| /* |
| * Copyright (c) 2016, Oracle and/or its affiliates. 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. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package sun.java2d; |
| |
| import java.lang.ref.Reference; |
| import java.util.concurrent.ConcurrentLinkedQueue; |
| |
| /** |
| * This ReentrantContextProvider implementation uses one ConcurrentLinkedQueue |
| * to store all ReentrantContext instances (thread and its child contexts) |
| * |
| * Note: this implementation keeps less contexts in memory depending on the |
| * concurrent active threads in contrary to a ThreadLocal provider. However, |
| * it is slower in highly concurrent workloads. |
| * |
| * @param <K> ReentrantContext subclass |
| */ |
| public abstract class ReentrantContextProviderCLQ<K extends ReentrantContext> |
| extends ReentrantContextProvider<K> |
| { |
| // ReentrantContext queue to store all contexts |
| private final ConcurrentLinkedQueue<Reference<K>> ctxQueue |
| = new ConcurrentLinkedQueue<Reference<K>>(); |
| |
| /** |
| * Create a new ReentrantContext provider using the given reference type |
| * among hard, soft or weak based using a ConcurrentLinkedQueue storage |
| * |
| * @param refType reference type |
| */ |
| public ReentrantContextProviderCLQ(final int refType) { |
| super(refType); |
| } |
| |
| /** |
| * Give a ReentrantContext instance for the current thread |
| * |
| * @return ReentrantContext instance |
| */ |
| @Override |
| public final K acquire() { |
| K ctx = null; |
| // Drain queue if all referent are null: |
| Reference<K> ref = null; |
| while ((ctx == null) && ((ref = ctxQueue.poll()) != null)) { |
| ctx = ref.get(); |
| } |
| if (ctx == null) { |
| // create a new ReentrantContext if none is available |
| ctx = newContext(); |
| ctx.usage = USAGE_CLQ; |
| } |
| return ctx; |
| } |
| |
| /** |
| * Restore the given ReentrantContext instance for reuse |
| * |
| * @param ctx ReentrantContext instance |
| */ |
| @Override |
| public final void release(final K ctx) { |
| if (ctx.usage == USAGE_CLQ) { |
| ctxQueue.offer(getOrCreateReference(ctx)); |
| } |
| } |
| } |