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src/share/classes/com/sun/tools/javac/util/SharedNameTable.java@0e5899f09dab (annotated)

src/share/classes/com/sun/tools/javac/util/SharedNameTable.java

Tue, 25 Sep 2012 13:06:58 -0700

author

jjg

date

Tue, 25 Sep 2012 13:06:58 -0700

changeset 1339

0e5899f09dab

parent 581

f2fdd52e4e87

child 2525

2eb010b6cb22

permissions

-rw-r--r--

7193657: provide internal ArrayUtils class to simplify common usage of arrays in javac
Reviewed-by: mcimadamore, jjg
Contributed-by: vicenterz@yahoo.es

jjg@113	1	/*
jjg@1339	2	* Copyright (c) 1999, 2012, Oracle and/or its affiliates. All rights reserved.
jjg@113	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
jjg@113	4	*
jjg@113	5	* This code is free software; you can redistribute it and/or modify it
jjg@113	6	* under the terms of the GNU General Public License version 2 only, as
ohair@554	7	* published by the Free Software Foundation. Oracle designates this
jjg@113	8	* particular file as subject to the "Classpath" exception as provided
ohair@554	9	* by Oracle in the LICENSE file that accompanied this code.
jjg@113	10	*
jjg@113	11	* This code is distributed in the hope that it will be useful, but WITHOUT
jjg@113	12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
jjg@113	13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
jjg@113	14	* version 2 for more details (a copy is included in the LICENSE file that
jjg@113	15	* accompanied this code).
jjg@113	16	*
jjg@113	17	* You should have received a copy of the GNU General Public License version
jjg@113	18	* 2 along with this work; if not, write to the Free Software Foundation,
jjg@113	19	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
jjg@113	20	*
ohair@554	21	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohair@554	22	* or visit www.oracle.com if you need additional information or have any
ohair@554	23	* questions.
jjg@113	24	*/
jjg@113	25
jjg@113	26	package com.sun.tools.javac.util;
jjg@113	27
jjg@113	28	import java.lang.ref.SoftReference;
jjg@113	29
jjg@113	30	/**
jjg@113	31	* Implementation of Name.Table that stores all names in a single shared
jjg@113	32	* byte array, expanding it as needed. This avoids the overhead incurred
jjg@113	33	* by using an array of bytes for each name.
jjg@113	34	*
jjg@581	35	* <p><b>This is NOT part of any supported API.
jjg@581	36	* If you write code that depends on this, you do so at your own risk.
jjg@113	37	* This code and its internal interfaces are subject to change or
jjg@113	38	* deletion without notice.</b>
jjg@113	39	*/
jjg@113	40	public class SharedNameTable extends Name.Table {
jjg@113	41	// maintain a freelist of recently used name tables for reuse.
jjg@113	42	private static List<SoftReference<SharedNameTable>> freelist = List.nil();
jjg@113	43
jjg@113	44	static public synchronized SharedNameTable create(Names names) {
jjg@113	45	while (freelist.nonEmpty()) {
jjg@113	46	SharedNameTable t = freelist.head.get();
jjg@113	47	freelist = freelist.tail;
jjg@113	48	if (t != null) {
jjg@113	49	return t;
jjg@113	50	}
jjg@113	51	}
jjg@113	52	return new SharedNameTable(names);
jjg@113	53	}
jjg@113	54
jjg@113	55	static private synchronized void dispose(SharedNameTable t) {
jjg@113	56	freelist = freelist.prepend(new SoftReference<SharedNameTable>(t));
jjg@113	57	}
jjg@113	58
jjg@113	59	/** The hash table for names.
jjg@113	60	*/
jjg@113	61	private NameImpl[] hashes;
jjg@113	62
jjg@113	63	/** The shared byte array holding all encountered names.
jjg@113	64	*/
jjg@113	65	public byte[] bytes;
jjg@113	66
jjg@113	67	/** The mask to be used for hashing
jjg@113	68	*/
jjg@113	69	private int hashMask;
jjg@113	70
jjg@113	71	/** The number of filled bytes in `names'.
jjg@113	72	*/
jjg@113	73	private int nc = 0;
jjg@113	74
jjg@113	75	/** Allocator
jjg@113	76	* @param names The main name table
jjg@113	77	* @param hashSize the (constant) size to be used for the hash table
jjg@113	78	* needs to be a power of two.
jjg@113	79	* @param nameSize the initial size of the name table.
jjg@113	80	*/
jjg@113	81	public SharedNameTable(Names names, int hashSize, int nameSize) {
jjg@113	82	super(names);
jjg@113	83	hashMask = hashSize - 1;
jjg@113	84	hashes = new NameImpl[hashSize];
jjg@113	85	bytes = new byte[nameSize];
jjg@113	86
jjg@113	87	}
jjg@113	88
jjg@113	89	public SharedNameTable(Names names) {
jjg@113	90	this(names, 0x8000, 0x20000);
jjg@113	91	}
jjg@113	92
jjg@113	93	@Override
jjg@113	94	public Name fromChars(char[] cs, int start, int len) {
jjg@113	95	int nc = this.nc;
jjg@1339	96	byte[] bytes = this.bytes = ArrayUtils.ensureCapacity(this.bytes, nc + len * 3);
jjg@113	97	int nbytes = Convert.chars2utf(cs, start, bytes, nc, len) - nc;
jjg@113	98	int h = hashValue(bytes, nc, nbytes) & hashMask;
jjg@113	99	NameImpl n = hashes[h];
jjg@113	100	while (n != null &&
jjg@113	101	(n.getByteLength() != nbytes ||
jjg@113	102	!equals(bytes, n.index, bytes, nc, nbytes))) {
jjg@113	103	n = n.next;
jjg@113	104	}
jjg@113	105	if (n == null) {
jjg@113	106	n = new NameImpl(this);
jjg@113	107	n.index = nc;
jjg@113	108	n.length = nbytes;
jjg@113	109	n.next = hashes[h];
jjg@113	110	hashes[h] = n;
jjg@113	111	this.nc = nc + nbytes;
jjg@113	112	if (nbytes == 0) {
jjg@113	113	this.nc++;
jjg@113	114	}
jjg@113	115	}
jjg@113	116	return n;
jjg@113	117	}
jjg@113	118
jjg@113	119	@Override
jjg@113	120	public Name fromUtf(byte[] cs, int start, int len) {
jjg@113	121	int h = hashValue(cs, start, len) & hashMask;
jjg@113	122	NameImpl n = hashes[h];
jjg@113	123	byte[] names = this.bytes;
jjg@113	124	while (n != null &&
jjg@113	125	(n.getByteLength() != len || !equals(names, n.index, cs, start, len))) {
jjg@113	126	n = n.next;
jjg@113	127	}
jjg@113	128	if (n == null) {
jjg@113	129	int nc = this.nc;
jjg@1339	130	names = this.bytes = ArrayUtils.ensureCapacity(names, nc + len);
jjg@113	131	System.arraycopy(cs, start, names, nc, len);
jjg@113	132	n = new NameImpl(this);
jjg@113	133	n.index = nc;
jjg@113	134	n.length = len;
jjg@113	135	n.next = hashes[h];
jjg@113	136	hashes[h] = n;
jjg@113	137	this.nc = nc + len;
jjg@113	138	if (len == 0) {
jjg@113	139	this.nc++;
jjg@113	140	}
jjg@113	141	}
jjg@113	142	return n;
jjg@113	143	}
jjg@113	144
jjg@113	145	@Override
jjg@113	146	public void dispose() {
jjg@113	147	dispose(this);
jjg@113	148	}
jjg@113	149
jjg@113	150	static class NameImpl extends Name {
jjg@113	151	/** The next name occupying the same hash bucket.
jjg@113	152	*/
jjg@113	153	NameImpl next;
jjg@113	154
jjg@113	155	/** The index where the bytes of this name are stored in the global name
jjg@113	156	* buffer `byte'.
jjg@113	157	*/
jjg@113	158	int index;
jjg@113	159
jjg@113	160	/** The number of bytes in this name.
jjg@113	161	*/
jjg@113	162	int length;
jjg@113	163
jjg@113	164	NameImpl(SharedNameTable table) {
jjg@113	165	super(table);
jjg@113	166	}
jjg@113	167
jjg@113	168	@Override
jjg@113	169	public int getIndex() {
jjg@113	170	return index;
jjg@113	171	}
jjg@113	172
jjg@113	173	@Override
jjg@113	174	public int getByteLength() {
jjg@113	175	return length;
jjg@113	176	}
jjg@113	177
jjg@113	178	@Override
jjg@113	179	public byte getByteAt(int i) {
jjg@113	180	return getByteArray()[index + i];
jjg@113	181	}
jjg@113	182
jjg@113	183	@Override
jjg@113	184	public byte[] getByteArray() {
jjg@113	185	return ((SharedNameTable) table).bytes;
jjg@113	186	}
jjg@113	187
jjg@113	188	@Override
jjg@113	189	public int getByteOffset() {
jjg@113	190	return index;
jjg@113	191	}
jjg@113	192
jjg@113	193	/** Return the hash value of this name.
jjg@113	194	*/
jjg@113	195	public int hashCode() {
jjg@113	196	return index;
jjg@113	197	}
jjg@113	198
jjg@113	199	/** Is this name equal to other?
jjg@113	200	*/
jjg@113	201	public boolean equals(Object other) {
jjg@113	202	if (other instanceof Name)
jjg@113	203	return
jjg@113	204	table == ((Name)other).table && index == ((Name) other).getIndex();
jjg@113	205	else return false;
jjg@113	206	}
jjg@113	207
jjg@113	208	}
jjg@113	209
jjg@113	210	}