| /* |
| * Copyright (c) 2003, 2017, 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_UTILITIES_HASHTABLE_HPP |
| #define SHARE_VM_UTILITIES_HASHTABLE_HPP |
| |
| #include "classfile/classLoaderData.hpp" |
| #include "memory/allocation.hpp" |
| #include "oops/oop.hpp" |
| #include "oops/symbol.hpp" |
| #include "runtime/handles.hpp" |
| |
| // This is a generic hashtable, designed to be used for the symbol |
| // and string tables. |
| // |
| // It is implemented as an open hash table with a fixed number of buckets. |
| // |
| // %note: |
| // - TableEntrys are allocated in blocks to reduce the space overhead. |
| |
| |
| |
| template <MEMFLAGS F> class BasicHashtableEntry : public CHeapObj<F> { |
| friend class VMStructs; |
| private: |
| unsigned int _hash; // 32-bit hash for item |
| |
| // Link to next element in the linked list for this bucket. EXCEPT |
| // bit 0 set indicates that this entry is shared and must not be |
| // unlinked from the table. Bit 0 is set during the dumping of the |
| // archive. Since shared entries are immutable, _next fields in the |
| // shared entries will not change. New entries will always be |
| // unshared and since pointers are align, bit 0 will always remain 0 |
| // with no extra effort. |
| BasicHashtableEntry<F>* _next; |
| |
| // Windows IA64 compiler requires subclasses to be able to access these |
| protected: |
| // Entry objects should not be created, they should be taken from the |
| // free list with BasicHashtable.new_entry(). |
| BasicHashtableEntry() { ShouldNotReachHere(); } |
| // Entry objects should not be destroyed. They should be placed on |
| // the free list instead with BasicHashtable.free_entry(). |
| ~BasicHashtableEntry() { ShouldNotReachHere(); } |
| |
| public: |
| |
| unsigned int hash() const { return _hash; } |
| void set_hash(unsigned int hash) { _hash = hash; } |
| unsigned int* hash_addr() { return &_hash; } |
| |
| static BasicHashtableEntry<F>* make_ptr(BasicHashtableEntry<F>* p) { |
| return (BasicHashtableEntry*)((intptr_t)p & -2); |
| } |
| |
| BasicHashtableEntry<F>* next() const { |
| return make_ptr(_next); |
| } |
| |
| void set_next(BasicHashtableEntry<F>* next) { |
| _next = next; |
| } |
| |
| BasicHashtableEntry<F>** next_addr() { |
| return &_next; |
| } |
| |
| bool is_shared() const { |
| return ((intptr_t)_next & 1) != 0; |
| } |
| |
| void set_shared() { |
| _next = (BasicHashtableEntry<F>*)((intptr_t)_next | 1); |
| } |
| }; |
| |
| |
| |
| template <class T, MEMFLAGS F> class HashtableEntry : public BasicHashtableEntry<F> { |
| friend class VMStructs; |
| private: |
| T _literal; // ref to item in table. |
| |
| public: |
| // Literal |
| T literal() const { return _literal; } |
| T* literal_addr() { return &_literal; } |
| void set_literal(T s) { _literal = s; } |
| |
| HashtableEntry* next() const { |
| return (HashtableEntry*)BasicHashtableEntry<F>::next(); |
| } |
| HashtableEntry** next_addr() { |
| return (HashtableEntry**)BasicHashtableEntry<F>::next_addr(); |
| } |
| }; |
| |
| |
| |
| template <MEMFLAGS F> class HashtableBucket : public CHeapObj<F> { |
| friend class VMStructs; |
| private: |
| // Instance variable |
| BasicHashtableEntry<F>* _entry; |
| |
| public: |
| // Accessing |
| void clear() { _entry = NULL; } |
| |
| // The following methods use order access methods to avoid race |
| // conditions in multiprocessor systems. |
| BasicHashtableEntry<F>* get_entry() const; |
| void set_entry(BasicHashtableEntry<F>* l); |
| |
| // The following method is not MT-safe and must be done under lock. |
| BasicHashtableEntry<F>** entry_addr() { return &_entry; } |
| |
| }; |
| |
| |
| template <MEMFLAGS F> class BasicHashtable : public CHeapObj<F> { |
| friend class VMStructs; |
| |
| public: |
| BasicHashtable(int table_size, int entry_size); |
| BasicHashtable(int table_size, int entry_size, |
| HashtableBucket<F>* buckets, int number_of_entries); |
| |
| // Sharing support. |
| size_t count_bytes_for_buckets(); |
| size_t count_bytes_for_table(); |
| void copy_buckets(char* top, char* end); |
| void copy_table(char* top, char* end); |
| |
| // Bucket handling |
| int hash_to_index(unsigned int full_hash) const { |
| int h = full_hash % _table_size; |
| assert(h >= 0 && h < _table_size, "Illegal hash value"); |
| return h; |
| } |
| |
| private: |
| // Instance variables |
| int _table_size; |
| HashtableBucket<F>* _buckets; |
| BasicHashtableEntry<F>* volatile _free_list; |
| char* _first_free_entry; |
| char* _end_block; |
| int _entry_size; |
| volatile int _number_of_entries; |
| |
| protected: |
| |
| void initialize(int table_size, int entry_size, int number_of_entries); |
| |
| // Accessor |
| int entry_size() const { return _entry_size; } |
| |
| // The following method is MT-safe and may be used with caution. |
| BasicHashtableEntry<F>* bucket(int i) const; |
| |
| // The following method is not MT-safe and must be done under lock. |
| BasicHashtableEntry<F>** bucket_addr(int i) { return _buckets[i].entry_addr(); } |
| |
| // Attempt to get an entry from the free list |
| BasicHashtableEntry<F>* new_entry_free_list(); |
| |
| // Table entry management |
| BasicHashtableEntry<F>* new_entry(unsigned int hashValue); |
| |
| // Used when moving the entry to another table |
| // Clean up links, but do not add to free_list |
| void unlink_entry(BasicHashtableEntry<F>* entry) { |
| entry->set_next(NULL); |
| --_number_of_entries; |
| } |
| |
| // Move over freelist and free block for allocation |
| void copy_freelist(BasicHashtable* src) { |
| _free_list = src->_free_list; |
| src->_free_list = NULL; |
| _first_free_entry = src->_first_free_entry; |
| src->_first_free_entry = NULL; |
| _end_block = src->_end_block; |
| src->_end_block = NULL; |
| } |
| |
| // Free the buckets in this hashtable |
| void free_buckets(); |
| |
| // Helper data structure containing context for the bucket entry unlink process, |
| // storing the unlinked buckets in a linked list. |
| // Also avoids the need to pass around these four members as parameters everywhere. |
| struct BucketUnlinkContext { |
| int _num_processed; |
| int _num_removed; |
| // Head and tail pointers for the linked list of removed entries. |
| BasicHashtableEntry<F>* _removed_head; |
| BasicHashtableEntry<F>* _removed_tail; |
| |
| BucketUnlinkContext() : _num_processed(0), _num_removed(0), _removed_head(NULL), _removed_tail(NULL) { |
| } |
| |
| void free_entry(BasicHashtableEntry<F>* entry); |
| }; |
| // Add of bucket entries linked together in the given context to the global free list. This method |
| // is mt-safe wrt. to other calls of this method. |
| void bulk_free_entries(BucketUnlinkContext* context); |
| public: |
| int table_size() const { return _table_size; } |
| void set_entry(int index, BasicHashtableEntry<F>* entry); |
| |
| void add_entry(int index, BasicHashtableEntry<F>* entry); |
| |
| void free_entry(BasicHashtableEntry<F>* entry); |
| |
| int number_of_entries() const { return _number_of_entries; } |
| |
| template <class T> void verify_table(const char* table_name) PRODUCT_RETURN; |
| }; |
| |
| |
| template <class T, MEMFLAGS F> class Hashtable : public BasicHashtable<F> { |
| friend class VMStructs; |
| |
| public: |
| Hashtable(int table_size, int entry_size) |
| : BasicHashtable<F>(table_size, entry_size) { } |
| |
| Hashtable(int table_size, int entry_size, |
| HashtableBucket<F>* buckets, int number_of_entries) |
| : BasicHashtable<F>(table_size, entry_size, buckets, number_of_entries) { } |
| |
| // Debugging |
| void print() PRODUCT_RETURN; |
| |
| unsigned int compute_hash(const Symbol* name) const { |
| return (unsigned int) name->identity_hash(); |
| } |
| |
| int index_for(const Symbol* name) const { |
| return this->hash_to_index(compute_hash(name)); |
| } |
| |
| void print_table_statistics(outputStream* st, const char *table_name); |
| |
| protected: |
| |
| // Table entry management |
| HashtableEntry<T, F>* new_entry(unsigned int hashValue, T obj); |
| // Don't create and use freelist of HashtableEntry. |
| HashtableEntry<T, F>* allocate_new_entry(unsigned int hashValue, T obj); |
| |
| // The following method is MT-safe and may be used with caution. |
| HashtableEntry<T, F>* bucket(int i) const { |
| return (HashtableEntry<T, F>*)BasicHashtable<F>::bucket(i); |
| } |
| |
| // The following method is not MT-safe and must be done under lock. |
| HashtableEntry<T, F>** bucket_addr(int i) { |
| return (HashtableEntry<T, F>**)BasicHashtable<F>::bucket_addr(i); |
| } |
| |
| }; |
| |
| template <class T, MEMFLAGS F> class RehashableHashtable : public Hashtable<T, F> { |
| friend class VMStructs; |
| protected: |
| |
| enum { |
| rehash_count = 100, |
| rehash_multiple = 60 |
| }; |
| |
| // Check that the table is unbalanced |
| bool check_rehash_table(int count); |
| |
| public: |
| RehashableHashtable(int table_size, int entry_size) |
| : Hashtable<T, F>(table_size, entry_size) { } |
| |
| RehashableHashtable(int table_size, int entry_size, |
| HashtableBucket<F>* buckets, int number_of_entries) |
| : Hashtable<T, F>(table_size, entry_size, buckets, number_of_entries) { } |
| |
| |
| // Function to move these elements into the new table. |
| void move_to(RehashableHashtable<T, F>* new_table); |
| static bool use_alternate_hashcode(); |
| static juint seed(); |
| |
| private: |
| static juint _seed; |
| }; |
| |
| template <class T, MEMFLAGS F> juint RehashableHashtable<T, F>::_seed = 0; |
| template <class T, MEMFLAGS F> juint RehashableHashtable<T, F>::seed() { return _seed; }; |
| template <class T, MEMFLAGS F> bool RehashableHashtable<T, F>::use_alternate_hashcode() { return _seed != 0; }; |
| |
| #endif // SHARE_VM_UTILITIES_HASHTABLE_HPP |