joyent/v8plus#7 v8plus should not hold the event loop open forever

*** 29,43 ****
--- 29,46 ----
      STAILQ_HEAD_INITIALIZER(_v8plus_callq);
  static pthread_mutex_t _v8plus_callq_mtx;
  static pthread_t _v8plus_uv_event_thread;
  static uv_async_t _v8plus_uv_async;
  
+ static int _v8plus_eventloop_refcount;
+ 
  typedef enum v8plus_async_call_type {
          ACT_OBJECT_CALL = 1,
          ACT_OBJECT_RELEASE,
          ACT_JSFUNC_CALL,
          ACT_JSFUNC_RELEASE,
+         ACT_EVENTLOOP_RELEASE
  } v8plus_async_call_type_t;
  
  typedef enum v8plus_async_call_flags {
          ACF_COMPLETED   = 0x01,
          ACF_NOREPLY     = 0x02
*** 119,128 ****
--- 122,134 ----
                              vac->vac_func, vac->vac_lp);
                          break;
                  case ACT_JSFUNC_RELEASE:
                          v8plus_jsfunc_rele_direct(vac->vac_func);
                          break;
+                 case ACT_EVENTLOOP_RELEASE:
+                         v8plus_eventloop_rele_direct();
+                         break;
                  }
  
                  if (vac->vac_flags & ACF_NOREPLY) {
                          /*
                           * The caller posted this event and is not sleeping
*** 302,311 ****
--- 308,360 ----
          if (uv_async_init(uv_default_loop(), &_v8plus_uv_async,
              v8plus_async_callback) != 0)
                  v8plus_panic("unable to initialise uv_async_t");
          if (pthread_mutex_init(&_v8plus_callq_mtx, NULL) != 0)
                  v8plus_panic("unable to initialise mutex");
+ 
+         /*
+          * If we do not unreference the async handle, then its mere
+          * existence will keep the event loop open forever.  If the consumer
+          * _wants_ this behaviour, they may call v8plus_eventloop_hold()
+          * from the event loop thread.
+          */
+         uv_unref((uv_handle_t *)&_v8plus_uv_async);
+ }
+ 
+ void
+ v8plus_eventloop_hold(void)
+ {
+         ++_v8plus_eventloop_refcount;
+         uv_ref((uv_handle_t *)&_v8plus_uv_async);
+ }
+ 
+ void
+ v8plus_eventloop_rele_direct(void)
+ {
+         if (--_v8plus_eventloop_refcount < 1) {
+                 _v8plus_eventloop_refcount = 0;
+                 uv_unref((uv_handle_t *)&_v8plus_uv_async);
+         }
+ }
+ 
+ void
+ v8plus_eventloop_rele(void)
+ {
+         v8plus_async_call_t *vac;
+ 
+         if (v8plus_in_event_thread() == B_TRUE) {
+                 return (v8plus_eventloop_rele_direct());
+         }
+ 
+         vac = calloc(1, sizeof (*vac));
+         if (vac == NULL)
+                 v8plus_panic("could not allocate async call structure");
+ 
+         vac->vac_type = ACT_EVENTLOOP_RELEASE;
+         vac->vac_flags = ACF_NOREPLY;
+ 
+         (void) v8plus_cross_thread_call(vac);
  }
  
  nvlist_t *
  v8plus_verror(v8plus_errno_t e, const char *fmt, va_list ap)
  {