ohrstrom@1504: /*
ohrstrom@1504:  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
ohrstrom@1504:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
ohrstrom@1504:  *
ohrstrom@1504:  * This code is free software; you can redistribute it and/or modify it
ohrstrom@1504:  * under the terms of the GNU General Public License version 2 only, as
ohrstrom@1504:  * published by the Free Software Foundation.  Oracle designates this
ohrstrom@1504:  * particular file as subject to the "Classpath" exception as provided
ohrstrom@1504:  * by Oracle in the LICENSE file that accompanied this code.
ohrstrom@1504:  *
ohrstrom@1504:  * This code is distributed in the hope that it will be useful, but WITHOUT
ohrstrom@1504:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
ohrstrom@1504:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
ohrstrom@1504:  * version 2 for more details (a copy is included in the LICENSE file that
ohrstrom@1504:  * accompanied this code).
ohrstrom@1504:  *
ohrstrom@1504:  * You should have received a copy of the GNU General Public License version
ohrstrom@1504:  * 2 along with this work; if not, write to the Free Software Foundation,
ohrstrom@1504:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
ohrstrom@1504:  *
ohrstrom@1504:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohrstrom@1504:  * or visit www.oracle.com if you need additional information or have any
ohrstrom@1504:  * questions.
ohrstrom@1504:  */
ohrstrom@1504: 
ohrstrom@1504: package com.sun.tools.sjavac.server;
ohrstrom@1504: 
ohrstrom@1504: import java.util.concurrent.ExecutorService;
ohrstrom@1504: import java.util.concurrent.Executors;
ohrstrom@1504: import java.util.concurrent.Semaphore;
ohrstrom@1504: import java.util.Stack;
ohrstrom@1504: import java.util.concurrent.Future;
ohrstrom@1504: 
ohrstrom@1504: /** The compiler pool maintains compiler threads.
ohrstrom@1504:  *
ohrstrom@1504:  * <p><b>This is NOT part of any supported API.
ohrstrom@1504:  * If you write code that depends on this, you do so at your own
ohrstrom@1504:  * risk.  This code and its internal interfaces are subject to change
ohrstrom@1504:  * or deletion without notice.</b></p>
ohrstrom@1504:  */
ohrstrom@1504: public class CompilerPool {
ohrstrom@1504:     // The javac server that created this pool.
ohrstrom@1504:     private JavacServer javacServer;
ohrstrom@1504:     // A semaphore protecting the poolsize number of threads.
ohrstrom@1504:     private Semaphore available;
ohrstrom@1504:     // The stack of compiler threads.
ohrstrom@1504:     private Stack<CompilerThread> compilers = new Stack<CompilerThread>();
ohrstrom@1504:     // And the executor server to spawn threads.
ohrstrom@1504:     private final ExecutorService executorPool;
ohrstrom@1504:     // How many requests are active right now?
ohrstrom@1504:     private int concurrentRequests = 0;
ohrstrom@1504:     // When was the last request finished?
ohrstrom@1504:     private long lastRequestFinished = 0;
ohrstrom@1504:     // The total number of requests to this pool.
ohrstrom@1504:     private int numRequests = 0;
ohrstrom@1504:     // Protect access to the three above values.
ohrstrom@1504:     private static final Object conc = new Object();
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Return the javac server that this pool belongs to.
ohrstrom@1504:      */
ohrstrom@1504:     public JavacServer getJavacServer() {
ohrstrom@1504:         return javacServer;
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Return how many threads are running at this very moment.
ohrstrom@1504:      */
ohrstrom@1504:     public int numActiveRequests()
ohrstrom@1504:     {
ohrstrom@1504:         synchronized (conc) {
ohrstrom@1504:             return concurrentRequests;
ohrstrom@1504:         }
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Return when the last request was finished.
ohrstrom@1504:      * I.e. the pool has been idle since.
ohrstrom@1504:      */
ohrstrom@1504:     public long lastRequestFinished()
ohrstrom@1504:     {
ohrstrom@1504:         synchronized (conc) {
ohrstrom@1504:             return lastRequestFinished;
ohrstrom@1504:         }
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Up the number of active requests.
ohrstrom@1504:      */
ohrstrom@1504:     public int startRequest() {
ohrstrom@1504:         int n;
ohrstrom@1504:         synchronized (conc) {
ohrstrom@1504:             concurrentRequests++;
ohrstrom@1504:             numRequests++;
ohrstrom@1504:             n = numRequests;
ohrstrom@1504:         }
ohrstrom@1504:         return n;
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Down the number of active requests. Return the current time.
ohrstrom@1504:      */
ohrstrom@1504:     public long stopRequest() {
ohrstrom@1504:         synchronized (conc) {
ohrstrom@1504:             concurrentRequests--;
ohrstrom@1504:             lastRequestFinished = System.currentTimeMillis();
ohrstrom@1504:         }
ohrstrom@1504:         return lastRequestFinished;
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Create a new compiler pool.
ohrstrom@1504:      */
ohrstrom@1504:     CompilerPool(int poolsize, JavacServer server) {
ohrstrom@1504:         available = new Semaphore(poolsize, true);
ohrstrom@1504:         javacServer = server;
ohrstrom@1504:         executorPool = Executors.newFixedThreadPool(poolsize);
ohrstrom@1504:         lastRequestFinished = System.currentTimeMillis();
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Execute a compiler thread.
ohrstrom@1504:      */
ohrstrom@1504:     public void execute(CompilerThread ct) {
ohrstrom@1504:         executorPool.execute(ct);
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Execute a minor task, for example generating bytecodes and writing them to disk,
ohrstrom@1504:      * that belong to a major compiler thread task.
ohrstrom@1504:      */
ohrstrom@1504:     public Future<?> executeSubtask(CompilerThread t, Runnable r) {
ohrstrom@1504:         return executorPool.submit(r);
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Shutdown the pool.
ohrstrom@1504:      */
ohrstrom@1504:     public void shutdown() {
ohrstrom@1504:         executorPool.shutdown();
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Acquire a compiler thread from the pool, or block until a thread is available.
ohrstrom@1504:      * If the pools is empty, create a new thread, but never more than is "available".
ohrstrom@1504:      */
ohrstrom@1504:     public CompilerThread grabCompilerThread() throws InterruptedException {
ohrstrom@1504:         available.acquire();
ohrstrom@1504:         if (compilers.empty()) {
ohrstrom@1504:             return new CompilerThread(this);
ohrstrom@1504:         }
ohrstrom@1504:         return compilers.pop();
ohrstrom@1504:     }
ohrstrom@1504: 
ohrstrom@1504:     /**
ohrstrom@1504:      * Return the specified compiler thread to the pool.
ohrstrom@1504:      */
ohrstrom@1504:     public void returnCompilerThread(CompilerThread h) {
ohrstrom@1504:         compilers.push(h);
ohrstrom@1504:         available.release();
ohrstrom@1504:     }
ohrstrom@1504: }
ohrstrom@1504: