diff -r 7e2249b1c13d -r eff38cc97183 src/share/classes/com/sun/tools/javac/util/SharedNameTable.java --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/share/classes/com/sun/tools/javac/util/SharedNameTable.java Tue Sep 16 18:35:18 2008 -0700 @@ -0,0 +1,221 @@ +/* + * Copyright 1999-2006 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. Sun designates this + * particular file as subject to the "Classpath" exception as provided + * by Sun in the LICENSE file that accompanied this code. + * + * 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. + */ + +package com.sun.tools.javac.util; + +import java.lang.ref.SoftReference; + +/** + * Implementation of Name.Table that stores all names in a single shared + * byte array, expanding it as needed. This avoids the overhead incurred + * by using an array of bytes for each name. + * + *

This is NOT part of any API supported by Sun Microsystems. If + * you write code that depends on this, you do so at your own risk. + * This code and its internal interfaces are subject to change or + * deletion without notice. + */ +public class SharedNameTable extends Name.Table { + // maintain a freelist of recently used name tables for reuse. + private static List> freelist = List.nil(); + + static public synchronized SharedNameTable create(Names names) { + while (freelist.nonEmpty()) { + SharedNameTable t = freelist.head.get(); + freelist = freelist.tail; + if (t != null) { + return t; + } + } + return new SharedNameTable(names); + } + + static private synchronized void dispose(SharedNameTable t) { + freelist = freelist.prepend(new SoftReference(t)); + } + + /** The hash table for names. + */ + private NameImpl[] hashes; + + /** The shared byte array holding all encountered names. + */ + public byte[] bytes; + + /** The mask to be used for hashing + */ + private int hashMask; + + /** The number of filled bytes in `names'. + */ + private int nc = 0; + + /** Allocator + * @param names The main name table + * @param hashSize the (constant) size to be used for the hash table + * needs to be a power of two. + * @param nameSize the initial size of the name table. + */ + public SharedNameTable(Names names, int hashSize, int nameSize) { + super(names); + hashMask = hashSize - 1; + hashes = new NameImpl[hashSize]; + bytes = new byte[nameSize]; + + } + + public SharedNameTable(Names names) { + this(names, 0x8000, 0x20000); + } + + @Override + public Name fromChars(char[] cs, int start, int len) { + int nc = this.nc; + byte[] bytes = this.bytes; + while (nc + len * 3 >= bytes.length) { + // System.err.println("doubling name buffer of length " + names.length + " to fit " + len + " chars");//DEBUG + byte[] newnames = new byte[bytes.length * 2]; + System.arraycopy(bytes, 0, newnames, 0, bytes.length); + bytes = this.bytes = newnames; + } + int nbytes = Convert.chars2utf(cs, start, bytes, nc, len) - nc; + int h = hashValue(bytes, nc, nbytes) & hashMask; + NameImpl n = hashes[h]; + while (n != null && + (n.getByteLength() != nbytes || + !equals(bytes, n.index, bytes, nc, nbytes))) { + n = n.next; + } + if (n == null) { + n = new NameImpl(this); + n.index = nc; + n.length = nbytes; + n.next = hashes[h]; + hashes[h] = n; + this.nc = nc + nbytes; + if (nbytes == 0) { + this.nc++; + } + } + return n; + } + + @Override + public Name fromUtf(byte[] cs, int start, int len) { + int h = hashValue(cs, start, len) & hashMask; + NameImpl n = hashes[h]; + byte[] names = this.bytes; + while (n != null && + (n.getByteLength() != len || !equals(names, n.index, cs, start, len))) { + n = n.next; + } + if (n == null) { + int nc = this.nc; + while (nc + len > names.length) { + // System.err.println("doubling name buffer of length + " + names.length + " to fit " + len + " bytes");//DEBUG + byte[] newnames = new byte[names.length * 2]; + System.arraycopy(names, 0, newnames, 0, names.length); + names = this.bytes = newnames; + } + System.arraycopy(cs, start, names, nc, len); + n = new NameImpl(this); + n.index = nc; + n.length = len; + n.next = hashes[h]; + hashes[h] = n; + this.nc = nc + len; + if (len == 0) { + this.nc++; + } + } + return n; + } + + @Override + public void dispose() { + dispose(this); + } + + static class NameImpl extends Name { + /** The next name occupying the same hash bucket. + */ + NameImpl next; + + /** The index where the bytes of this name are stored in the global name + * buffer `byte'. + */ + int index; + + /** The number of bytes in this name. + */ + int length; + + NameImpl(SharedNameTable table) { + super(table); + } + + @Override + public int getIndex() { + return index; + } + + @Override + public int getByteLength() { + return length; + } + + @Override + public byte getByteAt(int i) { + return getByteArray()[index + i]; + } + + @Override + public byte[] getByteArray() { + return ((SharedNameTable) table).bytes; + } + + @Override + public int getByteOffset() { + return index; + } + + /** Return the hash value of this name. + */ + public int hashCode() { + return index; + } + + /** Is this name equal to other? + */ + public boolean equals(Object other) { + if (other instanceof Name) + return + table == ((Name)other).table && index == ((Name) other).getIndex(); + else return false; + } + + } + +}