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.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init foo
$ cd foo
$ echo a > a
$ hg ci -qAm a
Default queue:
$ hg qqueue
patches (active)
$ echo b > a
$ hg qnew -fgDU somestuff
Applied patches in default queue:
$ hg qap
somestuff
Try to change patch (create succeeds, switch fails):
$ hg qqueue foo --create
abort: new queue created, but cannot make active as patches are applied
[255]
$ hg qqueue
foo
patches (active)
Empty default queue:
$ hg qpop
popping somestuff
patch queue now empty
Switch queue:
$ hg qqueue foo
$ hg qqueue
foo (active)
patches
List queues, quiet:
$ hg qqueue --quiet
foo
patches
Fail creating queue with already existing name:
$ hg qqueue --create foo
abort: queue "foo" already exists
[255]
$ hg qqueue
foo (active)
patches
Create new queue for rename:
$ hg qqueue --create bar
$ hg qqueue
bar (active)
foo
patches
Rename queue, same name:
$ hg qqueue --rename bar
abort: can't rename "bar" to its current name
[255]
Rename queue to existing:
$ hg qqueue --rename foo
abort: queue "foo" already exists
[255]
Rename queue:
$ hg qqueue --rename buz
$ hg qqueue
buz (active)
foo
patches
Switch back to previous queue:
$ hg qqueue foo
$ hg qqueue --delete buz
$ hg qqueue
foo (active)
patches
Create queue for purge:
$ hg qqueue --create purge-me
$ hg qqueue
foo
patches
purge-me (active)
Create patch for purge:
$ hg qnew patch-purge-me
$ ls -1d .hg/patches-purge-me 2>/dev/null || true
.hg/patches-purge-me
$ hg qpop -a
popping patch-purge-me
patch queue now empty
Purge queue:
$ hg qqueue foo
$ hg qqueue --purge purge-me
$ hg qqueue
foo (active)
patches
$ ls -1d .hg/patches-purge-me 2>/dev/null || true
Unapplied patches:
$ hg qun
$ echo c > a
$ hg qnew -fgDU otherstuff
Fail switching back:
$ hg qqueue patches
abort: new queue created, but cannot make active as patches are applied
[255]
Fail deleting current:
$ hg qqueue foo --delete
abort: cannot delete currently active queue
[255]
Switch back and delete foo:
$ hg qpop -a
popping otherstuff
patch queue now empty
$ hg qqueue patches
$ hg qqueue foo --delete
$ hg qqueue
patches (active)
Tricky cases:
$ hg qqueue store --create
$ hg qnew journal
$ hg qqueue
patches
store (active)
$ hg qpop -a
popping journal
patch queue now empty
$ hg qqueue patches
$ hg qun
somestuff
Invalid names:
$ hg qqueue test/../../bar --create
abort: invalid queue name, may not contain the characters ":\/."
[255]
$ hg qqueue . --create
abort: invalid queue name, may not contain the characters ":\/."
[255]
$ cd ..