procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
A python hook for "hg fix" that prints out the number of files and revisions
that were affected, along with which fixer tools were applied. Also checks how
many times it sees a specific key generated by one of the fixer tools defined
below.
$ cat >> $TESTTMP/postfixhook.py <<EOF
> import collections
> def file(ui, repo, rev=None, path=b'', metadata=None, **kwargs):
> ui.status(b'fixed %s in revision %d using %s\n' %
> (path, rev, b', '.join(metadata.keys())))
> def summarize(ui, repo, replacements=None, wdirwritten=False,
> metadata=None, **kwargs):
> counts = collections.defaultdict(int)
> keys = 0
> for fixername, metadatalist in metadata.items():
> for metadata in metadatalist:
> if metadata is None:
> continue
> counts[fixername] += 1
> if 'key' in metadata:
> keys += 1
> ui.status(b'saw "key" %d times\n' % (keys,))
> for name, count in sorted(counts.items()):
> ui.status(b'fixed %d files with %s\n' % (count, name))
> if replacements:
> ui.status(b'fixed %d revisions\n' % (len(replacements),))
> if wdirwritten:
> ui.status(b'fixed the working copy\n')
> EOF
Some mock output for fixer tools that demonstrate what could go wrong with
expecting the metadata output format.
$ printf 'new content\n' > $TESTTMP/missing
$ printf 'not valid json\0new content\n' > $TESTTMP/invalid
$ printf '{"key": "value"}\0new content\n' > $TESTTMP/valid
Configure some fixer tools based on the output defined above, and enable the
hooks defined above. Disable parallelism to make output of the parallel file
processing phase stable.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> fix =
> [fix]
> metadatafalse:command=cat $TESTTMP/missing
> metadatafalse:pattern=metadatafalse
> metadatafalse:metadata=false
> missing:command=cat $TESTTMP/missing
> missing:pattern=missing
> missing:metadata=true
> invalid:command=cat $TESTTMP/invalid
> invalid:pattern=invalid
> invalid:metadata=true
> valid:command=cat $TESTTMP/valid
> valid:pattern=valid
> valid:metadata=true
> [hooks]
> postfixfile = python:$TESTTMP/postfixhook.py:file
> postfix = python:$TESTTMP/postfixhook.py:summarize
> [worker]
> enabled=false
> EOF
See what happens when we execute each of the fixer tools. Some print warnings,
some write back to the file.
$ hg init repo
$ cd repo
$ printf "old content\n" > metadatafalse
$ printf "old content\n" > invalid
$ printf "old content\n" > missing
$ printf "old content\n" > valid
$ hg add -q
$ hg fix -w
ignored invalid output from fixer tool: invalid
fixed metadatafalse in revision 2147483647 using metadatafalse
ignored invalid output from fixer tool: missing
fixed valid in revision 2147483647 using valid
saw "key" 1 times
fixed 1 files with valid
fixed the working copy
$ cat metadatafalse
new content
$ cat missing
old content
$ cat invalid
old content
$ cat valid
new content
$ cd ..