1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package sun.java2d;
  26 
  27 /**
  28  *
  29  * @param <K>
  30  */
  31 public abstract class ReentrantContextProviderTL<K extends ReentrantContext>
  32     extends ReentrantContextProvider<K>
  33 {
  34     // Thread-local storage:
  35     private final ThreadLocal<Object> ctxTL = new ThreadLocal<Object>();
  36 
  37     // ReentrantContext CLQ provider for child contexts:
  38     private final ReentrantContextProviderCLQ<K> ctxProviderCLQ;
  39 
  40     public ReentrantContextProviderTL(final int refType) {
  41         super(refType);
  42 
  43         final ReentrantContextProviderTL<K> parent = this;
  44 
  45         this.ctxProviderCLQ = new ReentrantContextProviderCLQ<K>(refType) {
  46             @Override
  47             protected K newContext() {
  48                 return parent.newContext();
  49             }
  50         };
  51     }
  52 
  53     /**
  54      * Give a ReentrantContext instance from thread-local or CLQ storage
  55      *
  56      * @return ReentrantContext instance
  57      */
  58     @Override
  59     public final K acquire() {
  60         K ctx = null;
  61 
  62         final Object ref = ctxTL.get();
  63         if (ref != null) {
  64             ctx = refWrapper.resolveReference(ref);
  65         }
  66         if (ctx == null) {
  67             // create a new ReentrantContext if none is available
  68             ctx = newContext();
  69             // update thread local reference:
  70             ctxTL.set(refWrapper.getOrCreateReference(ctx));
  71         }
  72         // Check reentrance:
  73         if (ctx.usage == USAGE_TL_INACTIVE) {
  74            ctx.usage = USAGE_TL_IN_USE;
  75         } else {
  76             // get or create another ReentrantContext from CLQ provider:
  77             ctx = ctxProviderCLQ.acquire();
  78         }
  79         return ctx;
  80     }
  81 
  82     /**
  83      * Restore the given ReentrantContext instance for reuse
  84      * @param ctx ReentrantContext instance
  85      */
  86     @Override
  87     public final void release(final K ctx) {
  88         if (ctx.usage == USAGE_TL_IN_USE) {
  89            ctx.usage = USAGE_TL_INACTIVE;
  90         } else {
  91             ctxProviderCLQ.release(ctx);
  92         }
  93     }
  94 }