koda@google.com
655b16b2d6
R=johnmccutchan@google.com Review URL: https://codereview.chromium.org//350403005 git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@37956 260f80e4-7a28-3924-810f-c04153c831b5
91 lines
3.2 KiB
C++
91 lines
3.2 KiB
C++
// Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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#ifndef VM_OBJECT_GRAPH_H_
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#define VM_OBJECT_GRAPH_H_
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#include "vm/allocation.h"
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#include "vm/object.h"
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namespace dart {
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class Isolate;
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// Utility to traverse the object graph in an ordered fashion.
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// Example uses:
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// - find a retaining path from the isolate roots to a particular object, or
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// - determine how much memory is retained by some particular object(s).
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class ObjectGraph : public StackResource {
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public:
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class Stack;
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// Allows climbing the search tree all the way to the root.
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class StackIterator {
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public:
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// The object this iterator currently points to.
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RawObject* Get() const;
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// Returns false if there is no parent.
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bool MoveToParent();
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// Offset into parent for the pointer to current object. -1 if no parent.
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intptr_t OffsetFromParentInWords() const;
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private:
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StackIterator(const Stack* stack, intptr_t index)
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: stack_(stack), index_(index) { }
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const Stack* stack_;
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intptr_t index_;
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friend class ObjectGraph::Stack;
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DISALLOW_IMPLICIT_CONSTRUCTORS(StackIterator);
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};
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class Visitor {
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public:
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// Directs how the search should continue after visiting an object.
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enum Direction {
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kProceed, // Recurse on this object's pointers.
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kBacktrack, // Ignore this object's pointers.
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kAbort, // Terminate the entire search immediately.
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};
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virtual ~Visitor() { }
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// Visits the object pointed to by *it. The iterator is only valid
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// during this call. This method must not allocate from the heap or
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// trigger GC in any way.
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virtual Direction VisitObject(StackIterator* it) = 0;
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};
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explicit ObjectGraph(Isolate* isolate);
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~ObjectGraph();
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// Visits all strongly reachable objects in the isolate's heap, in a
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// pre-order, depth first traversal.
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void IterateObjects(Visitor* visitor);
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// Like 'IterateObjects', but restricted to objects reachable from 'root'
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// (including 'root' itself).
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void IterateObjectsFrom(const Object& root, Visitor* visitor);
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// The number of bytes retained by 'obj'.
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intptr_t SizeRetainedByInstance(const Object& obj);
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// The number of bytes retained by the set of all objects of the given class.
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intptr_t SizeRetainedByClass(intptr_t class_id);
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// Finds some retaining path from the isolate roots to 'obj'. Populates the
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// provided array with pairs of (object, offset from parent in words),
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// starting with 'obj' itself, as far as there is room. Returns the number
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// of objects on the full path. A null input array behaves like a zero-length
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// input array. The 'offset' of a root is -1.
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//
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// To break the trivial path, the handle 'obj' is temporarily cleared during
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// the search, but restored before returning. If no path is found (i.e., the
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// provided handle was the only way to reach the object), zero is returned.
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intptr_t RetainingPath(Object* obj, const Array& path);
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private:
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DISALLOW_IMPLICIT_CONSTRUCTORS(ObjectGraph);
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};
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} // namespace dart
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#endif // VM_OBJECT_GRAPH_H_
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