Output newlines for each progress indicator when not on a tty.

include/util/isatty.hpp

@@ -0,0 +1,32 @@
+#ifndef ISATTY_HPP
+#define ISATTY_HPP
+
+// For isatty()
+#if defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
+#include <unistd.h>
+#else
+#ifdef WIN32
+#include <io.h>
+#define isatty _isatty
+#define fileno _fileno
+#else
+#error Unknown platform - don't know which header to include for isatty()
+#endif // win32
+#endif // unix
+
+#include <cstdio>
+
+namespace osrm
+{
+namespace util
+{
+
+// Returns true if stdout is a tty, false otherwise
+//   Useful for when you want to do something different when
+//   output is redirected to a logfile
+inline bool IsStdoutATTY() { return isatty(fileno(stdout)); }
+
+} // namespace util
+} // namespace osrm
+
+#endif

include/util/percent.hpp

@@ -4,6 +4,8 @@
 #include <atomic>
 #include <iostream>
 
+#include "util/isatty.hpp"
+
 namespace osrm
 {
 namespace util
@@ -71,6 +73,12 @@ class Percent
             {
                 std::cout << ".";
             }
+
+            // When not on a TTY, print newlines after each progress indicator so
+            // so that progress is visible to line-buffered logging systems
+            if (!IsStdoutATTY())
+                std::cout << std::endl;
+
             std::cout.flush();
         }
     }