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/*************************************************
*
* = PACKAGE
* ACE.ASX
*
* = FILENAME
* Module.java
*
*@author Prashant Jain
*
*************************************************/
package ACE.ASX;
import ACE.OS.*;
/**
* <hr>
* <h2>SYNOPSIS</h2>
*<blockquote>
* Provides an abstraction for managing a bi-directional flow of
* messages.
*</blockquote>
*
* <h2>DESCRIPTION</h2>
*<blockquote>
* This is based on the Module concept in System V Streams,
* which contains a pair of Tasks, one for handling upstream
* processing, one for handling downstream processing.
*</blockquote>
*/
public class Module
{
// = Initialization and termination methods.
/**
* Create an empty Module.
*/
public Module ()
{
// Do nothing...
this.name ("<unknown>");
}
/*
* Create an initialized module.
*@param modName identity of the module.
*@param writerQ writer task of the module.
*@param readerQ reader task of the module.
*@param flags Module flags
*/
public Module (String modName,
Task writerQ,
Task readerQ,
Object flags)
{
this.open (modName, writerQ, readerQ, flags);
}
/*
* Create an initialized module.
*@param modName identity of the module.
*@param writerQ writer task of the module.
*@param readerQ reader task of the module.
*@param flags Module flags
*/
public void open (String modName,
Task writerQ,
Task readerQ,
Object arg)
{
this.name (modName);
this.arg_ = arg;
if (writerQ == null)
writerQ = new ThruTask ();
if (readerQ == null)
readerQ = new ThruTask ();
this.reader (readerQ);
this.writer (writerQ);
// Setup back pointers.
readerQ.module (this);
writerQ.module (this);
}
/*
* Set the writer task.
*@param q the writer task
*/
public void writer (Task q)
{
this.qPair_[1] = q;
if (q != null)
q.flags (ACE.CLR_BITS (q.flags (), TaskFlags.ACE_READER));
}
/*
* Set the reader task.
*@param q the reader task
*/
public void reader (Task q)
{
this.qPair_[0] = q;
if (q != null)
q.flags (ACE.SET_BITS (q.flags (), TaskFlags.ACE_READER));
}
/*
* Link this Module on top of Module.
*@param m the module to link this on top of.
*/
public void link (Module m)
{
this.next (m);
this.writer ().next (m.writer ());
m.reader ().next (this.reader ());
}
/*
* Set and get pointer to sibling Task in Module.
*@param orig the task to get the sibling for
*@return the sibling of the task
*/
public Task sibling (Task orig)
{
if (this.qPair_[0] == orig)
return this.qPair_[1];
else if (this.qPair_[1] == orig)
return this.qPair_[0];
else
return null;
}
/*
* Close down the module and its tasks.
*@param flags Module flags
*@return 0 on success, -1 on failure
*/
public int close (long flags)
{
Task readerQ = this.reader ();
Task writerQ = this.writer ();
int result = 0;
if (readerQ != null)
{
if (readerQ.close (flags) == -1)
result = -1;
readerQ.flush (flags);
readerQ.next (null);
}
if (writerQ != null)
{
if (writerQ.close (flags) == -1)
result = -1;
writerQ.flush (flags);
writerQ.next (null);
}
return result;
}
/*
* Get the argument passed to tasks.
*@return the argument passed to tasks.
*/
public Object arg ()
{
return this.arg_;
}
/*
* Set the argument to be passed to tasks.
*@param a the argument to be passed to tasks.
*/
public void arg (Object a)
{
this.arg_ = a;
}
/*
* Get the name of the module.
*@return the name of the module.
*/
public String name ()
{
return this.name_;
}
/*
* Set the name of the module.
*@param n the name of the module.
*/
public void name (String n)
{
this.name_ = n;
}
/*
* Get the writer task of the module.
*@return the writer task of the module.
*/
public Task writer ()
{
return this.qPair_[1];
}
/*
* Get the reader task of the module.
*@return the reader task of the module.
*/
public Task reader ()
{
return this.qPair_[0];
}
/*
* Get the next pointer to the module above in the stream.
*@return the next pointer to the module above in the stream.
*/
public Module next ()
{
return this.next_;
}
/*
* Set the next pointer to the module above in the stream.
*@param m the next pointer to the module above in the stream.
*/
public void next (Module m)
{
this.next_ = m;
}
private Task qPair_[] = new Task[2];
// Pair of Tasks that form the "read-side" and "write-side" of the
// ACE_Module partitioning.
private String name_ = null;
// Name of the ACE_Module.
private Module next_;
// Next ACE_Module in the stack.
private Object arg_;
// Argument passed through to the reader and writer task when they
// are opened.
}
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