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.

#require no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > foo
  $ echo y > bar
  $ hg commit -qAm one

  $ cd ..

# partial shallow clone

  $ hg clone --shallow ssh://user@dummy/master shallow --noupdate --config remotefilelog.includepattern=foo
  streaming all changes
  3 files to transfer, 336 bytes of data (no-zstd !)
  transferred 336 bytes in * seconds (* */sec) (glob) (no-zstd !)
  3 files to transfer, 338 bytes of data (zstd !)
  transferred 338 bytes in * seconds (* */sec) (glob) (zstd !)
  searching for changes
  no changes found
  $ cat >> shallow/.hg/hgrc <<EOF
  > [remotefilelog]
  > cachepath=$PWD/hgcache
  > debug=True
  > includepattern=foo
  > reponame = master
  > [extensions]
  > remotefilelog=
  > EOF
  $ ls shallow/.hg/store/data
  bar.i

# update partial clone

  $ cd shallow
  $ hg update
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cat foo
  x
  $ cat bar
  y
  $ cd ..

# pull partial clone

  $ cd master
  $ echo a >> foo
  $ echo b >> bar
  $ hg commit -qm two
  $ cd ../shallow
  $ hg pull
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files
  new changesets a9688f18cb91
  (run 'hg update' to get a working copy)
  $ hg update
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cat foo
  x
  a
  $ cat bar
  y
  b

  $ cd ..