com.netflix.exhibitor.core.processes.ProcessMonitor.java Source code

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Here is the source code for com.netflix.exhibitor.core.processes.ProcessMonitor.java

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/*
 * Copyright 2012 Netflix, Inc.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package com.netflix.exhibitor.core.processes;

import com.google.common.collect.Maps;
import com.google.common.io.Closeables;
import com.netflix.exhibitor.core.Exhibitor;
import com.netflix.exhibitor.core.activity.ActivityLog;
import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicBoolean;

public class ProcessMonitor implements Closeable {
    private final ExecutorService service = Executors.newCachedThreadPool();
    private final Exhibitor exhibitor;
    private final Map<ProcessTypes, ProcessHolder> processes = Maps.newConcurrentMap();

    public ProcessMonitor(Exhibitor exhibitor) {
        this.exhibitor = exhibitor;
    }

    @Override
    public void close() throws IOException {
        service.shutdownNow();
    }

    public enum Mode {
        LEAVE_RUNNING_ON_INTERRUPT, DESTROY_ON_INTERRUPT
    }

    public enum Streams {
        ERROR, STANDARD, BOTH
    }

    private static class ProcessHolder {
        final Process process;
        final AtomicBoolean isBeingClosed = new AtomicBoolean(false);

        private ProcessHolder(Process process) {
            this.process = process;
        }
    }

    public void destroy(ProcessTypes type) {
        ProcessHolder previousHolder = processes.remove(type);
        closeHolder(previousHolder);
    }

    public void monitor(ProcessTypes type, final Process process, final String completionMessage, final Mode mode,
            final Streams whichStreams) {
        ProcessHolder newHolder = new ProcessHolder(process);
        ProcessHolder previousHolder = processes.put(type, newHolder);
        closeHolder(previousHolder);

        switch (whichStreams) {
        case ERROR: {
            service.submit(makeStreamProc(process.getErrorStream(), type.getDescription(), ActivityLog.Type.ERROR,
                    newHolder));
            break;
        }

        case STANDARD: {
            service.submit(makeStreamProc(process.getInputStream(), type.getDescription(), ActivityLog.Type.INFO,
                    newHolder));
            break;
        }

        case BOTH: {
            service.submit(makeStreamProc(process.getErrorStream(), type.getDescription(), ActivityLog.Type.ERROR,
                    newHolder));
            service.submit(makeStreamProc(process.getInputStream(), type.getDescription(), ActivityLog.Type.INFO,
                    newHolder));
            break;
        }
        }

        service.submit(makeEofProc(process, completionMessage, mode));
    }

    private void closeHolder(ProcessHolder previousHolder) {
        if (previousHolder != null) {
            previousHolder.isBeingClosed.set(true);

            Closeables.closeQuietly(previousHolder.process.getErrorStream());
            Closeables.closeQuietly(previousHolder.process.getInputStream());
            Closeables.closeQuietly(previousHolder.process.getOutputStream());

            previousHolder.process.destroy();
        }
    }

    private Runnable makeEofProc(final Process process, final String completionMessage, final Mode mode) {
        return new Runnable() {
            @Override
            public void run() {
                try {
                    process.waitFor();
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                    if (mode == Mode.DESTROY_ON_INTERRUPT) {
                        Closeables.closeQuietly(process.getErrorStream());
                        Closeables.closeQuietly(process.getInputStream());
                        Closeables.closeQuietly(process.getOutputStream());

                        process.destroy();
                    }
                }

                if (completionMessage != null) {
                    exhibitor.getLog().add(ActivityLog.Type.INFO, completionMessage);
                }
            }
        };
    }

    private Callable<Object> makeStreamProc(final InputStream stream, final String name,
            final ActivityLog.Type type, final ProcessHolder holder) {
        return new Callable<Object>() {
            public Object call() throws Exception {
                BufferedReader in = new BufferedReader(new InputStreamReader(stream));
                for (;;) {
                    String line = in.readLine();
                    if (line == null) {
                        break;
                    }
                    if (!holder.isBeingClosed.get()) {
                        exhibitor.getLog().add(type, name + ": " + line);
                    }
                }
                return null;
            }
        };
    }
}