implement a platform neutral usleep() using C++11

src/platform.cpp

@@ -61,7 +61,9 @@
 #endif
 ////////////////////////////////////////////////////////////////////////
 
+#include <chrono>
 #include <cstring>
+#include <thread>
 
 /* ------------------------------------------------------------------ */
 
@@ -172,6 +174,14 @@ double platform::walltime()
   return wtime;
 }
 
+/* ----------------------------------------------------------------------
+   sleep with microsecond resolution
+------------------------------------------------------------------------ */
+void platform::usleep(int usec)
+{
+  return std::this_thread::sleep_for(std::chrono::microseconds(usec));
+}
+
 /* ----------------------------------------------------------------------
    get Operating system and version info
 ------------------------------------------------------------------------- */

src/platform.h

@@ -42,6 +42,15 @@ namespace platform {
 
   double walltime();
 
+
+  /*! Suspend execution for a microsecond interval
+   *
+   * This emulates the usleep(3) BSD function call also mentioned in POSIX.1-2001.
+   *
+   * \param  usec  length of delay in microseconds */
+
+  void usleep(int usec);
+
   /*! Return string with the operating system version and architecture info
    *
    *  \return  string with info about the OS and the platform is is running on */

src/variable.cpp

@@ -39,7 +39,6 @@
 #include <cctype>
 #include <cmath>
 #include <cstring>
-#include <unistd.h>
 #include <unordered_map>
 
 using namespace LAMMPS_NS;
@@ -692,11 +691,11 @@ int Variable::next(int narg, char **arg)
       int seed = 12345 + universe->me + which[find(arg[0])];
       if (!random) random = new RanMars(lmp,seed);
       int delay = (int) (1000000*random->uniform());
-      usleep(delay);
+      platform::usleep(delay);
       while (1) {
         if (!rename("tmp.lammps.variable","tmp.lammps.variable.lock")) break;
         delay = (int) (1000000*random->uniform());
-        usleep(delay);
+        platform::usleep(delay);
       }
 
       // if the file cannot be found, we may have a race with some
@@ -719,7 +718,7 @@ int Variable::next(int narg, char **arg)
            break;
         }
         delay = (int) (1000000*random->uniform());
-        usleep(delay);
+        platform::usleep(delay);
       }
       delete random;
       random = nullptr;