From fc69b5e7aec6877cb39d5231556b35053342c01e Mon Sep 17 00:00:00 2001
From: Dennis Klein <d.klein@gsi.de>
Date: Wed, 10 Jun 2026 16:12:35 +0200
Subject: [PATCH] refactor: compile channel name validation regex only once

- the pattern is constant; compiling it on every Validate() call is
  wasted work and, when channels are validated from multiple threads,
  needlessly exercises libstdc++'s lazily-populated ctype caches
---
 fairmq/Channel.cxx | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fairmq/Channel.cxx b/fairmq/Channel.cxx
index b3e3207c..5fa04978 100644
--- a/fairmq/Channel.cxx
+++ b/fairmq/Channel.cxx
@@ -181,7 +181,8 @@ try {
 
     // validate channel name
     smatch m;
-    if (regex_search(fName, m, regex(R"([^a-zA-Z0-9\-_\[\]#])"))) {
+    static regex const invalidName(R"([^a-zA-Z0-9\-_\[\]#])");
+    if (regex_search(fName, m, invalidName)) {
         ss << "INVALID";
         LOG(debug) << ss.str();
         LOG(error) << "channel name contains illegal character: '" << m.str(0) << "', allowed characters are: a-z, A-Z, 0-9, -, _, [, ], #";