revlog: add option to mmap revlog index Following on from Jun Wu's patch last October[1], we have found that using mmap for the revlog index in repos with large revlogs gives a noticable performance improvment (~110ms on each hg invocation), particularly for commands that don't touch the index very much. This changeset adds this as an option, activated by a new experimental config option so that it can be enabled on a per-repo basis. The configuration option specifies an index size threshold at which Mercurial will switch to using mmap to access the index. If the configuration option is not specified, the default remains to load the full file, which seems to be the best option for smaller repos. Some initial performance numbers for average of 5 invocations of `hg log -l 5` for different cache states: | Repo: | HG | FB | |---|---|---| | Index size: | 2.3MB | much bigger | | read (warm): | 237ms | 432ms | | mmap (warm): | 227ms | 321ms | | | (-3%) | (-26%) | | read (cold): | 397ms | 696ms | | mmap (cold): | 410ms | 888ms | | | (+3%) | (+28%) | [1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-October/088737.html Test Plan: `hg log --config experimental.mmapindex=true` Differential Revision: https://phab.mercurial-scm.org/D477

util: add an mmapread method This is useful for large files that are only partly touched. Test Plan: Will be used and tested in a later patch. Differential Revision: https://phab.mercurial-scm.org/D476

changegroup: remove dictionary creation from deltachunk Previously delta chunk returned a dictionary. Now that we consume deltachunk within changegroup (instead of outside in revlog) we can just return a tuple and have it be returned directly by deltaiter. Differential Revision: https://phab.mercurial-scm.org/D746

bundlerepo: update to use new deltaiter api Differential Revision: https://phab.mercurial-scm.org/D745

debug: update debugbundle to use new deltaiter api Changegroup now has a deltaiter api for easy iteration over a series of deltas. Let's use that in the debugbundle command. Differential Revision: https://phab.mercurial-scm.org/D744

revlog: add revmap back to revlog.addgroup The recent c8b6ed51386b patch removed the linkmapper argument from addgroup, as part of trying to make addgroup more agnostic from the changegroup format. It turns out that the changegroup can't resolve linkrevs while iterating over the deltas, because applying the deltas might affect the linkrev resolution. For example, when applying a series of changelog entries, the linkmapper just returns len(cl). If we're iterating over the deltas without applying them to the changelog, this results in incorrect linkrevs. This was caught by the hgsql extension, which reads the revisions before applying them. The fix is to return linknodes as part of the delta iterator, and let the consumer choose what to do. Differential Revision: https://phab.mercurial-scm.org/D730

rebase: also include other namespaces in changeset description This makes use of the generic method of listing bookmarks and tags, so other extensions that add other namespaces will get their names added too. This does mean that bookmarks will come before tags, just like we apparently decided to order them in the "hg log" output. It doesn't seem like people would be parsing the rebase output anyway. We also did 79ab5369d55a (rebase: use _ctxdesc in one more place, 2017-08-29) recently, so now seems like a good time. Differential Revision: https://phab.mercurial-scm.org/D741