ysr@777: /*
ysr@777:  * Copyright 2001-2007 Sun Microsystems, Inc.  All Rights Reserved.
ysr@777:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ysr@777:  *
ysr@777:  * This code is free software; you can redistribute it and/or modify it
ysr@777:  * under the terms of the GNU General Public License version 2 only, as
ysr@777:  * published by the Free Software Foundation.
ysr@777:  *
ysr@777:  * This code is distributed in the hope that it will be useful, but WITHOUT
ysr@777:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ysr@777:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ysr@777:  * version 2 for more details (a copy is included in the LICENSE file that
ysr@777:  * accompanied this code).
ysr@777:  *
ysr@777:  * You should have received a copy of the GNU General Public License version
ysr@777:  * 2 along with this work; if not, write to the Free Software Foundation,
ysr@777:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ysr@777:  *
ysr@777:  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
ysr@777:  * CA 95054 USA or visit www.sun.com if you need additional information or
ysr@777:  * have any questions.
ysr@777:  *
ysr@777:  */
ysr@777: 
ysr@777: // Remembered set for a heap region.  Represent a set of "cards" that
ysr@777: // contain pointers into the owner heap region.  Cards are defined somewhat
ysr@777: // abstractly, in terms of what the "BlockOffsetTable" in use can parse.
ysr@777: 
ysr@777: class G1CollectedHeap;
ysr@777: class G1BlockOffsetSharedArray;
ysr@777: class HeapRegion;
ysr@777: class HeapRegionRemSetIterator;
ysr@777: class PosParPRT;
ysr@777: class SparsePRT;
ysr@777: 
ysr@777: 
ysr@777: // The "_coarse_map" is a bitmap with one bit for each region, where set
ysr@777: // bits indicate that the corresponding region may contain some pointer
ysr@777: // into the owning region.
ysr@777: 
ysr@777: // The "_fine_grain_entries" array is an open hash table of PerRegionTables
ysr@777: // (PRTs), indicating regions for which we're keeping the RS as a set of
ysr@777: // cards.  The strategy is to cap the size of the fine-grain table,
ysr@777: // deleting an entry and setting the corresponding coarse-grained bit when
ysr@777: // we would overflow this cap.
ysr@777: 
ysr@777: // We use a mixture of locking and lock-free techniques here.  We allow
ysr@777: // threads to locate PRTs without locking, but threads attempting to alter
ysr@777: // a bucket list obtain a lock.  This means that any failing attempt to
ysr@777: // find a PRT must be retried with the lock.  It might seem dangerous that
ysr@777: // a read can find a PRT that is concurrently deleted.  This is all right,
ysr@777: // because:
ysr@777: //
ysr@777: //   1) We only actually free PRT's at safe points (though we reuse them at
ysr@777: //      other times).
ysr@777: //   2) We find PRT's in an attempt to add entries.  If a PRT is deleted,
ysr@777: //      it's _coarse_map bit is set, so the that we were attempting to add
ysr@777: //      is represented.  If a deleted PRT is re-used, a thread adding a bit,
ysr@777: //      thinking the PRT is for a different region, does no harm.
ysr@777: 
apetrusenko@984: class OtherRegionsTable VALUE_OBJ_CLASS_SPEC {
ysr@777:   friend class HeapRegionRemSetIterator;
ysr@777: 
ysr@777:   G1CollectedHeap* _g1h;
ysr@777:   Mutex            _m;
ysr@777:   HeapRegion*      _hr;
ysr@777: 
ysr@777:   // These are protected by "_m".
ysr@777:   BitMap      _coarse_map;
ysr@777:   size_t      _n_coarse_entries;
ysr@777:   static jint _n_coarsenings;
ysr@777: 
ysr@777:   PosParPRT** _fine_grain_regions;
ysr@777:   size_t      _n_fine_entries;
ysr@777: 
ysr@777: #define SAMPLE_FOR_EVICTION 1
ysr@777: #if SAMPLE_FOR_EVICTION
ysr@777:   size_t        _fine_eviction_start;
ysr@777:   static size_t _fine_eviction_stride;
ysr@777:   static size_t _fine_eviction_sample_size;
ysr@777: #endif
ysr@777: 
ysr@777:   SparsePRT   _sparse_table;
ysr@777: 
ysr@777:   // These are static after init.
ysr@777:   static size_t _max_fine_entries;
ysr@777:   static size_t _mod_max_fine_entries_mask;
ysr@777: 
ysr@777:   // Requires "prt" to be the first element of the bucket list appropriate
ysr@777:   // for "hr".  If this list contains an entry for "hr", return it,
ysr@777:   // otherwise return "NULL".
ysr@777:   PosParPRT* find_region_table(size_t ind, HeapRegion* hr) const;
ysr@777: 
ysr@777:   // Find, delete, and return a candidate PosParPRT, if any exists,
ysr@777:   // adding the deleted region to the coarse bitmap.  Requires the caller
ysr@777:   // to hold _m, and the fine-grain table to be full.
ysr@777:   PosParPRT* delete_region_table();
ysr@777: 
ysr@777:   // If a PRT for "hr" is in the bucket list indicated by "ind" (which must
ysr@777:   // be the correct index for "hr"), delete it and return true; else return
ysr@777:   // false.
ysr@777:   bool del_single_region_table(size_t ind, HeapRegion* hr);
ysr@777: 
ysr@777:   static jint _cache_probes;
ysr@777:   static jint _cache_hits;
ysr@777: 
ysr@777:   // Indexed by thread X heap region, to minimize thread contention.
ysr@777:   static int** _from_card_cache;
ysr@777:   static size_t _from_card_cache_max_regions;
ysr@777:   static size_t _from_card_cache_mem_size;
ysr@777: 
ysr@777: public:
ysr@777:   OtherRegionsTable(HeapRegion* hr);
ysr@777: 
ysr@777:   HeapRegion* hr() const { return _hr; }
ysr@777: 
ysr@777:   // For now.  Could "expand" some tables in the future, so that this made
ysr@777:   // sense.
ysr@777:   void add_reference(oop* from, int tid);
ysr@777: 
ysr@777:   void add_reference(oop* from) {
ysr@777:     return add_reference(from, 0);
ysr@777:   }
ysr@777: 
ysr@777:   // Removes any entries shown by the given bitmaps to contain only dead
ysr@777:   // objects.
ysr@777:   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
ysr@777: 
ysr@777:   // Not const because it takes a lock.
ysr@777:   size_t occupied() const;
ysr@777:   size_t occ_fine() const;
ysr@777:   size_t occ_coarse() const;
ysr@777:   size_t occ_sparse() const;
ysr@777: 
ysr@777:   static jint n_coarsenings() { return _n_coarsenings; }
ysr@777: 
ysr@777:   // Returns size in bytes.
ysr@777:   // Not const because it takes a lock.
ysr@777:   size_t mem_size() const;
ysr@777:   static size_t static_mem_size();
ysr@777:   static size_t fl_mem_size();
ysr@777: 
ysr@777:   bool contains_reference(oop* from) const;
ysr@777:   bool contains_reference_locked(oop* from) const;
ysr@777: 
ysr@777:   void clear();
ysr@777: 
ysr@777:   // Specifically clear the from_card_cache.
ysr@777:   void clear_fcc();
ysr@777: 
ysr@777:   // "from_hr" is being cleared; remove any entries from it.
ysr@777:   void clear_incoming_entry(HeapRegion* from_hr);
ysr@777: 
ysr@777:   // Declare the heap size (in # of regions) to the OtherRegionsTable.
ysr@777:   // (Uses it to initialize from_card_cache).
ysr@777:   static void init_from_card_cache(size_t max_regions);
ysr@777: 
ysr@777:   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
ysr@777:   // Make sure any entries for higher regions are invalid.
ysr@777:   static void shrink_from_card_cache(size_t new_n_regs);
ysr@777: 
ysr@777:   static void print_from_card_cache();
ysr@777: 
ysr@777: };
ysr@777: 
ysr@777: 
ysr@777: class HeapRegionRemSet : public CHeapObj {
ysr@777:   friend class VMStructs;
ysr@777:   friend class HeapRegionRemSetIterator;
ysr@777: 
ysr@777: public:
ysr@777:   enum Event {
ysr@777:     Event_EvacStart, Event_EvacEnd, Event_RSUpdateEnd
ysr@777:   };
ysr@777: 
ysr@777: private:
ysr@777:   G1BlockOffsetSharedArray* _bosa;
ysr@777:   G1BlockOffsetSharedArray* bosa() const { return _bosa; }
ysr@777: 
ysr@777:   static bool _par_traversal;
ysr@777: 
ysr@777:   OtherRegionsTable _other_regions;
ysr@777: 
ysr@777:   // One set bit for every region that has an entry for this one.
ysr@777:   BitMap _outgoing_region_map;
ysr@777: 
ysr@777:   // Clear entries for the current region in any rem sets named in
ysr@777:   // the _outgoing_region_map.
ysr@777:   void clear_outgoing_entries();
ysr@777: 
ysr@777: #if MAYBE
ysr@777:   // Audit the given card index.
ysr@777:   void audit_card(size_t card_num, HeapRegion* hr, u2* rc_arr,
ysr@777:                   HeapRegionRemSet* empty_cards, size_t* one_obj_cards);
ysr@777: 
ysr@777:   // Assumes that "audit_stage1" has been called for "hr", to set up
ysr@777:   // "shadow" and "new_rs" appropriately.  Identifies individual popular
ysr@777:   // objects; returns "true" if any are found.
ysr@777:   bool audit_find_pop(HeapRegion* hr, u2* rc_arr);
ysr@777: 
ysr@777:   // Assumes that "audit_stage1" has been called for "hr", to set up
ysr@777:   // "shadow" and "new_rs" appropriately.  Identifies individual popular
ysr@777:   // objects, and determines the number of entries in "new_rs" if any such
ysr@777:   // popular objects are ignored.  If this is sufficiently small, returns
ysr@777:   // "false" to indicate that a constraint should not be introduced.
ysr@777:   // Otherwise, returns "true" to indicate that we should go ahead with
ysr@777:   // adding the constraint.
ysr@777:   bool audit_stag(HeapRegion* hr, u2* rc_arr);
ysr@777: 
ysr@777: 
ysr@777:   u2* alloc_rc_array();
ysr@777: 
ysr@777:   SeqHeapRegionRemSet* audit_post(u2* rc_arr, size_t multi_obj_crds,
ysr@777:                                   SeqHeapRegionRemSet* empty_cards);
ysr@777: #endif
ysr@777: 
ysr@777:   enum ParIterState { Unclaimed, Claimed, Complete };
ysr@777:   ParIterState _iter_state;
ysr@777: 
ysr@777:   // Unused unless G1RecordHRRSOops is true.
ysr@777: 
ysr@777:   static const int MaxRecorded = 1000000;
ysr@777:   static oop**        _recorded_oops;
ysr@777:   static HeapWord**   _recorded_cards;
ysr@777:   static HeapRegion** _recorded_regions;
ysr@777:   static int          _n_recorded;
ysr@777: 
ysr@777:   static const int MaxRecordedEvents = 1000;
ysr@777:   static Event*       _recorded_events;
ysr@777:   static int*         _recorded_event_index;
ysr@777:   static int          _n_recorded_events;
ysr@777: 
ysr@777:   static void print_event(outputStream* str, Event evnt);
ysr@777: 
ysr@777: public:
ysr@777:   HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
ysr@777:                    HeapRegion* hr);
ysr@777: 
ysr@777:   static int num_par_rem_sets();
ysr@777:   static bool par_traversal() { return _par_traversal; }
ysr@777:   static void set_par_traversal(bool b);
ysr@777: 
ysr@777:   HeapRegion* hr() const {
ysr@777:     return _other_regions.hr();
ysr@777:   }
ysr@777: 
ysr@777:   size_t occupied() const {
ysr@777:     return _other_regions.occupied();
ysr@777:   }
ysr@777:   size_t occ_fine() const {
ysr@777:     return _other_regions.occ_fine();
ysr@777:   }
ysr@777:   size_t occ_coarse() const {
ysr@777:     return _other_regions.occ_coarse();
ysr@777:   }
ysr@777:   size_t occ_sparse() const {
ysr@777:     return _other_regions.occ_sparse();
ysr@777:   }
ysr@777: 
ysr@777:   static jint n_coarsenings() { return OtherRegionsTable::n_coarsenings(); }
ysr@777: 
ysr@777:   /* Used in the sequential case.  Returns "true" iff this addition causes
ysr@777:      the size limit to be reached. */
ysr@777:   bool add_reference(oop* from) {
ysr@777:     _other_regions.add_reference(from);
ysr@777:     return false;
ysr@777:   }
ysr@777: 
ysr@777:   /* Used in the parallel case.  Returns "true" iff this addition causes
ysr@777:      the size limit to be reached. */
ysr@777:   bool add_reference(oop* from, int tid) {
ysr@777:     _other_regions.add_reference(from, tid);
ysr@777:     return false;
ysr@777:   }
ysr@777: 
ysr@777:   // Records the fact that the current region contains an outgoing
ysr@777:   // reference into "to_hr".
ysr@777:   void add_outgoing_reference(HeapRegion* to_hr);
ysr@777: 
ysr@777:   // Removes any entries shown by the given bitmaps to contain only dead
ysr@777:   // objects.
ysr@777:   void scrub(CardTableModRefBS* ctbs, BitMap* region_bm, BitMap* card_bm);
ysr@777: 
ysr@777:   // The region is being reclaimed; clear its remset, and any mention of
ysr@777:   // entries for this region in other remsets.
ysr@777:   void clear();
ysr@777: 
ysr@777:   // Forget any entries due to pointers from "from_hr".
ysr@777:   void clear_incoming_entry(HeapRegion* from_hr) {
ysr@777:     _other_regions.clear_incoming_entry(from_hr);
ysr@777:   }
ysr@777: 
ysr@777: #if 0
ysr@777:   virtual void cleanup() = 0;
ysr@777: #endif
ysr@777: 
ysr@777:   // Should be called from single-threaded code.
ysr@777:   void init_for_par_iteration();
ysr@777:   // Attempt to claim the region.  Returns true iff this call caused an
ysr@777:   // atomic transition from Unclaimed to Claimed.
ysr@777:   bool claim_iter();
ysr@777:   // Sets the iteration state to "complete".
ysr@777:   void set_iter_complete();
ysr@777:   // Returns "true" iff the region's iteration is complete.
ysr@777:   bool iter_is_complete();
ysr@777: 
ysr@777:   // Initialize the given iterator to iterate over this rem set.
ysr@777:   void init_iterator(HeapRegionRemSetIterator* iter) const;
ysr@777: 
ysr@777: #if 0
ysr@777:   // Apply the "do_card" method to the start address of every card in the
ysr@777:   // rem set.  Returns false if some application of the closure aborted.
ysr@777:   virtual bool card_iterate(CardClosure* iter) = 0;
ysr@777: #endif
ysr@777: 
ysr@777:   // The actual # of bytes this hr_remset takes up.
ysr@777:   size_t mem_size() {
ysr@777:     return _other_regions.mem_size()
ysr@777:       // This correction is necessary because the above includes the second
ysr@777:       // part.
ysr@777:       + sizeof(this) - sizeof(OtherRegionsTable);
ysr@777:   }
ysr@777: 
ysr@777:   // Returns the memory occupancy of all static data structures associated
ysr@777:   // with remembered sets.
ysr@777:   static size_t static_mem_size() {
ysr@777:     return OtherRegionsTable::static_mem_size();
ysr@777:   }
ysr@777: 
ysr@777:   // Returns the memory occupancy of all free_list data structures associated
ysr@777:   // with remembered sets.
ysr@777:   static size_t fl_mem_size() {
ysr@777:     return OtherRegionsTable::fl_mem_size();
ysr@777:   }
ysr@777: 
ysr@777:   bool contains_reference(oop* from) const {
ysr@777:     return _other_regions.contains_reference(from);
ysr@777:   }
ysr@777:   void print() const;
ysr@777: 
ysr@777: #if MAYBE
ysr@777:   // We are about to introduce a constraint, requiring the collection time
ysr@777:   // of the region owning this RS to be <= "hr", and forgetting pointers
ysr@777:   // from the owning region to "hr."  Before doing so, examines this rem
ysr@777:   // set for pointers to "hr", possibly identifying some popular objects.,
ysr@777:   // and possibly finding some cards to no longer contain pointers to "hr",
ysr@777:   //
ysr@777:   // These steps may prevent the the constraint from being necessary; in
ysr@777:   // which case returns a set of cards now thought to contain no pointers
ysr@777:   // into HR.  In the normal (I assume) case, returns NULL, indicating that
ysr@777:   // we should go ahead and add the constraint.
ysr@777:   virtual SeqHeapRegionRemSet* audit(HeapRegion* hr) = 0;
ysr@777: #endif
ysr@777: 
ysr@777:   // Called during a stop-world phase to perform any deferred cleanups.
ysr@777:   // The second version may be called by parallel threads after then finish
ysr@777:   // collection work.
ysr@777:   static void cleanup();
ysr@777:   static void par_cleanup();
ysr@777: 
ysr@777:   // Declare the heap size (in # of regions) to the HeapRegionRemSet(s).
ysr@777:   // (Uses it to initialize from_card_cache).
ysr@777:   static void init_heap(size_t max_regions) {
ysr@777:     OtherRegionsTable::init_from_card_cache(max_regions);
ysr@777:   }
ysr@777: 
ysr@777:   // Declares that only regions i s.t. 0 <= i < new_n_regs are in use.
ysr@777:   static void shrink_heap(size_t new_n_regs) {
ysr@777:     OtherRegionsTable::shrink_from_card_cache(new_n_regs);
ysr@777:   }
ysr@777: 
ysr@777: #ifndef PRODUCT
ysr@777:   static void print_from_card_cache() {
ysr@777:     OtherRegionsTable::print_from_card_cache();
ysr@777:   }
ysr@777: #endif
ysr@777: 
ysr@777:   static void record(HeapRegion* hr, oop* f);
ysr@777:   static void print_recorded();
ysr@777:   static void record_event(Event evnt);
ysr@777: 
ysr@777:   // Run unit tests.
ysr@777: #ifndef PRODUCT
ysr@777:   static void test();
ysr@777: #endif
ysr@777: 
ysr@777: };
ysr@777: 
ysr@777: class HeapRegionRemSetIterator : public CHeapObj {
ysr@777: 
ysr@777:   // The region over which we're iterating.
ysr@777:   const HeapRegionRemSet* _hrrs;
ysr@777: 
ysr@777:   // Local caching of HRRS fields.
ysr@777:   const BitMap*             _coarse_map;
ysr@777:   PosParPRT**               _fine_grain_regions;
ysr@777: 
ysr@777:   G1BlockOffsetSharedArray* _bosa;
ysr@777:   G1CollectedHeap*          _g1h;
ysr@777: 
ysr@777:   // The number yielded since initialization.
ysr@777:   size_t _n_yielded_fine;
ysr@777:   size_t _n_yielded_coarse;
ysr@777:   size_t _n_yielded_sparse;
ysr@777: 
ysr@777:   // If true we're iterating over the coarse table; if false the fine
ysr@777:   // table.
ysr@777:   enum IterState {
ysr@777:     Sparse,
ysr@777:     Fine,
ysr@777:     Coarse
ysr@777:   };
ysr@777:   IterState _is;
ysr@777: 
ysr@777:   // In both kinds of iteration, heap offset of first card of current
ysr@777:   // region.
ysr@777:   size_t _cur_region_card_offset;
ysr@777:   // Card offset within cur region.
ysr@777:   size_t _cur_region_cur_card;
ysr@777: 
ysr@777:   // Coarse table iteration fields:
ysr@777: 
ysr@777:   // Current region index;
ysr@777:   int _coarse_cur_region_index;
ysr@777:   int _coarse_cur_region_cur_card;
ysr@777: 
ysr@777:   bool coarse_has_next(size_t& card_index);
ysr@777: 
ysr@777:   // Fine table iteration fields:
ysr@777: 
ysr@777:   // Index of bucket-list we're working on.
ysr@777:   int _fine_array_index;
ysr@777:   // Per Region Table we're doing within current bucket list.
ysr@777:   PosParPRT* _fine_cur_prt;
ysr@777: 
ysr@777:   /* SparsePRT::*/ SparsePRTIter _sparse_iter;
ysr@777: 
ysr@777:   void fine_find_next_non_null_prt();
ysr@777: 
ysr@777:   bool fine_has_next();
ysr@777:   bool fine_has_next(size_t& card_index);
ysr@777: 
ysr@777: public:
ysr@777:   // We require an iterator to be initialized before use, so the
ysr@777:   // constructor does little.
ysr@777:   HeapRegionRemSetIterator();
ysr@777: 
ysr@777:   void initialize(const HeapRegionRemSet* hrrs);
ysr@777: 
ysr@777:   // If there remains one or more cards to be yielded, returns true and
ysr@777:   // sets "card_index" to one of those cards (which is then considered
ysr@777:   // yielded.)   Otherwise, returns false (and leaves "card_index"
ysr@777:   // undefined.)
ysr@777:   bool has_next(size_t& card_index);
ysr@777: 
ysr@777:   size_t n_yielded_fine() { return _n_yielded_fine; }
ysr@777:   size_t n_yielded_coarse() { return _n_yielded_coarse; }
ysr@777:   size_t n_yielded_sparse() { return _n_yielded_sparse; }
ysr@777:   size_t n_yielded() {
ysr@777:     return n_yielded_fine() + n_yielded_coarse() + n_yielded_sparse();
ysr@777:   }
ysr@777: };
ysr@777: 
ysr@777: #if 0
ysr@777: class CardClosure: public Closure {
ysr@777: public:
ysr@777:   virtual void do_card(HeapWord* card_start) = 0;
ysr@777: };
ysr@777: 
ysr@777: #endif