Mercurial > hg > truffle
view src/share/vm/utilities/hashtable.hpp @ 4892:ea677dbdd883
Merge
author | fparain |
---|---|
date | Tue, 07 Feb 2012 12:34:31 -0800 |
parents | b2cd0ee8f778 |
children | e9140bf80b4a |
line wrap: on
line source
/* * Copyright (c) 2003, 2012, 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 "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. class BasicHashtableEntry : public CHeapObj { 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* _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* make_ptr(BasicHashtableEntry* p) { return (BasicHashtableEntry*)((intptr_t)p & -2); } BasicHashtableEntry* next() const { return make_ptr(_next); } void set_next(BasicHashtableEntry* next) { _next = next; } BasicHashtableEntry** next_addr() { return &_next; } bool is_shared() const { return ((intptr_t)_next & 1) != 0; } void set_shared() { _next = (BasicHashtableEntry*)((intptr_t)_next | 1); } }; template <class T> class HashtableEntry : public BasicHashtableEntry { 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::next(); } HashtableEntry** next_addr() { return (HashtableEntry**)BasicHashtableEntry::next_addr(); } }; class HashtableBucket : public CHeapObj { friend class VMStructs; private: // Instance variable BasicHashtableEntry* _entry; public: // Accessing void clear() { _entry = NULL; } // The following methods use order access methods to avoid race // conditions in multiprocessor systems. BasicHashtableEntry* get_entry() const; void set_entry(BasicHashtableEntry* l); // The following method is not MT-safe and must be done under lock. BasicHashtableEntry** entry_addr() { return &_entry; } }; class BasicHashtable : public CHeapObj { friend class VMStructs; public: BasicHashtable(int table_size, int entry_size); BasicHashtable(int table_size, int entry_size, HashtableBucket* buckets, int number_of_entries); // Sharing support. void copy_buckets(char** top, char* end); void copy_table(char** top, char* end); // Bucket handling int hash_to_index(unsigned int full_hash) { int h = full_hash % _table_size; assert(h >= 0 && h < _table_size, "Illegal hash value"); return h; } // Reverse the order of elements in each of the buckets. void reverse(); static unsigned int hash_symbol(const char* s, int len); private: // Instance variables int _table_size; HashtableBucket* _buckets; BasicHashtableEntry* _free_list; char* _first_free_entry; char* _end_block; int _entry_size; int _number_of_entries; protected: #ifdef ASSERT int _lookup_count; int _lookup_length; void verify_lookup_length(double load); #endif 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* bucket(int i); // The following method is not MT-safe and must be done under lock. BasicHashtableEntry** bucket_addr(int i) { return _buckets[i].entry_addr(); } // Table entry management BasicHashtableEntry* new_entry(unsigned int hashValue); public: int table_size() { return _table_size; } void set_entry(int index, BasicHashtableEntry* entry); void add_entry(int index, BasicHashtableEntry* entry); void free_entry(BasicHashtableEntry* entry); int number_of_entries() { return _number_of_entries; } void verify() PRODUCT_RETURN; }; template <class T> class Hashtable : public BasicHashtable { friend class VMStructs; public: Hashtable(int table_size, int entry_size) : BasicHashtable(table_size, entry_size) { } Hashtable(int table_size, int entry_size, HashtableBucket* buckets, int number_of_entries) : BasicHashtable(table_size, entry_size, buckets, number_of_entries) { } // Debugging void print() PRODUCT_RETURN; // Reverse the order of elements in each of the buckets. Hashtable // entries which refer to objects at a lower address than 'boundary' // are separated from those which refer to objects at higher // addresses, and appear first in the list. void reverse(void* boundary = NULL); protected: unsigned int compute_hash(Symbol* name) { return (unsigned int) name->identity_hash(); } int index_for(Symbol* name) { return hash_to_index(compute_hash(name)); } // Table entry management HashtableEntry<T>* new_entry(unsigned int hashValue, T obj); // The following method is MT-safe and may be used with caution. HashtableEntry<T>* bucket(int i) { return (HashtableEntry<T>*)BasicHashtable::bucket(i); } // The following method is not MT-safe and must be done under lock. HashtableEntry<T>** bucket_addr(int i) { return (HashtableEntry<T>**)BasicHashtable::bucket_addr(i); } }; // Verions of hashtable where two handles are used to compute the index. template <class T> class TwoOopHashtable : public Hashtable<T> { friend class VMStructs; protected: TwoOopHashtable(int table_size, int entry_size) : Hashtable<T>(table_size, entry_size) {} TwoOopHashtable(int table_size, int entry_size, HashtableBucket* t, int number_of_entries) : Hashtable<T>(table_size, entry_size, t, number_of_entries) {} public: unsigned int compute_hash(Symbol* name, Handle loader) { // Be careful with identity_hash(), it can safepoint and if this // were one expression, the compiler could choose to unhandle each // oop before calling identity_hash() for either of them. If the first // causes a GC, the next would fail. unsigned int name_hash = name->identity_hash(); unsigned int loader_hash = loader.is_null() ? 0 : loader->identity_hash(); return name_hash ^ loader_hash; } int index_for(Symbol* name, Handle loader) { return this->hash_to_index(compute_hash(name, loader)); } }; #endif // SHARE_VM_UTILITIES_HASHTABLE_HPP