jenkins-bot has submitted this change and it was merged.
Change subject: Add a monotonic clock implementation
..
Add a monotonic clock implementation
I needed a monotonic clock for a change I wanted to make to PeriodicThread.
Python 3.3 introduced `time.monotonic`, but there's nothing equivalent for
earlier versions of Python. So I set out to write a fallback implementation.
One thing led to another, and I ended up with a small, self-standing library,
which I published to GitHub and PyPI:
- https://github.com/atdt/monotonic
- https://pypi.python.org/pypi/monotonic
So now there's the question of how to integrate it with EventLogging. We could
treat it like a normal external dependency, but that's a lot of inconvenience
for a library that fits in a single file and of which I am the primary author.
So I decided to just bundle it here instead.
Change-Id: If6166d2353f51d30a447b0a6405dbe8871431502
---
M server/eventlogging/compat.py
A server/eventlogging/lib/__init__.py
A server/eventlogging/lib/monotonic.py
M server/tests/test_compat.py
4 files changed, 147 insertions(+), 2 deletions(-)
Approvals:
Ori.livneh: Looks good to me, approved
jenkins-bot: Verified
diff --git a/server/eventlogging/compat.py b/server/eventlogging/compat.py
index e85da14..608bc42 100644
--- a/server/eventlogging/compat.py
+++ b/server/eventlogging/compat.py
@@ -14,12 +14,22 @@
# pylint: disable=E0611, F0401, E1101
from __future__ import unicode_literals
+import ctypes
+import ctypes.util
import functools
import hashlib
import operator
import sys
+import time
import uuid
+import warnings
+try:
+from .lib.monotonic import monotonic as monotonic_clock
+except ImportError:
+warnings.warn('Using non-monotonic time.time() as last-resort fallback '
+ 'for eventlogging.monotonic_clock()', RuntimeWarning)
+monotonic_clock = time.time
try:
import simplejson as json
@@ -27,9 +37,11 @@
import json
-__all__ = ('http_get', 'items', 'json', 'unquote_plus', 'urisplit',
- 'urlopen', 'uuid5')
+__all__ = ('http_get', 'items', 'json', 'monotonic_clock', 'unquote_plus',
+ 'urisplit', 'urlopen', 'uuid5')
+LIBC = ctypes.CDLL(ctypes.util.find_library('c'), use_errno=True)
+CLOCK_MONOTONIC_RAW = 4
PY3 = sys.version_info[0] == 3
if PY3:
diff --git a/server/eventlogging/lib/__init__.py
b/server/eventlogging/lib/__init__.py
new file mode 100644
index 000..e69de29
--- /dev/null
+++ b/server/eventlogging/lib/__init__.py
diff --git a/server/eventlogging/lib/monotonic.py
b/server/eventlogging/lib/monotonic.py
new file mode 100644
index 000..d6dff9f
--- /dev/null
+++ b/server/eventlogging/lib/monotonic.py
@@ -0,0 +1,120 @@
+# -*- coding: utf-8 -*-
+"""
+ monotonic
+ ~
+
+ This module provides a ``monotonic()`` function which returns the
+ value (in fractional seconds) of a clock which never goes backwards.
+
+ On Python 3.3 or newer, ``monotonic`` will be an alias of
+ ``time.monotonic`` from the standard library. On older versions,
+ it will fall back to an equivalent implementation:
+
+ +-++
+ | Linux, BSD | clock_gettime(3) |
+ +-++
+ | Windows | GetTickCount64 |
+ +-++
+ | OS X| mach_absolute_time |
+ +-++
+
+ If no suitable implementation exists for the current platform,
+ attempting to import this module (or to import from it) will
+ cause a RuntimeError exception to be raised.
+
+
+ Copyright 2014 Ori Livneh
+
+ Licensed under the Apache License, Version 2.0 (the "License");
+ you may not use this file except in compliance with the License.
+ You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+ Unless required by applicable law or agreed to in writing, software
+ distributed under the License is distributed on an "AS IS" BASIS,
+ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ See the License for the specific language governing permissions and
+ limitations under the License.
+
+"""
+from __future__ import absolute_import, division
+
+import ctypes
+import ctypes.util
+import os
+import sys
+import time
+
+
+__all__ = ('monotonic',)
+
+try:
+monotonic = time.monotonic
+except AttributeError:
+try:
+if sys.platform == 'darwin': # OS X, iOS
+# See Technical Q&A QA1398 of the Mac Developer Library:
+#
+libc = ctypes.CDLL('libc.dylib', use_errno=True)
+
+class mach_timebase_info_data_t(ctypes.Structure):
+"""System timebase info. Defined in ."""
+_fields_ = (('numer', ctypes.c_uint32),
+('denom', ctypes.c_uint32))
+
+mach_absolute_time = libc.mach_absolute_time
