From 1db0039c505c6081f1d0d84cc24133ed6659e539 Mon Sep 17 00:00:00 2001
From: Anna Henningsen <anna@addaleax.net>
Date: Mon, 25 Sep 2017 22:53:17 +0200
Subject: src: keep track of open requests

Workers cannot shut down while requests are open, so keep a counter
that is increased whenever libuv requests are made and decreased
whenever their callback is called.

This also applies to other embedders, who may want to shut down
an `Environment` instance early.

Many thanks for Stephen Belanger for reviewing the original version of
this commit in the Ayo.js project.

Fixes: https://github.com/nodejs/node/issues/20517
Refs: https://github.com/ayojs/ayo/pull/85
PR-URL: https://github.com/nodejs/node/pull/19377
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
---
 src/util.h | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

(limited to 'src/util.h')

diff --git a/src/util.h b/src/util.h
index 7a1c6c109f..2c66104e9d 100644
--- a/src/util.h
+++ b/src/util.h
@@ -447,8 +447,16 @@ struct MallocedBuffer {
   MallocedBuffer& operator=(const MallocedBuffer&) = delete;
 };
 
-}  // namespace node
+// Test whether some value can be called with ().
+template<typename T, typename = void>
+struct is_callable : std::is_function<T> { };
+
+template<typename T>
+struct is_callable<T, typename std::enable_if<
+    std::is_same<decltype(void(&T::operator())), void>::value
+    >::type> : std::true_type { };
 
+}  // namespace node
 
 #endif  // defined(NODE_WANT_INTERNALS) && NODE_WANT_INTERNALS
 
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