17.2.2.2 Scheduler

Bigloo function: make-scheduler [envs]

Creates a new scheduler. The optional arguments envs are fair thread environments which will be defined in forthcoming Bigloo releases.

Bigloo function: scheduler? obj

Returns #t if obj is a scheduler. Otherwise returns #f.

Bigloo function: current-scheduler

Returns the current scheduler. The current scheduler is the scheduler used in the last call to scheduler-react! or scheduler-start!. It always exists a current scheduler. That is, it is optional for an application to create a scheduler.

Bigloo function: scheduler-react! [scheduler]

Executes all the treads started (see thread-start!, Section Thread) in the scheduler until all the threads are blocked. A thread is blocked if the has explicitly yield the processor (thread-yield! and thread-sleep!) or because it is waiting a signal (thread-await!). A thread can be selected several times during the same reaction. The function scheduler-react! returns a symbol denoting the state of the scheduler. The possible states are:

• ready The Scheduler is ready to execute some threads.
• done All the threads started in the scheduler have terminated.
• await All the threads started in the scheduler are waiting for a signal.

An invocation of scheduler-react! is called a reaction.

Bigloo function: scheduler-start! [arg [scheduler]]

Executes scheduler-react! as long as the scheduler is not done. If the optional argument scheduler is not provided, scheduler-start! uses the current scheduler (see current-scheduler). The optional arg can either be:

• An integer standing for the number of times scheduler-react! must be called.
• A procedure f of one argument. The procedure f is invoked after each reaction. It is passed a value i which is the iteration number of the scheduler. The reactions of the scheduler are stopped when f returns #f.

(let* ((s (make-scheduler)) (t (make-thread (lambda () (let loop ((n 0)) (display n) (thread-yield!) (loop (+ 1 n))))))) (scheduler-start! 10 s)) -| 0123456789 (let* ((s (make-scheduler)) (t (make-thread (lambda () (let loop ((n 0)) (display n) (thread-yield!) (loop (+ 1 n))))))) (scheduler-start! (lambda (i) (read-char)) s)) -| 0123456789

Bigloo function: scheduler-terminate! [scheduler]

Terminates all the threads in scheduler.

Bigloo function: scheduler-instant [scheduler]

Returns the current reaction number of scheduler. The reaction number is the number of times scheduler-react! has been invoked passing scheduler as argument.