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.
#testcases tree flat-fncache flat-nofncache
Tests narrow stream clones
$ . "$TESTDIR/narrow-library.sh"
#if tree
$ cat << EOF >> $HGRCPATH
> [experimental]
> treemanifest = 1
> EOF
#endif
#if flat-nofncache
$ cat << EOF >> $HGRCPATH
> [format]
> usefncache = 0
> EOF
#endif
Server setup
$ hg init master
$ cd master
$ mkdir dir
$ mkdir dir/src
$ cd dir/src
$ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done
$ cd ..
$ mkdir tests
$ cd tests
$ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done
$ cd ../../..
Trying to stream clone when the server does not support it
$ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
streaming all changes
remote: abort: server does not support narrow stream clones
abort: pull failed on remote
[100]
Enable stream clone on the server
$ echo "[experimental]" >> master/.hg/hgrc
$ echo "server.stream-narrow-clones=True" >> master/.hg/hgrc
Cloning a specific file when stream clone is supported
$ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
streaming all changes
* files to transfer, * KB of data (glob)
transferred * KB in * seconds (* */sec) (glob)
$ cd narrow
$ ls -A
.hg
$ hg tracked
I path:dir/src/F10
Making sure we have the correct set of requirements
$ hg debugrequires
dotencode (tree !)
dotencode (flat-fncache !)
dirstate-v2 (dirstate-v2 !)
fncache (tree !)
fncache (flat-fncache !)
generaldelta
narrowhg-experimental
persistent-nodemap (rust !)
revlog-compression-zstd (zstd !)
revlogv1
share-safe
sparserevlog
store
treemanifest (tree !)
Making sure store has the required files
$ ls .hg/store/
00changelog.i
00manifest.i
data
fncache (tree !)
fncache (flat-fncache !)
meta (tree !)
narrowspec
requires
undo
undo.backupfiles
undo.narrowspec
undo.phaseroots
Checking that repository has all the required data and not broken
$ hg verify
checking changesets
checking manifests
checking directory manifests (tree !)
crosschecking files in changesets and manifests
checking files
checked 40 changesets with 1 changes to 1 files