~bzr-pqm/bzr/bzr.dev

5195.3.31 by Parth Malwankar
close review comments from jam.
1
# Copyright (C) 2010 Canonical Ltd
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
2
#
3
# This program is free software; you can redistribute it and/or modify
4
# it under the terms of the GNU General Public License as published by
5
# the Free Software Foundation; either version 2 of the License, or
6
# (at your option) any later version.
7
#
8
# This program is distributed in the hope that it will be useful,
9
# but WITHOUT ANY WARRANTY; without even the implied warranty of
10
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11
# GNU General Public License for more details.
12
#
13
# You should have received a copy of the GNU General Public License
14
# along with this program; if not, write to the Free Software
15
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
16
"""Record counting support for showing progress of revision fetch."""
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
17
5195.3.31 by Parth Malwankar
close review comments from jam.
18
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
19
class RecordCounter(object):
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
20
    """Container for maintains estimates of work requires for fetch.
21
22
    Instance of this class is used along with a progress bar to provide
23
    the user an estimate of the amount of work pending for a fetch (push,
24
    pull, branch, checkout) operation.
25
    """
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
26
    def __init__(self):
27
        self.initialized = False
28
        self.current = 0
29
        self.key_count = 0
30
        self.max = 0
5195.3.33 by Parth Malwankar
added comments on choice of STEP value and estimate multiplies
31
32
        # Users of RecordCounter instance update progress bar every
33
        # _STEP_ records. We choose are reasonably high number to keep
5289.1.1 by Parth Malwankar
reduced STEP in recordcounter to allow more frequent updates
34
        # display updates from being too frequent. This is an odd number
5195.3.33 by Parth Malwankar
added comments on choice of STEP value and estimate multiplies
35
        # to ensure that the last digit of the records fetched in
36
        # fetches vs estimate ratio changes periodically.
5289.1.1 by Parth Malwankar
reduced STEP in recordcounter to allow more frequent updates
37
        self.STEP = 7
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
38
39
    def is_initialized(self):
40
        return self.initialized
41
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
42
    def _estimate_max(self, key_count):
43
        """Estimate the maximum amount of 'inserting stream' work.
44
45
        This is just an estimate.
46
        """
47
        # Note: The magic number below is based of empirical data
48
        # based on 3 seperate projects. Estimatation can probably
49
        # be improved but this should work well for most cases.
5195.3.33 by Parth Malwankar
added comments on choice of STEP value and estimate multiplies
50
        # The project used for the estimate (with approx. numbers) were:
51
        # lp:bzr with records_fetched = 7 * revs_required
52
        # lp:emacs with records_fetched = 8 * revs_required
53
        # bzr-svn checkout of lp:parrot = 10.63 * revs_required
54
        # Hence, 10.3 was chosen as for a realistic progress bar as:
55
        # 1. If records fetched is is lower than 10.3x then we simply complete
56
        #    with 10.3x. Under promise, over deliver.
57
        # 2. In case of remote fetch, when we start the count fetch vs estimate
58
        #    display with revs_required/estimate, having a multiplier with a
59
        #    decimal point produces a realistic looking _estimate_ number rather
60
        #    than using something like 3125/31250 (for 10x)
61
        # 3. Based on the above data, the possibility of overshooting this
62
        #    factor is minimal, and in case of an overshoot the estimate value
63
        #    should not need to be corrected too many times.
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
64
        return int(key_count * 10.3)
65
5195.3.24 by Parth Malwankar
progress indicator for local branch.
66
    def setup(self, key_count, current=0):
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
67
        """Setup RecordCounter with basic estimate of work pending.
68
69
        Setup self.max and self.current to reflect the amount of work
70
        pending for a fetch.
71
        """
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
72
        self.current = current
73
        self.key_count = key_count
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
74
        self.max = self._estimate_max(key_count)
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
75
        self.initialized = True
76
77
    def increment(self, count):
5195.3.21 by Parth Malwankar
Documentation and cleanup for RecordCounter
78
        """Increment self.current by count.
79
80
        Apart from incrementing self.current by count, also ensure
81
        that self.max > self.current.
82
        """
5195.3.17 by Parth Malwankar
remote push now shows estimated work.
83
        self.current += count
84
        if self.current > self.max:
85
            self.max += self.key_count
86