These activities enable asynchronous programming. send() broadcasts a signal or a list of signals. Arrivals can subscribe to signals and (optionally) assign a handler with trap(). Note that, while inside a batch, all the signals subscribed before entering the batch are ignored. Upon a signal reception, the arrival stops the current activity and executes the handler (if provided). Then, the execution returns to the activity following the point of the interruption. untrap() can be used to unsubscribe from signals. wait() blocks until a signal is received.

send(.trj, signals, delay = 0)

trap(.trj, signals, handler = NULL, interruptible = TRUE)

untrap(.trj, signals)




the trajectory object.


signal or list of signals, accepts either a string, a list of strings or a callable object (a function) which must return a string or a list of strings.


optional timeout to trigger the signals, accepts either a numeric or a callable object (a function) which must return a numeric.


optional trajectory object to handle a signal received.


whether the handler can be interrupted by signals.


Returns the trajectory object.

See also


## block, signal and continue with a handler signal <- "you shall pass" t_blocked <- trajectory() %>% trap( signal, trajectory() %>% log_("executing the handler")) %>% log_("waiting...") %>% wait() %>% log_("continuing!") t_signaler <- trajectory() %>% log_(signal) %>% send(signal) simmer() %>% add_generator("blocked", t_blocked, at(0)) %>% add_generator("signaler", t_signaler, at(5)) %>% run() %>% invisible
#> 0: blocked0: waiting... #> 5: signaler0: you shall pass #> 5: blocked0: executing the handler #> 5: blocked0: continuing!
## handlers can be interrupted, unless interruptible=FALSE t_worker <- trajectory() %>% trap( signal, handler = trajectory() %>% log_("ok, I'm packing...") %>% timeout(1)) %>% log_("performing a looong task...") %>% timeout(100) %>% log_("and I'm leaving!") simmer() %>% add_generator("worker", t_worker, at(0)) %>% add_generator("signaler", t_signaler, at(5, 5.5)) %>% run() %>% invisible
#> 0: worker0: performing a looong task... #> 5: signaler0: you shall pass #> 5: worker0: ok, I'm packing... #> 5.5: signaler1: you shall pass #> 5.5: worker0: ok, I'm packing... #> 6.5: worker0: and I'm leaving!