| /* |
| * Copyright (c) 2001, 2013, 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_G1_SPARSEPRT_HPP |
| #define SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP |
| |
| #include "gc_implementation/g1/g1CollectedHeap.inline.hpp" |
| #include "gc_implementation/g1/heapRegion.hpp" |
| #include "memory/allocation.hpp" |
| #include "memory/cardTableModRefBS.hpp" |
| #include "runtime/mutex.hpp" |
| #include "utilities/globalDefinitions.hpp" |
| |
| // 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<mtGC> { |
| public: |
| enum SomePublicConstants { |
| NullEntry = -1, |
| UnrollFactor = 4 |
| }; |
| private: |
| RegionIdx_t _region_ind; |
| int _next_index; |
| CardIdx_t _cards[1]; |
| // WARNING: Don't put any data members beyond this line. Card array has, in fact, variable length. |
| // It should always be the last data member. |
| public: |
| // Returns the size of the entry, used for entry allocation. |
| static size_t size() { return sizeof(SparsePRTEntry) + sizeof(CardIdx_t) * (cards_num() - 1); } |
| // Returns the size of the card array. |
| static int cards_num() { |
| // The number of cards should be a multiple of 4, because that's our current |
| // unrolling factor. |
| static const int s = MAX2<int>(G1RSetSparseRegionEntries & ~(UnrollFactor - 1), UnrollFactor); |
| return s; |
| } |
| |
| // Set the region_ind to the given value, and delete all cards. |
| inline void init(RegionIdx_t region_ind); |
| |
| RegionIdx_t r_ind() const { return _region_ind; } |
| bool valid_entry() const { return r_ind() >= 0; } |
| void set_r_ind(RegionIdx_t rind) { _region_ind = rind; } |
| |
| int next_index() const { return _next_index; } |
| int* next_index_addr() { return &_next_index; } |
| void set_next_index(int ni) { _next_index = ni; } |
| |
| // Returns "true" iff the entry contains the given card index. |
| inline bool contains_card(CardIdx_t 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(CardIdx_t card_index); |
| |
| // Copy the current entry's cards into "cards". |
| inline void copy_cards(CardIdx_t* cards) const; |
| // Copy the current entry's cards into the "_card" array of "e." |
| inline void copy_cards(SparsePRTEntry* e) const; |
| |
| inline CardIdx_t card(int i) const { return _cards[i]; } |
| }; |
| |
| |
| class RSHashTable : public CHeapObj<mtGC> { |
| |
| friend class RSHashTableIter; |
| |
| enum SomePrivateConstants { |
| NullEntry = -1 |
| }; |
| |
| size_t _capacity; |
| size_t _capacity_mask; |
| size_t _occupied_entries; |
| size_t _occupied_cards; |
| |
| SparsePRTEntry* _entries; |
| int* _buckets; |
| int _free_region; |
| int _free_list; |
| |
| // 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(RegionIdx_t 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(RegionIdx_t region_ind); |
| |
| // Returns the index of the next free entry in "_entries". |
| int alloc_entry(); |
| // Declares the entry "fi" to be free. (It must have already been |
| // deleted from any bucket lists. |
| void free_entry(int 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 successfully 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(RegionIdx_t region_id, CardIdx_t card_index); |
| |
| bool get_cards(RegionIdx_t region_id, CardIdx_t* cards); |
| |
| bool delete_entry(RegionIdx_t region_id); |
| |
| bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const; |
| |
| void add_entry(SparsePRTEntry* e); |
| |
| SparsePRTEntry* get_entry(RegionIdx_t region_id); |
| |
| 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; |
| |
| SparsePRTEntry* entry(int i) const { return (SparsePRTEntry*)((char*)_entries + SparsePRTEntry::size() * i); } |
| |
| void print(); |
| }; |
| |
| // ValueObj because will be embedded in HRRS iterator. |
| class RSHashTableIter VALUE_OBJ_CLASS_SPEC { |
| int _tbl_ind; // [-1, 0.._rsht->_capacity) |
| int _bl_ind; // [-1, 0.._rsht->_capacity) |
| short _card_ind; // [0..SparsePRTEntry::cards_num()) |
| RSHashTable* _rsht; |
| |
| // 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::NullEntry. |
| CardIdx_t 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(CardIdx_t ci); |
| |
| public: |
| RSHashTableIter(RSHashTable* rsht) : |
| _tbl_ind(RSHashTable::NullEntry), // So that first increment gets to 0. |
| _bl_ind(RSHashTable::NullEntry), |
| _card_ind((SparsePRTEntry::cards_num() - 1)), |
| _rsht(rsht) {} |
| |
| bool has_next(size_t& card_index); |
| }; |
| |
| // Concurrent access to a SparsePRT must be serialized by some external mutex. |
| |
| class SparsePRTIter; |
| class SparsePRTCleanupTask; |
| |
| class SparsePRT VALUE_OBJ_CLASS_SPEC { |
| friend class SparsePRTCleanupTask; |
| |
| // 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; } |
| |
| bool should_be_on_expanded_list(); |
| |
| 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 successfully 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(RegionIdx_t region_id, CardIdx_t 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 |
| // "SparePRTEntry::cards_num()", and returns "true"; otherwise, |
| // returns "false". |
| bool get_cards(RegionIdx_t region_ind, CardIdx_t* cards); |
| |
| // Return the pointer to the entry associated with the given region. |
| SparsePRTEntry* get_entry(RegionIdx_t region_ind); |
| |
| // If there is an entry for "region_ind", removes it and return "true"; |
| // otherwise returns "false." |
| bool delete_entry(RegionIdx_t 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; } |
| |
| static void add_to_expanded_list(SparsePRT* sprt); |
| static SparsePRT* get_from_expanded_list(); |
| |
| // The purpose of these three methods is to help the GC workers |
| // during the cleanup pause to recreate the expanded list, purging |
| // any tables from it that belong to regions that are freed during |
| // cleanup (if we don't purge those tables, there is a race that |
| // causes various crashes; see CR 7014261). |
| // |
| // We chose to recreate the expanded list, instead of purging |
| // entries from it by iterating over it, to avoid this serial phase |
| // at the end of the cleanup pause. |
| // |
| // The three methods below work as follows: |
| // * reset_for_cleanup_tasks() : Nulls the expanded list head at the |
| // start of the cleanup pause. |
| // * do_cleanup_work() : Called by the cleanup workers for every |
| // region that is not free / is being freed by the cleanup |
| // pause. It creates a list of expanded tables whose head / tail |
| // are on the thread-local SparsePRTCleanupTask object. |
| // * finish_cleanup_task() : Called by the cleanup workers after |
| // they complete their cleanup task. It adds the local list into |
| // the global expanded list. It assumes that the |
| // ParGCRareEvent_lock is being held to ensure MT-safety. |
| static void reset_for_cleanup_tasks(); |
| void do_cleanup_work(SparsePRTCleanupTask* sprt_cleanup_task); |
| static void finish_cleanup_task(SparsePRTCleanupTask* sprt_cleanup_task); |
| |
| bool contains_card(RegionIdx_t region_id, CardIdx_t card_index) const { |
| return _next->contains_card(region_id, card_index); |
| } |
| }; |
| |
| class SparsePRTIter: public RSHashTableIter { |
| public: |
| SparsePRTIter(const SparsePRT* sprt) : |
| RSHashTableIter(sprt->cur()) {} |
| |
| bool has_next(size_t& card_index) { |
| return RSHashTableIter::has_next(card_index); |
| } |
| }; |
| |
| // This allows each worker during a cleanup pause to create a |
| // thread-local list of sparse tables that have been expanded and need |
| // to be processed at the beginning of the next GC pause. This lists |
| // are concatenated into the single expanded list at the end of the |
| // cleanup pause. |
| class SparsePRTCleanupTask VALUE_OBJ_CLASS_SPEC { |
| private: |
| SparsePRT* _head; |
| SparsePRT* _tail; |
| |
| public: |
| SparsePRTCleanupTask() : _head(NULL), _tail(NULL) { } |
| |
| void add(SparsePRT* sprt); |
| SparsePRT* head() { return _head; } |
| SparsePRT* tail() { return _tail; } |
| }; |
| |
| #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SPARSEPRT_HPP |