Add the scaffolding for destroying waiters, now I just need to make it

also work.

bin/varnishd/waiter/cache_waiter.c

@@ -112,12 +112,27 @@ Wait_New(waiter_handle_f *func, volatile double *tmo)
 	Lck_Lock(&wait_mtx);
 	VTAILQ_INSERT_TAIL(&waiters, w, list);
 	nwaiters++;
+
+	/* We assume all waiters either use pipes or don't use pipes */
 	if (w->pipes[1] >= 0 && nwaiters == 1)
 		AZ(pthread_create(&wait_thr, NULL, wait_poker_thread, NULL));
 	Lck_Unlock(&wait_mtx);
 	return (w);
 }
 
+void
+Wait_Destroy(struct waiter **wp)
+{
+	struct waiter *w;
+
+	AN(wp);
+	w = *wp;
+	*wp = NULL;
+	CHECK_OBJ_NOTNULL(w, WAITER_MAGIC);
+	AN(w->impl->fini);
+	w->impl->fini(w);
+}
+
 void
 Wait_UsePipe(struct waiter *w)
 {

bin/varnishd/waiter/waiter.h

@@ -58,6 +58,7 @@ typedef void waiter_handle_f(struct waited *, enum wait_event, double now);
 /* cache_waiter.c */
 int Wait_Enter(const struct waiter *, struct waited *);
 struct waiter *Wait_New(waiter_handle_f *, volatile double *timeout);
+void Wait_Destroy(struct waiter **);
 const char *Wait_GetName(void);
 void Wait_Init(void);
 

bin/varnishd/waiter/waiter_priv.h

@@ -50,6 +50,7 @@ struct waiter {
 };
 
 typedef void waiter_init_f(struct waiter *);
+typedef void waiter_fini_f(struct waiter *);
 typedef int waiter_pass_f(void *priv, struct waited *);
 typedef void waiter_inject_f(const struct waiter *, struct waited *);
 typedef void waiter_evict_f(const struct waiter *, struct waited *);
@@ -57,6 +58,7 @@ typedef void waiter_evict_f(const struct waiter *, struct waited *);
 struct waiter_impl {
 	const char		*name;
 	waiter_init_f		*init;
+	waiter_fini_f		*fini;
 	waiter_pass_f		*pass;
 	waiter_inject_f		*inject;
 	waiter_evict_f		*evict;