treemanifest: optimize treemanifest._walk() to skip directories
This makes treemanifest.walk() not visit submanifests that are known not to
have any matching files. It does this by calling match.visitdir() on
submanifests as it walks.
This change also updates largefiles to be able to work with this new behavior
in treemanifests. It overrides match.visitdir(), the function that dictates
how walk() and matches() skip over directories.
The greatest speed improvements are seen with narrower scopes. For example,
this commit speeds up the following command on the Mozilla repo from 1.14s
to 1.02s:
hg files -r . dom/apps/
Whereas with a wider scope, dom/, the speed only improves from 1.21s to 1.13s.
As with similar a similar optimization to treemanifest.matches(), this change
will bring out even bigger performance improvements once treemanifests are
loaded lazily. Once that happens, we won't just skip over looking at
submanifests, but we'll skip even loading them.
Test how largefiles abort in case the disk runs full
$ cat > criple.py <<EOF
> import os, errno, shutil
> from mercurial import util
> #
> # this makes the original largefiles code abort:
> def copyfileobj(fsrc, fdst, length=16*1024):
> fdst.write(fsrc.read(4))
> raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
> shutil.copyfileobj = copyfileobj
> #
> # this makes the rewritten code abort:
> def filechunkiter(f, size=65536, limit=None):
> yield f.read(4)
> raise IOError(errno.ENOSPC, os.strerror(errno.ENOSPC))
> util.filechunkiter = filechunkiter
> #
> def oslink(src, dest):
> raise OSError("no hardlinks, try copying instead")
> util.oslink = oslink
> EOF
$ echo "[extensions]" >> $HGRCPATH
$ echo "largefiles =" >> $HGRCPATH
$ hg init alice
$ cd alice
$ echo "this is a very big file" > big
$ hg add --large big
$ hg commit --config extensions.criple=$TESTTMP/criple.py -m big
abort: No space left on device
[255]
The largefile is not created in .hg/largefiles:
$ ls .hg/largefiles
dirstate
The user cache is not even created:
>>> import os; os.path.exists("$HOME/.cache/largefiles/")
False
Make the commit with space on the device:
$ hg commit -m big
Now make a clone with a full disk, and make sure lfutil.link function
makes copies instead of hardlinks:
$ cd ..
$ hg --config extensions.criple=$TESTTMP/criple.py clone --pull alice bob
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch default
getting changed largefiles
abort: No space left on device
[255]
The largefile is not created in .hg/largefiles:
$ ls bob/.hg/largefiles
dirstate