scmutil: create directories in a race-safe way during update
With the new parallel update code, it is possible for multiple
workers to try to create a hierarchy of directories at the same
time. This is hard to trigger in general, but most likely during
initial checkout.
To deal with these races, we introduce a new ensuredirs function
whose contract is to ensure that a directory hierarchy exists - it
will ignore a failure that implies that the desired directory already
exists.
$ hg init t
$ cd t
$ mkdir a
$ echo foo > a/a
$ echo bar > a/b
$ hg ci -Am "0"
adding a/a
adding a/b
$ hg co -C 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv a b
moving a/a to b/a (glob)
moving a/b to b/b (glob)
$ hg ci -m "1 mv a/ b/"
$ hg co -C 0
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo baz > a/c
$ echo quux > a/d
$ hg add a/c
$ hg ci -m "2 add a/c"
created new head
$ hg merge --debug 1
searching for copies back to rev 1
unmatched files in local:
a/c
unmatched files in other:
b/a
b/b
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: f9b20c0d4c51, local: ce36d17b18fb+, remote: 397f8b00a740
a/a: other deleted -> r
a/b: other deleted -> r
a/c: remote renamed directory to b/c -> d
b/a: remote created -> g
b/b: remote created -> g
removing a/a
removing a/b
getting b/a
getting b/b
updating: b/b 4/5 files (80.00%)
updating: a/c 5/5 files (100.00%)
moving a/c to b/c
3 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
M b/a
M b/b
A b/c
a/c
R a/a
R a/b
R a/c
? a/d
$ hg ci -m "3 merge 2+1"
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88 (glob)
$ hg co -C 1
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge --debug 2
searching for copies back to rev 1
unmatched files in local:
b/a
b/b
unmatched files in other:
a/c
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: f9b20c0d4c51, local: 397f8b00a740+, remote: ce36d17b18fb
None: local renamed directory to b/c -> d
updating:None 1/1 files (100.00%)
getting a/c to b/c
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
A b/c
a/c
? a/d
$ hg ci -m "4 merge 1+2"
created new head
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88 (glob)
Second scenario with two repos:
$ cd ..
$ hg init r1
$ cd r1
$ mkdir a
$ echo foo > a/f
$ hg add a
adding a/f (glob)
$ hg ci -m "a/f == foo"
$ cd ..
$ hg clone r1 r2
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd r2
$ hg mv a b
moving a/f to b/f (glob)
$ echo foo1 > b/f
$ hg ci -m" a -> b, b/f == foo1"
$ cd ..
$ cd r1
$ mkdir a/aa
$ echo bar > a/aa/g
$ hg add a/aa
adding a/aa/g (glob)
$ hg ci -m "a/aa/g"
$ hg pull ../r2
pulling from ../r2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st -C
M b/f
A b/aa/g
a/aa/g
R a/aa/g
R a/f
$ cd ..