obsolete: don't use os.stat in repo.obsstore.__nonzero__ if it's static HTTP
If a repo is accessed via static HTTP, then we obviously can't use os.stat() to
just peek at the file size. Let's download the entire file to check its size.
Yes, this feels wasteful, but:
1. If we're cloning or pulling a repo from a static HTTP server, we need the
contents of the obsstore anyway.
2. Implementing statichttpvfs.stat() that uses HEAD will result in one more
request to a static-only HTTP server, which is already slow. Also parsing a
response to a HEAD request to construct os.stat_result is pretty hacky.
There's also a question of the remote server properly supporting HEAD method
and reporting at least file size.
3. Implementing statichttpvfs.stat() that uses GET is pretty much the same
thing as we do here, except we can't even cache the response easily, unlike
simply accessing obsstore._data, which is @propertycache'd.
Importing statichttprepo locally to avoid circular import.
See also: 4507bc001365 and commit message of f8f2ecdde4b5.
Differential Revision: https://phab.mercurial-scm.org/D12195
create verbosemmap.py
$ cat << EOF > verbosemmap.py
> # extension to make util.mmapread verbose
>
> from __future__ import absolute_import
>
> from mercurial import (
> extensions,
> pycompat,
> util,
> )
>
> def extsetup(ui):
> def mmapread(orig, fp):
> ui.write(b"mmapping %s\n" % pycompat.bytestr(fp.name))
> ui.flush()
> return orig(fp)
>
> extensions.wrapfunction(util, 'mmapread', mmapread)
> EOF
setting up base repo
$ hg init a
$ cd a
$ touch a
$ hg add a
$ hg commit -qm base
$ for i in `$TESTDIR/seq.py 1 100` ; do
> echo $i > a
> hg commit -qm $i
> done
set up verbosemmap extension
$ cat << EOF >> $HGRCPATH
> [extensions]
> verbosemmap=$TESTTMP/verbosemmap.py
> EOF
mmap index which is now more than 4k long
$ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=4k
mmapping $TESTTMP/a/.hg/store/00changelog.i
100
99
98
97
96
do not mmap index which is still less than 32k
$ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=32k
100
99
98
97
96
$ cd ..