xpcom/base/nsCycleCollectionTraversalCallback.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsCycleCollectionTraversalCallback_h__
   8 #define nsCycleCollectionTraversalCallback_h__
   9
  10 #include <cstdint>
  11 #include "nscore.h"
  12
  13 class nsCycleCollectionParticipant;
  14 class nsISupports;
  15 class JSObject;
  16
  17 namespace JS {
  18 class GCCellPtr;
  19 }
  20
  21 class NS_NO_VTABLE nsCycleCollectionTraversalCallback {
  22  public:
  23   // You must call DescribeRefCountedNode() with an accurate
  24   // refcount, otherwise cycle collection will fail, and probably crash.
  25   // If the callback cares about objname, it should put
  26   // WANT_DEBUG_INFO in mFlags.
  27   NS_IMETHOD_(void)
  28   DescribeRefCountedNode(nsrefcnt aRefcount, const char* aObjName) = 0;
  29   // Note, aCompartmentAddress is 0 if it is unknown.
  30   NS_IMETHOD_(void)
  31   DescribeGCedNode(bool aIsMarked, const char* aObjName,
  32                    uint64_t aCompartmentAddress = 0) = 0;
  33
  34   NS_IMETHOD_(void) NoteXPCOMChild(nsISupports* aChild) = 0;
  35   NS_IMETHOD_(void) NoteJSChild(JS::GCCellPtr aThing) = 0;
  36   NS_IMETHOD_(void)
  37   NoteNativeChild(void* aChild, nsCycleCollectionParticipant* aHelper) = 0;
  38
  39   NS_IMETHOD_(void)
  40   NoteWeakMapping(JSObject* aKey, nsISupports* aVal,
  41                   nsCycleCollectionParticipant* aValParticipant) = 0;
  42
  43   // Give a name to the edge associated with the next call to
  44   // NoteXPCOMChild, NoteJSObject, NoteJSScript, or NoteNativeChild.
  45   // Callbacks who care about this should set WANT_DEBUG_INFO in the
  46   // flags.
  47   NS_IMETHOD_(void) NoteNextEdgeName(const char* aName) = 0;
  48
  49   enum {
  50     // Values for flags:
  51
  52     // Caller should call NoteNextEdgeName and pass useful objName
  53     // to DescribeRefCountedNode and DescribeGCedNode.
  54     WANT_DEBUG_INFO = (1 << 0),
  55
  56     // Caller should not skip objects that we know will be
  57     // uncollectable.
  58     WANT_ALL_TRACES = (1 << 1)
  59   };
  60   uint32_t Flags() const { return mFlags; }
  61   bool WantDebugInfo() const { return (mFlags & WANT_DEBUG_INFO) != 0; }
  62   bool WantAllTraces() const { return (mFlags & WANT_ALL_TRACES) != 0; }
  63
  64  protected:
  65   nsCycleCollectionTraversalCallback() : mFlags(0) {}
  66
  67   uint32_t mFlags;
  68 };
  69
  70 #endif  // nsCycleCollectionTraversalCallback_h__