From aaf523fb6566150c8c3203b72790cf580e30094e Mon Sep 17 00:00:00 2001
From: stevenj <stevenj@alum.mit.edu>
Date: Thu, 3 Jun 2010 18:55:50 -0400
Subject: [PATCH] use thread_id, if available, in nlopt_srand_time to ensure
 that different threads get different seed even if they are called
 simultaneously

darcs-hash:20100603225550-c8de0-963cf98deef902085d264eb09e4067f0e8e32742.gz
---
 api/general.c | 22 +++++++++++++++++++++-
 configure.ac  | 15 ++++++++++++---
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/api/general.c b/api/general.c
index c7f6a54..5d300ea 100644
--- a/api/general.c
+++ b/api/general.c
@@ -100,6 +100,26 @@ const char *nlopt_algorithm_name(nlopt_algorithm a)
      return nlopt_algorithm_names[a];
 }
 
+/*************************************************************************/
+/* get thread id, if possible, for use in nlopt_srand_time to ensure that
+   different threads have a different default seed even if they are called
+   simultaneously */
+
+#if defined(_WIN32) || defined(__WIN32__)
+#  include <windows.h>
+#  define my_gettid GetCurrentThreadId
+#elif defined(HAVE_GETTID_SYSCALL)
+#  include <unistd.h>
+#  include <sys/syscall.h>
+#  define my_gettid() syscall(SYS_gettid)
+#elif defined(HAVE_GETPID)
+#  include <sys/types.h>
+#  include <unistd.h>
+#  define my_gettid getpid
+#else
+#  define my_gettid() (0)
+#endif
+
 /*************************************************************************/
 
 static THREADLOCAL int nlopt_srand_called = 0;
@@ -109,7 +129,7 @@ void nlopt_srand(unsigned long seed) {
 }
 
 void nlopt_srand_time() {
-     nlopt_srand(nlopt_time_seed());
+     nlopt_srand(nlopt_time_seed() + my_gettid() * 314159);
 }
 
 void nlopt_srand_time_default() {
diff --git a/configure.ac b/configure.ac
index b53f5ed..760e941 100644
--- a/configure.ac
+++ b/configure.ac
@@ -51,11 +51,20 @@ AC_CHECK_TYPES(uint32_t, [], [], [$ac_includes_default
 
 dnl Checks for libraries and functions
 AC_CHECK_LIB(m, sin)
-AC_CHECK_FUNCS([BSDgettimeofday gettimeofday time qsort_r])
+AC_CHECK_FUNCS([BSDgettimeofday gettimeofday time qsort_r getpid])
+
+AC_MSG_CHECKING([for gettid syscall])
+AC_TRY_LINK([#include <unistd.h>
+#include <sys/syscall.h>
+], [syscall(SYS_gettid);], [ok=yes], [ok=no])
+if test "$ok" = "yes"; then
+	AC_DEFINE(HAVE_GETTID_SYSCALL,1,[Define if syscall(SYS_gettid) available.])
+fi
+AC_MSG_RESULT(${ok})
 
 AC_MSG_CHECKING([for isnan])
 AC_TRY_LINK([#include <math.h>
-], if (!isnan(3.14159)) isnan(2.7183);, ok=yes, ok=no)
+], [if (!isnan(3.14159)) isnan(2.7183);], ok=yes, ok=no)
 if test "$ok" = "yes"; then
 	AC_DEFINE(HAVE_ISNAN,1,[Define if the isnan() function/macro is available.])
 fi
@@ -63,7 +72,7 @@ AC_MSG_RESULT(${ok})
 
 AC_MSG_CHECKING([for isinf])
 AC_TRY_LINK([#include <math.h>
-], if (!isinf(3.14159)) isinf(2.7183);, ok=yes, ok=no)
+], [if (!isinf(3.14159)) isinf(2.7183);], ok=yes, ok=no)
 if test "$ok" = "yes"; then
 	AC_DEFINE(HAVE_ISINF,1,[Define if the isinf() function/macro is available.])
 fi
-- 
2.30.2