From 6e6b4a1829577acebe3fc07861a954f296e729c1 Mon Sep 17 00:00:00 2001
From: Dimitrios Siganos <dimitris@siganos.org>
Date: Fri, 26 Aug 2022 18:37:36 +0100
Subject: [PATCH] observer_set: do not call the observer callbacks holding the
 lock (#3922)

It unnecessarily leaves the door open for deadlocks.
---
 nano/lib/utility.hpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/nano/lib/utility.hpp b/nano/lib/utility.hpp
index b547e5324..34167a2cb 100644
--- a/nano/lib/utility.hpp
+++ b/nano/lib/utility.hpp
@@ -158,8 +158,11 @@ public:
 	}
 	void notify (T... args)
 	{
-		nano::lock_guard<nano::mutex> lock (mutex);
-		for (auto & i : observers)
+		nano::unique_lock<nano::mutex> lock (mutex);
+		auto observers_copy = observers;
+		lock.unlock ();
+
+		for (auto & i : observers_copy)
 		{
 			i (args...);
 		}