1# Copyright 2014 The Chromium Authors. All rights reserved.
2# Use of this source code is governed by a BSD-style license that can be
3# found in the LICENSE file.
4
5
6class ProcessStatisticTimelineData(object):
7  """Holds value of a stat for one or more processes.
8
9  This object can hold a value for more than one pid by adding another
10  object."""
11
12  def __init__(self, pid, value):
13    super(ProcessStatisticTimelineData, self).__init__()
14    assert value >= 0
15    self._value_by_pid = {pid: value}
16
17  def __sub__(self, other):
18    """The results of subtraction is an object holding only the pids contained
19    in |self|.
20
21    The motivation is that some processes may have died between two consecutive
22    measurements. The desired behavior is to only make calculations based on
23    the processes that are alive at the end of the second measurement."""
24    # pylint: disable=protected-access
25    ret = self.__class__(0, 0)
26    my_dict = self._value_by_pid
27
28    ret._value_by_pid = (
29        {k: my_dict[k] - other._value_by_pid.get(k, 0) for
30            k in my_dict.keys()})
31    return ret
32
33  def __add__(self, other):
34    """The result contains pids from both |self| and |other|, if duplicate
35    pids are found between objects, an error will occur. """
36    # pylint: disable=protected-access
37    intersecting_pids = (set(self._value_by_pid.keys()) &
38        set(other._value_by_pid.keys()))
39    assert len(intersecting_pids) == 0
40
41    ret = self.__class__(0, 0)
42    ret._value_by_pid = {}
43    ret._value_by_pid.update(self._value_by_pid)
44    ret._value_by_pid.update(other._value_by_pid)
45    return ret
46
47  @property
48  def value_by_pid(self):
49    return self._value_by_pid
50
51  def total_sum(self):
52    """Returns the sum of all values contained by this object. """
53    return sum(self._value_by_pid.values())
54
55
56class IdleWakeupTimelineData(ProcessStatisticTimelineData):
57  """A ProcessStatisticTimelineData to hold idle wakeups."""
58  pass
59