From 2a0497e2c15d2440f7c222bbec2c580a4cd31081 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Wed, 18 Nov 2009 13:00:35 +0000
Subject: [PATCH] From Pau Garcia i Quiles, "On Linux/Unix, when you change the
 system time (for instance, using settimeofday), OSG animations will freeze
 your application because osg::Timer uses gettimeofday internally on non-Win32
 platforms. This is wrong and should be replace with times(2) or
 clock_gettime(2).

The attached patch fixes the issue in a binary-compatible way by using
clock_gettime when it's available, and falling back to gettimeofday
when it's not."
---
 CMakeLists.txt         |  3 +++
 src/osg/CMakeLists.txt |  4 ++--
 src/osg/Timer.cpp      | 28 ++++++++++++++++++++--------
 3 files changed, 25 insertions(+), 10 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 083edc0b6..e502aa0a6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -152,6 +152,9 @@ IF(UNIX)
     FIND_PACKAGE(X11)
     # Some Unicies need explicit linkage to the Math library or the build fails.
     FIND_LIBRARY(MATH_LIBRARY m)
+    IF( CMAKE_SYSTEM MATCHES "Linux" )
+        FIND_LIBRARY( RT_LIBRARY rt )
+    ENDIF( CMAKE_SYSTEM MATCHES "Linux" )
 ENDIF()
 
 # Make the headers visible to everything
diff --git a/src/osg/CMakeLists.txt b/src/osg/CMakeLists.txt
index 02dde57f4..a8b4cbe95 100644
--- a/src/osg/CMakeLists.txt
+++ b/src/osg/CMakeLists.txt
@@ -331,7 +331,7 @@ ADD_LIBRARY(${LIB_NAME}
 LINK_INTERNAL(${LIB_NAME}     
     OpenThreads
 )
-LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} )
-LINK_CORELIB_DEFAULT(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT} ${MATH_LIBRARY} )
+LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} ${RT_LIBRARY} )
+LINK_CORELIB_DEFAULT(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT} ${MATH_LIBRARY} ${RT_LIBRARY} )
 
 INCLUDE(ModuleInstall OPTIONAL)
diff --git a/src/osg/Timer.cpp b/src/osg/Timer.cpp
index 3a5c450c0..835b69561 100644
--- a/src/osg/Timer.cpp
+++ b/src/osg/Timer.cpp
@@ -71,8 +71,7 @@ Timer* Timer::instance()
     }
 
 #else
-
-    #include <sys/time.h>
+    #include <unistd.h>
 
     Timer::Timer( void )
     {
@@ -81,11 +80,24 @@ Timer* Timer::instance()
         setStartTick();        
     }
 
-    Timer_t Timer::tick() const
-    {
-        struct timeval tv;
-        gettimeofday(&tv, NULL);
-        return ((osg::Timer_t)tv.tv_sec)*1000000+(osg::Timer_t)tv.tv_usec;
-    }
+    #if defined(_POSIX_TIMERS) && ( _POSIX_TIMERS > 0 ) && defined(_POSIX_MONOTONIC_CLOCK)
+        #include <time.h>
+
+        Timer_t Timer::tick() const
+        {
+            struct timespec ts;
+            clock_gettime(CLOCK_MONOTONIC, &ts);
+            return ((osg::Timer_t)ts.tv_sec)*1000000+(osg::Timer_t)ts.tv_nsec/1000;
+        }
+    #else
+        #include <sys/time.h>
+
+        Timer_t Timer::tick() const
+        {
+            struct timeval tv;
+            gettimeofday(&tv, NULL);
+            return ((osg::Timer_t)tv.tv_sec)*1000000+(osg::Timer_t)tv.tv_usec;
+        }
+    #endif
 
 #endif