dirstate-tree: Add tree traversal/iteration
Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.
Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.
This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.
Differential Revision: https://phab.mercurial-scm.org/D10370
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > x
$ hg commit -qAm x
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cd master
$ echo xx > x
$ hg commit -qAm x2
$ cd ..
# Test cache misses with read only permissions on server
$ chmod -R a-w master/.hg/remotefilelogcache
$ cd shallow
$ hg pull -q
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cd ..
$ chmod -R u+w master/.hg/remotefilelogcache
# Test setting up shared cache with the right permissions
# (this is hard to test in a cross platform way, so we just make sure nothing
# crashes)
$ rm -rf $CACHEDIR
$ umask 002
$ mkdir $CACHEDIR
$ hg -q clone --shallow ssh://user@dummy/master shallow2 --config remotefilelog.cachegroup="`id -g -n`"
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over * (glob)
$ ls -ld $CACHEDIR/11
drwxrws* $TESTTMP/hgcache/11 (glob)