| // Copyright 2011 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 "../include/v8.h" |
| #include "../include/v8-profiler.h" |
| |
| #include "list.h" |
| #include "v8utils.h" |
| |
| namespace v8 { |
| namespace internal { |
| |
| class GCTracer; |
| class HeapStats; |
| class ObjectVisitor; |
| |
| // 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. |
| |
| // Data structures for tracking object groups and implicit references. |
| |
| // 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. |
| |
| // An implicit references group consists of two parts: a parent object and a |
| // list of children objects. If the parent is alive, all the children are alive |
| // too. |
| |
| struct ObjectGroup { |
| explicit ObjectGroup(size_t length) |
| : info(NULL), length(length) { |
| ASSERT(length > 0); |
| objects = new Object**[length]; |
| } |
| ~ObjectGroup(); |
| |
| v8::RetainedObjectInfo* info; |
| Object*** objects; |
| size_t length; |
| }; |
| |
| |
| struct ImplicitRefGroup { |
| ImplicitRefGroup(HeapObject** parent, size_t length) |
| : parent(parent), length(length) { |
| ASSERT(length > 0); |
| children = new Object**[length]; |
| } |
| ~ImplicitRefGroup(); |
| |
| HeapObject** parent; |
| Object*** children; |
| size_t length; |
| }; |
| |
| |
| // For internal bookkeeping. |
| struct ObjectGroupConnection { |
| ObjectGroupConnection(UniqueId id, Object** object) |
| : id(id), object(object) {} |
| |
| bool operator==(const ObjectGroupConnection& other) const { |
| return id == other.id; |
| } |
| |
| bool operator<(const ObjectGroupConnection& other) const { |
| return id < other.id; |
| } |
| |
| UniqueId id; |
| Object** object; |
| }; |
| |
| |
| struct ObjectGroupRetainerInfo { |
| ObjectGroupRetainerInfo(UniqueId id, RetainedObjectInfo* info) |
| : id(id), info(info) {} |
| |
| bool operator==(const ObjectGroupRetainerInfo& other) const { |
| return id == other.id; |
| } |
| |
| bool operator<(const ObjectGroupRetainerInfo& other) const { |
| return id < other.id; |
| } |
| |
| UniqueId id; |
| RetainedObjectInfo* info; |
| }; |
| |
| |
| class GlobalHandles { |
| public: |
| ~GlobalHandles(); |
| |
| // Creates a new global handle that is alive until Destroy is called. |
| Handle<Object> Create(Object* value); |
| |
| // Destroy a global handle. |
| static void Destroy(Object** location); |
| |
| typedef WeakReferenceCallbacks<v8::Value, void>::Revivable RevivableCallback; |
| |
| // 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, |
| RevivableCallback weak_reference_callback); |
| |
| void RecordStats(HeapStats* stats); |
| |
| // Returns the current number of weak handles. |
| int NumberOfWeakHandles(); |
| |
| // Returns the current number of weak handles to global objects. |
| // These handles are also included in NumberOfWeakHandles(). |
| int NumberOfGlobalObjectWeakHandles(); |
| |
| // Returns the current number of handles to global objects. |
| int global_handles_count() const { |
| return number_of_global_handles_; |
| } |
| |
| // Clear the weakness of a global handle. |
| static void ClearWeakness(Object** location); |
| |
| // Clear the weakness of a global handle. |
| static void MarkIndependent(Object** location); |
| |
| // Mark the reference to this object externaly unreachable. |
| static void MarkPartiallyDependent(Object** location); |
| |
| static bool IsIndependent(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. |
| // Returns true if next major GC is likely to collect more garbage. |
| bool PostGarbageCollectionProcessing(GarbageCollector collector, |
| GCTracer* tracer); |
| |
| // Iterates over all strong handles. |
| void IterateStrongRoots(ObjectVisitor* v); |
| |
| // Iterates over all handles. |
| void IterateAllRoots(ObjectVisitor* v); |
| |
| // Iterates over all handles that have embedder-assigned class ID. |
| void IterateAllRootsWithClassIds(ObjectVisitor* v); |
| |
| // Iterates over all handles in the new space that have embedder-assigned |
| // class ID. |
| void IterateAllRootsInNewSpaceWithClassIds(ObjectVisitor* v); |
| |
| // Iterates over all weak roots in heap. |
| void IterateWeakRoots(ObjectVisitor* v); |
| |
| // Find all weak handles satisfying the callback predicate, mark |
| // them as pending. |
| void IdentifyWeakHandles(WeakSlotCallback f); |
| |
| // NOTE: Three ...NewSpace... functions below are used during |
| // scavenge collections and iterate over sets of handles that are |
| // guaranteed to contain all handles holding new space objects (but |
| // may also include old space objects). |
| |
| // Iterates over strong and dependent handles. See the node above. |
| void IterateNewSpaceStrongAndDependentRoots(ObjectVisitor* v); |
| |
| // Finds weak independent or partially independent handles satisfying |
| // the callback predicate and marks them as pending. See the note above. |
| void IdentifyNewSpaceWeakIndependentHandles(WeakSlotCallbackWithHeap f); |
| |
| // Iterates over weak independent or partially independent handles. |
| // See the note above. |
| void IterateNewSpaceWeakIndependentRoots(ObjectVisitor* v); |
| |
| // Iterate over objects in object groups that have at least one object |
| // which requires visiting. The callback has to return true if objects |
| // can be skipped and false otherwise. |
| bool IterateObjectGroups(ObjectVisitor* v, WeakSlotCallbackWithHeap can_skip); |
| |
| // Add an object group. |
| // Should be only used in GC callback function before a collection. |
| // All groups are destroyed after a garbage collection. |
| void AddObjectGroup(Object*** handles, |
| size_t length, |
| v8::RetainedObjectInfo* info); |
| |
| // Associates handle with the object group represented by id. |
| // Should be only used in GC callback function before a collection. |
| // All groups are destroyed after a garbage collection. |
| void SetObjectGroupId(Object** handle, UniqueId id); |
| |
| // Set RetainedObjectInfo for an object group. Should not be called more than |
| // once for a group. Should not be called for a group which contains no |
| // handles. |
| void SetRetainedObjectInfo(UniqueId id, RetainedObjectInfo* info); |
| |
| // Add an implicit references' group. |
| // Should be only used in GC callback function before a collection. |
| // All groups are destroyed after a mark-compact collection. |
| void AddImplicitReferences(HeapObject** parent, |
| Object*** children, |
| size_t length); |
| |
| // Adds an implicit reference from a group to an object. Should be only used |
| // in GC callback function before a collection. All implicit references are |
| // destroyed after a mark-compact collection. |
| void SetReferenceFromGroup(UniqueId id, Object** child); |
| |
| // Adds an implicit reference from a parent object to a child object. Should |
| // be only used in GC callback function before a collection. All implicit |
| // references are destroyed after a mark-compact collection. |
| void SetReference(HeapObject** parent, Object** child); |
| |
| List<ObjectGroup*>* object_groups() { |
| ComputeObjectGroupsAndImplicitReferences(); |
| return &object_groups_; |
| } |
| |
| List<ImplicitRefGroup*>* implicit_ref_groups() { |
| ComputeObjectGroupsAndImplicitReferences(); |
| return &implicit_ref_groups_; |
| } |
| |
| // Remove bags, this should only happen after GC. |
| void RemoveObjectGroups(); |
| void RemoveImplicitRefGroups(); |
| |
| // Tear down the global handle structure. |
| void TearDown(); |
| |
| Isolate* isolate() { return isolate_; } |
| |
| #ifdef DEBUG |
| void PrintStats(); |
| void Print(); |
| #endif |
| |
| private: |
| explicit GlobalHandles(Isolate* isolate); |
| |
| // Migrates data from the internal representation (object_group_connections_, |
| // retainer_infos_ and implicit_ref_connections_) to the public and more |
| // efficient representation (object_groups_ and implicit_ref_groups_). |
| void ComputeObjectGroupsAndImplicitReferences(); |
| |
| // v8::internal::List is inefficient even for small number of elements, if we |
| // don't assign any initial capacity. |
| static const int kObjectGroupConnectionsCapacity = 20; |
| |
| // Internal node structures. |
| class Node; |
| class NodeBlock; |
| class NodeIterator; |
| |
| Isolate* isolate_; |
| |
| // Field always containing the number of handles to global objects. |
| int number_of_global_handles_; |
| |
| // List of all allocated node blocks. |
| NodeBlock* first_block_; |
| |
| // List of node blocks with used nodes. |
| NodeBlock* first_used_block_; |
| |
| // Free list of nodes. |
| Node* first_free_; |
| |
| // Contains all nodes holding new space objects. Note: when the list |
| // is accessed, some of the objects may have been promoted already. |
| List<Node*> new_space_nodes_; |
| |
| int post_gc_processing_count_; |
| |
| // Object groups and implicit references, public and more efficient |
| // representation. |
| List<ObjectGroup*> object_groups_; |
| List<ImplicitRefGroup*> implicit_ref_groups_; |
| |
| // Object groups and implicit references, temporary representation while |
| // constructing the groups. |
| List<ObjectGroupConnection> object_group_connections_; |
| List<ObjectGroupRetainerInfo> retainer_infos_; |
| List<ObjectGroupConnection> implicit_ref_connections_; |
| |
| friend class Isolate; |
| |
| DISALLOW_COPY_AND_ASSIGN(GlobalHandles); |
| }; |
| |
| |
| } } // namespace v8::internal |
| |
| #endif // V8_GLOBAL_HANDLES_H_ |