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 > bar
$ hg commit -Am default
adding bar
$ hg up -r null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg branch mine
marked working directory as branch mine
(branches are permanent and global, did you want a bookmark?)
$ echo hello > world
$ hg commit -Am hello
adding world
$ hg up -r null
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg branch other
marked working directory as branch other
$ echo good > bye
$ hg commit -Am other
adding bye
$ hg up -r mine
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg clone -U -u . .#other ../b -r 0 -r 1 -r 2 -b other
abort: cannot specify both --noupdate and --updaterev
[255]
$ hg clone -U .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
$ rm -rf ../b
$ hg clone -u . .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch mine
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 0 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 1 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch mine
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -u 2 .#other ../b -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
Test -r mine ... mine is ignored:
$ hg clone -u 2 .#other ../b -r mine -r 0 -r 1 -r 2 -b other
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone .#other ../b -b default -b mine
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 3 files (+2 heads)
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone .#other ../b
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b
$ hg clone -U . ../c -r 1 -r 2 > /dev/null
$ hg clone ../c ../b
updating to branch other
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ rm -rf ../b ../c