From: Matthias Maier <tamiko@43-1.org>
Date: Wed, 27 May 2020 04:18:17 +0000 (-0500)
Subject: add a comment
X-Git-Tag: v9.3.0-rc1~1535^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6142289d4087030cd5e64154847aaf897fac17dc;p=dealii.git

add a comment
---

diff --git a/include/deal.II/base/thread_local_storage.h b/include/deal.II/base/thread_local_storage.h
index 2c96321bb3..59cdd3d908 100644
--- a/include/deal.II/base/thread_local_storage.h
+++ b/include/deal.II/base/thread_local_storage.h
@@ -230,6 +230,11 @@ namespace Threads
 
     /**
      * A mutex to guard insertion into the data object.
+     *
+     * We use a std::shared_timed_mutex (or std::shared_mutex if available)
+     * here to be able to use std::unique_lock and std::shared_lock for a
+     * readers-writer lock
+     * (https://en.wikipedia.org/wiki/Readers%E2%80%93writer_lock).
      */
 #  ifdef DEAL_II_HAVE_CXX17
     std::shared_mutex insertion_mutex;