# HG changeset patch
# User Markus Mützel <markus.muetzel@gmx.de>
# Date 1627657556 -7200
# Node ID 2420f8f62ebe58ec644fbc4f23835d87faa87ce0
# Parent  6a8642d310c851792778a51120c162d2a7c07df5
dlmread: Improve performance on platforms with slow setlocale (bug #59702).

* libinterp/corefcn/dlmread.cc (Fdlmread): Set locale to "C" for the duration of
  reading floating point values from the input stream.

diff -r 6a8642d310c8 -r 2420f8f62ebe libinterp/corefcn/dlmread.cc
--- a/libinterp/corefcn/dlmread.cc	Thu Jul 29 20:43:13 2021 -0400
+++ b/libinterp/corefcn/dlmread.cc	Fri Jul 30 17:05:56 2021 +0200
@@ -30,6 +30,7 @@
 #  include "config.h"
 #endif
 
+#include <clocale>
 #include <cmath>
 #include <cctype>
 #include <fstream>
@@ -331,6 +332,15 @@
         }
     }
 
+  // Set "C" locale for the remainder of this function to avoid the performance
+  // panelty of frequently switching the locale when reading floating point
+  // values from the stream.
+  char *prev_locale = std::setlocale (LC_ALL, nullptr);
+  std::string old_locale (prev_locale ? prev_locale : "");
+  std::setlocale (LC_ALL, "C");
+  octave::unwind_action act
+    ([old_locale] () { std::setlocale (LC_ALL, old_locale.c_str ()); });
+
   std::string line;
 
   // Skip the r0 leading lines