Re: [ns] trace method for RED queue

[Ratul Mahajan <ratul@cs.washington.edu>]

> I was going through ~ns/tcl/test/test-suite-red.tcl, to understand how it
> is monitoring its current queue lgt and average queue lgt. I came across
> the function that enables tracing (for the red1 class). It does the
> following
> 
>         $self instvar tchan_ node_
>         set redq [[$ns link $node_(r1) $node_(r2)] queue]
>         set tchan_ [open all.q w]
>         $redq trace curq_
>         $redq trace ave_
>         $redq attach $tchan_
> 
> I tried to locate 'trace' function but could not, it not defined in
> Queue/RED, nor in Queue nor in Connector nor in NsObject (neither in OTcl
> nor in C++). Could anyone pls. tell me what exactly the line
> 
> $redq trace curq_
> 
> is doing ( I tried stepping through both TCL debugger and gdb, but could
> not figure it out )

Defined for TclObject in Tcl.cc (in tclcl/). 
It traces this variable and logs in the trace file everytime its value
changes.

	- Ratul