We want this logic to live next to where metadata types are defined so
downstream consumers of Files-based metadata don't have to reinvent the
wheel.
The work in this commit will be used to enable auto filing bugs during
pushes to MozReview.
The hglib Mercurial finder was nice. But it is somewhat slow, as it
involves a separate Mercurial process.
This commit introduces a native Mercurial finder that speaks directly
to a Mercurial repository instance. It is significantly faster.
The new code is isolated to its own file because it imports Mercurial
code, which is GPL.
This commit adds support for specifying a Mercurial revision with `mach
file-info`. Aside from being a potentially useful feature, it proves
that MercurialRevisionFinder works with BuildReader.
The moz.build reader uses absolute paths when referencing moz.build
files. *Finder classes expect paths to be relative to a base. When we
switched the reader to use *Finder instances for I/O, we simply provided
a default FileFinder based at the filesystem root. This was quick and
easy. Things worked.
Unfortunately, that solution isn't ideal because not all *Finder
instances can accept absolute paths like that. The
MercurialRevisionFinder is one of them.
Changing the moz.build reader to talk in terms of relative paths is a
lot of work. While this would be ideal, it is significantly easier to
defer the problem until later and hack up MercurialRevisionFinder to
accept absolute paths. This commit does exactly that.
Bug 1171069 has been filed to track converting BuildReader to relative
paths.
Now that moz.build files use finders for I/O, we can start reading
moz.build data from other sources.
Version control is essentially a filesystem. We implement a finder
that speaks to Mercurial to obtain file data. It is able to obtain
file data from a specific revision in the repository.
We use the hglib package (which uses the Mercurial command server) for
speaking with Mercurial. This adds overhead compared to consuming the
raw Mercurial APIs. However, it also avoids GPL side-effects of
importing Mercurial's Python modules.
Testing shows that performance is good but not great. A follow-up
commit will introduce a GPL licensed Mercurial finder. For now, get
the base functionality in place.
Sometimes moz.build data may not come from the local filesystem. To
support defining moz.build data in other backing stores, we switch
moz.build reading to use mozpack's *Finder classes for I/O.
The use of a FileFinder bound to / is sub-optimal. We should ideally
be creating a finder bound to topsrcdir. However, doing this would
require refactoring a lot of path handling in the reader, as that code
makes many assumptions that paths are absolute. This would be excellent
follow-up work.
While I was here, I cleaned up some linter warnings for unused imports.
On my machine, this commit results in a slight slowdown of moz.build
reading. Before, `mach build-backend` was consistently reporting 1.99s
for reading 2,572 moz.build files. After, it is consistently reporting
2.07s, an increase of 4%. This is likely due to a) function call
overhead b) the cost of instantiating a few thousand File instances
c) FileFinder performing an os.path.exists() before returning File
instances. I believe the regression is tolerable.
Passing raw file handles around is a bit dangerous because it could lead
to leaking file descriptors. Add a read() method that handles the simple
case of obtaining the full contents of a File instance.
This should ideally be a method on BaseFile. But this would require
extra work and isn't needed. So we've deferred it until bug 1170329.
Today, the *Finder classes are optimized for doing matching and
returning multiple results. However, sometimes only looking for a
single file is wanted.
This commit implements the "get" method on all the *Finder classes.
It returns a BaseFile or None.
FileFinder._find_file has been refactored into FileFinder.get
to avoid code duplication.
The current mode of execution of templates doesn't allow them to more advanced
control flow, like returning early, returning or yielding values, because that
mode of execution is equivalent to running the code at the top level of a .py
file.
Making the templates executed through a function call, although trickier,
allows those control flows, which will be useful for template as context
managers.
inspect.getsourcelines() and inspect.getfile() involve I/O out of our control.
Our use of those functions, however, doesn't require all their smarts. In fact,
we only use them on function objects, for which we can just do the work
ourselves without involving inspect functions that trigger I/O.
`mach help <command>` currently only displays a brief description of the
command along with its arguments. Sometimes more detailed help text is
needed.
With this commit, the docstrings of mach command handlers will appear in
the output of `mach help <command>` if they are defined.
I've implemented basic docstrings for the three flavors of mach commands
(normal command, main subcommand, subcommand) to demonstate things work.
My hope is others will start to fill in docstrings once this feature
lands so the output for `mach help` can serve as a better learning guide
for new contributors.
The old way of writing scripts for generated files would invoke the script thusly:
python script.py arg1...
Invoking the script this way means that the script's directory is
automatically added to sys.path, and importing modules from that
directory is easy. Let's make it equally easy in the new world for
GENERATED_FILES, too.
Add generic support for different forms of paths in moz.build:
'/topsrcdir/relative/paths'
'srcdir/relative/paths'
'!/topobjdir/relative/paths'
'!objdir/relative/paths'
This drops the use of UserString for performance reasons, which required
going around with a meta class.
This code has been commented since it landed, and enabling it requires
adding the proper conditionals around all non_unified_sources in gyp
configurations, which is a daunting task. OTOH, the commented code is
already outdated (it would need updates to work) and the related code
that is not commented gets in the way of upcoming changes, so remove
it.
This helps upcoming changes, and relieves backends from path resolution.
This has the side effect of chaning the order of some unified sources,
which consequently breaks nsTextFormatter because it declares snprintf
methods after nsStringAPI #defines it.
