timeval: Add monotonic time functionality for NetBSD and FreeBSD.

This patch also checks the system platform as clock_gettime
could exist on different platforms but with different values of
CLOCK_MONOTONIC and different definitions of 'struct timespec'.
In this case, the system call would be expected to catch the
error, which is dangerous.

This patch ensures Linux, NetBSD and FreeBSD platforms use
clock_gettime with their corresponding correct values and
definitions. All other platforms use time.time().

Signed-off-by: Ryan Wilson <wryan@nicira.com>
Acked-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: YAMAMOTO Takashi <yamamoto@valinux.co.jp>

1 files changed, 27 insertions, 7 deletions

diff --git a/python/ovs/timeval.py b/python/ovs/timeval.py
index 4463e8769..a16bf60d4 100644
--- a/python/ovs/timeval.py
+++ b/python/ovs/timeval.py
@@ -12,22 +12,41 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import sys
 import time
 
-LIBRT = 'librt.so.1'
-CLOCK_MONOTONIC = 1
-
 try:
     import ctypes
 
+    LIBRT = 'librt.so.1'
+    clock_gettime_name = 'clock_gettime'
+
+    if sys.platform.startswith("linux"):
+        CLOCK_MONOTONIC = 1
+        time_t = ctypes.c_long
+    elif sys.platform.startswith("netbsd"):
+        # NetBSD uses function renaming for ABI versioning.  While the proper
+        # way to get the appropriate version is of course "#include <time.h>",
+        # it is difficult with ctypes.  The following is appropriate for
+        # recent versions of NetBSD, including NetBSD-6.
+        LIBRT = 'libc.so.12'
+        clock_gettime_name = '__clock_gettime50'
+        CLOCK_MONOTONIC = 3
+        time_t = ctypes.c_int64
+    elif sys.platform.startswith("freebsd"):
+        CLOCK_MONOTONIC = 4
+        time_t = ctypes.c_int64
+    else:
+        raise Exception
+
     class timespec(ctypes.Structure):
         _fields_ = [
-            ('tv_sec', ctypes.c_long),
+            ('tv_sec', time_t),
             ('tv_nsec', ctypes.c_long),
         ]
 
     librt = ctypes.CDLL(LIBRT)
-    clock_gettime = librt.clock_gettime
+    clock_gettime = getattr(librt, clock_gettime_name)
     clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]
 except:
     # Librt shared library could not be loaded
@@ -48,8 +67,9 @@ if not hasattr(time, 'monotonic'):
     time.monotonic = monotonic
 
 def msec():
-    """Returns the current time, as the amount of time since the epoch, in
-    milliseconds, as a float."""
+    """ Returns the system's monotonic time if possible, otherwise returns the
+    current time as the amount of time since the epoch, in milliseconds, as a
+    float."""
     return time.monotonic() * 1000.0