/* * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP #define SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP #include "gc_interface/collectedHeap.hpp" #include "memory/universe.hpp" #include "oops/markOop.hpp" #include "oops/oop.hpp" #include "runtime/timer.hpp" #include "utilities/growableArray.hpp" #include "utilities/stack.hpp" #include "utilities/taskqueue.hpp" class ReferenceProcessor; class DataLayout; // MarkSweep takes care of global mark-compact garbage collection for a // GenCollectedHeap using a four-phase pointer forwarding algorithm. All // generations are assumed to support marking; those that can also support // compaction. // // Class unloading will only occur when a full gc is invoked. // If VALIDATE_MARK_SWEEP is defined, the -XX:+ValidateMarkSweep flag will // be operational, and will provide slow but comprehensive self-checks within // the GC. This is not enabled by default in product or release builds, // since the extra call to track_adjusted_pointer() in _adjust_pointer() // would be too much overhead, and would disturb performance measurement. // However, debug builds are sometimes way too slow to run GC tests! #ifdef ASSERT #define VALIDATE_MARK_SWEEP 1 #endif #ifdef VALIDATE_MARK_SWEEP #define VALIDATE_MARK_SWEEP_ONLY(code) code #else #define VALIDATE_MARK_SWEEP_ONLY(code) #endif // declared at end class PreservedMark; class MarkSweep : AllStatic { // // Inline closure decls // class FollowRootClosure: public OopsInGenClosure { public: virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); }; class MarkAndPushClosure: public OopClosure { public: virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); virtual const bool should_remember_mdo() const { return true; } virtual void remember_mdo(DataLayout* p) { MarkSweep::revisit_mdo(p); } }; class FollowStackClosure: public VoidClosure { public: virtual void do_void(); }; class AdjustPointerClosure: public OopsInGenClosure { private: bool _is_root; public: AdjustPointerClosure(bool is_root) : _is_root(is_root) {} virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); }; // Used for java/lang/ref handling class IsAliveClosure: public BoolObjectClosure { public: virtual void do_object(oop p); virtual bool do_object_b(oop p); }; class KeepAliveClosure: public OopClosure { protected: template void do_oop_work(T* p); public: virtual void do_oop(oop* p); virtual void do_oop(narrowOop* p); }; // // Friend decls // friend class AdjustPointerClosure; friend class KeepAliveClosure; friend class VM_MarkSweep; friend void marksweep_init(); // // Vars // protected: // Traversal stacks used during phase1 static Stack _marking_stack; static Stack _objarray_stack; // Stack for live klasses to revisit at end of marking phase static Stack _revisit_klass_stack; // Set (stack) of MDO's to revisit at end of marking phase static Stack _revisit_mdo_stack; // Space for storing/restoring mark word static Stack _preserved_mark_stack; static Stack _preserved_oop_stack; static size_t _preserved_count; static size_t _preserved_count_max; static PreservedMark* _preserved_marks; // Reference processing (used in ...follow_contents) static ReferenceProcessor* _ref_processor; #ifdef VALIDATE_MARK_SWEEP static GrowableArray* _root_refs_stack; static GrowableArray * _live_oops; static GrowableArray * _live_oops_moved_to; static GrowableArray* _live_oops_size; static size_t _live_oops_index; static size_t _live_oops_index_at_perm; static GrowableArray* _other_refs_stack; static GrowableArray* _adjusted_pointers; static bool _pointer_tracking; static bool _root_tracking; // The following arrays are saved since the time of the last GC and // assist in tracking down problems where someone has done an errant // store into the heap, usually to an oop that wasn't properly // handleized across a GC. If we crash or otherwise fail before the // next GC, we can query these arrays to find out the object we had // intended to do the store to (assuming it is still alive) and the // offset within that object. Covered under RecordMarkSweepCompaction. static GrowableArray * _cur_gc_live_oops; static GrowableArray * _cur_gc_live_oops_moved_to; static GrowableArray* _cur_gc_live_oops_size; static GrowableArray * _last_gc_live_oops; static GrowableArray * _last_gc_live_oops_moved_to; static GrowableArray* _last_gc_live_oops_size; #endif // Non public closures static IsAliveClosure is_alive; static KeepAliveClosure keep_alive; // Class unloading. Update subklass/sibling/implementor links at end of marking phase. static void follow_weak_klass_links(); // Class unloading. Clear weak refs in MDO's (ProfileData) // at the end of the marking phase. static void follow_mdo_weak_refs(); // Debugging static void trace(const char* msg) PRODUCT_RETURN; public: // Public closures static FollowRootClosure follow_root_closure; static CodeBlobToOopClosure follow_code_root_closure; // => follow_root_closure static MarkAndPushClosure mark_and_push_closure; static FollowStackClosure follow_stack_closure; static AdjustPointerClosure adjust_root_pointer_closure; static AdjustPointerClosure adjust_pointer_closure; // Reference Processing static ReferenceProcessor* const ref_processor() { return _ref_processor; } // Call backs for marking static void mark_object(oop obj); // Mark pointer and follow contents. Empty marking stack afterwards. template static inline void follow_root(T* p); // Mark pointer and follow contents. template static inline void mark_and_follow(T* p); // Check mark and maybe push on marking stack template static inline void mark_and_push(T* p); static inline void push_objarray(oop obj, size_t index); static void follow_stack(); // Empty marking stack. static void preserve_mark(oop p, markOop mark); // Save the mark word so it can be restored later static void adjust_marks(); // Adjust the pointers in the preserved marks table static void restore_marks(); // Restore the marks that we saved in preserve_mark template static inline void adjust_pointer(T* p, bool isroot); static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); } static void adjust_pointer(oop* p) { adjust_pointer(p, false); } static void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); } #ifdef VALIDATE_MARK_SWEEP static void track_adjusted_pointer(void* p, bool isroot); static void check_adjust_pointer(void* p); static void track_interior_pointers(oop obj); static void check_interior_pointers(); static void reset_live_oop_tracking(bool at_perm); static void register_live_oop(oop p, size_t size); static void validate_live_oop(oop p, size_t size); static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top); static void compaction_complete(); // Querying operation of RecordMarkSweepCompaction results. // Finds and prints the current base oop and offset for a word // within an oop that was live during the last GC. Helpful for // tracking down heap stomps. static void print_new_location_of_heap_address(HeapWord* q); #endif // Call backs for class unloading // Update subklass/sibling/implementor links at end of marking. static void revisit_weak_klass_link(Klass* k); // For weak refs clearing in MDO's static void revisit_mdo(DataLayout* p); }; class PreservedMark VALUE_OBJ_CLASS_SPEC { private: oop _obj; markOop _mark; public: void init(oop obj, markOop mark) { _obj = obj; _mark = mark; } void adjust_pointer() { MarkSweep::adjust_pointer(&_obj); } void restore() { _obj->set_mark(_mark); } }; #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_MARKSWEEP_HPP