annotate mercurial/help/diffs.txt @ 21811:789b69d597cc

dirstate.status: assign members one by one instead of unpacking the tuple

With this patch, hg status and hg diff regain their previous speed.

The following tests are run against a working copy with over 270,000 files.
Here, 'before' means without this or the previous patch applied.

Note that in this case `hg perfstatus` isn't representative since it doesn't
take dirstate parsing time into account.

$ time hg status  # best of 5
before: 2.03s user 1.25s system 99% cpu 3.290 total
after:  2.01s user 1.25s system 99% cpu 3.261 total

$ time hg diff    # best of 5
before: 1.32s user 0.78s system 99% cpu 2.105 total
after:  1.27s user 0.79s system 99% cpu 2.066 total

Mercurial's default format for showing changes between two versions of
a file is compatible with the unified format of GNU diff, which can be
used by GNU patch and many other standard tools.

While this standard format is often enough, it does not encode the
following information:

- executable status and other permission bits
- copy or rename information
- changes in binary files
- creation or deletion of empty files

Mercurial also supports the extended diff format from the git VCS
which addresses these limitations. The git diff format is not produced
by default because a few widespread tools still do not understand this
format.

This means that when generating diffs from a Mercurial repository
(e.g. with :hg:`export`), you should be careful about things like file
copies and renames or other things mentioned above, because when
applying a standard diff to a different repository, this extra
information is lost. Mercurial's internal operations (like push and
pull) are not affected by this, because they use an internal binary
format for communicating changes.

To make Mercurial produce the git extended diff format, use the --git
option available for many commands, or set 'git = True' in the [diff]
section of your configuration file. You do not need to set this option
when importing diffs in this format or using them in the mq extension.