/*

 * Copyright (c) 2014, 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.comp;

import java.io.File;

import java.net.URI;

import java.util.List;

import java.util.Objects;

import java.util.Set;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.ThreadFactory;

import java.util.concurrent.TimeUnit;

import java.util.concurrent.atomic.AtomicInteger;

import com.sun.tools.sjavac.Log;

import com.sun.tools.sjavac.server.CompilationResult;

import com.sun.tools.sjavac.server.Sjavac;

import com.sun.tools.sjavac.server.SysInfo;

/**

 * An sjavac implementation that limits the number of concurrent calls by

 * wrapping invocations in Callables and delegating them to a FixedThreadPool.

 *

 *  <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>

 */

public class PooledSjavac implements Sjavac {

    final Sjavac delegate;

    final ExecutorService pool;

    public PooledSjavac(Sjavac delegate, int poolsize) {

        Objects.requireNonNull(delegate);

        this.delegate = delegate;

        pool = Executors.newFixedThreadPool(poolsize, new ThreadFactory() {

            AtomicInteger count = new AtomicInteger();

            @Override

            public Thread newThread(Runnable runnable) {

                String cls = PooledSjavac.class.getSimpleName();

                int num = count.incrementAndGet();

                Thread t = new Thread(runnable, cls + "-" + num);

                t.setDaemon(true);

                return t;

            }

        });

    }

    @Override

    public SysInfo getSysInfo() {

        try {

            return pool.submit(new Callable<SysInfo>() {

                @Override

                public SysInfo call() throws Exception {

                    return delegate.getSysInfo();

                }

            }).get();

        } catch (Exception e) {

            e.printStackTrace();

            throw new RuntimeException("Error during getSysInfo", e);

        }

    }

    @Override

    public CompilationResult compile(final String protocolId,

                                     final String invocationId,

                                     final String[] args,

                                     final List<File> explicitSources,

                                     final Set<URI> sourcesToCompile,

                                     final Set<URI> visibleSources) {

        try {

            return pool.submit(new Callable<CompilationResult>() {

                @Override

                public CompilationResult call() throws Exception {

                    return delegate.compile(protocolId,

                                            invocationId,

                                            args,

                                            explicitSources,

                                            sourcesToCompile,

                                            visibleSources);

                }

            }).get();

        } catch (Exception e) {

            e.printStackTrace();

            throw new RuntimeException("Error during compile", e);

        }

    }

    @Override

    public void shutdown() {

        pool.shutdown(); // Disable new tasks from being submitted

        try {

            // Wait a while for existing tasks to terminate

            if (!pool.awaitTermination(60, TimeUnit.SECONDS)) {

                pool.shutdownNow(); // Cancel currently executing tasks

                // Wait a while for tasks to respond to being cancelled

                if (!pool.awaitTermination(60, TimeUnit.SECONDS))

                    Log.error("ThreadPool did not terminate");

            }

            // Grace period for thread termination

            Thread.sleep(1000);

        } catch (InterruptedException ie) {

          // (Re-)Cancel if current thread also interrupted

          pool.shutdownNow();

          // Preserve interrupt status

          Thread.currentThread().interrupt();

        }

        delegate.shutdown();

    }

    @Override

    public String serverSettings() {

        return delegate.serverSettings();

    }

}