Tcl Library Source Code

Okay! So when defining cron handlers, you cannot nest them:
=========================================================
#! /usr/bin/tclsh
package require cron

# Done timer
::cron::in done 20 {incr ::done}

# Ten second timer
::cron::in ten_seconds 10 {
    puts "10 second timer triggered!"
    # Nested timer
    ::cron::in five_seconds 5 {
        puts "5 seconds triggered!"
    }
}

vwait ::done
=========================================================
Gives us this output:
=========================================================
second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
10 second timer triggered!
5 seconds triggered!
[hooga@samserv01 ~]$
=========================================================

If you instead turn the inner cron statement to an after Xms y, it works as expected:
=========================================================
#! /usr/bin/tclsh
package require cron

# Done timer
::cron::in done 20 {incr ::done}

# Ten second timer
::cron::in ten_seconds 10 {
    puts "10 second timer triggered!"
    # Nested timer
    after 5000 {
        puts "After 5 seconds triggered!"
    }
}

vwait ::done
=========================================================

=========================================================
[hooga@samserv01 ~]$ ./cron.tcl
10 second timer triggered!
After 5 seconds triggered!
[hooga@samserv01 ~]$
=========================================================

Revision [c4c84d1854] claims to be a fix.
If so, should this ticket not be closed ?

I have fixed the bug in checkin [c4c84d18547f70193d0cfc9ff434aebf20d1300c].

The trick was to add a lock variable that is true while periodic task scripts are actively processed. When
true, this flag turns cron::wake into a noop. (cron::wake is intended to immediately rouse the system
when a new task hits the manager.)

Now when I run the test script I get:

=========================================================
baccarat:cron seandeelywoods$ tclsh inf.tcl 
10 second timer triggered!
5 seconds triggered!
=========================================================

Well that’s no fun at all. I’ll inject a mutex to at least throw an error if someone attempts that in the future.

Thanks for catching it!

—Sean