Revert of [profiler] Implement POC Sampling Heap Profiler

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 CompactionSpaceCollection;
-class InlineAllocationObserver;
 class Isolate;
 
 // -----------------------------------------------------------------------------
 // Heap structures:
 //
 // A JS heap consists of a young generation, an old generation, and a large
 // object space. The young generation is divided into two semispaces. A
 // scavenger implements Cheney's copying algorithm. The old generation is
 // separated into a map space and an old object space. The map space contains
 // all (and only) map objects, the rest of old objects go into the old space.
@@ skipping 2527 matching lines @@
 
  private:
   NewSpacePage* prev_page_;  // Previous page returned.
   // Next page that will be returned.  Cached here so that we can use this
   // iterator for operations that deallocate pages.
   NewSpacePage* next_page_;
   // Last page returned.
   NewSpacePage* last_page_;
 };
 
+// -----------------------------------------------------------------------------
+// Allows observation of inline allocation in the new space.
+class InlineAllocationObserver {
+ public:
+  explicit InlineAllocationObserver(intptr_t step_size)
+      : step_size_(step_size), bytes_to_next_step_(step_size) {
+    DCHECK(step_size >= kPointerSize);
+  }
+  virtual ~InlineAllocationObserver() {}
+
+ private:
+  intptr_t step_size() const { return step_size_; }
+  intptr_t bytes_to_next_step() const { return bytes_to_next_step_; }
+
+  // Pure virtual method provided by the subclasses that gets called when at
+  // least step_size bytes have been allocated. soon_object is the address just
+  // allocated (but not yet initialized.) size is the size of the object as
+  // requested (i.e. w/o the alignment fillers). Some complexities to be aware
+  // of:
+  // 1) soon_object will be nullptr in cases where we end up observing an
+  //    allocation that happens to be a filler space (e.g. page boundaries.)
+  // 2) size is the requested size at the time of allocation. Right-trimming
+  //    may change the object size dynamically.
+  // 3) soon_object may actually be the first object in an allocation-folding
+  //    group. In such a case size is the size of the group rather than the
+  //    first object.
+  virtual void Step(int bytes_allocated, Address soon_object, size_t size) = 0;
+
+  // Called each time the new space does an inline allocation step. This may be
+  // more frequently than the step_size we are monitoring (e.g. when there are
+  // multiple observers, or when page or space boundary is encountered.)
+  void InlineAllocationStep(int bytes_allocated, Address soon_object,
+                            size_t size) {
+    bytes_to_next_step_ -= bytes_allocated;
+    if (bytes_to_next_step_ <= 0) {
+      Step(static_cast<int>(step_size_ - bytes_to_next_step_), soon_object,
+           size);
+      bytes_to_next_step_ = step_size_;
+    }
+  }
+
+  intptr_t step_size_;
+  intptr_t bytes_to_next_step_;
+
+  friend class NewSpace;
+
+  DISALLOW_COPY_AND_ASSIGN(InlineAllocationObserver);
+};
 
 // -----------------------------------------------------------------------------
 // The young generation space.
 //
 // The new space consists of a contiguous pair of semispaces.  It simply
 // forwards most functions to the appropriate semispace.
 
 class NewSpace : public Space {
  public:
   // Constructor.
@@ skipping 592 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_