bisect: avoid copying ancestor list for non-merge commits
During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.
To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.
During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:
Setup:
$ cd mozilla-central
$ hg bisect --reset
$ hg bisect --good 0
$ hg log -r tip -T '{rev}\n'
628417
Test:
$ time hg bisect --bad tip --noupdate
Before:
real 3m35.927s
user 3m35.553s
sys 0m0.319s
After:
real 1m41.142s
user 1m40.810s
sys 0m0.285s
$ cat >> $HGRCPATH << EOF
> [command-templates]
> log="{rev}:{node|short} {desc} [{tags}]\n"
> EOF
$ hg init legacy-lookup
$ cd legacy-lookup
$ echo a > a
$ hg add a
$ hg commit -m 'first'
$ echo aa > a
$ hg commit -m 'second'
$ hg log -G
@ 1:43114e71eddd second [tip]
|
o 0:a87874c6ec31 first []
Create a tag that looks like a revset
$ hg tag 'rev(0)'
$ hg log -G
@ 2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]
|
o 1:43114e71eddd second [rev(0)]
|
o 0:a87874c6ec31 first []
See how various things are resolved
-----------------------------------
Revision numbers
$ hg log -r '0'
0:a87874c6ec31 first []
$ hg log -r '1'
1:43114e71eddd second [rev(0)]
"rev(x)" form (the one conflicting with the tags)
(resolved as a label)
$ hg log -r 'rev(0)'
1:43114e71eddd second [rev(0)]
$ hg log -r 'rev(1)'
1:43114e71eddd second [rev(0)]
same within a simple revspec
(still resolved as the label)
$ hg log -r ':rev(0)'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
$ hg log -r 'rev(0):'
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]
within a more advances revset
(still resolved as the label)
$ hg log -r 'rev(0) and branch(default)'
0:a87874c6ec31 first []
with explicit revset resolution
(still resolved as the label)
$ hg log -r 'revset(rev(0))'
0:a87874c6ec31 first []
some of the above with quote to force its resolution as a label
$ hg log -r ':"rev(0)"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
$ hg log -r '"rev(0)":'
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd [tip]
$ hg log -r '"rev(0)" and branch(default)'
1:43114e71eddd second [rev(0)]
confusing bits within parents
$ hg log -r '(rev(0))'
0:a87874c6ec31 first []
$ hg log -r '( rev(0))'
0:a87874c6ec31 first []
$ hg log -r '("rev(0)")'
1:43114e71eddd second [rev(0)]
Test label with quote in them.
$ hg tag '"foo"'
$ hg log -r '"foo"'
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
$ hg log -r '("foo")'
abort: unknown revision 'foo'
[10]
$ hg log -r 'revset("foo")'
abort: unknown revision 'foo'
[10]
$ hg log -r '("\"foo\"")'
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
$ hg log -r 'revset("\"foo\"")'
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
Test label with dash in them.
$ hg tag 'foo-bar'
$ hg log -r 'foo-bar'
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
$ hg log -r '(foo-bar)'
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
$ hg log -r '"foo-bar"'
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
$ hg log -r '("foo-bar")'
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
Test label with + in them.
$ hg tag 'foo+bar'
$ hg log -r 'foo+bar'
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
$ hg log -r '(foo+bar)'
abort: unknown revision 'foo'
[10]
$ hg log -r 'revset(foo+bar)'
abort: unknown revision 'foo'
[10]
$ hg log -r '"foo+bar"'
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
$ hg log -r '("foo+bar")'
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
Test tag with numeric version number.
$ hg tag '1.2'
$ hg log -r '1.2'
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r '(1.2)'
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r 'revset(1.2)'
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r '"1.2"'
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r '("1.2")'
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r '::"1.2"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
$ hg log -r '::1.2'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
Test tag with parenthesis (but not a valid revset)
$ hg tag 'release_4.1(candidate1)'
$ hg log -r 'release_4.1(candidate1)'
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
$ hg log -r '(release_4.1(candidate1))'
hg: parse error: unknown identifier: release_4.1
[10]
$ hg log -r 'revset(release_4.1(candidate1))'
hg: parse error: unknown identifier: release_4.1
[10]
$ hg log -r '"release_4.1(candidate1)"'
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
$ hg log -r '("release_4.1(candidate1)")'
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
$ hg log -r '::"release_4.1(candidate1)"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
$ hg log -r '::release_4.1(candidate1)'
hg: parse error: unknown identifier: release_4.1
[10]
Test tag with parenthesis and other function like char
$ hg tag 'release_4.1(arch=x86,arm)'
$ hg log -r 'release_4.1(arch=x86,arm)'
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
$ hg log -r '(release_4.1(arch=x86,arm))'
hg: parse error: unknown identifier: release_4.1
[10]
$ hg log -r 'revset(release_4.1(arch=x86,arm))'
hg: parse error: unknown identifier: release_4.1
[10]
$ hg log -r '"release_4.1(arch=x86,arm)"'
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
$ hg log -r '("release_4.1(arch=x86,arm)")'
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
$ hg log -r '::"release_4.1(arch=x86,arm)"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
$ hg log -r '::release_4.1(arch=x86,arm)'
hg: parse error: unknown identifier: release_4.1
[10]
Test tag conflicting with revset function
$ hg tag 'secret(team=foo,project=bar)'
$ hg log -r 'secret(team=foo,project=bar)'
8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
$ hg log -r '(secret(team=foo,project=bar))'
hg: parse error: secret takes no arguments
[10]
$ hg log -r 'revset(secret(team=foo,project=bar))'
hg: parse error: secret takes no arguments
[10]
$ hg log -r '"secret(team=foo,project=bar)"'
8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
$ hg log -r '("secret(team=foo,project=bar)")'
8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
$ hg log -r '::"secret(team=foo,project=bar)"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
$ hg log -r '::secret(team=foo,project=bar)'
hg: parse error: secret takes no arguments
[10]
Test tag with space
$ hg tag 'my little version'
$ hg log -r 'my little version'
9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
$ hg log -r '(my little version)'
hg: parse error at 4: unexpected token: symbol
((my little version)
^ here)
[10]
$ hg log -r 'revset(my little version)'
hg: parse error at 10: unexpected token: symbol
(revset(my little version)
^ here)
[10]
$ hg log -r '"my little version"'
9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
$ hg log -r '("my little version")'
9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
$ hg log -r '::"my little version"'
0:a87874c6ec31 first []
1:43114e71eddd second [rev(0)]
2:fb616635b18f Added tag rev(0) for changeset 43114e71eddd ["foo"]
3:a50aae922707 Added tag "foo" for changeset fb616635b18f [foo-bar]
4:bbf52b87b370 Added tag foo-bar for changeset a50aae922707 [foo+bar]
5:ff42fde8edbb Added tag foo+bar for changeset bbf52b87b370 [1.2]
6:db72e24fe069 Added tag 1.2 for changeset ff42fde8edbb [release_4.1(candidate1)]
7:b29b25d7d687 Added tag release_4.1(candidate1) for changeset db72e24fe069 [release_4.1(arch=x86,arm)]
8:6b2e2d4ea455 Added tag release_4.1(arch=x86,arm) for changeset b29b25d7d687 [secret(team=foo,project=bar)]
9:269192bf8fc3 Added tag secret(team=foo,project=bar) for changeset 6b2e2d4ea455 [my little version]
$ hg log -r '::my little version'
hg: parse error at 5: invalid token
(::my little version
^ here)
[10]