My environment (Python version? PYTHONPATH? something else?) raises
ModuleNotFoundError in test-check-py3-compat.t. This patch allows any
"*Error". The error string contains "error importing", so it seems
specific enough even after.
Commit 3054ae3a66112970a091d3939fee32c2d0c1a23e from
https://github.com/indygreg/python-zstandard is imported without
modifications (other than removing unwanted files).
The vendored zstd library within has been upgraded from 1.1.2 to
1.1.3. This version introduced new APIs for threads, thread
pools, multi-threaded compression, and a new dictionary
builder (COVER). These features are not yet used by
python-zstandard (or Mercurial for that matter). However,
that will likely change in the next python-zstandard release
(and I think there are opportunities for Mercurial to take
advantage of the multi-threaded APIs).
Relevant to Mercurial, the CFFI bindings are now fully
implemented. This means zstd should "just work" with PyPy
(although I haven't tried). The python-zstandard test suite also
runs all tests against both the C extension and CFFI bindings to
ensure feature parity.
There is also a "decompress_content_dict_chain()" API. This was
derived from discussions with Yann Collet on list about alternate
ways of encoding delta chains.
The change most relevant to Mercurial is a performance enhancement in
the simple decompression API to reuse a data structure across
operations. This makes decompression of multiple inputs significantly
faster. (This scenario occurs when reading revlog delta chains, for
example.)
Using python-zstandard's bench.py to measure the performance
difference...
On changelog chunks in the mozilla-unified repo:
decompress discrete decompress() reuse zctx
1.262243 wall; 1.260000 CPU; 1.260000 user; 0.000000 sys 170.43 MB/s (best of 3)
0.949106 wall; 0.950000 CPU; 0.950000 user; 0.000000 sys 226.66 MB/s (best of 4)
decompress discrete dict decompress() reuse zctx
0.692170 wall; 0.690000 CPU; 0.690000 user; 0.000000 sys 310.80 MB/s (best of 5)
0.437088 wall; 0.440000 CPU; 0.440000 user; 0.000000 sys 492.17 MB/s (best of 7)
On manifest chunks in the mozilla-unified repo:
decompress discrete decompress() reuse zctx
1.367284 wall; 1.370000 CPU; 1.370000 user; 0.000000 sys 274.01 MB/s (best of 3)
1.086831 wall; 1.080000 CPU; 1.080000 user; 0.000000 sys 344.72 MB/s (best of 3)
decompress discrete dict decompress() reuse zctx
0.993272 wall; 0.990000 CPU; 0.990000 user; 0.000000 sys 377.19 MB/s (best of 3)
0.678651 wall; 0.680000 CPU; 0.680000 user; 0.000000 sys 552.06 MB/s (best of 5)
That should make reads on zstd revlogs a bit faster ;)
# no-check-commit
Update to upstream to version c77452. The refresh includes fixes to improve
windows compatibility.
There is a minor update to 'test-check-py3-compat.t' as c77452 no longer have
the py3 compatibility issues the previous version had.
# no-check-commit
__slots__ in Python 3 accepts only unicodes and there is no harm using
unicodes in __slots__. So just adding u'' is fine. Previous occurences of this
problem are treated the same way.
As the commit message for the previous changeset says, we wish
for zstd to be a 1st class citizen in Mercurial. To make that
happen, we need to enable Python to talk to the zstd C API. And
that requires bindings.
This commit vendors a copy of existing Python bindings. Why do we
need to vendor? As the commit message of the previous commit says,
relying on systems in the wild to have the bindings or zstd present
is a losing proposition. By distributing the zstd and bindings with
Mercurial, we significantly increase our chances that zstd will
work. Since zstd will deliver a better end-user experience by
achieving better performance, this benefits our users. Another
reason is that the Python bindings still aren't stable and the
API is somewhat fluid. While Mercurial could be coded to target
multiple versions of the Python bindings, it is safer to bundle
an explicit, known working version.
The added Python bindings are mostly a fully-featured interface
to the zstd C API. They allow one-shot operations, streaming,
reading and writing from objects implements the file object
protocol, dictionary compression, control over low-level compression
parameters, and more. The Python bindings work on Python 2.6,
2.7, and 3.3+ and have been tested on Linux and Windows. There are
CFFI bindings, but they are lacking compared to the C extension.
Upstream work will be needed before we can support zstd with PyPy.
But it will be possible.
The files added in this commit come from Git commit
e637c1b214d5f869cf8116c550dcae23ec13b677 from
https://github.com/indygreg/python-zstandard and are added without
modifications. Some files from the upstream repository have been
omitted, namely files related to continuous integration.
In the spirit of full disclosure, I'm the maintainer of the
"python-zstandard" project and have authored 100% of the code
added in this commit. Unfortunately, the Python bindings have
not been formally code reviewed by anyone. While I've tested
much of the code thoroughly (I even have tests that fuzz APIs),
there's a good chance there are bugs, memory leaks, not well
thought out APIs, etc. If someone wants to review the code and
send feedback to the GitHub project, it would be greatly
appreciated.
Despite my involvement with both projects, my opinions of code
style differ from Mercurial's. The code in this commit introduces
numerous code style violations in Mercurial's linters. So, the code
is excluded from most lints. However, some violations I agree with.
These have been added to the known violations ignore list for now.
Vendored from https://bitbucket.org/facebook/hg-experimental
changeset 73f9db47ae5a1a9fa29a98dfe92d557ad51234c3 without
modification.
This introduces a number of code style violations. The file
already has the magic words to skip test-check-code.t. I'll
make additional changes to clean up the test-check-py3-compat.t
warnings and to change some behavior in the code that isn't
suitable for general use.
test-check-commit.t also complains about numerous things. But
there's nothing we can do if we're importing as-is.
Otherwise no code transformation would be applied to the modules which are
imported only by imp.load_module().
This change means modules are imported from PYTHONPATH, not from the paths
given by command arguments. This isn't always correct, but seems acceptable.
For now, these sets will be unicode characters in Python 3, which is
probably wrong, but it un-blocks importing the module so we can get
further along. In the future we'll have to come up with a reasonable
encoding strategy for revsets in Python 3.
This patch was originally pair-programmed with Martijn.
sys.version is a string, and shouldn't be compared against a tuple for
version comparisons. This was always true, so we were never disabling
gc on 2.6.
>>> (2, 7) >= '2.7'
True
>>> (2, 6) >= '2.7'
True
There is a case and more can be present where these functions have
multiple arguments. Our transformer used to handle the first argument, so
added a loop to handle more arguments if present.
encoding.encoding is bytes, we need to pass it to encode() which accepts
unicodes in py3, so used pycomapt.sysstr() Also this can't be done using
transformer as that only transforms the string values not variables.
If we don't do this, people without pygments installed in their Python
3 environment silently stop checking test-check-py3-compat, which
isn't really what we wanted. This preserves stability of the test
output while still letting anyone with a recent-enough Python 3 run
the majority of the Python 3 compat checking test.
This should be less invasive than mucking builtins.
Since tokenize.untokenize() looks start/end positions of tokens, we calculates
them from the NEWLINE token of the future import.
_winreg module is renamed to winreg in python 3. Added the conditionalize
statements in the respective file because adding this in pycompat will result
in pycompat throwing error as this is a windows registry module and we have
buildbots and most of the contributors on linux.
Before this patch, check-py3-compat.py implies unintentional ".pure"
sub-package name at loading pure modules, because module name is
composed by just replacing "/" in the path to actual ".py" file by
".".
This makes pure modules belong to "mercurial.pure" package, and
prevents them from importing a module belonging to "mercurial" package
relatively by "from . import foo" or so.
This is reason why pure modules fail to import another module
relatively only at examination by check-py3-compat.py.
Recent work on mercurial/pure/mpatch.py made it import
mercurial.policy, and changed output of check-py3-compat.py with
python3 in test-check-py3-compat.t. But test-check-py3-compat.t isn't
yet updated.
The lower part of test-check-py3-compat.t runs only on py3 and hence its
remain unchanged. Hence this patch updates the output so that change in output
in the next patches will be only related to the change in the patch.
The BaseHTTPServer, SimpleHTTPServer and CGIHTTPServer has been merged into
http.server in python 3. All of them has been merged as util.httpserver to use
in both python 2 and 3. This patch adds a regex to check-code to warn against
the use of BaseHTTPServer. Moreover this patch also includes updates to lower
part of test-check-py3-compat.t which used to remain unchanged.
The most painful part of ensuring Python code runs on both Python 2
and 3 is string encoding. Making this difficult is that string
literals in Python 2 are bytes and string literals in Python 3 are
unicode. So, to ensure consistent types are used, you have to
use "from __future__ import unicode_literals" and/or prefix literals
with their type (e.g. b'foo' or u'foo').
Nearly every string in Mercurial is bytes. So, to use the same source
code on both Python 2 and 3 would require prefixing nearly every
string literal with "b" to make it a byte literal. This is ugly and
not something mpm is willing to do at this point in time.
This patch implements a custom module loader on Python 3 that performs
source transformation to convert string literals (unicode in Python 3)
to byte literals. In effect, it changes Python 3's string literals to
behave like Python 2's.
In addition, the module loader recognizes well-known built-in
functions (getattr, setattr, hasattr) and methods (encode and decode)
that barf when bytes are used and prevents these from being rewritten.
This prevents excessive source changes to accommodate this change
(we would have to rewrite every occurrence of these functions passing
string literals otherwise).
The module loader is only used on Python packages belonging to
Mercurial.
The loader works by tokenizing the loaded source and replacing
"string" tokens if necessary. The modified token stream is
untokenized back to source and loaded like normal. This does add some
overhead. However, this all occurs before caching: .pyc files will
cache the transformed version. This means the transformation penalty
is only paid on first load.
As the extensive inline comments explain, the presence of a custom
source transformer invalidates assumptions made by Python's built-in
bytecode caching mechanism. So, we have to wrap bytecode loading and
writing and add an additional header to bytecode files to facilitate
additional cache validation when the source transformations
change in the future.
There are still a few things this code doesn't handle well, namely
support for zip files as module sources and for extensions. Since
Mercurial doesn't officially support Python 3 yet, I'm inclined to
leave these as to-do items: getting a basic module loading mechanism
in place to unblock further Python 3 porting effort is more important
than comprehensive module importing support.
check-py3-compat.py has been updated to ignore frames. This is
necessary because CPython has built-in code to strip frames from the
built-in importer. When our custom code is present, this doesn't work
and the frames get all messed up. The new code is not perfect. It
works for now. But once you start chasing import failures you find
some edge cases where the files aren't being printed properly. This
only burdens people doing future Python 3 porting work so I'm inclined
to punt on the issue: the most important thing is for the source
transforming module loader to land.
There was a bit of churn in test-check-py3-compat.t because we now
trip up on str/unicode/bytes failures as a result of source
transformation. This is unfortunate but what are you going to do.
It's worth noting that other approaches were investigated.
We considered using a custom file encoding whose decode() would
apply source transformations. This was rejected because it would
require each source file to declare its custom Mercurial encoding.
Furthermore, when changing the source transformation we'd need to
version bump the encoding name otherwise the module caching layer
wouldn't know the .pyc file was invalidated. This would mean mass
updating every file when the source transformation changes. Yuck.
We also considered transforming at the AST layer. However, Python's
ast module is quite gnarly and doing AST transforms is quite
complicated, even for trivial rewrites. There are whole Python packages
that exist to make AST transformations usable. AST transforms would
still require import machinery, so the choice was basically to
perform source-level, token-level, or ast-level transforms.
Token-level rewriting delivers the metadata we need to rewrite
intelligently while being relatively easy to understand. So it won.
General consensus seems to be that this approach is the best available
to avoid bulk rewriting of '' to b''. However, we aren't confident
that this approach will never be a future maintenance burden. This
approach does unblock serious Python 3 porting efforts. So we can
re-evaulate once more work is done to support Python 3.
This patch includes addition of absolute_import and print_function to the
files where they are missing. The modern importing conventions are also followed.
The httplib library is renamed to http.client in python 3. So the
import is conditionalized and a test is added in check-code to warn
to use util.httplib
