formatter: add fm.nested(field) to either write or build sub items We sometimes need to build nested items by formatter, but there was no convenient way other than building and putting them manually by fm.data(): exts = [] for n, v in extensions: fm.plain('%s %s\n' % (n, v)) exts.append({'name': n, 'ver': v}) fm.data(extensions=exts) This should work for simple cases, but doing this would make it harder to change the underlying data type for better templating support. So this patch provides fm.nested(field), which returns new nested formatter (or self if items aren't structured and just written to ui.) A nested formatter stores items which will later be rendered by the parent formatter. fn = fm.nested('extensions') for n, v in extensions: fn.startitem() fn.write('name ver', '%s %s\n', n, v) fn.end() Nested items are directly exported to a template for now: {extensions % "{name} {ver}\n"} There's no {extensions} nor {join(extensions, sep)} yet. I have a plan for them by extending fm.nested() API, but I want to revisit it after trying out this API in the real world.

formatter: factor out format*() functions to separate classes New converter classes will be reused by a nested formatter. See the next patch for details. This change is also good in that the default values are defined uniquely by the baseformatter.

crecord: restore SIGWINCH handler before return Previously, the SIGWINCH handler does not get cleared and if the commit message editor also needs SIGWINCH handling (like vim), the two SIGWINCH handlers (the editor's, ours) will have a race. And we may erase the editor's screen content. This patch restores SIGWINCH handler to address the above issue.

bdiff: implement cffi version of bdiff

bdiff: implement cffi version of blocks

util: checknlink should remove file it creates if an exception occurs There's no reason to leave the file behind.

merge: remove files with extra actions from merge action list See the comment for a detailed explanation why. Even though this is a bug, I've sent it to 'default' rather than 'stable' because it isn't triggered in any code paths in stock Mercurial, just with the merge driver included. For the same reason I haven't included any tests here -- the merge driver is getting a new test.

revlog: use an LRU cache for delta chain bases Profiling using statprof revealed a hotspot during changegroup application calculating delta chain bases on generaldelta repos. Essentially, revlog._addrevision() was performing a lot of redundant work tracing the delta chain as part of determining when the chain distance was acceptable. This was most pronounced when adding revisions to manifests, which can have delta chains thousands of revisions long. There was a delta chain base cache on revlogs before, but it only captured a single revision. This was acceptable before generaldelta, when _addrevision would build deltas from the previous revision and thus we'd pretty much guarantee a cache hit when resolving the delta chain base on a subsequent _addrevision call. However, it isn't suitable for generaldelta because parent revisions aren't necessarily the last processed revision. This patch converts the delta chain base cache to an LRU dict cache. The cache can hold multiple entries, so generaldelta repos have a higher chance of getting a cache hit. The impact of this change when processing changegroup additions is significant. On a generaldelta conversion of the "mozilla-unified" repo (which contains heads of the main Firefox repositories in chronological order - this means there are lots of transitions between heads in revlog order), this change has the following impact when performing an `hg unbundle` of an uncompressed bundle of the repo: before: 5:42 CPU time after: 4:34 CPU time Most of this time is saved when applying the changelog and manifest revlogs: before: 2:30 CPU time after: 1:17 CPU time That nearly a 50% reduction in CPU time applying changesets and manifests! Applying a gzipped bundle of the same repo (effectively simulating a `hg clone` over HTTP) showed a similar speedup: before: 5:53 CPU time after: 4:46 CPU time Wall time improvements were basically the same as CPU time. I didn't measure explicitly, but it feels like most of the time is saved when processing manifests. This makes sense, as large manifests tend to have very long delta chains and thus benefit the most from this cache. So, this change effectively makes changegroup application (which is used by `hg unbundle`, `hg clone`, `hg pull`, `hg unshelve`, and various other commands) significantly faster when delta chains are long (which can happen on repos with large numbers of files and thus large manifests). In theory, this change can result in more memory utilization. However, we're caching a dict of ints. At most we have 200 ints + Python object overhead per revlog. And, the cache is really only populated when performing read-heavy operations, such as adding changegroups or scanning an individual revlog. For memory bloat to be an issue, we'd need to scan/read several revisions from several revlogs all while having active references to several revlogs. I don't think there are many operations that do this, so I don't think memory bloat from the cache will be an issue.

revlog: remove unused variables

util: properly implement lrucachedict.get() Before, it was returning the raw _lrucachenode instance instead of its value.