

Done.

+  // once in a while. This is done by setting allocation_info_.limit to be lower
+  // than the actual limit and and increasing it in steps to guarantee that the
+  // observers are notified periodically.
+  List<AllocationObserver*>* allocation_observers_ =

[Hannes Payer (out of office), 2016/02/08 10:13:48]

allocate the allocation_observers in the constructor

And deallocate it when the space is shut down.

[mattloring, 2016/02/09 20:20:05]

What is the best strategy for deallocating a list where the contents may be
shared with other lists as well (some observers may be observing other spaces as
well)?

[ofrobots, 2016/02/10 08:15:38]

Does allocation_observers_ need to be dynamically allocated using new? Would an
object rather than pointer work instead:
List<AllocationObserver*> allocation_observers_;

[mattloring, 2016/02/10 13:19:23]

If I do not dynamically allocate it, it causes the copy constructor for spaces
to be deleted yielding: 

copy constructor of 'Space' is implicitly deleted because field
'allocation_observers_' has a deleted copy constructor

is it better to explicitly implement a copy constructor?

[Hannes Payer (out of office), 2016/02/11 11:50:08]

I am not sure if I understand your question.
When the space dies, all other spaces will die as well (shortly afterwards).
Deallocating the list will not impact the lifetime of the the list content. The
actual observers have to be freed somewhere else.

[mattloring, 2016/02/11 14:54:14]

Sorry for the confusion. This should be handled now by a smart pointer.

+      new List<AllocationObserver*>();
+  bool allocation_observers_paused_;
+
  private:
   Heap* heap_;
   AllocationSpace id_;
   Executability executable_;
 
   // Keeps track of committed memory in a space.
   intptr_t committed_;
   intptr_t max_committed_;
 };
 
@@ skipping 1528 matching lines @@
 // forwards most functions to the appropriate semispace.
 
 class NewSpace : public Space {
  public:
   // Constructor.
   explicit NewSpace(Heap* heap)
       : Space(heap, NEW_SPACE, NOT_EXECUTABLE),
         to_space_(heap, kToSpace),
         from_space_(heap, kFromSpace),
         reservation_(),
-        top_on_previous_step_(0),
-        inline_allocation_observers_paused_(false) {}
+        top_on_previous_step_(0) {}
 
   // Sets up the new space using the given chunk.
   bool SetUp(int reserved_semispace_size_, int max_semi_space_size);
 
   // Tears down the space.  Heap memory was not allocated by the space, so it
   // is not deallocated here.
   void TearDown();
 
   // True if the space has been set up but not torn down.
   bool HasBeenSetUp() {
@@ skipping 151 matching lines @@
       int size_in_bytes, AllocationAlignment alignment));
 
   MUST_USE_RESULT inline AllocationResult AllocateRawSynchronized(
       int size_in_bytes, AllocationAlignment alignment);
 
   // Reset the allocation pointer to the beginning of the active semispace.
   void ResetAllocationInfo();
 
   void UpdateInlineAllocationLimit(int size_in_bytes);
 
-  // Allows observation of inline allocation. The observer->Step() method gets
-  // called after every step_size bytes have been allocated (approximately).
-  // This works by adjusting the allocation limit to a lower value and adjusting
-  // it after each step.
-  void AddInlineAllocationObserver(InlineAllocationObserver* observer);
-
-  // Removes a previously installed observer.
-  void RemoveInlineAllocationObserver(InlineAllocationObserver* observer);
-
   void DisableInlineAllocationSteps() {
     top_on_previous_step_ = 0;
     UpdateInlineAllocationLimit(0);
   }
 
+  // Allows observation of inline allocation. The observer->Step() method gets
+  // called after every step_size bytes have been allocated (approximately).
+  // This works by adjusting the allocation limit to a lower value and adjusting
+  // it after each step.
+  void AddAllocationObserver(AllocationObserver* observer) override;
+
+  void RemoveAllocationObserver(AllocationObserver* observer) override;
+
   // Get the extent of the inactive semispace (for use as a marking stack,
   // or to zap it). Notice: space-addresses are not necessarily on the
   // same page, so FromSpaceStart() might be above FromSpaceEnd().
   Address FromSpacePageLow() { return from_space_.page_low(); }
   Address FromSpacePageHigh() { return from_space_.page_high(); }
   Address FromSpaceStart() { return from_space_.space_start(); }
   Address FromSpaceEnd() { return from_space_.space_end(); }
 
   // Get the extent of the active semispace's pages' memory.
   Address ToSpaceStart() { return to_space_.space_start(); }
@@ skipping 50 matching lines @@
 
   bool UncommitFromSpace() {
     if (!from_space_.is_committed()) return true;
     return from_space_.Uncommit();
   }
 
   bool IsFromSpaceCommitted() { return from_space_.is_committed(); }
 
   SemiSpace* active_space() { return &to_space_; }
 
+  void PauseAllocationObservers() override;
+  void ResumeAllocationObservers() override;
+
  private:
   // Update allocation info to match the current to-space page.
   void UpdateAllocationInfo();
 
   base::Mutex mutex_;
 
   Address chunk_base_;
   uintptr_t chunk_size_;
 
   // The semispaces.
   SemiSpace to_space_;
   SemiSpace from_space_;
   base::VirtualMemory reservation_;
   int pages_used_;
 
   // Start address and bit mask for containment testing.
   Address start_;
   uintptr_t address_mask_;
   uintptr_t object_mask_;
   uintptr_t object_expected_;
 
   // Allocation pointer and limit for normal allocation and allocation during
   // mark-compact collection.
   AllocationInfo allocation_info_;
 
-  // When inline allocation stepping is active, either because of incremental
-  // marking or because of idle scavenge, we 'interrupt' inline allocation every
-  // once in a while. This is done by setting allocation_info_.limit to be lower
-  // than the actual limit and and increasing it in steps to guarantee that the
-  // observers are notified periodically.
-  List<InlineAllocationObserver*> inline_allocation_observers_;
   Address top_on_previous_step_;
-  bool inline_allocation_observers_paused_;
 
   HistogramInfo* allocated_histogram_;
   HistogramInfo* promoted_histogram_;
 
   bool EnsureAllocation(int size_in_bytes, AllocationAlignment alignment);
 
   // If we are doing inline allocation in steps, this method performs the 'step'
   // operation. top is the memory address of the bump pointer at the last
   // inline allocation (i.e. it determines the numbers of bytes actually
   // allocated since the last step.) new_top is the address of the bump pointer
   // where the next byte is going to be allocated from. top and new_top may be
   // different when we cross a page boundary or reset the space.
   void InlineAllocationStep(Address top, Address new_top, Address soon_object,
                             size_t size);
   intptr_t GetNextInlineAllocationStepSize();
   void StartNextInlineAllocationStep();
-  void PauseInlineAllocationObservers();
-  void ResumeInlineAllocationObservers();
 
-  friend class PauseInlineAllocationObserversScope;
   friend class SemiSpaceIterator;
 };
 
-class PauseInlineAllocationObserversScope {
+class PauseAllocationObserversScope {
  public:
-  explicit PauseInlineAllocationObserversScope(NewSpace* new_space)
-      : new_space_(new_space) {
-    new_space_->PauseInlineAllocationObservers();
-  }
-  ~PauseInlineAllocationObserversScope() {
-    new_space_->ResumeInlineAllocationObservers();
-  }
+  explicit PauseAllocationObserversScope(Heap* heap);
+  ~PauseAllocationObserversScope();
 
  private:
-  NewSpace* new_space_;
-  DISALLOW_COPY_AND_ASSIGN(PauseInlineAllocationObserversScope);
+  Heap* heap_;
+  DISALLOW_COPY_AND_ASSIGN(PauseAllocationObserversScope);
 };
 
 // -----------------------------------------------------------------------------
 // Compaction space that is used temporarily during compaction.
 
 class CompactionSpace : public PagedSpace {
  public:
   CompactionSpace(Heap* heap, AllocationSpace id, Executability executable)
       : PagedSpace(heap, id, executable) {}
 
@@ skipping 232 matching lines @@
     count = 0;
   }
   // Must be small, since an iteration is used for lookup.
   static const int kMaxComments = 64;
 };
 #endif
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_SPACES_H_