From 1e5dcee51b6737231112268c1708be6d8a442388 Mon Sep 17 00:00:00 2001
From: Spiros Eliopoulos <seliopou@gmail.com>
Date: Fri, 3 Apr 2020 11:12:31 -0400
Subject: [PATCH] call-if-some: add Optional_thunk.call_if_some and use it

Replace calls to to `Optional_thunk.unchecked_value f ()` with
`Optional_think.call_if_some f`. Sounds safer, and if the none type ever
changes representation no call sites need to change.
---
 lib/body.ml              | 2 +-
 lib/optional_thunk.ml    | 1 +
 lib/optional_thunk.mli   | 1 +
 lib/reqd.ml              | 2 +-
 lib/server_connection.ml | 4 ++--
 5 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/lib/body.ml b/lib/body.ml
index cdbc513f..f1a13dbe 100644
--- a/lib/body.ml
+++ b/lib/body.ml
@@ -79,7 +79,7 @@ let schedule_bigstring t ?off ?len (b:Bigstringaf.t) =
 let ready_to_write t =
   let callback = t.when_ready_to_write in
   t.when_ready_to_write <- Optional_thunk.none;
-  Optional_thunk.unchecked_value callback ()
+  Optional_thunk.call_if_some callback
 
 let flush t kontinue =
   Faraday.flush t.faraday kontinue;
diff --git a/lib/optional_thunk.ml b/lib/optional_thunk.ml
index 5a8cf961..6d6d8220 100644
--- a/lib/optional_thunk.ml
+++ b/lib/optional_thunk.ml
@@ -8,4 +8,5 @@ let some f =
 
 let is_none t = t == none
 let is_some t = not (is_none t)
+let call_if_some t = t ()
 let unchecked_value t = t
diff --git a/lib/optional_thunk.mli b/lib/optional_thunk.mli
index dd36f50d..88945206 100644
--- a/lib/optional_thunk.mli
+++ b/lib/optional_thunk.mli
@@ -6,4 +6,5 @@ val some : (unit -> unit) -> t
 val is_none : t -> bool
 val is_some : t -> bool
 
+val call_if_some : t -> unit
 val unchecked_value : t -> unit -> unit
diff --git a/lib/reqd.ml b/lib/reqd.ml
index 87dbbea0..c74b4f95 100644
--- a/lib/reqd.ml
+++ b/lib/reqd.ml
@@ -92,7 +92,7 @@ let create error_handler request request_body writer response_body_buffer =
 let done_waiting when_done_waiting =
   let f = !when_done_waiting in
   when_done_waiting := Optional_thunk.none;
-  Optional_thunk.unchecked_value f ()
+  Optional_thunk.call_if_some f
 
 let request { request; _ } = request
 let request_body { request_body; _ } = request_body
diff --git a/lib/server_connection.ml b/lib/server_connection.ml
index d57b5c44..7fb9d935 100644
--- a/lib/server_connection.ml
+++ b/lib/server_connection.ml
@@ -91,7 +91,7 @@ let yield_reader t k =
 let wakeup_reader t =
   let f = t.wakeup_reader in
   t.wakeup_reader <- Optional_thunk.none;
-  Optional_thunk.unchecked_value f ()
+  Optional_thunk.call_if_some f
 ;;
 
 let on_wakeup_writer t k =
@@ -105,7 +105,7 @@ let on_wakeup_writer t k =
 let wakeup_writer t =
   let f = t.wakeup_writer in
   t.wakeup_writer <- Optional_thunk.none;
-  Optional_thunk.unchecked_value f ()
+  Optional_thunk.call_if_some f
 ;;
 
 let transfer_writer_callback t reqd =