Operations

evSchedule

Schedules an event that executes function f with argument a after delay t usec; t may equal 0. A handle to the event is returned, and this can be used to cancel the event at some later time. When an event fires, a new thread is created to run function f. Note that even after an event fires and a thread had been scheduled to handle it, the thread does not run until sometime after the currently executing thread gives up the processor. See Section 7 for a description of how threads are scheduled.

Event evSchedule (EvFunc f, void* a, int t)

typedef void (* EvFunc ) ( Event, void * )

Function f must be of type void and take two arguments: the first, of type Event, is a handle to the event itself and the second, of type void *, is the argument passed to evSchedule. In order to satisfy the C compiler type checking rules when accessing the arguments, function f must begin by casting its second argument to be a non-void type.

evDetach

Releases a handle to an event. As soon as f completes, the internal resources associated with the event are freed. All events should eventually be either detached or canceled to assure that system resources are released.

void evDetach (Event e)

evCancel

Cancels event e and returns EVENT_FINISHEDif the event has already happened, EVENT_RUNNINGif the event is currently running, and EVENT_CANCELLEDif the event has not run and can be guaranteed to not run. In the case where evCancel returns EVENT_RUNNING, the caller must be careful to not delete resources required by the event.

EvCancelReturn evCancel (Event e)

evIsCancelled

Returns true if an evCancel has been performed on the event. Because event handlers receive their event as the first calling argument, it is possible for a handler to check for cancellation of itself from other threads.

int evIsCancelled (Event e)

evDump

Displays a ps-style listing of x-kernel threads in x-kernel's compiled with DEBUG mode. The address of the entry function, the thread state (pending, scheduled, running, finished, or blocked), the time relevant to the thread state, and flags (detached or cancelled), are displayed for each thread controlled by x-kernel monitor. The meaning of the time entry varies according to the state. For pending threads, the time is the time until it will be scheduled; for other states it is the time the thread has spent in that state. The time is reset on each transition, i.e., it is not cumulative.

void evDump (void)