0
0
mirror of https://gitlab.nic.cz/labs/bird.git synced 2024-12-23 02:01:55 +00:00
bird/lib/event.h
Maria Matejka e91754f5b9 Event lists rewritten to a single linked list
In multithreaded environment, we need to pass messages between workers.
This is done by queuing events to their respective queues. The
double-linked list is not really useful for that as it needs locking
everywhere.

This commit rewrites the event subsystem to use a single-linked list
where events are enqueued by a single atomic instruction and the queue
is processed after atomically moving the whole queue aside.
2022-07-18 13:28:35 +02:00

89 lines
2.1 KiB
C

/*
* BIRD Library -- Event Processing
*
* (c) 1999 Martin Mares <mj@ucw.cz>
*
* Can be freely distributed and used under the terms of the GNU GPL.
*/
#ifndef _BIRD_EVENT_H_
#define _BIRD_EVENT_H_
#include "lib/resource.h"
#include "lib/locking.h"
#include <stdatomic.h>
struct birdloop;
typedef struct event {
resource r;
void (*hook)(void *);
void *data;
struct event * _Atomic next;
} event;
typedef union event_list {
struct {
event * _Atomic receiver; /* Event receive list */
event * _Atomic _executor; /* Event execute list */
const char *name;
struct birdloop *loop; /* The executor loop */
char _end[0];
};
event _sentinel; /* Sentinel node to actively detect list end */
} event_list;
extern event_list global_event_list;
extern event_list global_work_list;
event *ev_new(pool *);
void ev_run(event *);
void ev_init_list(event_list *, struct birdloop *loop, const char *name);
void ev_enqueue(event_list *, event *);
#define ev_send ev_enqueue
#define ev_send_loop(l, e) ev_send(birdloop_event_list((l)), (e))
#define ev_schedule(e) ({ ASSERT_THE_BIRD_LOCKED; if (!ev_active((e))) ev_send(&global_event_list, (e)); })
#define ev_schedule_work(e) ({ ASSERT_THE_BIRD_LOCKED; if (!ev_active((e))) ev_send(&global_work_list, (e)); })
void ev_postpone(event *);
int ev_run_list_limited(event_list *, uint);
#define ev_run_list(l) ev_run_list_limited((l), ~0)
#define LEGACY_EVENT_LIST(l) (((l) == &global_event_list) || ((l) == &global_work_list))
static inline int
ev_active(event *e)
{
return atomic_load_explicit(&e->next, memory_order_relaxed) != NULL;
}
static inline event_list *
ev_get_list(event *e)
{
/* We are looking for the sentinel node at the list end.
* After this, we have s->next == NULL */
event *s = e;
for (event *sn; sn = atomic_load_explicit(&s->next, memory_order_acquire); s = sn)
;
/* No sentinel, no list. */
if (s == e)
return NULL;
else
return SKIP_BACK(event_list, _sentinel, s);
}
static inline event*
ev_new_init(pool *p, void (*hook)(void *), void *data)
{
event *e = ev_new(p);
e->hook = hook;
e->data = data;
return e;
}
#endif