Tarball conversion

1 files changed, 89 insertions, 0 deletions

diff --git a/bzrlib/recordcounter.py b/bzrlib/recordcounter.py
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+++ b/bzrlib/recordcounter.py
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+# Copyright (C) 2010 Canonical Ltd
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+"""Record counting support for showing progress of revision fetch."""
+
+from __future__ import absolute_import
+
+
+class RecordCounter(object):
+    """Container for maintains estimates of work requires for fetch.
+
+    Instance of this class is used along with a progress bar to provide
+    the user an estimate of the amount of work pending for a fetch (push,
+    pull, branch, checkout) operation.
+    """
+    def __init__(self):
+        self.initialized = False
+        self.current = 0
+        self.key_count = 0
+        self.max = 0
+
+        # Users of RecordCounter instance update progress bar every
+        # _STEP_ records. We choose are reasonably high number to keep
+        # display updates from being too frequent. This is an odd number
+        # to ensure that the last digit of the records fetched in
+        # fetches vs estimate ratio changes periodically.
+        self.STEP = 7
+
+    def is_initialized(self):
+        return self.initialized
+
+    def _estimate_max(self, key_count):
+        """Estimate the maximum amount of 'inserting stream' work.
+
+        This is just an estimate.
+        """
+        # Note: The magic number below is based of empirical data
+        # based on 3 seperate projects. Estimatation can probably
+        # be improved but this should work well for most cases.
+        # The project used for the estimate (with approx. numbers) were:
+        # lp:bzr with records_fetched = 7 * revs_required
+        # lp:emacs with records_fetched = 8 * revs_required
+        # bzr-svn checkout of lp:parrot = 10.63 * revs_required
+        # Hence, 10.3 was chosen as for a realistic progress bar as:
+        # 1. If records fetched is is lower than 10.3x then we simply complete
+        #    with 10.3x. Under promise, over deliver.
+        # 2. In case of remote fetch, when we start the count fetch vs estimate
+        #    display with revs_required/estimate, having a multiplier with a
+        #    decimal point produces a realistic looking _estimate_ number rather
+        #    than using something like 3125/31250 (for 10x)
+        # 3. Based on the above data, the possibility of overshooting this
+        #    factor is minimal, and in case of an overshoot the estimate value
+        #    should not need to be corrected too many times.
+        return int(key_count * 10.3)
+
+    def setup(self, key_count, current=0):
+        """Setup RecordCounter with basic estimate of work pending.
+
+        Setup self.max and self.current to reflect the amount of work
+        pending for a fetch.
+        """
+        self.current = current
+        self.key_count = key_count
+        self.max = self._estimate_max(key_count)
+        self.initialized = True
+
+    def increment(self, count):
+        """Increment self.current by count.
+
+        Apart from incrementing self.current by count, also ensure
+        that self.max > self.current.
+        """
+        self.current += count
+        if self.current > self.max:
+            self.max += self.key_count
+