[Tcl-bugs] [ tcl-Bugs-3175754 ] memchan fifo events

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Bugs item #3175754, was opened at 2011-02-08 08:34
Message generated for change (Settings changed) made by andreas_kupries
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Category: 27. Channel Types
Group: current: 8.5.9
>Status: Closed
>Resolution: Fixed
Priority: 5
Private: No
Submitted By: https://www.google.com/accounts ()
Assigned to: Andreas Kupries (andreas_kupries)
Summary: memchan fifo events 

Initial Comment:
Using the Memchan fifo command, the read events are not being consistent, not triggered at all, triggered only after reading at least one character first. 

Example: 
% package req Memchan 
2.3 
% set c [fifo] 
fifo0 
% chan event $c readable r 
% proc r {} {puts "read -- [read $::c]"} 
% puts $c "testing read" 
% flush $c 
% update 
% read $c 1 
t 
% update 
read -- esting read 
##########################

It can also 
generate false positives: 
  % package require Memchan 
  2.3 
  % set c [fifo] 
  fifo0 
  % fileevent $c readable {puts stderr READ:; puts stderr "([read $::c 
1])"} 
  % update 
  READ: 
  () 
  % update 
  READ: 
  () 

#############################

Even stranger, fileevents stop when data are ready ! 
  % fconfigure $c -buffering line 
  % puts $c aa 
  % update 
  % update 
  % update 
  % read $c 1 
  a 
  % update 
  READ: 
  (a) 
  READ: 
  ( 
  ) 
  % update 
  READ: 
  () 
  % update 
  READ: 
  () 
########################

I tried it Tcl 8.5 and 8.6. Same issue on both. 

----------------------------------------------------------------------

Comment By: Andreas Kupries (andreas_kupries)
Date: 2011-02-14 12:46

Message:
Fixed. Indeed, an inverted condition dropping readable events when actually
needed.

Side note: This bug was found in Memchan, and should have been reported to
the Memchan project @ SF, and not the Tcl core. It was fixed in Memchan
too. I accepted the misfile this time because I would have been the person
to fix it anyway, regardless of filing location.


----------------------------------------------------------------------

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