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comparison mercurial/utils/procutil.py @ 45043:fd205a9c358a

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procutil: factor out conditional creation of LineBufferedWrapper At the same time, document the logic and generalize it to work on all Python versions.
author Manuel Jacob <me@manueljacob.de>
date Sat, 04 Jul 2020 12:15:41 +0200
parents 2bfbd7d2c204
children 1053f878dd46
comparison
equal deleted inserted replaced
45042:2bfbd7d2c204 45043:fd205a9c358a
63 orig.flush() 63 orig.flush()
64 return res 64 return res
65 65
66 66
67 io.BufferedIOBase.register(LineBufferedWrapper) 67 io.BufferedIOBase.register(LineBufferedWrapper)
68
69
70 def make_line_buffered(stream):
71 if pycompat.ispy3 and not isinstance(stream, io.BufferedIOBase):
72 # On Python 3, buffered streams can be expected to subclass
73 # BufferedIOBase. This is definitively the case for the streams
74 # initialized by the interpreter. For unbuffered streams, we don't need
75 # to emulate line buffering.
76 return stream
77 if isinstance(stream, LineBufferedWrapper):
78 return stream
79 return LineBufferedWrapper(stream)
68 80
69 81
70 # glibc determines buffering on first write to stdout - if we replace a TTY 82 # glibc determines buffering on first write to stdout - if we replace a TTY
71 # destined stdout with a pipe destined stdout (e.g. pager), we want line 83 # destined stdout with a pipe destined stdout (e.g. pager), we want line
72 # buffering (or unbuffered, on Windows) 84 # buffering (or unbuffered, on Windows)
75 # Windows doesn't support line buffering 87 # Windows doesn't support line buffering
76 stdout = os.fdopen(stdout.fileno(), 'wb', 0) 88 stdout = os.fdopen(stdout.fileno(), 'wb', 0)
77 elif pycompat.ispy3: 89 elif pycompat.ispy3:
78 # On Python 3, buffered binary streams can't be set line-buffered. 90 # On Python 3, buffered binary streams can't be set line-buffered.
79 # Therefore we have a wrapper that implements line buffering. 91 # Therefore we have a wrapper that implements line buffering.
80 if isinstance(stdout, io.BufferedIOBase) and not isinstance( 92 stdout = make_line_buffered(stdout)
81 stdout, LineBufferedWrapper
82 ):
83 stdout = LineBufferedWrapper(stdout)
84 else: 93 else:
85 stdout = os.fdopen(stdout.fileno(), 'wb', 1) 94 stdout = os.fdopen(stdout.fileno(), 'wb', 1)
86 95
87 if pycompat.iswindows: 96 if pycompat.iswindows:
88 from .. import windows as platform 97 from .. import windows as platform