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/*
 * Copyright (c) 2010-2015 Pivotal Software, Inc. All rights reserved.
 *
 * 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. See accompanying
 * LICENSE file.
 */
   
package com.gemstone.gemfire.internal;

import java.io.*;
import java.util.*;

import com.gemstone.gemfire.internal.i18n.LocalizedStrings;

/**
 * A ProcessOutputReader will read both stdout and stderr
 * from a {@link java.lang.Process} process. The constructor
 * does not return until all output from the process has been
 * read and the process has exited.
 *
 * @author darrel
 *
 */
public class ProcessOutputReader {
    private int exitCode;
    private String output;
    /**
     * Creates a process output reader for the given process.
     * @param p the process whose output should be read.
     */
    public ProcessOutputReader(final Process p) {
	final List lines = Collections.synchronizedList(new ArrayList());

	class ProcessStreamReader extends Thread {
	    private BufferedReader reader;
	    public int linecount = 0; 
	    public ProcessStreamReader(InputStream stream) {
		reader = new BufferedReader(new InputStreamReader(stream));
	    }
	    @Override
	    public void run() {
		try {
		    String line;
		    while ((line = reader.readLine()) != null) {
			linecount++;
			lines.add(line);
		    }
		    reader.close();
		} catch (Exception e) {
		}
	    }
	};

	ProcessStreamReader stdout =
	    new ProcessStreamReader(p.getInputStream());
	ProcessStreamReader stderr =
	    new ProcessStreamReader(p.getErrorStream());
	stdout.start();
	stderr.start();
	try {stderr.join();} catch (InterruptedException ignore) {Thread.currentThread().interrupt();}
	try {stdout.join();} catch (InterruptedException ignore) {Thread.currentThread().interrupt();}
	this.exitCode = 0;
	int retryCount = 9;
	while (retryCount > 0) {
	    retryCount--;
	    try {
		exitCode = p.exitValue();
		break;
	    } catch (IllegalThreadStateException e) {
		// due to bugs in Process we may not be able to get
		// a process's exit value.
		// We can't use Process.waitFor() because it can hang forever
		if (retryCount == 0) {
		    if (stderr.linecount > 0) {
			// The process wrote to stderr so manufacture
			// an error exist code
			lines.add(LocalizedStrings.ProcessOutputReader_FAILED_TO_GET_EXIT_STATUS_AND_IT_WROTE_TO_STDERR_SO_SETTING_EXIT_STATUS_TO_1.toLocalizedString());
			exitCode = 1;
		    }
		} else {
		    // We need to wait around to give a chance for
		    // the child to be reaped.See bug 19682
		    try {
		      Thread.sleep(1000);
		      }
		    catch (InterruptedException ignore) {
                      Thread.currentThread().interrupt();
                      // TODO a cancellation check here?
                    }
		}
	    }
	}

	java.io.StringWriter sw = new java.io.StringWriter();
	PrintWriter pw = new PrintWriter(sw);
	Iterator it = lines.iterator();
	while (it.hasNext()) {
	    pw.println((String)it.next());
	}
	pw.close();
	try {
	    sw.close();
	} catch (java.io.IOException ignore) {}
	StringBuffer buf = sw.getBuffer();
	if (buf != null && buf.length() > 0) {
	    this.output = sw.toString();
	} else {
	    this.output = "";
	}
    }

    /**
     * Gets the process's exit status code. A code equal to 0 indicates
     * all is well.
     */
    public int getExitCode() {
	return exitCode;
    }
    /**
     * Gets everything the process wrote to both stdout and stderr.
     */
    public String getOutput() {
	return output;
    }
}