[Tcl-bugs] [ tcl-Patches-1499394 ] TIP 285: Script Cancellation with Tcl_CancelEval

SourceForge Headquarters 225 Broadway Suite 1600 San Diego, CA 92101 +1 (858) 454-5900

Patches item #1499394, was opened at 2006-06-02 02:28
Message generated for change (Comment added) made by mistachkin
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=310894&aid=1499394&group_id=10894

Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: 44. Parsing and Eval
Group: TIP Implementation
Status: Open
Resolution: None
Priority: 7
Private: No
Submitted By: Joe Mistachkin (mistachkin)
Assigned to: miguel sofer (msofer)
Summary: TIP 285: Script Cancellation with Tcl_CancelEval

Initial Comment:

Patch that implements a forthcoming TIP, entitled
"Script cancellation with Tcl_CancelEval" or something
similar.

Please test.  I would like to get some feedback on this
patch so that any necessary changes can be made prior
to writing the formal TIP.

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

>Comment By: Joe Mistachkin (mistachkin)
Date: 2008-05-15 20:39

Message:
Logged In: YES 
user_id=113501
Originator: YES

Updated, fixes to tests.

File Added: tip285_v18.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-05-14 22:37

Message:
Logged In: YES 
user_id=113501
Originator: YES

Updated to HEAD.  Minor enhancements and fixes.

File Added: tip285_v17.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-29 07:39

Message:
Logged In: YES 
user_id=113501
Originator: YES

Updated CANCELED interp flag to not use the previously used 0x10 value.

File Added: script_cancellation_16.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-04 21:11

Message:
Logged In: YES 
user_id=113501
Originator: YES

Adding preliminary patch for Tk changes.

File Added: tk_cancellation_1.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-04 19:49

Message:
Logged In: YES 
user_id=113501
Originator: YES

More minor corrections.

File Added: script_cancellation_15.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-04 12:14

Message:
Logged In: YES 
user_id=113501
Originator: YES

Minor corrections.

File Added: script_cancellation_14.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-04 03:36

Message:
Logged In: YES 
user_id=113501
Originator: YES

Patch updated.

Changed [cancel] to [interp cancel] and added appropriate docs.

File Added: script_cancellation_13.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2008-04-04 02:02

Message:
Logged In: YES 
user_id=113501
Originator: YES

Patch updated to latest HEAD.  

Still need to change [cancel] to [interp cancel] and add docs for it.

File Added: script_cancellation_12.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2007-12-12 22:52

Message:
Logged In: YES 
user_id=113501
Originator: YES

Patch needs to be updated for latest HEAD.  Also, the plan is to change
the script visible command to [interp cancel] instead of [cancel].

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2007-07-24 03:09

Message:
Logged In: YES 
user_id=113501
Originator: YES

Updated (v11) patch to latest HEAD.

File Added: script_cancellation_11.zip

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-10-17 07:51

Message:
Logged In: YES 
user_id=113501

New v10 patch, various adjustments, corrected whitespace.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-10-16 00:12

Message:
Logged In: YES 
user_id=113501

New v9 patch.  More cleanup and consistency fixes, now
complete with tests.  Docs for Tcl_Canceled and
Tcl_CancelEval complete.  Still working on [cancel] docs. 
TIP has been submitted and should be forthcoming.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-10-11 19:26

Message:
Logged In: YES 
user_id=113501

Sorry, I'm still working on the TIP, man pages, and tests.  

In the meantime, the code fully works.  The basic
functionality provided is the ability to cancel a script
running in an interpreter from any thread in the process via
Tcl_CancelEval or from within the interpreter itself via the
[cancel] command.  Some examples are provided below.

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

Comment By: miguel sofer (msofer)
Date: 2006-10-11 18:17

Message:
Logged In: YES 
user_id=148712

An almost 1500 loc patch without a spec, man page or tests.
I'm not up to guessing what it is supposed to do, sorry.
When the forthcoming tip does come forth, I'll take a look.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-10-11 18:01

Message:
Logged In: YES 
user_id=113501

Latest patch is against HEAD and cleans up a few things.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-08-31 00:36

Message:
Logged In: YES 
user_id=113501

A new patch revision is forthcoming...

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-07-10 21:45

Message:
Logged In: YES 
user_id=113501

Refreshed v6 patch against current HEAD (now v7).

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-17 17:55

Message:
Logged In: YES 
user_id=113501

Refactored error message handling to be simpler and more
robust (v6).

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-13 02:01

Message:
Logged In: YES 
user_id=113501

Updated (v5) patch supports a custom error message for
script cancellation via Tcl_CancelEval and [cancel].  Also
corrected mutex locking issue with CancelEvalProc.

Here is a quick Tk example of [cancel] usage:

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

package require Tk

pack [text .clock] -side top -expand true \
        -fill both -padx 10 -pady 10

pack [button .go -padx 10 -pady 10 -text "Go" \
        -command [list goButton]] \
        -side left -padx 10 -pady 10
pack [button .cancel -padx 10 -pady 10 -text "Cancel" \
        -command [list cancelButton "clock stopped."]] \
        -side right -padx 10 -pady 10

proc goButton {args} {
  while {1} {
    catch {.clock delete 1.0 end}
    .clock insert end [clock format [clock seconds]]
    update
  }
}

proc cancelButton {msg} {
  cancel -unwind {} $msg
}

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-12 01:45

Message:
Logged In: YES 
user_id=113501

The v4 patch is basically code complete.  However, I'm still
working on the documentation and test cases for [cancel].

Quite a lot of fine tuning has been done to both the new
code and the comments.  The Tcl_CancelEval function now
accepts a new flag TCL_CANCEL_UNWIND that allows the
evaluation stack for the target interpreter to be completely
unwound in the event of the pathological test cases like:

while {1} { catch { while {1} {incr x} } }

Here are some other test cases that work correctly with the
v4 patch:

# Tcl_CancelEval after delay test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
after 30000

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

# Tcl_CancelEval vwait test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
vwait forever

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

# Tcl_CancelEval very tight loop test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
while {1} {}

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

# Tcl_CancelEval tight loop with body test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
while {1} {incr x}

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

# Tcl_CancelEval with TCL_CANCEL_UNWIND test.
# This can only be cancelled if the TCL_CANCEL_UNWIND
# flag is used with Tcl_CancelEval.  It will return 
# TCL_ERROR "eval unwound" in that case.
while {1} { catch { while {1} {incr x} } }

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

# Tcl_CancelEval with TCL_CANCEL_UNWIND slightly more 
# pathological unwind test
# returns TCL_ERROR "eval unwound" 
while {1} {
  catch { 
    while {1} {
      catch { 
        while {1} {incr x}
      } 
    } 
  } 
}

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

# Tcl_CancelEval slave interp test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
interp create foo; foo eval { while {1} {incr x} }

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

# Tcl_CancelEval [subst] test
# returns TCL_ERROR "eval cancelled" or "eval unwound" 
# based on flags passed to Tcl_CancelEval
subst {[while {1} {incr x}]}

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

# Tcl_CancelEval with TCL_CANCEL_UNWIND pathological slave 
# interp test
# returns TCL_ERROR "eval unwound"
interp create foo; foo eval {
  while {1} {
    catch { 
      while {1} { 
        catch { 
          while {1} {incr x}
        }
      }
    } 
  } 
}

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

# basic [cancel] test
# returns TCL_ERROR "eval cancelled"
cancel

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

# basic [cancel] test with "--"
# returns TCL_ERROR "eval cancelled"
cancel --

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

# basic [cancel -unwind] test
# returns TCL_ERROR "eval unwound"
cancel -unwind --

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

# [cancel] test
# returns TCL_ERROR "eval cancelled"
catch {unset foo i}
while {1} {
  incr i; lappend foo $i
  # pretend this is some complex 
  # logic or Tk button command.
  if {$i > 3} then {cancel} 
}

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

# [cancel -unwind] test
# returns TCL_ERROR "eval unwound"
catch {unset foo i}
while {1} { 
  catch { 
    while {1} { 
      incr i; lappend foo $i
      # pretend this is some complex 
      # logic or Tk button command.
      if {$i > 3} then {cancel -unwind} 
    }
  } 
}

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

# recursion test
# returns TCL_ERROR "eval cancelled"
proc foo { i } {
  if {$i > 10} then { 
    cancel 
  } else {
    return [foo [expr {$i + 1}]] 
  }
}; foo 0

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-09 02:07

Message:
Logged In: YES 
user_id=113501

Attaching updated (v3) patch that works around the
Tcl_GetMaster (bug #1502071) issue.

The previous (v2) patch demonstrates the issue.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-06 02:46

Message:
Logged In: YES 
user_id=113501

NOTE: This patch needs to be reviewed by kennykb and msofer.

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

Comment By: Joe Mistachkin (mistachkin)
Date: 2006-06-06 02:41

Message:
Logged In: YES 
user_id=113501

Fixed interp deletion issue, slave interp support, and some
issues with commands that block (after, vwait).  Tweaked docs.

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

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=310894&aid=1499394&group_id=10894

[Tcl-bugs] [ tcl-Patches-1499394 ] TIP 285: Script Cancellation with Tcl_CancelEval

The Tool Command Language implementation

[Tcl-bugs] [ tcl-Patches-1499394 ] TIP 285: Script Cancellation with Tcl_CancelEval