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.
== New Features ==
* `hg mv -A` can now be used with `--at-rev`. It behaves just like
`hg cp -A --at-rev`, i.e. it marks the destination as a copy of the
source whether or not the source still exists (but the source must
exist in the parent revision).
* New revset predicate `diffcontains(pattern)` for filtering revisions
in the same way as `hg grep --diff pattern`.
* The memory footprint per changeset and per file during pull/unbundle
operations has been significantly reduced.
== New Experimental Features ==
== Bug Fixes ==
== Backwards Compatibility Changes ==
== Internal API Changes ==
* `merge.update()` is now private (renamed to `_update()`). Hopefully
the higher-level functions available in the same module cover your
use cases.
* `phases.registernew` now takes a set of revisions instead of a list
of nodes. `phases.advanceboundary` takes an optional set of revisions
in addition to the list of nodes. The corresponeding members of the
`phasecache` class follow this change.
* The `addgroup` member of `revlog` classes no longer keeps a list of
all found nodes. It now returns True iff a node was found in the group.
An optional callback for duplicated nodes can be used by callers to keep
track of all nodes themselve.
* The `_chaininfocache` of `revlog` classes has been changed from a dict
to a LRU cache.