package edu.vt.marian.server;

import java.io.*;
import java.net.*;
import java.lang.*;
import java.util.*;

import edu.vt.marian.common.*;



/**
	class name:  session_execution
	class description: this thread is responsible to inform the corresponding 
		session	object to execute functions from client and C/C++ marian server.
	uses the services of class(es): 
	designer(s): Jianxin Zhao (jxzhao@csgrad.cs.vt.edu)
	implementator(s): Ning Chai (nchai@csgrad.cs.vt.edu)
	finished time: Nov 26th, 1998
	known bugs: 
	JDK version: 1.1.5
	side effects:

*/

public class session_execution extends Thread
{
	public final static int OK = 0;
	public final static int INVALID_PRIORITY = 1;
	public final static int NULL_PROTOCOL = 2;
	public final static int PROTOCOL_GREATER_THAN_1 = 1;

	private String protocol;
	private int client_priority;
	private int c_priority;
	private session s;

	/** this is just used for debugging
	*/
	Debug debug;


	/**
		method description: this constructor will create a session execution 
			object from the specified directory, the directory contains all 
			the configuration information about this object, this object is 
			created by the specified session object.
		uses the services of class(es):
		input parameter(s): 
			file_name -- this directory/file contains all the configuration 
				information	about session executation object
			s -- this is the session object which created this object
			debug -- used for debugging
		output parameter(s): none
		return value: none
		synchronization: none
	*/      
	public session_execution(String file_name, session s, Debug debug)
	{
		BufferedReader in_file = null;
		
		String line = null;
		StringTokenizer token_line = null;	
		String stoken = null;
		String stoken1 = null;

		init();

		this.debug = debug;
		this.s = s;

		if (s == null)
		{
			debug.dumpTrace("Class:session_execution Method:constructor Session is null.");
		}

		if ((file_name == null) || file_name.equals(""))
		{
			debug.dumpTrace("Class:session_execution Method:constructor File_name is null or empty.");
		}

		try
		{
			in_file = new BufferedReader(new FileReader(file_name));
			
			line = in_file.readLine();
			while (line != null)
			{
				token_line = new StringTokenizer(line," ",false);
				if (token_line.countTokens() > 1) //in case an empty line is encountered
				{
					stoken = token_line.nextToken();
					//ignore empty lines and lines with only one token
					if (!stoken.startsWith("#")) //Ignore comments(begin with "#")
					{
						if (stoken.equals("client_priority"))
						{
							stoken1 = token_line.nextToken();
							try
							{
								client_priority = Integer.parseInt(stoken1);
								if (client_priority <= 0)
								{
									client_priority = 1;
									debug.dumpTrace("Class:session_execution Method:constructor client_priority must be greater than 0.");
								}
							}
							catch (Exception e)
							{
								client_priority = 1;
								debug.dumpTrace("Class:session_execution Method:constructor client_priority must be an integer.");
							}
						}

						if (stoken.equals("c_priority"))
						{
							stoken1 = token_line.nextToken();
							try
							{
								c_priority = Integer.parseInt(stoken1);
								if (c_priority <= 0)
								{
									c_priority = 1;
									debug.dumpTrace("Class:session_execution Method:constructor c_priority must be greater than 0.");
								}
							}
							catch (Exception e)
							{
								c_priority = 1;
								debug.dumpTrace("Class:session_execution Method:constructor c_priority must be an integer.");
							}
						}

						if (stoken.equals("protocol"))
						{
							protocol = token_line.nextToken();
							if (!protocol.equals("1.0"))
							{
								protocol = new String("1.0");
								debug.dumpTrace("Class:session_execution Method:constructor protocol must be 1.0.");
							}
						}
					} // end if (!stoken.startsWith("#"))
				} // end if (token_line.countTokens() > 1)
				line = in_file.readLine();
			} // end while
			in_file.close();
		} 
		catch (IOException e) 
		{
			debug.dumpTrace("Class:session_execution Method:constructor File open error or get parameters(client_priority,c_priority,protocol) error.");
			return; 
		}
	}

	/**
		method description: this constructor will create a session execution 
			object, this object is created by the specified session object.
		uses the services of class(es):
		input parameter(s): 
			s -- this is the session object which created this object
			debug -- used for debugging
		output parameter(s): none
		return value: none
		synchronization: none
	*/      
	public session_execution(session s, Debug debug)
	{
		init();
		this.s = s;
		this.debug = debug;
		
		if ( s == null)
		{
			debug.dumpTrace("Class:session_execution Method:constructor Session is null.");
		}

		return;
	}


	/**
		method description: this method is the main part of the thread, 
			it's responsible for inform corresponding session object to 
			execute functions sent from	client and C/C++ marian server
		uses the services of class(es): session
		input parameter(s): none
		output parameter(s): none
		return value: none
		synchronization: none
	*/      
	public void run()
	{
		int i;

		boolean executed;

		for (;;)
		{
			do 
			{
				executed = false;
				i = client_priority;
				do
				{
					if (s.execute_next_call_from_client() == s.OK)
					{
						executed = true;
						i--;
					}
					else
					{
						break;
					}
				}
				while (i != 0);

				i = c_priority;
				do
				{
					if (s.execute_next_call_from_c() == s.OK)
					{
						executed = true;
						i--;
					}
					else
					{
						break;
					}
				} 
				while ( i != 0 );
			}
			while (executed);

			// probably sleep some time here can increase the speed of the 
			// whole system since most of the time the function queueswill 
			// be empty
			try
			{
				suspend();
			}
			catch (Exception e)
			{
				debug.dumpTrace("class session_execution, method run, error happened when suspend");
			}
		}
	}


	/**
		method description: this method will return the priority of 
			the functions sent by client.
		uses the services of class(es): none
		input parameter(s): none
		output parameter(s): none
		return value: 
			the priority of functions sent by client as an integer
		synchronization: none
	*/      
	public int get_client_priority()
	{
		return client_priority;
	}


	/**
		method description: this method will return the priority of functions
			sent by	C/C++ marian server
		uses the services of class(es): 
		input parameter(s): none
		output parameter(s): none
		return value: 
			the priority of functions sent by C/C++ server as an integer
		synchronization: none
	*/      
	public int get_c_priority()
	{
		return c_priority;
	}


	/**
		method description: this method will set the priority of the functions 
			sent by	client.
		uses the services of class(es): none
		input parameter(s): 
			priority -- this will become the new priority of functions sent
				by client
		output parameter(s): none
		return value: 
			OK 
				-- the value has been set correctly
			INVALID_PRIORITY 
				-- negative value which doesn't make sense has been identified
			other --
		synchronization: none
	*/      
	public int set_client_priority(int priority)
	{
		if (priority > 0)
		{
			client_priority = priority;
			return OK;
		}
		
		debug.dumpTrace("Class:session_execution Method:set_client_priority Priority less than 0.");
		return INVALID_PRIORITY;
	}


	/**
		method description: this method will set the priority of the functions 
			sent by	C/C++ server.
		uses the services of class(es): none 
		input parameter(s): 
			priority -- this will become the new priority of functions sent
				by C/C++ server
		output parameter(s): none
		return value: 
			OK -- the value has been set correctly
			INVALID_PRIORITY 
				-- negative value which doesn't make sense has been identified
			other --
		synchronization: none
	*/      
	public int set_c_priority(int priority)
	{
		if (priority > 0)
		{
			c_priority = priority;
			return OK;
		}
		
		debug.dumpTrace("Class:session_execution Method:set_c_priority Priority less than 0.");
		return INVALID_PRIORITY;
	}

	
	/**
		method description: this method will tell the protocol this thread 
			currently used to inform corresponding session object to execute 
			functions from client and C/C++
		uses the services of class(es): none
		input parameter(s): none
		output parameter(s): none
		return value: 
			the protocol currently used by this object to execute functions
			as a string
		synchronization: none
	*/      
	public String get_execution_protocol()
	{
		return protocol;
	}


	/**
		method description: this method will set the protocol this thread
			will use to	inform corresponding session object to execute 
			functions sent by client and C/C++ marian server.
		uses the services of class(es): none
		input parameter(s): 
			protocol -- this will become the new protocol
		output parameter(s): none
		return value: 
			OK 
				-- the new protocol has been set correctly
			PROTOCOL_GREATER_THAN_1 
				-- the protocol is not supported
			NULL_PROTOCOL 
				-- null protocol identified
		synchronization: none
	*/      
	public int set_execution_protocol(String protocol)
	{
		if (protocol == null)
		{
			debug.dumpTrace("Class:session_execution Method:set_execution_protocol Protocol is null.");
			return NULL_PROTOCOL;
		}

		if (!protocol.equals("1.0"))
		{
			debug.dumpTrace("Class:session_execution Method:set_execution_protocol Protocol is greater than 1.0.");
			return PROTOCOL_GREATER_THAN_1;
		}

		this.protocol = protocol;
		return OK;
	}


	/**	
		method description: this method will initialize the data members of
			this object
		uses the services of class(es): none
		input parameter(s): none
		output parameter(s): none
		return value: none
		synchronization: none
	*/      
	private void init()
	{
		c_priority = 1;
		client_priority = 1;
		protocol = new String("1.0");
		s = null;
		debug = null;
		return;
	}
}