Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2001-2009 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* next() const { return _next; }

   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->next());

   }

   bool has_next(size_t& card_index) {

     return RSHashTableIter::has_next(card_index);

   }

 };