templater: introduce {latesttag()} function to match a pattern (
issue4184)
This allows the latest class of tag to be found, such as a release candidate or
final build, instead of just the absolute latest.
It doesn't appear that the existing keyword can be given an optional argument.
There is a keyword, function and filter for 'date', so it doesn't seem harmful
to introduce a new function with the same name as an existing keyword. Most
functions are pretty Mercurial agnostic, but there is {revset()} as precedent.
Even though templatekw.getlatesttags() returns a single tuple, one entry of
which is a list, it is simplest to present this as a list of tags instead of a
single item, with each tag having a distance and change count attribute. It is
also closer to how {latesttag} returns a list of tags, and how this function
works when not given a '%' operator.
templatekw: introduce showlatesttags() to handle {latesttag} keywords
The keywords {changes}, {distance} and {tag} will be available on a future
template method that will allow pattern matching against tag names. For
consistency, these should be available on the existing {latesttag} keyword as
well.
I debated whether or not to add {tag} instead of just continuing with the
existing {latesttag}. But it seems clearer not to have the same name for two
distinct things (a list in the LHS of %, and an individual tag value on the
right).
The value of latesttags[0] is the date of commit for the cset to which the tag
is applied (i.e. not the date the tag was applied), and therefore isn't made
visible because it doesn't seem interesting. It appears that this is merely an
internal implementation detail for sorting csets in a stable manner when there
are different branches.
templatekw: factor out the changessincetag calculation to a private method
This will be reused in the next patch.
templatekw: allow getlatesttags() to match a specific tag pattern
This will allow the latest class of tag to be found, such as a release candidate
or final build, instead of just the absolute latest. It will be exposed in a
future patch.
It's unfortunate that the original 'latesttags' cache can't be used to determine
the proper values, but it isn't fully populated for the entire repo. For
example, the {latesttagdistance} keyword on the Mecurial repo builds the cache
up back to the revision for 1.4. If the pattern was 're:^0\.\d$', that wouldn't
be in the cache. Maybe this can be optimized some other way, but for now, this
is the simpliest implementation.
util: extract stringmatcher() from revset
This is used to match against tags, bookmarks, etc in revsets. It will be used
in a future patch to do the same tag matching in templater.
util.chunkbuffer: avoid extra mutations when reading partial chunks
Previously, a read(N) where N was less than the length of the first
available chunk would mutate the deque instance twice and allocate a new
str from the slice of the existing chunk. Profiling drawed my attention
to these as a potential hot spot during changegroup reading.
This patch makes the code more complicated in order to avoid the
aforementioned 3 operations.
On a pre-generated mozilla-central gzip bundle, this series has the
following impact on `hg unbundle` performance on my MacBook Pro:
before: 358.21 real 317.69 user 38.49 sys
after: 301.57 real 262.69 user 37.11 sys
delta: -56.64 real -55.00 user -1.38 sys