--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/utilities/hashtable.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,280 @@
+/*
+ * 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));
+ }
+};