Converting the former BFD loop to a universal IO loop and protocol loop.

There is a simple universal IO loop, taking care of events, timers and
sockets. Primarily, one instance of a protocol should use exactly one IO
loop to do all its work, as is now done in BFD.

Contrary to previous versions, the loop is now launched and cleaned by
the nest/proto.c code, allowing for a protocol to just request its own
loop by setting the loop's lock order in config higher than the_bird.

It is not supported nor checked if any protocol changed the requested
lock order in reconfigure. No protocol should do it at all.

1 files changed, 79 insertions, 52 deletions

diff --git a/lib/event.c b/lib/event.c
index 273447e0..6c5c8b14 100644
--- a/lib/event.c
+++ b/lib/event.c
@@ -19,8 +19,14 @@
  * events in them and explicitly ask to run them.
  */
 
+#undef LOCAL_DEBUG
+
 #include "nest/bird.h"
 #include "lib/event.h"
+#include "lib/locking.h"
+#include "lib/io-loop.h"
+
+extern _Thread_local struct coroutine *this_coro;
 
 event_list global_event_list;
 event_list global_work_list;
@@ -28,11 +34,16 @@ event_list global_work_list;
 inline void
 ev_postpone(event *e)
 {
+  event_list *el = e->list;
+  if (!el)
+    return;
+
+  ASSERT_DIE(birdloop_inside(el->loop));
+
+  LOCK_DOMAIN(event, el->lock);
   if (ev_active(e))
-    {
-      rem_node(&e->n);
-      e->n.next = NULL;
-    }
+    rem_node(&e->n);
+  UNLOCK_DOMAIN(event, el->lock);
 }
 
 static void
@@ -95,40 +106,25 @@ ev_run(event *e)
  * list @l which can be run by calling ev_run_list().
  */
 inline void
-ev_enqueue(event_list *l, event *e)
+ev_send(event_list *l, event *e)
 {
-  ev_postpone(e);
-  add_tail(l, &e->n);
-}
+  DBG("ev_send(%p, %p)\n", l, e);
+  ASSERT_DIE(e->hook);
+  ASSERT_DIE(!e->list || (e->list == l) || (e->list->loop == l->loop));
 
-/**
- * ev_schedule - schedule an event
- * @e: an event
- *
- * This function schedules an event by enqueueing it to a system-wide
- * event list which is run by the platform dependent code whenever
- * appropriate.
- */
-void
-ev_schedule(event *e)
-{
-  ev_enqueue(&global_event_list, e);
-}
+  e->list = l;
 
-/**
- * ev_schedule_work - schedule a work-event.
- * @e: an event
- *
- * This function schedules an event by enqueueing it to a system-wide work-event
- * list which is run by the platform dependent code whenever appropriate. This
- * is designated for work-events instead of regular events. They are executed
- * less often in order to not clog I/O loop.
- */
-void
-ev_schedule_work(event *e)
-{
-  if (!ev_active(e))
-    add_tail(&global_work_list, &e->n);
+  LOCK_DOMAIN(event, l->lock);
+  if (enlisted(&e->n))
+  {
+    UNLOCK_DOMAIN(event, l->lock);
+    return;
+  }
+
+  add_tail(&l->events, &e->n);
+  UNLOCK_DOMAIN(event, l->lock);
+
+  birdloop_ping(l->loop);
 }
 
 void io_log_event(void *hook, void *data);
@@ -142,35 +138,64 @@ void io_log_event(void *hook, void *data);
 int
 ev_run_list(event_list *l)
 {
+  const _Bool legacy = LEGACY_EVENT_LIST(l);
+
+  if (legacy)
+    ASSERT_THE_BIRD_LOCKED;
+
   node *n;
-  list tmp_list;
 
+  list tmp_list;
   init_list(&tmp_list);
-  add_tail_list(&tmp_list, l);
-  init_list(l);
+
+  /* Move the event list contents to a local list to avoid executing repeatedly added events */
+  LOCK_DOMAIN(event, l->lock);
+  add_tail_list(&tmp_list, &l->events);
+  init_list(&l->events);
+  UNLOCK_DOMAIN(event, l->lock);
+
   WALK_LIST_FIRST(n, tmp_list)
     {
       event *e = SKIP_BACK(event, n, n);
 
-      /* This is ugly hack, we want to log just events executed from the main I/O loop */
-      if ((l == &global_event_list) || (l == &global_work_list))
+      if (legacy)
+      {
+	/* The legacy way of event execution */
 	io_log_event(e->hook, e->data);
-
-      ev_run(e);
+	ev_postpone(e);
+	e->hook(e->data);
+      }
+      else
+      {
+	// io_log_event(e->hook, e->data); /* TODO: add support for event logging in other io loops */
+	ASSERT_DIE(e->list == l);
+	LOCK_DOMAIN(event, l->lock);
+	rem_node(&e->n);
+	UNLOCK_DOMAIN(event, l->lock);
+	e->hook(e->data);
+      }
     }
 
-  return !EMPTY_LIST(*l);
+  LOCK_DOMAIN(event, l->lock);
+  int repeat = ! EMPTY_LIST(l->events);
+  UNLOCK_DOMAIN(event, l->lock);
+  return repeat;
 }
 
 int
 ev_run_list_limited(event_list *l, uint limit)
 {
+  ASSERT_DIE(LEGACY_EVENT_LIST(l));
+  ASSERT_THE_BIRD_LOCKED;
+
   node *n;
   list tmp_list;
 
+  LOCK_DOMAIN(event, l->lock);
   init_list(&tmp_list);
-  add_tail_list(&tmp_list, l);
-  init_list(l);
+  add_tail_list(&tmp_list, &l->events);
+  init_list(&l->events);
+  UNLOCK_DOMAIN(event, l->lock);
 
   WALK_LIST_FIRST(n, tmp_list)
     {
@@ -179,21 +204,23 @@ ev_run_list_limited(event_list *l, uint limit)
       if (!limit)
 	break;
 
-      /* This is ugly hack, we want to log just events executed from the main I/O loop */
-      if ((l == &global_event_list) || (l == &global_work_list))
-	io_log_event(e->hook, e->data);
+      io_log_event(e->hook, e->data);
 
       ev_run(e);
       limit--;
     }
 
+  LOCK_DOMAIN(event, l->lock);
   if (!EMPTY_LIST(tmp_list))
   {
     /* Attach new items after the unprocessed old items */
-    add_tail_list(&tmp_list, l);
-    init_list(l);
-    add_tail_list(l, &tmp_list);
+    add_tail_list(&tmp_list, &l->events);
+    init_list(&l->events);
+    add_tail_list(&l->events, &tmp_list);
   }
 
-  return !EMPTY_LIST(*l);
+  int repeat = ! EMPTY_LIST(l->events);
+  UNLOCK_DOMAIN(event, l->lock);
+
+  return repeat;
 }