| /* |
| * Copyright 2003-2005 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. |
| * |
| */ |
| |
| // 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); |
| } |
| }; |
| |
| |
| |
| class HashtableEntry : public BasicHashtableEntry { |
| friend class VMStructs; |
| private: |
| oop _literal; // ref to item in table. |
| |
| public: |
| // Literal |
| oop literal() const { return _literal; } |
| oop* literal_addr() { return &_literal; } |
| void set_literal(oop 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(); |
| |
| 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; } |
| int table_size() { return _table_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: |
| 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; |
| }; |
| |
| |
| 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) { } |
| |
| // Invoke "f->do_oop" on the locations of all oops in the table. |
| void oops_do(OopClosure* f); |
| |
| // Debugging |
| void print() PRODUCT_RETURN; |
| |
| // GC support |
| // Delete pointers to otherwise-unreachable objects. |
| void unlink(BoolObjectClosure* cl); |
| |
| // 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: |
| |
| static unsigned int hash_symbol(const char* s, int len); |
| |
| unsigned int compute_hash(symbolHandle name) { |
| return (unsigned int) name->identity_hash(); |
| } |
| |
| int index_for(symbolHandle name) { |
| return hash_to_index(compute_hash(name)); |
| } |
| |
| // Table entry management |
| HashtableEntry* new_entry(unsigned int hashValue, oop obj); |
| |
| // The following method is MT-safe and may be used with caution. |
| HashtableEntry* bucket(int i) { |
| return (HashtableEntry*)BasicHashtable::bucket(i); |
| } |
| |
| // The following method is not MT-safe and must be done under lock. |
| HashtableEntry** bucket_addr(int i) { |
| return (HashtableEntry**)BasicHashtable::bucket_addr(i); |
| } |
| }; |
| |
| |
| // Verions of hashtable where two handles are used to compute the index. |
| |
| class TwoOopHashtable : public Hashtable { |
| friend class VMStructs; |
| protected: |
| TwoOopHashtable(int table_size, int entry_size) |
| : Hashtable(table_size, entry_size) {} |
| |
| TwoOopHashtable(int table_size, int entry_size, HashtableBucket* t, |
| int number_of_entries) |
| : Hashtable(table_size, entry_size, t, number_of_entries) {} |
| |
| public: |
| unsigned int compute_hash(symbolHandle 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(symbolHandle name, Handle loader) { |
| return hash_to_index(compute_hash(name, loader)); |
| } |
| }; |