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 t
$ cd t
$ echo 1 > foo
$ hg ci -Am1 # 0
adding foo
$ hg branch branchA
marked working directory as branch branchA
(branches are permanent and global, did you want a bookmark?)
$ echo a1 > foo
$ hg ci -ma1 # 1
$ cd ..
$ hg init tt
$ cd tt
$ hg pull ../t
pulling from ../t
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 495a0ec48aaf:50e089d141b7
(run 'hg update' to get a working copy)
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../t
$ echo a2 > foo
$ hg ci -ma2 # 2
Create branch B:
$ hg up 0
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch branchB
marked working directory as branch branchB
$ echo b1 > foo
$ hg ci -mb1 # 3
$ cd ../tt
A new branch is there
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files (+1 heads)
new changesets 9f878dea0b96:5be59ce5067b
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Develop both branches:
$ cd ../t
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a3 > foo
$ hg ci -ma3 # 4
$ hg up branchB
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b2 > foo
$ hg ci -mb2 # 5
$ cd ../tt
Should succeed, no new heads:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 7c8fe7e20c32:453e93fa00a5
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Add a head on other branch:
$ cd ../t
$ hg up branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a4 > foo
$ hg ci -ma4 # 6
$ hg up branchB
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b3.1 > foo
$ hg ci -m b3.1 # 7
$ hg up 5
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b3.2 > foo
$ hg ci -m b3.2 # 8
created new head
$ cd ../tt
Should succeed because there is only one head on our branch:
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 3 changesets with 3 changes to 1 files (+1 heads)
new changesets da3a8a0161c6:b61cab8fe4e8
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../t
$ hg up -C branchA
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a5.1 > foo
$ hg ci -ma5.1 # 9
$ hg up 6
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a5.2 > foo
$ hg ci -ma5.2 # 10
created new head
$ hg up 7
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b4.1 > foo
$ hg ci -m b4.1 # 11
$ hg up -C 8
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo b4.2 > foo
$ hg ci -m b4.2 # 12
$ cd ../tt
$ hg pull -u ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 4 changesets with 4 changes to 1 files (+1 heads)
new changesets 0c4d148ae29e:ecfc3f4a6fd9
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
updated to "d740e1a584e7: a5.2"
1 other heads for branch "branchA"
Make changes on new branch on tt
$ hg up 6
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg branch branchC
marked working directory as branch branchC
$ echo b1 > bar
$ hg ci -Am "commit on branchC on tt"
adding bar
Make changes on default branch on t
$ cd ../t
$ hg up -C default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar
$ hg ci -Am "commit on default on t"
adding bar
Pull branchC from tt
$ hg pull ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 7d8ffa4c0b22
13 local changesets published
(run 'hg heads' to see heads)
Make changes on default and branchC on tt
$ cd ../tt
$ hg pull ../t
pulling from ../t
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 2b94b54b6b5f
1 local changesets published
(run 'hg heads' to see heads)
$ hg up -C default
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar1
$ hg ci -Am "commit on default on tt"
adding bar1
$ hg up branchC
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo a1 > bar2
$ hg ci -Am "commit on branchC on tt"
adding bar2
Make changes on default and branchC on t
$ cd ../t
$ hg up default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo a1 > bar3
$ hg ci -Am "commit on default on t"
adding bar3
$ hg up branchC
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo a1 > bar4
$ hg ci -Am "commit on branchC on tt"
adding bar4
Pull from tt
$ hg pull ../tt
pulling from ../tt
searching for changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files (+2 heads)
new changesets eed40c14b407:e634733b0309
1 local changesets published
(run 'hg heads .' to see heads, 'hg merge' to merge)
$ cd ..