Merge pull request #141 from bikallem/stream-is_empty

lib_eio: implement Stream.is_empty

lib_eio/eio.mli

@@ -308,6 +308,12 @@ module Stream : sig
       it returns [None] if the stream is empty rather than waiting.
       Note that if another domain may add to the stream then a [None]
       result may already be out-of-date by the time this returns. *)
+
+  val length : 'a t -> int
+  (** [length t] returns the number of items currently in [t]. *)
+
+  val is_empty : 'a t -> bool
+  (** [is_empty t] is [length t = 0]. *)
 end
 
 (** Cancelling other fibres when an exception occurs. *)

lib_eio/stream.ml

@@ -118,3 +118,11 @@ let take_nonblocking t =
     end;
     Mutex.unlock t.mutex;
     Some v
+
+let length t =
+  Mutex.lock t.mutex;
+  let len = Queue.length t.items in
+  Mutex.unlock t.mutex;
+  len
+
+let is_empty t = (length t = 0)