event_queue.c File Reference

Event queue implementatino. More...

Functions
void	event_queue_init (struct event_queue *q, struct waitset *waitset, enum event_queue_mode mode)
	Initialise a new event queue. More...
void	event_queue_add (struct event_queue *q, struct event_queue_node *qn, struct event_closure event)
	Add a new event to an event queue. More...
errval_t	event_queue_cancel (struct event_queue *q, struct event_queue_node *qn)
	Cancel an event previously added to an event queue. More...
errval_t	event_queue_flush (struct event_queue *q)
	Flush all pending events from the event queue. More...
errval_t	event_queue_trigger (struct event_queue *q)
	Trigger the next event on a queue which is operating in one-shot mode. More...

Detailed Description

Event queue implementatino.

This code implements a thread-safe queue of pending events which are serviced by a single waitset.

[!] WARNING: current realization of event queues is unsuitable for cross-core operation. Crux of the issue: trigger channel for waitset belonging to another core but waitsets are assumed to be local to a dispatcher.

Example scenario:

• Consumer C (on core 0) calls get_next_event and blocks on ws->waiting_threads.
• Producer P (on core 1) invokes event_queue_add which in turn triggers channel. P disables its dispatcher, unblocks a thread and C is returned. Code assumes remote wakeup should not occur but C is on core 0.

For further details see: https://lists.inf.ethz.ch/mailman/private/barrelfish/2013/002746.html

Function Documentation

void event_queue_add	(	struct event_queue *	q,
		struct event_queue_node *	qn,
		struct event_closure	event
	)

Add a new event to an event queue.

Parameters

q	Event queue
qn	Storage for queue node (uninitialised)
event	Event closure

errval_t event_queue_cancel	(	struct event_queue *	q,
		struct event_queue_node *	qn
	)

Cancel an event previously added to an event queue.

Parameters

q	Event queue
qn	Queue node which was previously added to #q by event_queue_add()

errval_t event_queue_flush

(

struct event_queue *

q

)

Flush all pending events from the event queue.

Parameters

q	Event queue.

void event_queue_init	(	struct event_queue *	q,
		struct waitset *	waitset,
		enum event_queue_mode	mode
	)

Initialise a new event queue.

Parameters

q	Storage for event queue
waitset	Waitset that will service the queue
mode	Operating mode for the queue

errval_t event_queue_trigger

(

struct event_queue *

q

)

Trigger the next event on a queue which is operating in one-shot mode.

Must not be called before the previously-triggered event has run.

Parameters

q	Event queue