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openmpi/opal/class/opal_hotel.c
Jeff Squyres 270cc11156 opal hotel: only delete events that have not yet fired
The eviction callback, for convenience (and to avoid code
duplication), use to call opal_hotel_checkout().  However,
opal_hotel_checkout() deletes the eviction event -- which is fine to
do when opal_hotel_checkout() is invoked by the application.  But when
it's invoked by the same event that it's deleting, it can cause Bad
Things to happen.

For simplicity, instead of invoking opal_hotel_checkout() from the
eviction callback, just duplicate the checkout logic into the eviction
callback function (and skip the delete-the-evict-event part).

For good measure, put a comment in all three places where the checkout
logic occurs (because it's inlined): don't change this logic without
changing all 3 places.

Finally, also add a line in the docs for opal_hotel_init() warning
users from calling opal_hotel_checkout() from their eviction
callback.
2016-01-13 10:59:06 -08:00

141 строка
4.2 KiB
C

/*
* Copyright (c) 2012-2016 Cisco Systems, Inc. All rights reserved.
* Copyright (c) 2012 Los Alamos National Security, LLC. All rights reserved
* Copyright (c) 2015 Intel, Inc. All rights reserved
* $COPYRIGHT$
*
* Additional copyrights may follow
*
* $HEADER$
*/
#include "opal_config.h"
#include <stdio.h>
#include <stddef.h>
#include "opal/mca/event/event.h"
#include "opal/class/opal_hotel.h"
static void local_eviction_callback(int fd, short flags, void *arg)
{
opal_hotel_room_eviction_callback_arg_t *eargs =
(opal_hotel_room_eviction_callback_arg_t*) arg;
void *occupant = eargs->hotel->rooms[eargs->room_num].occupant;
/* Remove the occurpant from the room.
Do not change this logic without also changing the same logic
in opal_hotel_checkout() and
opal_hotel_checkout_and_return_occupant(). */
opal_hotel_t *hotel = eargs->hotel;
opal_hotel_room_t *room = &(hotel->rooms[eargs->room_num]);
room->occupant = NULL;
hotel->last_unoccupied_room++;
assert(hotel->last_unoccupied_room < hotel->num_rooms);
hotel->unoccupied_rooms[hotel->last_unoccupied_room] = eargs->room_num;
/* Invoke the user callback to tell them that they were evicted */
hotel->evict_callback_fn(hotel,
eargs->room_num,
occupant);
}
int opal_hotel_init(opal_hotel_t *h, int num_rooms,
opal_event_base_t *evbase,
uint32_t eviction_timeout,
int eviction_event_priority,
opal_hotel_eviction_callback_fn_t evict_callback_fn)
{
int i;
/* Bozo check */
if (num_rooms <= 0 ||
NULL == evict_callback_fn) {
return OPAL_ERR_BAD_PARAM;
}
h->num_rooms = num_rooms;
h->evbase = evbase;
h->eviction_timeout.tv_usec = eviction_timeout % 1000000;
h->eviction_timeout.tv_sec = eviction_timeout / 1000000;
h->evict_callback_fn = evict_callback_fn;
h->rooms = (opal_hotel_room_t*)malloc(num_rooms * sizeof(opal_hotel_room_t));
if (NULL != evict_callback_fn) {
h->eviction_args =
(opal_hotel_room_eviction_callback_arg_t*)malloc(num_rooms * sizeof(opal_hotel_room_eviction_callback_arg_t));
}
h->unoccupied_rooms = (int*) malloc(num_rooms * sizeof(int));
h->last_unoccupied_room = num_rooms - 1;
for (i = 0; i < num_rooms; ++i) {
/* Mark this room as unoccupied */
h->rooms[i].occupant = NULL;
/* Setup this room in the unoccupied index array */
h->unoccupied_rooms[i] = i;
/* Setup the eviction callback args */
h->eviction_args[i].hotel = h;
h->eviction_args[i].room_num = i;
/* Create this room's event (but don't add it) */
if (NULL != h->evbase) {
opal_event_set(h->evbase,
&(h->rooms[i].eviction_timer_event),
-1, 0, local_eviction_callback,
&(h->eviction_args[i]));
/* Set the priority so it gets serviced properly */
opal_event_set_priority(&(h->rooms[i].eviction_timer_event),
eviction_event_priority);
}
}
return OPAL_SUCCESS;
}
static void constructor(opal_hotel_t *h)
{
h->num_rooms = 0;
h->evbase = NULL;
h->eviction_timeout.tv_sec = 0;
h->eviction_timeout.tv_usec = 0;
h->evict_callback_fn = NULL;
h->rooms = NULL;
h->eviction_args = NULL;
h->unoccupied_rooms = NULL;
h->last_unoccupied_room = -1;
}
static void destructor(opal_hotel_t *h)
{
int i;
/* Go through all occupied rooms and destroy their events */
if (NULL != h->evbase) {
for (i = 0; i < h->num_rooms; ++i) {
if (NULL != h->rooms[i].occupant) {
opal_event_del(&(h->rooms[i].eviction_timer_event));
}
}
}
if (NULL != h->rooms) {
free(h->rooms);
}
if (NULL != h->eviction_args) {
free(h->eviction_args);
}
if (NULL != h->unoccupied_rooms) {
free(h->unoccupied_rooms);
}
}
OBJ_CLASS_INSTANCE(opal_hotel_t,
opal_object_t,
constructor,
destructor);