Gregory Szorc <gregory.szorc@gmail.com> [Thu, 06 Jul 2017 10:58:45 -0700] rev 33296
sparse: use vfs.tryread()
vfs.exists() followed by a file read is an anti-pattern because it
incurs an extra stat() to test for file presence. vfs.tryread()
returns empty string on missing file and avoids the stat().
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 01 Jul 2017 11:56:39 -0700] rev 33295
sparse: refactor sparsechecksum()
This was relying on garbage collection to close the opened
file, which is a bug. Both callers simply called into self.vfs
to resolve the path. So refactor to use the vfs layer.
While we're here, rename the method to reflect it is internal
and to break anyone relying on the old behavior.
Gregory Szorc <gregory.szorc@gmail.com> [Thu, 06 Jul 2017 10:57:26 -0700] rev 33294
sparse: document config file format
This was previously undocumented. Seems useful to have.
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 01 Jul 2017 10:29:27 -0700] rev 33293
sparse: rename command to debugsparse
Sparse checkout is still highly experimental and not protected
by BC guarantees yet. We also haven't had a discussion on the UX.
To discourage use, we rename the sparse command to debugsparse.
Gregory Szorc <gregory.szorc@gmail.com> [Thu, 06 Jul 2017 10:54:23 -0700] rev 33292
sparse: remove reference to simplecache
This is a 3rd party extension authored by Facebook. References in
core are not appropriate.
It will be possible to restore this code/optimization via
monkeypatching. So Facebook won't lose any functionality.
The removed code is important for performance. So add a comment
tracking it.
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 01 Jul 2017 10:24:31 -0700] rev 33291
sparse: remove reference to hgwatchman
This is a legacy extension. Now that the extension is in core,
we only need to support what's in core, which is fsmonitor.
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 01 Jul 2017 10:36:03 -0700] rev 33290
sparse: expand module docstring
Clarify lack of BC guarantees. And say a bit more about the extension.
Gregory Szorc <gregory.szorc@gmail.com> [Sat, 01 Jul 2017 10:43:29 -0700] rev 33289
sparse: vendor Facebook-developed extension
Facebook has developed an extension to enable "sparse" checkouts -
a working directory with a subset of files. This feature is a critical
component in enabling repositories to scale to infinite number of
files while retaining reasonable performance. It's worth noting
that sparse checkout is only one possible solution to this problem:
another is virtual filesystems that realize files on first access.
But given that virtual filesystems may not be accessible to all
users, sparse checkout is necessary as a fallback.
Per mailing list discussion at
https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-March/095868.html
we want to add sparse checkout to the Mercurial distribution via
roughly the following mechanism:
1. Vendor extension as-is with minimal modifications (this patch)
2. Refactor extension so it is more clearly experimental and inline
with Mercurial practices
3. Move code from extension into core where possible
4. Drop experimental labeling and/or move feature into core
after sign-off from narrow clone feature owners
This commit essentially copies the sparse extension and tests
from revision 71e0a2aeca92a4078fe1b8c76e32c88ff1929737 of the
https://bitbucket.org/facebook/hg-experimental repository.
A list of modifications made as part of vendoring is as follows:
* "EXPERIMENTAL" added to module docstring
* Imports were changed to match Mercurial style conventions
* "testedwith" value was updated to core Mercurial special value and
comment boilerplate was inserted
* A "clone_sparse" function was renamed to "clonesparse" to appease
the style checker
* Paths to the sparse extension in tests reflect built-in location
* test-sparse-extensions.t was renamed to test-sparse-fsmonitor.t
and references to "simplecache" were removed. The test always skips
because it isn't trivial to run it given the way we currently run
fsmonitor tests
* A double empty line was removed from test-sparse-profiles.t
There are aspects of the added code that are obviously not ideal.
The goal is to make a minimal number of modifications as part of
the vendoring to make it easier to track changes from the original
implementation. Refactoring will occur in subsequent patches.
Augie Fackler <augie@google.com> [Thu, 06 Jul 2017 15:15:02 -0400] rev 33288
contrib: widen "direct use of `python`" net again
I think I've now caught all of them.
Differential Revision: https://phab.mercurial-scm.org/D15
Kevin Bullock <kbullock+mercurial@ringworld.org> [Thu, 06 Jul 2017 14:33:48 -0500] rev 33287
tests: clean up a newly-introduced instance of `python`
Differential Revision: https://phab.mercurial-scm.org/D16