view src/org/tmatesoft/hg/internal/Pool.java @ 338:3cfa4d908fc9

Add options to control DataAccessProvider, allow to turn off use of file memory mapping in particular to solve potential sharing violation (os file handle gets released on MappedByteByffer being GC'd, not on FileChannel.close())
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Tue, 15 Nov 2011 04:47:03 +0100
parents 6bb5e7ed051a
children 12f668401613
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/*
 * Copyright (c) 2011 TMate Software Ltd
 *  
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program 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 for more details.
 *
 * For information on how to redistribute this software under
 * the terms of a license other than GNU General Public License
 * contact TMate Software at support@hg4j.com
 */
package org.tmatesoft.hg.internal;

import java.util.HashMap;

/**
 * Instance pooling.
 * 
 * @author Artem Tikhomirov
 * @author TMate Software Ltd.
 */
public class Pool<T> {
	private final HashMap<T,T> unify;
	
	public Pool() {
		unify = new HashMap<T, T>();
	}
	
	public Pool(int sizeHint) {
		if (sizeHint <= 0) {
			unify = new HashMap<T, T>();
		} else {
			unify = new HashMap<T, T>(sizeHint * 4 / 3, 0.75f);
		}
	}
	
	public T unify(T t) {
		T rv = unify.get(t);
		if (rv == null) {
			// first time we see a new value
			unify.put(t, t);
			rv = t;
		}
		return rv;
	}
	
	public boolean contains(T t) {
		return unify.containsKey(t);
	}
	
	public void record(T t) {
		unify.put(t, t);
	}
	
	public void clear() {
		unify.clear();
	}

	public int size() {
		return unify.size();
	}

	@Override
	public String toString() {
		StringBuilder sb = new StringBuilder();
		sb.append(Pool.class.getSimpleName());
		sb.append('<');
		if (!unify.isEmpty()) {
			sb.append(unify.keySet().iterator().next().getClass().getName());
		}
		sb.append('>');
		sb.append(':');
		sb.append(unify.size());
		return sb.toString();
	}
}