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 ==
* There is a new config section for templates used by hg commands. It
is called `[command-templates]`. Some existing config options have
been deprecated in favor of config options in the new
section. These are: `ui.logtemplate` to `command-templates.log`,
`ui.graphnodetemplate` to `command-templates.graphnode`,
`ui.mergemarkertemplate` to `command-templates.mergemarker`,
`ui.pre-merge-tool-output-template` to
`command-templates.pre-merge-tool-output`.
* There is a new set of config options for the template used for the
one-line commit summary displayed by various commands, such as `hg
rebase`. The main one is `command-templates.oneline-summary`. That
can be overridden per command with
`command-templates.oneline-summary.<command>`, where `<command>`
can be e.g. `rebase`. As part of this effort, the default format
from `hg rebase` was reorganized a bit.
* `hg purge` is now a core command using `--confirm` by default.
* `hg diff` and `hg extdiff` now support `--from <rev>` and `--to <rev>`
arguments as clearer alternatives to `-r <revs>`. `-r <revs>` has been
deprecated.
* The memory footprint per changeset during pull/unbundle
operations has been further reduced.
* There is a new internal merge tool called `internal:mergediff` (can
be set as the value for the `merge` config in the `[ui]`
section). It resolves merges the same was as `internal:merge` and
`internal:merge3`, but it shows conflicts differently. Instead of
showing 2 or 3 snapshots of the conflicting pieces of code, it
shows one snapshot and a diff. This may be useful when at least one
side of the conflict is similar to the base. The new marker style
is also supported by "premerge" as
`merge-tools.<tool>.premerge=keep-mergediff`.
* External hooks are now called with `HGPLAIN=1` preset. This has the side
effect of ignoring aliases, templates, revsetaliases, and a few other config
options in any `hg` command spawned by the hook. The previous behavior
can be restored by setting HGPLAINEXCEPT appropriately in the parent process.
See `hg help environment` for the list of items, and how to set it.
* The `branchmap` cache is updated more intelligently and can be
significantly faster for repositories with many branches and changesets.
* The `rev-branch-cache` is now updated incrementally whenever changesets
are added.
== New Experimental Features ==
* `experimental.single-head-per-branch:public-changes-only` can be used
restrict the single head check to public revision. This is useful for
overlay repository that have both a publishing and non-publishing view
of the same storage.
== Bug Fixes ==
== Backwards Compatibility Changes ==
* `--force-lock` and `--force-wlock` options on `hg debuglock` command are
renamed to `--force-free-lock` and `--force-free-wlock` respectively.
== Internal API Changes ==
* `changelog.branchinfo` is deprecated and will be removed after 5.8.
It is superseded by `changelogrevision.branchinfo`.