001: /*
002: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
003: *
004: * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
005: *
006: * The contents of this file are subject to the terms of either the GNU General
007: * Public License Version 2 only ("GPL") or the Common Development and Distribution
008: * License("CDDL") (collectively, the "License"). You may not use this file except in
009: * compliance with the License. You can obtain a copy of the License at
010: * http://www.netbeans.org/cddl-gplv2.html or nbbuild/licenses/CDDL-GPL-2-CP. See the
011: * License for the specific language governing permissions and limitations under the
012: * License. When distributing the software, include this License Header Notice in
013: * each file and include the License file at nbbuild/licenses/CDDL-GPL-2-CP. Sun
014: * designates this particular file as subject to the "Classpath" exception as
015: * provided by Sun in the GPL Version 2 section of the License file that
016: * accompanied this code. If applicable, add the following below the License Header,
017: * with the fields enclosed by brackets [] replaced by your own identifying
018: * information: "Portions Copyrighted [year] [name of copyright owner]"
019: *
020: * Contributor(s):
021: *
022: * The Original Software is NetBeans. The Initial Developer of the Original Software
023: * is Sun Microsystems, Inc. Portions Copyright 1997-2007 Sun Microsystems, Inc. All
024: * Rights Reserved.
025: *
026: * If you wish your version of this file to be governed by only the CDDL or only the
027: * GPL Version 2, indicate your decision by adding "[Contributor] elects to include
028: * this software in this distribution under the [CDDL or GPL Version 2] license." If
029: * you do not indicate a single choice of license, a recipient has the option to
030: * distribute your version of this file under either the CDDL, the GPL Version 2 or
031: * to extend the choice of license to its licensees as provided above. However, if
032: * you add GPL Version 2 code and therefore, elected the GPL Version 2 license, then
033: * the option applies only if the new code is made subject to such option by the
034: * copyright holder.
035: */
036:
037: package org.netbeans.installer.downloader.dispatcher.impl;
038:
039: import static java.lang.Thread.State.NEW;
040: import java.util.Queue;
041: import java.util.LinkedList;
042:
043: /**
044: * @author Danila_Dugurov
045: */
046: public class WorkersPool {
047: /////////////////////////////////////////////////////////////////////////////////
048: // Instance
049: private final int capacity;
050:
051: private int inUse;
052: private Queue<Worker> freeWorkers = new LinkedList<Worker>();
053:
054: public WorkersPool(final int poolCapacity) {
055: this .capacity = poolCapacity;
056: }
057:
058: public int capacity() {
059: return capacity;
060: }
061:
062: public synchronized int remaining() {
063: return capacity - inUse;
064: }
065:
066: //noblocking
067: public synchronized Worker tryAcquire() {
068: if (inUse == capacity) {
069: return null;
070: }
071: inUse++;
072: final Worker worker = freeWorkers.poll();
073: return worker != null && worker.isAlive() ? worker
074: : new Worker();
075: }
076:
077: public synchronized Worker acquire() throws InterruptedException {
078: while (true) {
079: final Worker worker = tryAcquire();
080: if (worker == null) {
081: wait();
082: } else {
083: return worker;
084: }
085: }
086: }
087:
088: public synchronized void release(final Worker worker) {
089: inUse--;
090: if (worker.isAlive()) {
091: freeWorkers.offer(worker);
092: } else if (NEW == worker.getState()) {
093: freeWorkers.offer(worker);
094: }
095: notify();
096: }
097:
098: public synchronized void stopWaitingWorkers() {
099: }
100: }
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