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britney.py: Minor optimisation to sort_actions

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Avoid some cases of O(n^2) behaviour in sort_actions and reduce the
size of n for the remaining O(n^2)-ish behaviour by filtering out
removals early on.

Signed-off-by: Niels Thykier <niels@thykier.net>
This commit is contained in:
Niels Thykier 2015-06-02 21:33:52 +02:00
parent d7baa1d7f0
commit e4c7c4f2a2
1 changed files with 29 additions and 19 deletions
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britney.py
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@ -2745,29 +2745,39 @@ class Britney(object):
so the ones with most reverse dependencies are at the end of the loop.
If an action depends on another one, it is put after it.
"""
upgrade_me = [x.name for x in self.excuses if x.name in [y.uvname for y in self.upgrade_me]]
for e in self.excuses:
if e.name not in upgrade_me: continue
# try removes at the end of the loop
elif e.name[0] == '-':
upgrade_me.remove(e.name)
upgrade_me.append(e.name)
# otherwise, put it in a good position checking its dependencies
uvnames = frozenset(y.uvname for y in self.upgrade_me)
excuses = [e for e in self.excuses if e.name in uvnames]
removals = []
upgrade_me = []
for e in excuses:
# We order removals and regular migrations differently, so
# split them out early.
if e.name[0] == '-':
removals.append(e.name)
else:
pos = []
udeps = [upgrade_me.index(x) for x in e.deps if x in upgrade_me and x != e.name]
if len(udeps) > 0:
pos.append(max(udeps))
sdeps = [upgrade_me.index(x) for x in e.sane_deps if x in upgrade_me and x != e.name]
if len(sdeps) > 0:
pos.append(min(sdeps))
if len(pos) == 0: continue
upgrade_me.remove(e.name)
upgrade_me.insert(max(pos)+1, e.name)
self.dependencies[e.name] = e.deps
upgrade_me.append(e.name)
for e in excuses:
# put the item (regular migration) in a good position
# checking its dependencies
pos = []
udeps = [upgrade_me.index(x) for x in e.deps if x in upgrade_me and x != e.name]
if udeps:
pos.append(max(udeps))
sdeps = [upgrade_me.index(x) for x in e.sane_deps if x in upgrade_me and x != e.name]
if sdeps:
pos.append(min(sdeps))
if not pos:
continue
upgrade_me.remove(e.name)
upgrade_me.insert(max(pos)+1, e.name)
self.dependencies[e.name] = e.deps
# replace the list of actions with the new one
self.upgrade_me = [ make_migrationitem(x, self.sources) for x in upgrade_me ]
self.upgrade_me.extend(make_migrationitem(x, self.sources) for x in removals)
def auto_hinter(self):
"""Auto-generate "easy" hints.