Code import

venv/lib/python2.7/site-packages/eventlet/support/monotonic.py

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+# -*- 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     | ``GetTickCount`` or ``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, 2015, 2016 Ori Livneh <ori@wikimedia.org>
+
+  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.
+
+"""
+import ctypes
+import ctypes.util
+import os
+import sys
+import threading
+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:
+            #  <https://developer.apple.com/library/mac/qa/qa1398/>
+            libc = ctypes.CDLL('/usr/lib/libc.dylib', use_errno=True)
+
+            class mach_timebase_info_data_t(ctypes.Structure):
+                """System timebase info. Defined in <mach/mach_time.h>."""
+                _fields_ = (('numer', ctypes.c_uint32),
+                            ('denom', ctypes.c_uint32))
+
+            mach_absolute_time = libc.mach_absolute_time
+            mach_absolute_time.restype = ctypes.c_uint64
+
+            timebase = mach_timebase_info_data_t()
+            libc.mach_timebase_info(ctypes.byref(timebase))
+            ticks_per_second = timebase.numer / timebase.denom * 1.0e9
+
+            def monotonic():
+                """Monotonic clock, cannot go backward."""
+                return mach_absolute_time() / ticks_per_second
+
+        elif sys.platform.startswith('win32') or sys.platform.startswith('cygwin'):
+            if sys.platform.startswith('cygwin'):
+                # Note: cygwin implements clock_gettime (CLOCK_MONOTONIC = 4) since
+                # version 1.7.6. Using raw WinAPI for maximum version compatibility.
+
+                # Ugly hack using the wrong calling convention (in 32-bit mode) 
+                # because ctypes has no windll under cygwin (and it also seems that 
+                # the code letting you select stdcall in _ctypes doesn't exist under 
+                # the preprocessor definitions relevant to cygwin).
+                # This is 'safe' because:
+                # 1. The ABI of GetTickCount and GetTickCount64 is identical for 
+                #    both calling conventions because they both have no parameters.
+                # 2. libffi masks the problem because after making the call it doesn't
+                #    touch anything through esp and epilogue code restores a correct
+                #    esp from ebp afterwards.
+                try:
+                    kernel32 = ctypes.cdll.kernel32
+                except OSError:  # 'No such file or directory'
+                    kernel32 = ctypes.cdll.LoadLibrary('kernel32.dll')
+            else:
+                kernel32 = ctypes.windll.kernel32
+
+            GetTickCount64 = getattr(kernel32, 'GetTickCount64', None)
+            if GetTickCount64:
+                # Windows Vista / Windows Server 2008 or newer.
+                GetTickCount64.restype = ctypes.c_ulonglong
+
+                def monotonic():
+                    """Monotonic clock, cannot go backward."""
+                    return GetTickCount64() / 1000.0
+
+            else:
+                # Before Windows Vista.
+                GetTickCount = kernel32.GetTickCount
+                GetTickCount.restype = ctypes.c_uint32
+
+                get_tick_count_lock = threading.Lock()
+                get_tick_count_last_sample = 0
+                get_tick_count_wraparounds = 0
+
+                def monotonic():
+                    """Monotonic clock, cannot go backward."""
+                    global get_tick_count_last_sample
+                    global get_tick_count_wraparounds
+
+                    with get_tick_count_lock:
+                        current_sample = GetTickCount()
+                        if current_sample < get_tick_count_last_sample:
+                            get_tick_count_wraparounds += 1
+                        get_tick_count_last_sample = current_sample
+
+                        final_milliseconds = get_tick_count_wraparounds << 32
+                        final_milliseconds += get_tick_count_last_sample
+                        return final_milliseconds / 1000.0
+
+        else:
+            try:
+                clock_gettime = ctypes.CDLL(ctypes.util.find_library('c'),
+                                            use_errno=True).clock_gettime
+            except AttributeError:
+                clock_gettime = ctypes.CDLL(ctypes.util.find_library('rt'),
+                                            use_errno=True).clock_gettime
+
+            class timespec(ctypes.Structure):
+                """Time specification, as described in clock_gettime(3)."""
+                _fields_ = (('tv_sec', ctypes.c_long),
+                            ('tv_nsec', ctypes.c_long))
+
+            if sys.platform.startswith('linux'):
+                CLOCK_MONOTONIC = 1
+            elif sys.platform.startswith('freebsd'):
+                CLOCK_MONOTONIC = 4
+            elif sys.platform.startswith('sunos5'):
+                CLOCK_MONOTONIC = 4
+            elif 'bsd' in sys.platform:
+                CLOCK_MONOTONIC = 3
+
+            def monotonic():
+                """Monotonic clock, cannot go backward."""
+                ts = timespec()
+                if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(ts)):
+                    errno = ctypes.get_errno()
+                    raise OSError(errno, os.strerror(errno))
+                return ts.tv_sec + ts.tv_nsec / 1.0e9
+
+        # Perform a sanity-check.
+        if monotonic() - monotonic() > 0:
+            raise ValueError('monotonic() is not monotonic!')
+
+    except Exception:
+        raise RuntimeError('no suitable implementation for this system')