duke@435: /* xdono@1383: * Copyright 1997-2009 Sun Microsystems, Inc. All Rights Reserved. duke@435: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. duke@435: * duke@435: * This code is free software; you can redistribute it and/or modify it duke@435: * under the terms of the GNU General Public License version 2 only, as duke@435: * published by the Free Software Foundation. duke@435: * duke@435: * This code is distributed in the hope that it will be useful, but WITHOUT duke@435: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or duke@435: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License duke@435: * version 2 for more details (a copy is included in the LICENSE file that duke@435: * accompanied this code). duke@435: * duke@435: * You should have received a copy of the GNU General Public License version duke@435: * 2 along with this work; if not, write to the Free Software Foundation, duke@435: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. duke@435: * duke@435: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, duke@435: * CA 95054 USA or visit www.sun.com if you need additional information or duke@435: * have any questions. duke@435: * duke@435: */ duke@435: duke@435: class ReferenceProcessor; ysr@1376: class DataLayout; duke@435: duke@435: // MarkSweep takes care of global mark-compact garbage collection for a duke@435: // GenCollectedHeap using a four-phase pointer forwarding algorithm. All duke@435: // generations are assumed to support marking; those that can also support duke@435: // compaction. duke@435: // duke@435: // Class unloading will only occur when a full gc is invoked. duke@435: duke@435: // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will duke@435: // be operational, and will provide slow but comprehensive self-checks within duke@435: // the GC. This is not enabled by default in product or release builds, duke@435: // since the extra call to track_adjusted_pointer() in _adjust_pointer() duke@435: // would be too much overhead, and would disturb performance measurement. duke@435: // However, debug builds are sometimes way too slow to run GC tests! duke@435: #ifdef ASSERT duke@435: #define VALIDATE_MARK_SWEEP 1 duke@435: #endif duke@435: #ifdef VALIDATE_MARK_SWEEP duke@435: #define VALIDATE_MARK_SWEEP_ONLY(code) code duke@435: #else duke@435: #define VALIDATE_MARK_SWEEP_ONLY(code) duke@435: #endif duke@435: duke@435: // declared at end duke@435: class PreservedMark; duke@435: duke@435: class MarkSweep : AllStatic { duke@435: // coleenp@548: // Inline closure decls duke@435: // coleenp@548: class FollowRootClosure: public OopsInGenClosure { duke@435: public: coleenp@548: virtual void do_oop(oop* p); coleenp@548: virtual void do_oop(narrowOop* p); duke@435: virtual const bool do_nmethods() const { return true; } duke@435: }; duke@435: duke@435: class MarkAndPushClosure: public OopClosure { duke@435: public: coleenp@548: virtual void do_oop(oop* p); coleenp@548: virtual void do_oop(narrowOop* p); duke@435: virtual const bool do_nmethods() const { return true; } ysr@1376: virtual const bool should_remember_mdo() const { return true; } ysr@1376: virtual void remember_mdo(DataLayout* p) { MarkSweep::revisit_mdo(p); } duke@435: }; duke@435: duke@435: class FollowStackClosure: public VoidClosure { duke@435: public: coleenp@548: virtual void do_void(); duke@435: }; duke@435: duke@435: class AdjustPointerClosure: public OopsInGenClosure { coleenp@548: private: duke@435: bool _is_root; duke@435: public: duke@435: AdjustPointerClosure(bool is_root) : _is_root(is_root) {} coleenp@548: virtual void do_oop(oop* p); coleenp@548: virtual void do_oop(narrowOop* p); duke@435: }; duke@435: duke@435: // Used for java/lang/ref handling duke@435: class IsAliveClosure: public BoolObjectClosure { duke@435: public: coleenp@548: virtual void do_object(oop p); coleenp@548: virtual bool do_object_b(oop p); duke@435: }; duke@435: duke@435: class KeepAliveClosure: public OopClosure { coleenp@548: protected: coleenp@548: template void do_oop_work(T* p); duke@435: public: coleenp@548: virtual void do_oop(oop* p); coleenp@548: virtual void do_oop(narrowOop* p); duke@435: }; duke@435: duke@435: // duke@435: // Friend decls duke@435: // duke@435: friend class AdjustPointerClosure; duke@435: friend class KeepAliveClosure; duke@435: friend class VM_MarkSweep; duke@435: friend void marksweep_init(); ysr@1376: friend class DataLayout; duke@435: duke@435: // duke@435: // Vars duke@435: // duke@435: protected: duke@435: // Traversal stack used during phase1 duke@435: static GrowableArray* _marking_stack; duke@435: // Stack for live klasses to revisit at end of marking phase duke@435: static GrowableArray* _revisit_klass_stack; ysr@1376: // Set (stack) of MDO's to revisit at end of marking phase ysr@1376: static GrowableArray* _revisit_mdo_stack; duke@435: duke@435: // Space for storing/restoring mark word duke@435: static GrowableArray* _preserved_mark_stack; duke@435: static GrowableArray* _preserved_oop_stack; duke@435: static size_t _preserved_count; duke@435: static size_t _preserved_count_max; duke@435: static PreservedMark* _preserved_marks; duke@435: duke@435: // Reference processing (used in ...follow_contents) duke@435: static ReferenceProcessor* _ref_processor; duke@435: duke@435: #ifdef VALIDATE_MARK_SWEEP coleenp@548: static GrowableArray* _root_refs_stack; duke@435: static GrowableArray * _live_oops; duke@435: static GrowableArray * _live_oops_moved_to; duke@435: static GrowableArray* _live_oops_size; duke@435: static size_t _live_oops_index; duke@435: static size_t _live_oops_index_at_perm; coleenp@548: static GrowableArray* _other_refs_stack; coleenp@548: static GrowableArray* _adjusted_pointers; duke@435: static bool _pointer_tracking; duke@435: static bool _root_tracking; duke@435: duke@435: // The following arrays are saved since the time of the last GC and duke@435: // assist in tracking down problems where someone has done an errant duke@435: // store into the heap, usually to an oop that wasn't properly duke@435: // handleized across a GC. If we crash or otherwise fail before the duke@435: // next GC, we can query these arrays to find out the object we had duke@435: // intended to do the store to (assuming it is still alive) and the duke@435: // offset within that object. Covered under RecordMarkSweepCompaction. duke@435: static GrowableArray * _cur_gc_live_oops; duke@435: static GrowableArray * _cur_gc_live_oops_moved_to; duke@435: static GrowableArray* _cur_gc_live_oops_size; duke@435: static GrowableArray * _last_gc_live_oops; duke@435: static GrowableArray * _last_gc_live_oops_moved_to; duke@435: static GrowableArray* _last_gc_live_oops_size; duke@435: #endif duke@435: duke@435: // Non public closures coleenp@548: static IsAliveClosure is_alive; duke@435: static KeepAliveClosure keep_alive; duke@435: duke@435: // Class unloading. Update subklass/sibling/implementor links at end of marking phase. duke@435: static void follow_weak_klass_links(); duke@435: ysr@1376: // Class unloading. Clear weak refs in MDO's (ProfileData) ysr@1376: // at the end of the marking phase. ysr@1376: static void follow_mdo_weak_refs(); ysr@1376: duke@435: // Debugging duke@435: static void trace(const char* msg) PRODUCT_RETURN; duke@435: duke@435: public: duke@435: // Public closures coleenp@548: static FollowRootClosure follow_root_closure; coleenp@548: static MarkAndPushClosure mark_and_push_closure; coleenp@548: static FollowStackClosure follow_stack_closure; duke@435: static AdjustPointerClosure adjust_root_pointer_closure; duke@435: static AdjustPointerClosure adjust_pointer_closure; duke@435: duke@435: // Reference Processing duke@435: static ReferenceProcessor* const ref_processor() { return _ref_processor; } duke@435: duke@435: // Call backs for marking duke@435: static void mark_object(oop obj); coleenp@548: // Mark pointer and follow contents. Empty marking stack afterwards. coleenp@548: template static inline void follow_root(T* p); coleenp@548: // Mark pointer and follow contents. coleenp@548: template static inline void mark_and_follow(T* p); coleenp@548: // Check mark and maybe push on marking stack coleenp@548: template static inline void mark_and_push(T* p); duke@435: coleenp@548: static void follow_stack(); // Empty marking stack. duke@435: coleenp@548: static void preserve_mark(oop p, markOop mark); coleenp@548: // Save the mark word so it can be restored later coleenp@548: static void adjust_marks(); // Adjust the pointers in the preserved marks table coleenp@548: static void restore_marks(); // Restore the marks that we saved in preserve_mark duke@435: coleenp@548: template static inline void adjust_pointer(T* p, bool isroot); duke@435: coleenp@548: static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); } coleenp@548: static void adjust_pointer(oop* p) { adjust_pointer(p, false); } coleenp@548: static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); } duke@435: duke@435: #ifdef VALIDATE_MARK_SWEEP coleenp@548: static void track_adjusted_pointer(void* p, bool isroot); coleenp@548: static void check_adjust_pointer(void* p); duke@435: static void track_interior_pointers(oop obj); duke@435: static void check_interior_pointers(); duke@435: duke@435: static void reset_live_oop_tracking(bool at_perm); duke@435: static void register_live_oop(oop p, size_t size); duke@435: static void validate_live_oop(oop p, size_t size); duke@435: static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top); duke@435: static void compaction_complete(); duke@435: duke@435: // Querying operation of RecordMarkSweepCompaction results. duke@435: // Finds and prints the current base oop and offset for a word duke@435: // within an oop that was live during the last GC. Helpful for duke@435: // tracking down heap stomps. duke@435: static void print_new_location_of_heap_address(HeapWord* q); duke@435: #endif duke@435: duke@435: // Call backs for class unloading ysr@1376: // Update subklass/sibling/implementor links at end of marking. ysr@1376: static void revisit_weak_klass_link(Klass* k); ysr@1376: // For weak refs clearing in MDO's ysr@1376: static void revisit_mdo(DataLayout* p); duke@435: }; duke@435: duke@435: class PreservedMark VALUE_OBJ_CLASS_SPEC { duke@435: private: duke@435: oop _obj; duke@435: markOop _mark; duke@435: duke@435: public: duke@435: void init(oop obj, markOop mark) { duke@435: _obj = obj; duke@435: _mark = mark; duke@435: } duke@435: duke@435: void adjust_pointer() { duke@435: MarkSweep::adjust_pointer(&_obj); duke@435: } duke@435: duke@435: void restore() { duke@435: _obj->set_mark(_mark); duke@435: } duke@435: };