//******************************************************************************
//
// File:    Configuration.java
// Package: edu.rit.pj.cluster
// Unit:    Class edu.rit.pj.cluster.Configuration
//
// This Java source file is copyright (C) 2012 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ 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 for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.pj.cluster;

import java.io.File;
import java.io.IOException;

import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Scanner;

/**
 * Class Configuration provides configuration information about a parallel
 * computer running Parallel Java. The configuration information is read from a
 * plain text file. Each configuration file entry is on a single line. Lines
 * beginning with <TT>#</TT> and blank lines are ignored. The order of the
 * entries in the file does not matter (unless stated otherwise below). The
 * items in each entry are separated by whitespace; there cannot be any
 * whitespace within an item (unless stated otherwise below). The configuration
 * file entries are:
 * <UL>
 * <P><LI>
 * <TT>cluster &lt;name&gt;</TT>
 * <BR>The name of the cluster is <TT>&lt;name&gt;</TT>. The name may contain
 * whitespace. This entry must be specified; there is no default.
 * <P><LI>
 * <TT>logfile &lt;file&gt;</TT>
 * <BR>The Job Scheduler will append log entries to the log file named
 * <TT>&lt;file&gt;</TT>. This entry must be specified; there is no default.
 * <P><LI>
 * <TT>webhost &lt;host&gt;</TT>
 * <BR>The host name for the Job Scheduler's web interface is
 * <TT>&lt;host&gt;</TT>. This entry must be specified; there is no default.
 * <P><LI>
 * <TT>webport &lt;port&gt;</TT>
 * <BR>The port number for the Job Scheduler's web interface is
 * <TT>&lt;port&gt;</TT>. If not specified, the default port number is 8080.
 * <P><LI>
 * <TT>schedulerhost &lt;host&gt;</TT>
 * <BR>The host name to which the Job Scheduler listens for connections from job
 * frontend processes is <TT>&lt;host&gt;</TT>. If not specified, the default is
 * <TT>"localhost"</TT>.
 * <P><LI>
 * <TT>schedulerport &lt;port&gt;</TT>
 * <BR>The port number to which the Job Scheduler listens for connections from
 * job frontend processes is <TT>&lt;port&gt;</TT>. If not specified, the
 * default port number is 20617.
 * <P><LI>
 * <TT>frontendhost &lt;host&gt;</TT>
 * <BR>The host name to which job frontend processes listen for connections from
 * job backend processes is <TT>&lt;host&gt;</TT>. This entry must be specified;
 * there is no default.
 * <P><LI>
 * <TT>backend &lt;name&gt; &lt;cpus&gt; &lt;host&gt; &lt;jvm&gt;
 * &lt;classpath&gt; [&lt;jvmflag&gt; ...]</TT>
 * <BR>The parallel computer includes a backend node named
 * <TT>&lt;name&gt;</TT> with <TT>&lt;cpus&gt;</TT> CPUs. The host name for SSH
 * remote logins to the backend node is <TT>&lt;host&gt;</TT>. The full pathname
 * for executing the Java Virtual Machine (JVM) on the backend node is
 * <TT>&lt;jvm&gt;</TT>. The Java class path for the Parallel Java Library
 * on the backend node is <TT>&lt;classpath&gt;</TT>. Each
 * <TT>&lt;jvmflag&gt;</TT> (zero or more) gives a flag passed to the JVM on the
 * command line. At least one of this entry must be specified.
 * <P><LI>
 * <TT>backendshell &lt;name&gt; &lt;shell command&gt;</TT>
 * <BR>On the backend node named <TT>&lt;name&gt;</TT>, use the given shell
 * command string when starting a job backend process. This entry, if present,
 * must appear after the corresponding <TT>backend &lt;name&gt;</TT> entry. If
 * this entry is omitted, the default shell command string is
 * <TT>"bash&nbsp;-l&nbsp;-c"</TT>.
 * <P><LI>
 * <TT>jobtime &lt;time&gt;</TT>
 * <BR>The maximum time in seconds any Parallel Java job is allowed to run. The
 * Job Scheduler will abort a job if it runs for this many seconds. If not
 * specified, the default is not to impose a maximum time on jobs. <I>Note:</I>
 * If the Job Scheduler is configured with a maximum job time and a particular
 * job is given a maximum time with the <TT>-Dpj.jobtime</TT> property, the
 * smaller of the Job Scheduler's maximum job time and the job's maximum time
 * will be used for that job.
 * </UL>
 * <P>
 * Here is an example of a configuration file:
 * <P>
 * <TABLE BORDER=1 CELLPADDING=10 CELLSPACING=0>
 * <TR>
 * <TD ALIGN="left" VALIGN="top">
 * <FONT SIZE="-1">
 * <PRE> # Parallel Java Job Scheduler configuration file
 * # Frontend node: tardis.cs.rit.edu
 * # Backend nodes: dr00-dr09
 * 
 * cluster RIT CS Tardis Hybrid SMP Cluster
 * logfile /var/tmp/parajava/scheduler.log
 * webhost tardis.cs.rit.edu
 * webport 8080
 * schedulerhost localhost
 * schedulerport 20617
 * frontendhost 10.10.221.1
 * backend dr00 4 10.10.221.10 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr01 4 10.10.221.11 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr02 4 10.10.221.12 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr03 4 10.10.221.13 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr04 4 10.10.221.14 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr05 4 10.10.221.15 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr06 4 10.10.221.16 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr07 4 10.10.221.17 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr08 4 10.10.221.18 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar
 * backend dr09 4 10.10.221.19 /usr/local/versions/jdk-1.5.0_15/bin/java /var/tmp/parajava/pj.jar</PRE>
 * </FONT>
 * </TD>
 * </TR>
 * </TABLE>
 *
 * @author  Alan Kaminsky
 * @version 20-Jun-2012
 */
public class Configuration
	{

// Hidden data members.

	// Cluster name.
	private String myClusterName;

	// Log file.
	private String myLogFile;

	// Web interface host and port.
	private String myWebHost = Constants.ALL_NETWORK_INTERFACES;
	private int myWebPort = Constants.WEB_PORT;

	// Job Scheduler host and port.
	private String mySchedulerHost = "localhost";
	private int mySchedulerPort = Constants.PJ_PORT;

	// Frontend host.
	private String myFrontendHost;

	// List of backend information objects.
	private ArrayList<BackendInfo> myBackendInfo =
		new ArrayList<BackendInfo>();

	// Default shell comand string.
	private static final String DEFAULT_SHELL_COMMAND = "bash -l -c";

	// Maximum job time. 0 means no maximum.
	private int myJobTime;

// Exported constructors.

	/**
	 * Construct a new configuration. The configuration information is read from
	 * the given file.
	 *
	 * @param  configfile  Configuration file name.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred while reading the configuration file.
	 *     Thrown if there was an error in the configuration file.
	 */
	public Configuration
		(String configfile)
		throws IOException
		{
		parseConfigFile (configfile);
		}

// Exported operations.

	/**
	 * Returns the cluster name.
	 *
	 * @return  Cluster name.
	 */
	public String getClusterName()
		{
		return myClusterName;
		}

	/**
	 * Returns the Job Scheduler's log file name.
	 *
	 * @return  Log file name.
	 */
	public String getLogFile()
		{
		return myLogFile;
		}

	/**
	 * Returns the Job Scheduler's web interface host name.
	 *
	 * @return  Host name.
	 */
	public String getWebHost()
		{
		return myWebHost;
		}

	/**
	 * Returns the Job Scheduler's web interface port number.
	 *
	 * @return  Port number.
	 */
	public int getWebPort()
		{
		return myWebPort;
		}

	/**
	 * Returns the Job Scheduler's channel group host name. To send messages to
	 * the Job Scheduler, a job frontend connects a channel to this host.
	 *
	 * @return  Host name.
	 */
	public String getSchedulerHost()
		{
		return mySchedulerHost;
		}

	/**
	 * Returns the Job Scheduler's channel group port number. To send messages
	 * to the Job Scheduler, a job frontend connects a channel to this port.
	 *
	 * @return  Port number.
	 */
	public int getSchedulerPort()
		{
		return mySchedulerPort;
		}

	/**
	 * Returns the host name of the cluster's frontend processor.
	 *
	 * @return  Host name.
	 */
	public String getFrontendHost()
		{
		return myFrontendHost;
		}

	/**
	 * Returns the number of backend processors.
	 *
	 * @return  Count.
	 */
	public int getBackendCount()
		{
		return myBackendInfo.size();
		}

	/**
	 * Returns information about the given backend processor.
	 *
	 * @param  i  Index in the range 0 .. <TT>getBackendCount()-1</TT>.
	 *
	 * @return  Backend information object.
	 */
	public BackendInfo getBackendInfo
		(int i)
		{
		return myBackendInfo.get (i);
		}

	/**
	 * Returns information about all backend processors.
	 *
	 * @return  List of backend information objects.
	 */
	public List<BackendInfo> getBackendInfoList()
		{
		return myBackendInfo;
		}

	/**
	 * Returns the maximum job time.
	 *
	 * @return  Maximum job time (seconds), or 0 if no maximum.
	 */
	public int getJobTime()
		{
		return myJobTime;
		}

// Hidden operations.

	/**
	 * Parse the configuration file.
	 *
	 * @param  configfile  Configuration file name.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	private void parseConfigFile
		(String configfile)
		throws IOException
		{
		Scanner scanner = null;
		String line = null;
		long now = System.currentTimeMillis();
		try
			{
			scanner = new Scanner (new File (configfile));
			lineloop: while (scanner.hasNextLine())
				{
				line = scanner.nextLine();
				Scanner linescanner = new Scanner (line);
				if (! linescanner.hasNext()) continue lineloop;
				String command = linescanner.next();
				if (command.charAt(0) == '#')
					{
					}
				else if (command.equals ("cluster"))
					{
					myClusterName = linescanner.nextLine().trim();
					}
				else if (command.equals ("logfile"))
					{
					myLogFile = linescanner.next();
					}
				else if (command.equals ("webhost"))
					{
					myWebHost = linescanner.next();
					}
				else if (command.equals ("webport"))
					{
					myWebPort = Integer.parseInt (linescanner.next());
					}
				else if (command.equals ("schedulerhost"))
					{
					mySchedulerHost = linescanner.next();
					}
				else if (command.equals ("schedulerport"))
					{
					mySchedulerPort = Integer.parseInt (linescanner.next());
					}
				else if (command.equals ("frontendhost"))
					{
					myFrontendHost = linescanner.next();
					}
				else if (command.equals ("backend"))
					{
					String name = linescanner.next();
					int cpus = linescanner.nextInt();
					if (cpus < 1)
						{
						throw new IOException
							("Invalid backend command, <cpus> must be >= 1: " +
							 line);
						}
					String host = linescanner.next();
					String jvm = linescanner.next();
					String classpath = linescanner.next();
					ArrayList<String> jvmflags = new ArrayList<String>();
					while (linescanner.hasNext())
						{
						jvmflags.add (linescanner.next());
						}
					BackendInfo backendinfo =
						new BackendInfo
							(name,
							 cpus,
							 BackendInfo.State.IDLE,
							 now,
							 host,
							 jvm,
							 classpath,
							 jvmflags.toArray (new String [jvmflags.size()]),
							 DEFAULT_SHELL_COMMAND);
					myBackendInfo.add (backendinfo);
					}
				else if (command.equals ("backendshell"))
					{
					String name = linescanner.next();
					String shellCommand = linescanner.nextLine().trim();
					BackendInfo backendinfo = backendInfoForName (name);
					if (backendinfo == null)
						{
						throw new IOException
							("Invalid backendshell command, no backend named \""+
							 name+"\"");
						}
					backendinfo.shellCommand = shellCommand;
					}
				else if (command.equals ("jobtime"))
					{
					int time = linescanner.nextInt();
					if (time < 1)
						{
						throw new IOException
							("Invalid configuration command: " + line);
						}
					myJobTime = time;
					}
				else
					{
					throw new IOException
						("Invalid configuration command: " + line);
					}
				}
			if (myClusterName == null)
				{
				throw new IOException
					("Missing configuration command: cluster <name>");
				}
			if (myLogFile == null)
				{
				throw new IOException
					("Missing configuration command: logfile <file>");
				}
			if (myWebHost == null)
				{
				throw new IOException
					("Missing configuration command: webhost <host>");
				}
			if (myFrontendHost == null)
				{
				throw new IOException
					("Missing configuration command: frontendhost <host>");
				}
			if (myBackendInfo.isEmpty())
				{
				throw new IOException
					("Missing configuration command: backend <name> <host> <port>");
				}
			}
		catch (NoSuchElementException exc)
			{
			throw new IOException ("Invalid configuration command: " + line);
			}
		catch (NumberFormatException exc)
			{
			throw new IOException ("Invalid configuration command: " + line);
			}
		finally
			{
			if (scanner != null) scanner.close();
			}
		}

// Hidden operations.

	/**
	 * Returns the backend info object for the given backend name.
	 *
	 * @param  name  Backend name.
	 *
	 * @return  Backend info, or null if <TT>name</TT> does not exist.
	 */
	private BackendInfo backendInfoForName
		(String name)
		{
		for (BackendInfo backendinfo : myBackendInfo)
			{
			if (backendinfo.name.equals (name)) return backendinfo;
			}
		return null;
		}

	}