changegroup: store old heads as a set
Previously, the "oldheads" variable was a list. On a repository at
Mozilla with 46,492 heads, profiling revealed that list membership
testing was dominating execution time of applying small changegroups.
This patch converts the list of old heads to a set. This makes
membership testing significantly faster. On the aforementioned
repository with 46,492 heads:
$ hg unbundle <file with 1 changeset>
before: 18.535s wall
after: 1.303s
Consumers of this variable only check for truthiness (`if oldheads`),
length (`len(oldheads)`), and (most importantly) item membership
(`h not in oldheads` - which occurs twice). So, the change to a set
should be safe and suitable for stable.
The practical effect of this change is that changegroup application
and related operations (like `hg push`) no longer exhibit an O(n^2)
CPU explosion as the number of heads grows.
# Base Revsets to be used with revsetbenchmarks.py script
#
# The goal of this file is to gather a limited amount of revsets that allow a
# good coverage of the internal revsets mechanisms. Revsets included should not
# be selected for their individual implementation, but for what they reveal of
# the internal implementation of smartsets classes (and their interactions).
#
# Use and update this file when you change internal implementation of these
# smartsets classes. Please include a comment explaining what each of your
# addition is testing. Also check if your changes to the smartset class makes
# some of the tests inadequate and replace them with a new one testing the same
# behavior.
#
# If you want to benchmark revsets predicate itself, check 'all-revsets.txt'.
#
# The current content of this file is currently likely not reaching this goal
# entirely, feel free, to audit its content and comment on each revset to
# highlight what internal mechanisms they test.
all()
draft()
::tip
draft() and ::tip
::tip and draft()
0::tip
roots(0::tip)
author(lmoscovicz)
author(mpm)
author(lmoscovicz) or author(mpm)
author(mpm) or author(lmoscovicz)
tip:0
0::
# those two `roots(...)` inputs are close to what phase movement use.
roots((tip~100::) - (tip~100::tip))
roots((0::) - (0::tip))
42:68 and roots(42:tip)
::p1(p1(tip))::
public()
:10000 and public()
draft()
:10000 and draft()
roots((0:tip)::)
(not public() - obsolete())
(_intlist('20000\x0020001')) and merge()
parents(20000)
(20000::) - (20000)
# The one below is used by rebase
(children(ancestor(tip~5, tip)) and ::(tip~5))::