From 059ee8a1d533cd0ebc26cc8b8f1e2ec373718443 Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Thu, 15 Jun 2023 10:35:41 -0400
Subject: [PATCH] add `Pool.num_tasks`

---
 src/pool.ml  | 7 ++++++-
 src/pool.mli | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/src/pool.ml b/src/pool.ml
index 8cb1912e..87257f7d 100644
--- a/src/pool.ml
+++ b/src/pool.ml
@@ -51,7 +51,12 @@ let run (self : t) (f : task) : unit =
   | Exit -> ()
   | Bb_queue.Closed -> raise Shutdown
 
-let size self = Array.length self.threads
+let[@inline] size self = Array.length self.threads
+
+let num_tasks (self : t) : int =
+  let n = ref 0 in
+  Array.iter (fun q -> n := !n + Bb_queue.size q) self.qs;
+  !n
 
 exception Got_task of task
 
diff --git a/src/pool.mli b/src/pool.mli
index d2e8a72c..3fc6c983 100644
--- a/src/pool.mli
+++ b/src/pool.mli
@@ -52,6 +52,11 @@ val create :
 val size : t -> int
 (** Number of threads *)
 
+val num_tasks : t -> int
+(** Current number of tasks. This is at best a snapshot, useful for metrics
+    and debugging.
+    @since 0.2 *)
+
 val shutdown : t -> unit
 (** Shutdown the pool and wait for it to terminate. Idempotent. *)