309 lines
9.7 KiB
C++
309 lines
9.7 KiB
C++
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/*
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* Copyright 2001-2007 Sun Microsystems, Inc. All Rights Reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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* CA 95054 USA or visit www.sun.com if you need additional information or
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* have any questions.
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*
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*/
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// Sparse remembered set for a heap region (the "owning" region). Maps
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// indices of other regions to short sequences of cards in the other region
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// that might contain pointers into the owner region.
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// These tables only expand while they are accessed in parallel --
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// deletions may be done in single-threaded code. This allows us to allow
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// unsynchronized reads/iterations, as long as expansions caused by
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// insertions only enqueue old versions for deletions, but do not delete
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// old versions synchronously.
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class SparsePRTEntry {
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public:
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enum SomePublicConstants {
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CardsPerEntry = (short)4,
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NullEntry = (short)-1,
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DeletedEntry = (short)-2
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};
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private:
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short _region_ind;
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short _next_index;
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short _cards[CardsPerEntry];
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public:
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// Set the region_ind to the given value, and delete all cards.
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inline void init(short region_ind);
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short r_ind() const { return _region_ind; }
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bool valid_entry() const { return r_ind() >= 0; }
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void set_r_ind(short rind) { _region_ind = rind; }
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short next_index() const { return _next_index; }
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short* next_index_addr() { return &_next_index; }
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void set_next_index(short ni) { _next_index = ni; }
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// Returns "true" iff the entry contains the given card index.
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inline bool contains_card(short card_index) const;
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// Returns the number of non-NULL card entries.
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inline int num_valid_cards() const;
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// Requires that the entry not contain the given card index. If there is
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// space available, add the given card index to the entry and return
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// "true"; otherwise, return "false" to indicate that the entry is full.
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enum AddCardResult {
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overflow,
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found,
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added
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};
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inline AddCardResult add_card(short card_index);
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// Copy the current entry's cards into "cards".
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inline void copy_cards(short* cards) const;
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// Copy the current entry's cards into the "_card" array of "e."
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inline void copy_cards(SparsePRTEntry* e) const;
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inline short card(int i) const { return _cards[i]; }
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};
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class RSHashTable : public CHeapObj {
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friend class RSHashTableIter;
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enum SomePrivateConstants {
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NullEntry = -1
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};
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size_t _capacity;
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size_t _capacity_mask;
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size_t _occupied_entries;
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size_t _occupied_cards;
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SparsePRTEntry* _entries;
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short* _buckets;
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short _free_region;
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short _free_list;
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static RSHashTable* _head_deleted_list;
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RSHashTable* _next_deleted;
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RSHashTable* next_deleted() { return _next_deleted; }
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void set_next_deleted(RSHashTable* rsht) { _next_deleted = rsht; }
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bool _deleted;
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void set_deleted(bool b) { _deleted = b; }
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// Requires that the caller hold a lock preventing parallel modifying
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// operations, and that the the table be less than completely full. If
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// an entry for "region_ind" is already in the table, finds it and
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// returns its address; otherwise returns "NULL."
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SparsePRTEntry* entry_for_region_ind(short region_ind) const;
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// Requires that the caller hold a lock preventing parallel modifying
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// operations, and that the the table be less than completely full. If
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// an entry for "region_ind" is already in the table, finds it and
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// returns its address; otherwise allocates, initializes, inserts and
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// returns a new entry for "region_ind".
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SparsePRTEntry* entry_for_region_ind_create(short region_ind);
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// Returns the index of the next free entry in "_entries".
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short alloc_entry();
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// Declares the entry "fi" to be free. (It must have already been
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// deleted from any bucket lists.
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void free_entry(short fi);
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public:
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RSHashTable(size_t capacity);
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~RSHashTable();
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// Attempts to ensure that the given card_index in the given region is in
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// the sparse table. If successful (because the card was already
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// present, or because it was successfullly added) returns "true".
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// Otherwise, returns "false" to indicate that the addition would
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// overflow the entry for the region. The caller must transfer these
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// entries to a larger-capacity representation.
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bool add_card(short region_id, short card_index);
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bool get_cards(short region_id, short* cards);
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bool delete_entry(short region_id);
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bool contains_card(short region_id, short card_index) const;
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void add_entry(SparsePRTEntry* e);
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void clear();
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size_t capacity() const { return _capacity; }
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size_t capacity_mask() const { return _capacity_mask; }
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size_t occupied_entries() const { return _occupied_entries; }
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size_t occupied_cards() const { return _occupied_cards; }
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size_t mem_size() const;
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bool deleted() { return _deleted; }
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SparsePRTEntry* entry(int i) const { return &_entries[i]; }
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void print();
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static void add_to_deleted_list(RSHashTable* rsht);
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static RSHashTable* get_from_deleted_list();
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};
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// ValueObj because will be embedded in HRRS iterator.
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class RSHashTableIter: public CHeapObj {
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short _tbl_ind;
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short _bl_ind;
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short _card_ind;
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RSHashTable* _rsht;
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size_t _heap_bot_card_ind;
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enum SomePrivateConstants {
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CardsPerRegion = HeapRegion::GrainBytes >> CardTableModRefBS::card_shift
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};
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// If the bucket list pointed to by _bl_ind contains a card, sets
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// _bl_ind to the index of that entry, and returns the card.
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// Otherwise, returns SparseEntry::NullEnty.
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short find_first_card_in_list();
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// Computes the proper card index for the card whose offset in the
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// current region (as indicated by _bl_ind) is "ci".
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// This is subject to errors when there is iteration concurrent with
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// modification, but these errors should be benign.
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size_t compute_card_ind(short ci);
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public:
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RSHashTableIter(size_t heap_bot_card_ind) :
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_tbl_ind(RSHashTable::NullEntry),
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_bl_ind(RSHashTable::NullEntry),
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_card_ind((SparsePRTEntry::CardsPerEntry-1)),
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_rsht(NULL),
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_heap_bot_card_ind(heap_bot_card_ind)
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{}
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void init(RSHashTable* rsht) {
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_rsht = rsht;
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_tbl_ind = -1; // So that first increment gets to 0.
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_bl_ind = RSHashTable::NullEntry;
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_card_ind = (SparsePRTEntry::CardsPerEntry-1);
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}
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bool has_next(size_t& card_index);
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};
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// Concurrent accesss to a SparsePRT must be serialized by some external
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// mutex.
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class SparsePRTIter;
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class SparsePRT : public CHeapObj {
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// Iterations are done on the _cur hash table, since they only need to
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// see entries visible at the start of a collection pause.
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// All other operations are done using the _next hash table.
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RSHashTable* _cur;
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RSHashTable* _next;
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HeapRegion* _hr;
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enum SomeAdditionalPrivateConstants {
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InitialCapacity = 16
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};
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void expand();
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bool _expanded;
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bool expanded() { return _expanded; }
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void set_expanded(bool b) { _expanded = b; }
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SparsePRT* _next_expanded;
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SparsePRT* next_expanded() { return _next_expanded; }
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void set_next_expanded(SparsePRT* nxt) { _next_expanded = nxt; }
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static SparsePRT* _head_expanded_list;
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public:
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SparsePRT(HeapRegion* hr);
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~SparsePRT();
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size_t occupied() const { return _next->occupied_cards(); }
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size_t mem_size() const;
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// Attempts to ensure that the given card_index in the given region is in
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// the sparse table. If successful (because the card was already
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// present, or because it was successfullly added) returns "true".
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// Otherwise, returns "false" to indicate that the addition would
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// overflow the entry for the region. The caller must transfer these
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// entries to a larger-capacity representation.
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bool add_card(short region_id, short card_index);
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// If the table hold an entry for "region_ind", Copies its
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// cards into "cards", which must be an array of length at least
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// "CardsPerEntry", and returns "true"; otherwise, returns "false".
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bool get_cards(short region_ind, short* cards);
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// If there is an entry for "region_ind", removes it and return "true";
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// otherwise returns "false."
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bool delete_entry(short region_ind);
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// Clear the table, and reinitialize to initial capacity.
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void clear();
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// Ensure that "_cur" and "_next" point to the same table.
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void cleanup();
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// Clean up all tables on the expanded list. Called single threaded.
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static void cleanup_all();
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RSHashTable* next() const { return _next; }
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void init_iterator(SparsePRTIter* sprt_iter);
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static void add_to_expanded_list(SparsePRT* sprt);
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static SparsePRT* get_from_expanded_list();
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bool contains_card(short region_id, short card_index) const {
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return _next->contains_card(region_id, card_index);
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}
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#if 0
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void verify_is_cleared();
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void print();
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#endif
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};
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class SparsePRTIter: public /* RSHashTable:: */RSHashTableIter {
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public:
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SparsePRTIter(size_t heap_bot_card_ind) :
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/* RSHashTable:: */RSHashTableIter(heap_bot_card_ind)
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{}
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void init(const SparsePRT* sprt) {
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RSHashTableIter::init(sprt->next());
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}
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bool has_next(size_t& card_index) {
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return RSHashTableIter::has_next(card_index);
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}
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};
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