Reimplement the event queue in event.c using klist.h

 - Add a new macro to klist.h: kl_empty()

   The whole point of abstract data structures is to avoid reimplementing
   common actions. The emptiness test seems to be such an action.

 - Add a new function attribute to func_attr.h: FUNC_ATTR_UNUSED

   Some of the many functions created by the macros in klist.h may end up not
   being used. Unused functions cause compilation errors as we compile with
   -Werror. To mark those functions as possibly unused we can use the
   FUNC_ATTR_UNUSED now.

 - Pass `Event` by value

   `Event` is such a small struct that I don't think we should allocate heap space
   and pass it by reference. Let's use the stack and memory cache in our favor
   passing it by value.

1 files changed, 8 insertions, 10 deletions

diff --git a/src/os/signal.c b/src/os/signal.c
index 2ac31060aa..503269208d 100644
--- a/src/os/signal.c
+++ b/src/os/signal.c
@@ -67,12 +67,11 @@ void signal_accept_deadly()
   rejecting_deadly = false;
 }
 
-void signal_handle(Event *event)
+void signal_handle(Event event)
 {
-  int signum = *(int *)event->data;
+  int signum = *(int *)event.data;
 
-  free(event->data);
-  free(event);
+  free(event.data);
 
   switch (signum) {
     case SIGINT:
@@ -148,8 +147,6 @@ static void deadly_signal(int signum)
 
 static void signal_cb(uv_signal_t *handle, int signum)
 {
-  Event *event;
-
   if (rejecting_deadly) {
     if (signum == SIGINT) {
       got_int = true;
@@ -158,9 +155,10 @@ static void signal_cb(uv_signal_t *handle, int signum)
     return;
   } 
 
-  event = (Event *)xmalloc(sizeof(Event));
-  event->type = kEventSignal;
-  event->data = xmalloc(sizeof(int));
-  *(int *)event->data = signum;
+  Event event = {
+    .type = kEventSignal,
+    .data = xmalloc(sizeof(int))
+  };
+  *(int *)event.data = signum;
   event_push(event);
 }