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.
$ hg init
$ echo 0 > a
$ echo 0 > b
$ hg ci -A -m m
adding a
adding b
$ hg rm a
$ hg cat a
0
$ hg cat --decode a # more tests in test-encode
0
$ echo 1 > b
$ hg ci -m m
$ echo 2 > b
$ hg cat -r 0 a
0
$ hg cat -r 0 b
0
$ hg cat -r 1 a
a: no such file in rev 7040230c159c
[1]
$ hg cat -r 1 b
1
Test multiple files
$ echo 3 > c
$ hg ci -Am addmore c
$ hg cat b c
1
3
$ hg cat .
1
3
$ hg cat . c
1
3
Test fileset
$ hg cat 'set:not(b) or a'
3
$ hg cat 'set:c or b'
1
3
$ mkdir tmp
$ hg cat --output tmp/HH_%H c
$ hg cat --output tmp/RR_%R c
$ hg cat --output tmp/h_%h c
$ hg cat --output tmp/r_%r c
$ hg cat --output tmp/%s_s c
$ hg cat --output tmp/%d%%_d c
$ hg cat --output tmp/%p_p c
$ hg log -r . --template "{rev}: {node|short}\n"
2: 45116003780e
$ find tmp -type f | sort
tmp/.%_d
tmp/HH_45116003780e3678b333fb2c99fa7d559c8457e9
tmp/RR_2
tmp/c_p
tmp/c_s
tmp/h_45116003780e
tmp/r_2
Test template output
$ hg --cwd tmp cat ../b ../c -T '== {path|relpath} ({path}) r{rev} ==\n{data}'
== ../b (b) r2 ==
1
== ../c (c) r2 ==
3
$ hg cat b c -Tjson --output -
[
{
"data": "1\n",
"path": "b"
},
{
"data": "3\n",
"path": "c"
}
]
$ hg cat b c -Tjson --output 'tmp/%p.json'
$ cat tmp/b.json
[
{
"data": "1\n",
"path": "b"
}
]
$ cat tmp/c.json
[
{
"data": "3\n",
"path": "c"
}
]
Test working directory
$ echo b-wdir > b
$ hg cat -r 'wdir()' b
b-wdir
Environment variables are not visible by default
$ PATTERN='t4' hg log -r '.' -T "{ifcontains('PATTERN', envvars, 'yes', 'no')}\n"
no
Environment variable visibility can be explicit
$ PATTERN='t4' hg log -r '.' -T "{envvars % '{key} -> {value}\n'}" \
> --config "experimental.exportableenviron=PATTERN"
PATTERN -> t4
Test behavior of output when directory structure does not already exist
$ mkdir foo
$ echo a > foo/a
$ hg add foo/a
$ hg commit -qm "add foo/a"
$ hg cat --output "output/%p" foo/a
$ cat output/foo/a
a