Source Code for Module DebTorrent.clock

 1  # Written by John Hoffman 
 2  # Modified by Cameron Dale 
 3  # see LICENSE.txt for license information 
 4  # 
 5  # $Id: clock.py 71 2007-05-29 05:58:07Z camrdale-guest $ 
 6   
 7  """Implement wall clock time for Unix systems. 
 8   
 9  This module implements a clock() function that will return a non-decreasing 
10  time, regardless of the system it is called on. This is necessary for Unix  
11  systems, whose clock() function instead returns the current processor time. 
12   
13  @type _MAXFORWARD: C{int} 
14  @var _MAXFORWARD: the maximum number of seconds to allow the clock 
15      to move forward 
16  @type _FUDGE: C{int} 
17  @var _FUDGE: the fudged time change to use if the clock moved forward more 
18      than L{_MAXFORWARD}, or if the clock moved back 
19  @type _RTIME: L{RelativeTime} 
20  @var _RTIME: the RelativeTime instance to use 
21   
22  """ 
23   
24  from time import * 
25  import sys 
26   
27  _MAXFORWARD = 100 
28  _FUDGE = 1 
29   
30 -class RelativeTime: 
31      """Calculate relative time on Unix systems. 
32       
33      @type time: C{float} 
34      @ivar time: the last time value measured 
35      @type offset: C{float} 
36      @ivar offset: the offset to use from the current time values due to 
37          any changes made in the clock while the program was running 
38       
39      """ 
40       
41 -    def __init__(self): 
42          """Initialize the time values.""" 
43          self.time = time() 
44          self.offset = 0 
45   
46 -    def get_time(self):         
47          """Calculate a non-decreasing time. 
48           
49          Uses the time() function to calculate non-decreasing time values. 
50          Checks to make sure the time values are non-decreasing, and also 
51          don't change by more than L{_MAXFORWARD} seconds within a reading. 
52          These could occur if the system clock was changed during the running 
53          of the program. 
54           
55          @rtype: C{float} 
56          @return: the current time 
57           
58          """ 
59           
60          t = time() + self.offset 
61          if t < self.time or t > self.time + _MAXFORWARD: 
62              self.time += _FUDGE 
63              self.offset += self.time - t 
64              return self.time 
65          self.time = t 
66          return t 
67   
68  if sys.platform != 'win32': 
69      _RTIME = RelativeTime() 
70 -    def clock(): 
71          """Override the clock() function for Unix systems. 
72           
73          This function will return a non-decreasing measure of the current 
74          time. This is only used on Unix systems. On Windows systems, the  
75          clock() function from the C{time} module will be used. 
76           
77          @rtype: C{float} 
78          @return: the relative time from the L{RelativeTime} instance 
79           
80          """ 
81          return _RTIME.get_time() 
82