revlog: optionally cache the full text when adding revisions
revlog instances can cache the full text of a single revision. Typically
the most recently read revision is cached.
When adding a delta group via addgroup() and _addrevision(), the
full text isn't always computed: sometimes only the passed in delta is
sufficient for adding a new revision to the revlog.
When writing the changelog from a delta group, the just-added full
text revision is always read immediately after it is written because
the changegroup code needs to extract the set of files from the entry.
In other words, revision() is *always* being called and caching the full
text of the just-added revision is guaranteed to result in a cache hit,
making the cache worthwhile.
This patch adds support to _addrevision() for always building and
caching the full text. This option is currently only active when
processing changelog entries from a changegroup.
While the total number of revision() calls is the same, the location
matters: buildtext() calls into revision() on the base revision when
building the full text of the just-added revision. Since the previous
revision's _addrevision() built the full text and the the previous
revision is likely the base revision, this means that the base
revision's full text is likely cached and can be used to compute the
current full text from just a delta. No extra I/O required.
The end result is the changelog isn't opened and read after adding every
revision from a changegroup.
On my 2013 MacBook Pro running OS X 10.10.5 from an SSD and Python 2.7,
this patch impacted the time taken to apply ~262,000 changesets from a
mozilla-central gzip bundle:
before: ~43s
after: ~32s
~25% reduction in changelog processing times. Not bad.
revlog: drop local assignment of cache variable
The purpose of this code was to provide thread safety. With the
conversion of hgweb to use separate localrepository instances per
request/thread, we should no longer have any consumers that need to
access revlog instances from multiple threads. Remove the code.
hg: always create new localrepository instance
cachedlocalrepo.copy() didn't actually create new localrepository
instances. This meant that the new thread isolation code in hgweb wasn't
actually using separate localrepository instances, even though it was
properly using separate cachedlocalrepo instances.
Because the behavior of the API changed, the single caller in hgweb had
to be refactored to always call _webifyrepo() or it may not have used
the proper filter.
I confirmed via print() debugging that id(repo) is in fact different on
each thread. This was not the case before.
For reasons I can't yet explain, this does not fix
issue4756. I suspect
there is shared cache somewhere that isn't thread safe.
test-bad-extension: reduce dependencies on other things
test-bad-extension would jitter if the format of the first line
of hg help changed, which isn't relevant to its goal.
help: fix help argument parsing and documentation
support combining -c and -e
previously -k was misdocumented:
* the first line didn't mention it
* the help half implied you could do help -k keyword topic
with these changes, -k just changes the search method
support -c and -e for -k searches