job(n) Tnm Tcl Extension job(n)_________________________________________________________________NAMEjob - Invoke Tcl procedures at regular intervals.
_________________________________________________________________DESCRIPTION
The job command provides a convenient mechanism to imple-
ment Tcl procedures that are invoked at regular intervals.
Jobs are activated from the Tcl event loop. Every job can
have arbitrary attributes to store job specific state
information between two invocations. These attributes help
to avoid global variables in order to keep the Tcl name-
space clean.
JOB COMMAND
The job command allows to create new jobs and to wait for
jobs to complete. The job command can also be used to
retrieve status information from the job scheduler.
job create [option value ...]
The job create command creates a new job object.
The options can be used to configure the behaviour
of the new job. See the configure command below for
the details.
job current
The job current command returns the name of the
currently running job. An empty string is returned
if no job is running.
job info
The job info command returns a list of all job
names. The list will be empty if there are no jobs
known in this Tcl interpreter.
job schedule
The job schedule command invoke the scheduler. This
is usually done automatically from the event loop.
This command may be used during long computations
since the scheduler is not preemptive. Note, this
command can cause arbitrary side effects and should
be used with care.
job wait
The job wait command blocks until all existing jobs
have been finished. The command will wait
infinitely if there is at least one job left.
Events are processed while waiting for the jobs to
finish which can have arbitrary side effects.
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job(n) Tnm Tcl Extension job(n)JOB INSTANCE COMMAND
Every job is represented by a job object command which
allows to manipulate the job.
job# attribute [name [value]]
The job# attribute command allows to save job spe-
cific data in job attributes. If called without any
arguments, all existing attribute names for this
job will be returned. If called with a name argu-
ment, the current value of the attribute will be
returned. Non-existing attributes do not produce an
error. Instead, an empty string is returned. Call-
ing the option with a name and a value causes the
value to be saved in the job attribute.
job# cget option
The job# cget command returns the current value of
a configuration option. See the description of sup-
ported options below.
job# configure [option value ...]
The job# configure command manipulates configura-
tion options. See the description of supported
options below. A list describing all current
options is returns if the options argument is miss-
ing.
job# destroy
The job# destroy command destroys the job object.
This command forces the object to change into the
expired state. The scheduler will cleanup this
object the next time it is active.
job# wait
The job# wait command blocks and processes events
until the current job changes into the expired
state.
JOB OPTIONS
Every job has associated configuration options which con-
trol when a job is activated and which Tcl command is
bound to the job.
-command command
The -command option defines the Tcl command that is
evaluated whenever the job is activated.
-interval time
The -interval option defines the time interval
between two job activations in milliseconds.
-iterations number
The -iterations option defines the total number of
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job(n) Tnm Tcl Extension job(n)
times that a job is activated. If this value
reaches 0, the job will change its state to
expired. Note, if the iterations options is never
used, it will also have the value 0 but nothing
special happens to the job object.
-status state
The -status option provides access to the current
job state. A job is always in one of the states
waiting, suspended, running and expired. A job in
the expired state will be removed from the system
once the scheduler gets activated again. Suspended
jobs are not activated by the job scheduler. A sus-
pended job can be resumed by changing its state to
running.
-time time
The -time option returns the number of milliseconds
until this job is activated the next time. This
option is read-only.
SEE ALSOscotty(1), Tnm(n), Tcl(n)AUTHORS
Juergen Schoenwaelder <schoenw@cs.utwente.nl>
Tnm 3
