| // Copyright 2007-2008 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| #ifndef V8_GLOBAL_HANDLES_H_ |
| #define V8_GLOBAL_HANDLES_H_ |
| |
| #include "list-inl.h" |
| |
| namespace v8 { namespace internal { |
| |
| // Structure for tracking global handles. |
| // A single list keeps all the allocated global handles. |
| // Destroyed handles stay in the list but is added to the free list. |
| // At GC the destroyed global handles are removed from the free list |
| // and deallocated. |
| |
| // Callback function on handling weak global handles. |
| // typedef bool (*WeakSlotCallback)(Object** pointer); |
| |
| // An object group is indexed by an id. An object group is treated like |
| // a single JS object: if one of object in the group is alive, |
| // all objects in the same group are considered alive. |
| // An object group is used to simulate object relationship in a DOM tree. |
| class ObjectGroup : public Malloced { |
| public: |
| explicit ObjectGroup(void* id) : id_(id), objects_(4) {} |
| |
| void* id_; |
| List<Object**> objects_; |
| }; |
| |
| |
| class GlobalHandles : public AllStatic { |
| public: |
| // Creates a new global handle that is alive until Destroy is called. |
| static Handle<Object> Create(Object* value); |
| |
| // Destroy a global handle. |
| static void Destroy(Object** location); |
| |
| // Make the global handle weak and set the callback parameter for the |
| // handle. When the garbage collector recognizes that only weak global |
| // handles point to an object the handles are cleared and the callback |
| // function is invoked (for each handle) with the handle and corresponding |
| // parameter as arguments. Note: cleared means set to Smi::FromInt(0). The |
| // reason is that Smi::FromInt(0) does not change during garage collection. |
| static void MakeWeak(Object** location, |
| void* parameter, |
| WeakReferenceCallback callback); |
| |
| // Returns the current number of weak handles. |
| static int NumberOfWeakHandles() { return number_of_weak_handles_; } |
| |
| // Returns the current number of weak handles to global objects. |
| // These handles are also included in NumberOfWeakHandles(). |
| static int NumberOfGlobalObjectWeakHandles() { |
| return number_of_global_object_weak_handles_; |
| } |
| |
| // Clear the weakness of a global handle. |
| static void ClearWeakness(Object** location); |
| |
| // Tells whether global handle is near death. |
| static bool IsNearDeath(Object** location); |
| |
| // Tells whether global handle is weak. |
| static bool IsWeak(Object** location); |
| |
| // Process pending weak handles. |
| static void PostGarbageCollectionProcessing(); |
| |
| // Iterates over all handles. |
| static void IterateRoots(ObjectVisitor* v); |
| |
| // Iterates over all weak roots in heap. |
| static void IterateWeakRoots(ObjectVisitor* v); |
| |
| // Mark the weak pointers based on the callback. |
| static void MarkWeakRoots(WeakSlotCallback f); |
| |
| // Add an object to a group indexed by an id. |
| // Should only used in GC callback function before a collection. |
| // All groups are destroyed after a mark-compact collection. |
| static void AddToGroup(void* id, Object** location); |
| |
| // Returns the object groups. |
| static List<ObjectGroup*>& ObjectGroups() { |
| return object_groups_; |
| } |
| |
| // Remove bags, this should only happen after GC. |
| static void RemoveObjectGroups(); |
| |
| // Tear down the global handle structure. |
| static void TearDown(); |
| |
| #ifdef DEBUG |
| static void PrintStats(); |
| static void Print(); |
| #endif |
| private: |
| // Internal node structure, one for each global handle. |
| class Node; |
| |
| // Field always containing the number of weak and near-death handles. |
| static int number_of_weak_handles_; |
| |
| // Field always containing the number of weak and near-death handles |
| // to global objects. These objects are also included in |
| // number_of_weak_handles_. |
| static int number_of_global_object_weak_handles_; |
| |
| // Global handles are kept in a single linked list pointed to by head_. |
| static Node* head_; |
| static Node* head() { return head_; } |
| static void set_head(Node* value) { head_ = value; } |
| |
| // Free list for DESTROYED global handles not yet deallocated. |
| static Node* first_free_; |
| static Node* first_free() { return first_free_; } |
| static void set_first_free(Node* value) { first_free_ = value; } |
| |
| // A list of object groups. |
| static List<ObjectGroup*> object_groups_; |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_GLOBAL_HANDLES_H_ |