org.springframework.integration.gemfire.fork.ForkUtil.java Source code

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Here is the source code for org.springframework.integration.gemfire.fork.ForkUtil.java

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/*
 * Copyright 2011-2019 the original author or authors.
 *
 * 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
 *
 *      https://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 org.springframework.integration.gemfire.fork;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintStream;
import java.util.concurrent.atomic.AtomicBoolean;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Utility for forking Java processes. Modified from the SGF version for SI
 *
 * @author Costin Leau
 * @author David Turanski
 * @author Gary Russell
 *
 *
 */
public class ForkUtil {

    private static final Log logger = LogFactory.getLog(ForkUtil.class);

    private static String TEMP_DIR = System.getProperty("java.io.tmpdir");

    private ForkUtil() {
        super();
    }

    public static OutputStream cloneJVM(String argument) {
        String cp = System.getProperty("java.class.path");
        String home = System.getProperty("java.home");

        Process proc = null;
        String java = home + "/bin/java".replace("\\", "/");

        String argClass = argument;

        String[] cmdArray = { java, "-cp", cp, argClass };
        try {
            // ProcessBuilder builder = new ProcessBuilder(cmd, argCp,
            // argClass);
            // builder.redirectErrorStream(true);
            proc = Runtime.getRuntime().exec(cmdArray);
        } catch (IOException ioe) {
            throw new IllegalStateException("Cannot start command " + cmdArray, ioe);
        }

        logger.info("Started fork");
        final Process p = proc;

        final BufferedReader br = new BufferedReader(new InputStreamReader(p.getInputStream()));
        final BufferedReader ebr = new BufferedReader(new InputStreamReader(p.getErrorStream()));
        final AtomicBoolean run = new AtomicBoolean(true);

        Thread reader = copyStdXxx(br, run, System.out);
        Thread errReader = copyStdXxx(ebr, run, System.err);

        reader.start();
        errReader.start();

        Runtime.getRuntime().addShutdownHook(new Thread() {
            @Override
            public void run() {
                logger.info("Stopping fork...");
                run.set(false);
                if (p != null) {
                    p.destroy();
                }

                try {
                    p.waitFor();
                } catch (InterruptedException e) {
                    // ignore
                }
                logger.info("Fork stopped");
            }
        });

        return proc.getOutputStream();
    }

    private static Thread copyStdXxx(final BufferedReader br, final AtomicBoolean run, final PrintStream out) {
        Thread reader = new Thread(() -> {
            try {
                String line = null;
                do {
                    while ((line = br.readLine()) != null) {
                        out.println("[FORK] " + line);
                    }
                } while (run.get());
            } catch (Exception ex) {
                // ignore and exit
            }
        });
        return reader;
    }

    public static OutputStream cacheServer() {
        return startCacheServer("org.springframework.integration.gemfire.fork.CacheServerProcess");
    }

    public static OutputStream cacheServer(String className) {
        return startCacheServer(className);
    }

    private static OutputStream startCacheServer(String className) {

        if (controlFileExists(className)) {
            deleteControlFile(className);
        }
        OutputStream os = cloneJVM(className);
        int maxTime = 60000;
        int time = 0;
        while (!controlFileExists(className) && time < maxTime) {
            try {
                Thread.sleep(500);
                time += 500;
            } catch (InterruptedException ex) {
                // ignore and move on
            }
        }
        if (controlFileExists(className)) {
            logger.info("Started cache server");
        } else {
            throw new RuntimeException("could not fork cache server");
        }
        return os;
    }

    public static boolean deleteControlFile(String name) {
        String path = TEMP_DIR + File.separator + name;
        return new File(path).delete();
    }

    public static boolean createControlFile(String name) throws IOException {
        String path = TEMP_DIR + File.separator + name;
        return new File(path).createNewFile();
    }

    public static boolean controlFileExists(String name) {
        String path = TEMP_DIR + File.separator + name;
        return new File(path).exists();
    }

}