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|
/*************************************************
*
* = PACKAGE
* JACE.ASX
*
* = FILENAME
* Stream.java
*
*@author Prashant Jain
*
*************************************************/
package JACE.ASX;
import JACE.OS.*;
/**
* This class is the primary abstraction for the ASX framework.
* It is moduled after System V Stream. <P>
*
* A Stream consists of a stack of Modules, each of which
* contains two Tasks.
*
*@see Module
*@see Task
*/
public class Stream
{
public Stream ()
{
this (null, null, null);
}
// Create a Stream consisting of <head> and <tail> as the Stream
// head and Stream tail, respectively. If these are 0 then the
// <ACE_Stream_Head> and <ACE_Stream_Tail> are used, respectively.
// <arg> is the value past in to the open() methods of the tasks.
public Stream (Object a,
Module head,
Module tail)
{
this.linkedUs_ = null;
// this.final_close_ = this.lock_;
if (this.open (a, head, tail) == -1)
ACE.ERROR ("open" + head.name () + " " + tail.name ());
}
public int push (Module newTop)
{
if (this.pushModule (newTop,
this.streamHead_.next (),
this.streamHead_) == -1)
return -1;
else
return 0;
}
// Note that the timeout tv is absolute time
public int put (MessageBlock mb, TimeValue tv)
{
return this.streamHead_.writer ().put (mb, tv);
}
// Note that the timeout tv is absolute time
public MessageBlock get (TimeValue tv) throws InterruptedException
{
return this.streamHead_.reader ().getq (tv);
}
// Return the "top" ACE_Module in a ACE_Stream, skipping over the
// stream_head.
public Module top ()
{
if (this.streamHead_.next () == this.streamTail_)
return null;
else
return this.streamHead_.next ();
}
// Remove the "top" ACE_Module in a ACE_Stream, skipping over the
// stream_head.
public int pop (long flags)
{
if (this.streamHead_.next () == this.streamTail_)
return -1;
else
{
// Skip over the ACE_Stream head.
Module top = this.streamHead_.next ();
Module newTop = top.next ();
this.streamHead_.next (newTop);
// Close the top ACE_Module.
top.close (flags);
this.streamHead_.writer ().next (newTop.writer ());
newTop.reader ().next (this.streamHead_.reader ());
return 0;
}
}
// Remove a named ACE_Module from an arbitrary place in the
// ACE_Stream.
public int remove (String name, long flags)
{
Module prev = null;
for (Module mod = this.streamHead_;
mod != null; mod = mod.next ())
if (name.compareTo (mod.name ()) == 0)
{
if (prev == null) // Deleting ACE_Stream Head
this.streamHead_.link (mod.next ());
else
prev.link (mod.next ());
mod.close (flags);
return 0;
}
else
prev = mod;
return -1;
}
public Module find (String name)
{
for (Module mod = this.streamHead_;
mod != null;
mod = mod.next ())
if (name.compareTo (mod.name ()) == 0)
return mod;
return null;
}
// Actually push a module onto the stack...
private int pushModule (Module newTop,
Module currentTop,
Module head)
{
Task ntReader = newTop.reader ();
Task ntWriter = newTop.writer ();
Task ctReader = null;
Task ctWriter = null;
if (currentTop != null)
{
ctReader = currentTop.reader ();
ctWriter = currentTop.writer ();
ctReader.next (ntReader);
}
ntWriter.next (ctWriter);
if (head != null)
{
if (head != newTop)
head.link (newTop);
}
else
ntReader.next (null);
newTop.next (currentTop);
if (ntReader.open (newTop.arg ()) == -1)
return -1;
if (ntWriter.open (newTop.arg ()) == -1)
return -1;
return 0;
}
public synchronized int open (Object a,
Module head,
Module tail)
{
Task h1 = null, h2 = null;
Task t1 = null, t2 = null;
if (head == null)
{
h1 = new StreamHead ();
h2 = new StreamHead ();
head = new Module ("ACEStreamHead", h1, h2, a);
}
if (tail == null)
{
t1 = new StreamTail ();
t2 = new StreamTail ();
tail = new Module ("ACEStreamTail",
t1, t2, a);
}
// Make sure *all* the allocation succeeded!
if (h1 == null || h2 == null || head == null
|| t1 == null || t2 == null || tail == null)
{
// Close up!
head.close (0);
tail.close (0);
return -1;
}
this.streamHead_ = head;
this.streamTail_ = tail;
if (this.pushModule (this.streamTail_,
null, null) == -1)
return -1;
else if (this.pushModule (this.streamHead_,
this.streamTail_,
this.streamHead_) == -1)
return -1;
else
return 0;
}
public synchronized int close (long flags)
{
if (this.streamHead_ != null
&& this.streamTail_ != null)
{
// Don't bother checking return value here.
this.unlinkInternal ();
int result = 0;
// Remove and cleanup all the intermediate modules.
while (this.streamHead_.next () != this.streamTail_)
{
if (this.pop (flags) == -1)
result = -1;
}
// Clean up the head and tail of the stream.
if (this.streamHead_.close (flags) == -1)
result = -1;
if (this.streamTail_.close (flags) == -1)
result = -1;
this.streamHead_ = null;
this.streamTail_ = null;
// Tell all threads waiting on the close that we are done.
// this.final_close_.broadcast ();
return result;
}
return 0;
}
public int control (int cmd, Object a) throws InterruptedException
{
IOCntlMsg ioc = new IOCntlMsg (cmd);
// Create a data block that contains the user-supplied data.
MessageBlock db =
new MessageBlock (MessageType.MB_IOCTL,
null,
a);
// Create a control block that contains the control field and a
// pointer to the data block.
MessageBlock cb =
new MessageBlock (MessageType.MB_IOCTL,
db,
(Object) ioc);
int result = 0;
if (this.streamHead_.writer ().put (cb, null) == -1)
result = -1;
else if ((cb = this.streamHead_.reader ().getq (null)) == null)
result = -1;
else
result = ((IOCntlMsg ) cb.obj ()).rval ();
return result;
}
// Link two streams together at their bottom-most Modules (i.e., the
// one just above the Stream tail). Note that all of this is premised
// on the fact that the Stream head and Stream tail are non-NULL...
// This must be called with locks held.
private int linkInternal (Stream us)
{
this.linkedUs_ = us;
// Make sure the other side is also linked to us!
us.linkedUs_ = this;
Module myTail = this.streamHead_;
if (myTail == null)
return -1;
// Locate the module just above our Stream tail.
while (myTail.next () != this.streamTail_)
myTail = myTail.next ();
Module otherTail = us.streamHead_;
if (otherTail == null)
return -1;
// Locate the module just above the other Stream's tail.
while (otherTail.next () != us.streamTail_)
otherTail = otherTail.next ();
// Reattach the pointers so that the two streams are linked!
myTail.writer ().next (otherTail.reader ());
otherTail.writer ().next (myTail.reader ());
return 0;
}
public synchronized int link (Stream us)
{
return this.linkInternal (us);
}
// Must be called with locks held...
private int unlinkInternal ()
{
// Only try to unlink if we are in fact still linked!
if (this.linkedUs_ != null)
{
Module myTail = this.streamHead_;
// Only relink if we still exist!
if (myTail != null)
{
// Find the module that's just before our stream tail.
while (myTail.next () != this.streamTail_)
myTail = myTail.next ();
// Restore the writer's next() link to our tail.
myTail.writer ().next (this.streamTail_.writer ());
}
Module otherTail = this.linkedUs_.streamHead_;
// Only fiddle with the other side if it in fact still remains.
if (otherTail != null)
{
while (otherTail.next () != this.linkedUs_.streamTail_)
otherTail = otherTail.next ();
otherTail.writer ().next (this.linkedUs_.streamTail_.writer ());
}
// Make sure the other side is also aware that it's been unlinked!
this.linkedUs_.linkedUs_ = null;
this.linkedUs_ = null;
return 0;
}
else
return -1;
}
public synchronized int unlink ()
{
return this.unlinkInternal ();
}
public void dump ()
{
ACE.DEBUG ("-------- module links --------");
for (Module mp = this.streamHead_; ; mp = mp.next ())
{
ACE.DEBUG ("module name = " + mp.name ());
if (mp == this.streamTail_)
break;
}
ACE.DEBUG ("-------- writer links --------");
Task tp;
for (tp = this.streamHead_.writer (); ; tp = tp.next ())
{
ACE.DEBUG ("writer queue name = " + tp.name ());
tp.dump ();
ACE.DEBUG ("-------\n");
if (tp == this.streamTail_.writer ()
|| (this.linkedUs_ != null && tp == this.linkedUs_.streamHead_.reader ()))
break;
}
ACE.DEBUG ("-------- reader links --------\n");
for (tp = this.streamTail_.reader (); ; tp = tp.next ())
{
ACE.DEBUG ("reader queue name = " + tp.name ());
tp.dump ();
ACE.DEBUG ("-------\n");
if (tp == this.streamHead_.reader ()
|| (this.linkedUs_ != null && tp == this.linkedUs_.streamHead_.writer ()))
break;
}
}
Module streamHead_ = null;
// Pointer to the head of the stream.
Module streamTail_ = null;
// Pointer to the tail of the stream.
Stream linkedUs_ = null;
// Pointer to an adjoining linked stream.
// = Synchronization objects used for thread-safe streams.
// ACE_SYNCH_MUTEX lock_;
// Protect the stream against race conditions.
// ACE_SYNCH_CONDITION final_close_;
// Use to tell all threads waiting on the close that we are done.
}
|
