timeout

smlTimeout.timeout : real -> ('a -> 'b) -> 'a -> 'b

Interrupts a function f after a time limit.

In case the limit is reached, the exception FunctionTimeout is raised, otherwise it behaves in the same way as a call to “f” on its argument.

Failure

Fails when the call to f exceeds the time limit or if f fails.

Example

> load "smlTimeout"; open smlTimeout;
val it = (): unit

> timeout 0.1 (fn (x:int) => (raise Match):int) 5;
Exception- Match raised

> timeout 0.2 OS.Process.sleep (Time.fromReal 2.0);
Exception- FunctionTimeout raised

> timeout 1.0 (fn x => x) 5;
val it = 5: int

Comments

Relies on a conditional variable to decide if and when to send an Interrupt signal to the worker thread in which the function f is called. In the case an interrupt is needed, a bit of time is given to the function f to catch the Interrupt and return a result. This last step has been implemented with a busy waiting loop that has experimentally been determined to be more efficient than relying on an additional condition variable.