Mercurial > jdk8-mips64-public > langtools / file revision

 /*

  * Copyright (c) 2012, 2013, 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 com.sun.tools.sjavac.server;

 import java.util.concurrent.ExecutorService;

 import java.util.concurrent.Executors;

 import java.util.concurrent.Semaphore;

 import java.util.Stack;

 import java.util.concurrent.Future;

 /** The compiler pool maintains compiler threads.

  *

  * <p><b>This is NOT part of any supported API.

  * 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.</b></p>

  */

 public class CompilerPool {

     // The javac server that created this pool.

     private JavacServer javacServer;

     // A semaphore protecting the poolsize number of threads.

     private Semaphore available;

     // The stack of compiler threads.

     private Stack<CompilerThread> compilers = new Stack<CompilerThread>();

     // And the executor server to spawn threads.

     private final ExecutorService executorPool;

     // How many requests are active right now?

     private int concurrentRequests = 0;

     // When was the last request finished?

     private long lastRequestFinished = 0;

     // The total number of requests to this pool.

     private int numRequests = 0;

     // Protect access to the three above values.

     private static final Object conc = new Object();

     /**

      * Return the javac server that this pool belongs to.

      */

     public JavacServer getJavacServer() {

         return javacServer;

     }

     /**

      * Return how many threads are running at this very moment.

      */

     public int numActiveRequests()

     {

         synchronized (conc) {

             return concurrentRequests;

         }

     }

     /**

      * Return when the last request was finished.

      * I.e. the pool has been idle since.

      */

     public long lastRequestFinished()

     {

         synchronized (conc) {

             return lastRequestFinished;

         }

     }

     /**

      * Up the number of active requests.

      */

     public int startRequest() {

         int n;

         synchronized (conc) {

             concurrentRequests++;

             numRequests++;

             n = numRequests;

         }

         return n;

     }

     /**

      * Down the number of active requests. Return the current time.

      */

     public long stopRequest() {

         synchronized (conc) {

             concurrentRequests--;

             lastRequestFinished = System.currentTimeMillis();

         }

         return lastRequestFinished;

     }

     /**

      * Create a new compiler pool.

      */

     CompilerPool(int poolsize, JavacServer server) {

         available = new Semaphore(poolsize, true);

         javacServer = server;

         executorPool = Executors.newFixedThreadPool(poolsize);

         lastRequestFinished = System.currentTimeMillis();

     }

     /**

      * Execute a compiler thread.

      */

     public void execute(CompilerThread ct) {

         executorPool.execute(ct);

     }

     /**

      * Execute a minor task, for example generating bytecodes and writing them to disk,

      * that belong to a major compiler thread task.

      */

     public Future<?> executeSubtask(CompilerThread t, Runnable r) {

         return executorPool.submit(r);

     }

     /**

      * Shutdown the pool.

      */

     public void shutdown() {

         executorPool.shutdown();

     }

     /**

      * Acquire a compiler thread from the pool, or block until a thread is available.

      * If the pools is empty, create a new thread, but never more than is "available".

      */

     public CompilerThread grabCompilerThread() throws InterruptedException {

         available.acquire();

         if (compilers.empty()) {

             return new CompilerThread(this);

         }

         return compilers.pop();

     }

     /**

      * Return the specified compiler thread to the pool.

      */

     public void returnCompilerThread(CompilerThread h) {

         compilers.push(h);

         available.release();

     }

 }