r22661: optimize the handling of directly triggered timed events:

- if someone adds a timed_event with a zero timeval
  we now avoid serval gettimeofday() calls and the
  event handler doesn't get the current time when it's
  called, instead we also pass a zero timeval

- this also makes sure multiple timed events with a zero timeval
  are processed in the order there're added.

the little benchmark shows that processing 2000000 directly timed events
is now much faster, while avoiding syscalls at all!

> time ./evtest (with the old code)

real    0m6.388s
user    0m1.740s
sys     0m4.632s
> time ./evtest (with the new code)

real    0m1.498s
user    0m1.496s
sys     0m0.004s
metze@SERNOX:~/devel/samba/4.0/samba4-ci/source> cat evtest.c
#include <stdio.h>
#include <stdint.h>
#include <sys/time.h>
#include <talloc.h>
#include <events.h>

static void dummy_fde_handler(struct event_context *ev_ctx, struct fd_event *fde,
                              uint16_t flags, void *private_data)
{
}

static void timeout_handler(struct event_context *ev, struct timed_event *te,
                            struct timeval tval, void *private_data)
{
        uint32_t *countp = (uint32_t *)private_data;
        (*countp)++;
        if (*countp > 2000000) exit(0);
        event_add_timed(ev, ev, tval, timeout_handler, countp);
}

int main(void)
{
        struct event_context *ev;
        struct timeval tval =  { 0, 0 };
        uint32_t count = 0;
        ev = event_context_init(NULL);
        event_add_fd(ev, ev, 0, 0, dummy_fde_handler, NULL);
        event_add_timed(ev, ev, tval, timeout_handler, &count);
        return event_loop_wait(ev);
}
(This used to be commit 4db64b4ce2320b88d648078cbf86385f6fb44f1f)

1 files changed, 3 insertions, 4 deletions

diff --git a/source4/lib/events/events_select.c b/source4/lib/events/events_select.c
index 291ddbde2b..b2f9cacf5f 100644
--- a/source4/lib/events/events_select.c
+++ b/source4/lib/events/events_select.c
@@ -218,7 +218,8 @@ static int select_event_loop_select(struct select_event_context *select_ev, stru
 	}
 
 	if (selrtn == 0 && tvalp) {
-		common_event_loop_timer(select_ev->ev);
+		/* we don't care about a possible delay here */
+		common_event_loop_timer_delay(select_ev->ev);
 		return 0;
 	}
 
@@ -252,10 +253,8 @@ static int select_event_loop_once(struct event_context *ev)
 		 					   struct select_event_context);
 	struct timeval tval;
 
-	tval = common_event_loop_delay(ev);
-
+	tval = common_event_loop_timer_delay(ev);
 	if (timeval_is_zero(&tval)) {
-		common_event_loop_timer(ev);
 		return 0;
 	}