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src/share/vm/utilities/hashtable.inline.hpp@c96030fff130 (annotated)

src/share/vm/utilities/hashtable.inline.hpp

Thu, 20 Nov 2008 16:56:09 -0800

author

ysr

date

Thu, 20 Nov 2008 16:56:09 -0800

changeset 888

c96030fff130

parent 435

a61af66fc99e

child 1907

c18cbe5936b8

permissions

-rw-r--r--

6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa

duke@435	1	/*
duke@435	2	* Copyright 2003 Sun Microsystems, Inc. All Rights Reserved.
duke@435	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435	4	*
duke@435	5	* This code is free software; you can redistribute it and/or modify it
duke@435	6	* under the terms of the GNU General Public License version 2 only, as
duke@435	7	* published by the Free Software Foundation.
duke@435	8	*
duke@435	9	* This code is distributed in the hope that it will be useful, but WITHOUT
duke@435	10	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435	11	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435	12	* version 2 for more details (a copy is included in the LICENSE file that
duke@435	13	* accompanied this code).
duke@435	14	*
duke@435	15	* You should have received a copy of the GNU General Public License version
duke@435	16	* 2 along with this work; if not, write to the Free Software Foundation,
duke@435	17	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435	18	*
duke@435	19	* Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
duke@435	20	* CA 95054 USA or visit www.sun.com if you need additional information or
duke@435	21	* have any questions.
duke@435	22	*
duke@435	23	*/
duke@435	24
duke@435	25	// Inline function definitions for hashtable.hpp.
duke@435	26
duke@435	27
duke@435	28	// --------------------------------------------------------------------------
duke@435	29	// Hash function
duke@435	30
duke@435	31	// We originally used hashpjw, but hash P(31) gives just as good results
duke@435	32	// and is slighly faster. We would like a hash function that looks at every
duke@435	33	// character, since package names have large common prefixes, and also because
duke@435	34	// hash_or_fail does error checking while iterating.
duke@435	35
duke@435	36	// hash P(31) from Kernighan & Ritchie
duke@435	37
duke@435	38	inline unsigned int Hashtable::hash_symbol(const char* s, int len) {
duke@435	39	unsigned int h = 0;
duke@435	40	while (len-- > 0) {
duke@435	41	h = 31*h + (unsigned) *s;
duke@435	42	s++;
duke@435	43	}
duke@435	44	return h;
duke@435	45	}
duke@435	46
duke@435	47
duke@435	48	// --------------------------------------------------------------------------
duke@435	49
duke@435	50	// Initialize a table.
duke@435	51
duke@435	52	inline BasicHashtable::BasicHashtable(int table_size, int entry_size) {
duke@435	53	// Called on startup, no locking needed
duke@435	54	initialize(table_size, entry_size, 0);
duke@435	55	_buckets = NEW_C_HEAP_ARRAY(HashtableBucket, table_size);
duke@435	56	for (int index = 0; index < _table_size; index++) {
duke@435	57	_buckets[index].clear();
duke@435	58	}
duke@435	59	}
duke@435	60
duke@435	61
duke@435	62	inline BasicHashtable::BasicHashtable(int table_size, int entry_size,
duke@435	63	HashtableBucket* buckets,
duke@435	64	int number_of_entries) {
duke@435	65	// Called on startup, no locking needed
duke@435	66	initialize(table_size, entry_size, number_of_entries);
duke@435	67	_buckets = buckets;
duke@435	68	}
duke@435	69
duke@435	70
duke@435	71	inline void BasicHashtable::initialize(int table_size, int entry_size,
duke@435	72	int number_of_entries) {
duke@435	73	// Called on startup, no locking needed
duke@435	74	_table_size = table_size;
duke@435	75	_entry_size = entry_size;
duke@435	76	_free_list = NULL;
duke@435	77	_first_free_entry = NULL;
duke@435	78	_end_block = NULL;
duke@435	79	_number_of_entries = number_of_entries;
duke@435	80	#ifdef ASSERT
duke@435	81	_lookup_count = 0;
duke@435	82	_lookup_length = 0;
duke@435	83	#endif
duke@435	84	}
duke@435	85
duke@435	86
duke@435	87	// The following method is MT-safe and may be used with caution.
duke@435	88	inline BasicHashtableEntry* BasicHashtable::bucket(int i) {
duke@435	89	return _buckets[i].get_entry();
duke@435	90	}
duke@435	91
duke@435	92
duke@435	93	inline void HashtableBucket::set_entry(BasicHashtableEntry* l) {
duke@435	94	// Warning: Preserve store ordering. The SystemDictionary is read
duke@435	95	// without locks. The new SystemDictionaryEntry must be
duke@435	96	// complete before other threads can be allowed to see it
duke@435	97	// via a store to _buckets[index].
duke@435	98	OrderAccess::release_store_ptr(&_entry, l);
duke@435	99	}
duke@435	100
duke@435	101
duke@435	102	inline BasicHashtableEntry* HashtableBucket::get_entry() const {
duke@435	103	// Warning: Preserve load ordering. The SystemDictionary is read
duke@435	104	// without locks. The new SystemDictionaryEntry must be
duke@435	105	// complete before other threads can be allowed to see it
duke@435	106	// via a store to _buckets[index].
duke@435	107	return (BasicHashtableEntry*) OrderAccess::load_ptr_acquire(&_entry);
duke@435	108	}
duke@435	109
duke@435	110
duke@435	111	inline void BasicHashtable::set_entry(int index, BasicHashtableEntry* entry) {
duke@435	112	_buckets[index].set_entry(entry);
duke@435	113	}
duke@435	114
duke@435	115
duke@435	116	inline void BasicHashtable::add_entry(int index, BasicHashtableEntry* entry) {
duke@435	117	entry->set_next(bucket(index));
duke@435	118	_buckets[index].set_entry(entry);
duke@435	119	++_number_of_entries;
duke@435	120	}
duke@435	121
duke@435	122	inline void BasicHashtable::free_entry(BasicHashtableEntry* entry) {
duke@435	123	entry->set_next(_free_list);
duke@435	124	_free_list = entry;
duke@435	125	--_number_of_entries;
duke@435	126	}