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.
$ hg init
$ echo foo > foo
$ echo bar > bar
$ hg ci -qAm 'add foo bar'
$ echo foo2 >> foo
$ echo bleh > bar
$ hg ci -m 'change foo bar'
$ hg up -qC 0
$ hg mv foo foo1
$ echo foo1 > foo1
$ hg cat foo >> foo1
$ hg ci -m 'mv foo foo1'
created new head
$ hg merge
merging foo1 and foo to foo1
1 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg debugstate --nodates
m 0 -2 unset bar
m 0 -2 unset foo1
copy: foo -> foo1
$ hg st -q
M bar
M foo1
Removing foo1 and bar:
$ cp foo1 F
$ cp bar B
$ hg rm -f foo1 bar
$ hg debugstate --nodates
r 0 -1 set bar
r 0 -1 set foo1
copy: foo -> foo1
$ hg st -qC
R bar
R foo1
Re-adding foo1 and bar:
$ cp F foo1
$ cp B bar
$ hg add -v foo1 bar
adding bar
adding foo1
$ hg debugstate --nodates
n 0 -2 unset bar
n 0 -2 unset foo1
copy: foo -> foo1
$ hg st -qC
M bar
M foo1
foo
Reverting foo1 and bar:
$ hg revert -vr . foo1 bar
saving current version of bar as bar.orig
reverting bar
saving current version of foo1 as foo1.orig
reverting foo1
$ hg debugstate --nodates
n 0 -2 unset bar
n 0 -2 unset foo1
copy: foo -> foo1
$ hg st -qC
M bar
M foo1
foo
$ hg diff
Merge should not overwrite local file that is untracked after remove
$ rm *
$ hg up -qC
$ hg rm bar
$ hg ci -m 'remove bar'
$ echo 'memories of buried pirate treasure' > bar
$ hg merge
bar: untracked file differs
abort: untracked files in working directory differ from files in requested revision
[255]
$ cat bar
memories of buried pirate treasure
Those who use force will lose
$ hg merge -f
other [merge rev] changed bar which local [working copy] deleted
use (c)hanged version, leave (d)eleted, or leave (u)nresolved? u
merging foo1 and foo to foo1
0 files updated, 1 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
[1]
$ cat bar
bleh
$ hg st
M bar
M foo1