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# (Be in -*- python -*- mode.)
#
# ====================================================================
# Copyright (c) 2006-2008 CollabNet. All rights reserved.
#
# This software is licensed as described in the file COPYING, which
# you should have received as part of this distribution. The terms
# are also available at http://subversion.tigris.org/license-1.html.
# If newer versions of this license are posted there, you may use a
# newer version instead, at your option.
#
# This software consists of voluntary contributions made by many
# individuals. For exact contribution history, see the revision
# history and logs, available at http://cvs2svn.tigris.org/.
# ====================================================================
"""Keep track of counts of different types of changeset links."""
# A cvs_item doesn't depend on any cvs_items in either pred or succ:
LINK_NONE = 0
# A cvs_item depends on one or more cvs_items in pred but none in succ:
LINK_PRED = 1
# A cvs_item depends on one or more cvs_items in succ but none in pred:
LINK_SUCC = 2
# A cvs_item depends on one or more cvs_items in both pred and succ:
LINK_PASSTHRU = LINK_PRED | LINK_SUCC
class ChangesetGraphLink(object):
def __init__(self, pred, changeset, succ):
"""Represent a link in a loop in a changeset graph.
This is the link that goes from PRED -> CHANGESET -> SUCC.
We are mainly concerned with how many CVSItems have LINK_PRED,
LINK_SUCC, and LINK_PASSTHRU type links to the neighboring
commitsets. If necessary, this class can also break up CHANGESET
into multiple changesets."""
self.pred = pred
self.pred_ids = set(pred.cvs_item_ids)
self.changeset = changeset
self.succ_ids = set(succ.cvs_item_ids)
self.succ = succ
# A count of each type of link for cvs_items in changeset
# (indexed by LINK_* constants):
link_counts = [0] * 4
for cvs_item in list(changeset.iter_cvs_items()):
link_counts[self.get_link_type(cvs_item)] += 1
[self.pred_links, self.succ_links, self.passthru_links] = link_counts[1:]
def get_link_type(self, cvs_item):
"""Return the type of links from CVS_ITEM to self.PRED and self.SUCC.
The return value is one of LINK_NONE, LINK_PRED, LINK_SUCC, or
LINK_PASSTHRU."""
retval = LINK_NONE
if cvs_item.get_pred_ids() & self.pred_ids:
retval |= LINK_PRED
if cvs_item.get_succ_ids() & self.succ_ids:
retval |= LINK_SUCC
return retval
def get_links_to_move(self):
"""Return the number of items that would be moved to split changeset."""
return min(self.pred_links, self.succ_links) \
or max(self.pred_links, self.succ_links)
def is_breakable(self):
"""Return True iff breaking the changeset will do any good."""
return self.pred_links != 0 or self.succ_links != 0
def __cmp__(self, other):
"""Compare SELF with OTHER in terms of which would be better to break.
The one that is better to break is considered the lesser."""
return (
- cmp(int(self.is_breakable()), int(other.is_breakable()))
or cmp(self.passthru_links, other.passthru_links)
or cmp(self.get_links_to_move(), other.get_links_to_move())
)
def break_changeset(self, changeset_key_generator):
"""Break up self.changeset and return the fragments.
Break it up in such a way that the link is weakened as efficiently
as possible."""
if not self.is_breakable():
raise ValueError('Changeset is not breakable: %r' % self.changeset)
pred_items = []
succ_items = []
# For each link type, should such CVSItems be moved to the
# changeset containing the predecessor items or the one containing
# the successor items?
destination = {
LINK_PRED : pred_items,
LINK_SUCC : succ_items,
}
if self.pred_links == 0:
destination[LINK_NONE] = pred_items
destination[LINK_PASSTHRU] = pred_items
elif self.succ_links == 0:
destination[LINK_NONE] = succ_items
destination[LINK_PASSTHRU] = succ_items
elif self.pred_links < self.succ_links:
destination[LINK_NONE] = succ_items
destination[LINK_PASSTHRU] = succ_items
else:
destination[LINK_NONE] = pred_items
destination[LINK_PASSTHRU] = pred_items
for cvs_item in self.changeset.iter_cvs_items():
link_type = self.get_link_type(cvs_item)
destination[link_type].append(cvs_item.id)
# Create new changesets of the same type as the old one:
return [
self.changeset.create_split_changeset(
changeset_key_generator.gen_id(), pred_items),
self.changeset.create_split_changeset(
changeset_key_generator.gen_id(), succ_items),
]
def __str__(self):
return 'Link<%x>(%d, %d, %d)' % (
self.changeset.id,
self.pred_links, self.succ_links, self.passthru_links)
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