jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/sparsePRT.hpp@0db4adb6e914 (annotated)

src/share/vm/gc_implementation/g1/sparsePRT.hpp@0db4adb6e914 (annotated)

src/share/vm/gc_implementation/g1/sparsePRT.hpp

Sat, 07 Mar 2009 11:07:36 -0500

author: tonyp
date: Sat, 07 Mar 2009 11:07:36 -0500
changeset 1052: 0db4adb6e914
parent 984: fe3d7c11b4b7
child 1063: 7bb995fbd3c0
permissions: -rw-r--r--

6810698: G1: two small bugs in the sparse remembered sets
Summary: The _expanded flag of the sparse RSets is not reset and this can leave a RSet in an inconsistent state if it is expanded more than once. Also, we should be iterating over the _cur, instead of the _next, sparse table
Reviewed-by: apetrusenko, iveresov

 /*
  * Copyright 2001-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 // Sparse remembered set for a heap region (the "owning" region).  Maps
 // indices of other regions to short sequences of cards in the other region
 // that might contain pointers into the owner region.
 // These tables only expand while they are accessed in parallel --
 // deletions may be done in single-threaded code.  This allows us to allow
 // unsynchronized reads/iterations, as long as expansions caused by
 // insertions only enqueue old versions for deletions, but do not delete
 // old versions synchronously.
 class SparsePRTEntry: public CHeapObj {
 public:
   enum SomePublicConstants {
     CardsPerEntry = (short)4,
     NullEntry = (short)-1,
     DeletedEntry = (short)-2
   };
 private:
   short _region_ind;
   short _next_index;
   short _cards[CardsPerEntry];
 public:
   // Set the region_ind to the given value, and delete all cards.
   inline void init(short region_ind);
   short r_ind() const { return _region_ind; }
   bool valid_entry() const { return r_ind() >= 0; }
   void set_r_ind(short rind) { _region_ind = rind; }
   short next_index() const { return _next_index; }
   short* next_index_addr() { return &_next_index; }
   void set_next_index(short ni) { _next_index = ni; }
   // Returns "true" iff the entry contains the given card index.
   inline bool contains_card(short card_index) const;
   // Returns the number of non-NULL card entries.
   inline int num_valid_cards() const;
   // Requires that the entry not contain the given card index.  If there is
   // space available, add the given card index to the entry and return
   // "true"; otherwise, return "false" to indicate that the entry is full.
   enum AddCardResult {
     overflow,
     found,
     added
   };
   inline AddCardResult add_card(short card_index);
   // Copy the current entry's cards into "cards".
   inline void copy_cards(short* cards) const;
   // Copy the current entry's cards into the "_card" array of "e."
   inline void copy_cards(SparsePRTEntry* e) const;
   inline short card(int i) const { return _cards[i]; }
 };
 class RSHashTable : public CHeapObj {
   friend class RSHashTableIter;
   enum SomePrivateConstants {
     NullEntry = -1
   };
   size_t _capacity;
   size_t _capacity_mask;
   size_t _occupied_entries;
   size_t _occupied_cards;
   SparsePRTEntry* _entries;
   short* _buckets;
   short  _free_region;
   short  _free_list;
   static RSHashTable* _head_deleted_list;
   RSHashTable* _next_deleted;
   RSHashTable* next_deleted() { return _next_deleted; }
   void set_next_deleted(RSHashTable* rsht) { _next_deleted = rsht; }
   bool _deleted;
   void set_deleted(bool b) { _deleted = b; }
   // Requires that the caller hold a lock preventing parallel modifying
   // operations, and that the the table be less than completely full.  If
   // an entry for "region_ind" is already in the table, finds it and
   // returns its address; otherwise returns "NULL."
   SparsePRTEntry* entry_for_region_ind(short region_ind) const;
   // Requires that the caller hold a lock preventing parallel modifying
   // operations, and that the the table be less than completely full.  If
   // an entry for "region_ind" is already in the table, finds it and
   // returns its address; otherwise allocates, initializes, inserts and
   // returns a new entry for "region_ind".
   SparsePRTEntry* entry_for_region_ind_create(short region_ind);
   // Returns the index of the next free entry in "_entries".
   short alloc_entry();
   // Declares the entry "fi" to be free.  (It must have already been
   // deleted from any bucket lists.
   void free_entry(short fi);
 public:
   RSHashTable(size_t capacity);
   ~RSHashTable();
   // Attempts to ensure that the given card_index in the given region is in
   // the sparse table.  If successful (because the card was already
   // present, or because it was successfullly added) returns "true".
   // Otherwise, returns "false" to indicate that the addition would
   // overflow the entry for the region.  The caller must transfer these
   // entries to a larger-capacity representation.
   bool add_card(short region_id, short card_index);
   bool get_cards(short region_id, short* cards);
   bool delete_entry(short region_id);
   bool contains_card(short region_id, short card_index) const;
   void add_entry(SparsePRTEntry* e);
   void clear();
   size_t capacity() const      { return _capacity;       }
   size_t capacity_mask() const { return _capacity_mask;  }
   size_t occupied_entries() const { return _occupied_entries; }
   size_t occupied_cards() const   { return _occupied_cards;   }
   size_t mem_size() const;
   bool deleted() { return _deleted; }
   SparsePRTEntry* entry(int i) const { return &_entries[i]; }
   void print();
   static void add_to_deleted_list(RSHashTable* rsht);
   static RSHashTable* get_from_deleted_list();
 };
   // ValueObj because will be embedded in HRRS iterator.
 class RSHashTableIter VALUE_OBJ_CLASS_SPEC {
     short _tbl_ind;
     short _bl_ind;
     short _card_ind;
     RSHashTable* _rsht;
     size_t _heap_bot_card_ind;
     enum SomePrivateConstants {
       CardsPerRegion = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift
     };
     // If the bucket list pointed to by _bl_ind contains a card, sets
     // _bl_ind to the index of that entry, and returns the card.
     // Otherwise, returns SparseEntry::NullEnty.
     short find_first_card_in_list();
     // Computes the proper card index for the card whose offset in the
     // current region (as indicated by _bl_ind) is "ci".
     // This is subject to errors when there is iteration concurrent with
     // modification, but these errors should be benign.
     size_t compute_card_ind(short ci);
   public:
     RSHashTableIter(size_t heap_bot_card_ind) :
       _tbl_ind(RSHashTable::NullEntry),
       _bl_ind(RSHashTable::NullEntry),
       _card_ind((SparsePRTEntry::CardsPerEntry-1)),
       _rsht(NULL),
       _heap_bot_card_ind(heap_bot_card_ind)
     {}
     void init(RSHashTable* rsht) {
       _rsht = rsht;
       _tbl_ind = -1; // So that first increment gets to 0.
       _bl_ind = RSHashTable::NullEntry;
       _card_ind = (SparsePRTEntry::CardsPerEntry-1);
     }
     bool has_next(size_t& card_index);
   };
 // Concurrent accesss to a SparsePRT must be serialized by some external
 // mutex.
 class SparsePRTIter;
 class SparsePRT VALUE_OBJ_CLASS_SPEC {
   //  Iterations are done on the _cur hash table, since they only need to
   //  see entries visible at the start of a collection pause.
   //  All other operations are done using the _next hash table.
   RSHashTable* _cur;
   RSHashTable* _next;
   HeapRegion* _hr;
   enum SomeAdditionalPrivateConstants {
     InitialCapacity = 16
   };
   void expand();
   bool _expanded;
   bool expanded() { return _expanded; }
   void set_expanded(bool b) { _expanded = b; }
   SparsePRT* _next_expanded;
   SparsePRT* next_expanded() { return _next_expanded; }
   void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
   static SparsePRT* _head_expanded_list;
 public:
   SparsePRT(HeapRegion* hr);
   ~SparsePRT();
   size_t occupied() const { return _next->occupied_cards(); }
   size_t mem_size() const;
   // Attempts to ensure that the given card_index in the given region is in
   // the sparse table.  If successful (because the card was already
   // present, or because it was successfullly added) returns "true".
   // Otherwise, returns "false" to indicate that the addition would
   // overflow the entry for the region.  The caller must transfer these
   // entries to a larger-capacity representation.
   bool add_card(short region_id, short card_index);
   // If the table hold an entry for "region_ind",  Copies its
   // cards into "cards", which must be an array of length at least
   // "CardsPerEntry", and returns "true"; otherwise, returns "false".
   bool get_cards(short region_ind, short* cards);
   // If there is an entry for "region_ind", removes it and return "true";
   // otherwise returns "false."
   bool delete_entry(short region_ind);
   // Clear the table, and reinitialize to initial capacity.
   void clear();
   // Ensure that "_cur" and "_next" point to the same table.
   void cleanup();
   // Clean up all tables on the expanded list.  Called single threaded.
   static void cleanup_all();
   RSHashTable* cur() const { return _cur; }
   void init_iterator(SparsePRTIter* sprt_iter);
   static void add_to_expanded_list(SparsePRT* sprt);
   static SparsePRT* get_from_expanded_list();
   bool contains_card(short region_id, short card_index) const {
     return _next->contains_card(region_id, card_index);
   }
 #if 0
   void verify_is_cleared();
   void print();
 #endif
 };
 class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
 public:
   SparsePRTIter(size_t heap_bot_card_ind) :
     /* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
   {}
   void init(const SparsePRT* sprt) {
     RSHashTableIter::init(sprt->cur());
   }
   bool has_next(size_t& card_index) {
     return RSHashTableIter::has_next(card_index);
   }
 };

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src/share/vm/gc_implementation/g1/sparsePRT.hpp@0db4adb6e914 (annotated)

src/share/vm/gc_implementation/g1/sparsePRT.hpp