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.

     1

  $ hg init

     2

     3

  $ echo "added file1" > file1

     4

  $ echo "added file2" > file2

     5

  $ hg add file1 file2

     6

  $ hg commit -m "added file1 and file2"

     7

     8

  $ echo "changed file1" >> file1

     9

  $ hg commit -m "changed file1"

    10

    11

  $ hg -q log

    12

  1:08a16e8e4408

    13

  0:d29c767a4b52

    14

  $ hg id

    15

  08a16e8e4408 tip

    16

    17

  $ hg update -C 0

    18

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

    19

  $ hg id

    20

  d29c767a4b52

    21

  $ echo "changed file1" >> file1

    22

  $ hg id

    23

  d29c767a4b52+

    24

    25

  $ hg revert --all

    26

  reverting file1

    27

  $ hg diff

    28

  $ hg status

    29

  ? file1.orig

    30

  $ hg id

    31

  d29c767a4b52

    32

    33

  $ hg update

    34

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

    35

  $ hg diff

    36

  $ hg status

    37

  ? file1.orig

    38

  $ hg id

    39

  08a16e8e4408 tip

    40

    41

  $ hg update -C 0

    42

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

    43

  $ echo "changed file1" >> file1

    44

    45

  $ hg update

    46

  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

    47

  $ hg diff

    48

  $ hg status

    49

  ? file1.orig

    50

  $ hg id

    51

  08a16e8e4408 tip

    52

    53

  $ hg revert --all

    54

  $ hg diff

    55

  $ hg status

    56

  ? file1.orig

    57

  $ hg id

    58

  08a16e8e4408 tip

    59

    60

  $ hg revert -r tip --all

    61

  $ hg diff

    62

  $ hg status

    63

  ? file1.orig

    64

  $ hg id

    65

  08a16e8e4408 tip

    66

    67

  $ hg update -C

    68

  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

    69

  $ hg diff

    70

  $ hg status

    71

  ? file1.orig

    72

  $ hg id

    73

  08a16e8e4408 tip

    74