rust-nodemap: pure Rust example To run, use `cargo run --release --example nodemap` This demonstrates that simple scenarios entirely written in Rust can content themselves with `NodeTree<T>`. The example mmaps both the nodemap file and the changelog index. We had of course to include an implementation of `RevlogIndex` directly, which isn't much at this stage. It felt a bit prematurate to include it in the lib. Here are some first performance measurements, obtained with this example, on a clone of mozilla-central with 440000 changesets: (create) Nodemap constructed in RAM in 153.638305ms (query CAE63161B68962) found in 22.362us: Ok(Some(269489)) (bench) Did 3 queries in 36.418µs (mean 12.139µs) (bench) Did 50 queries in 184.318µs (mean 3.686µs) (bench) Did 100000 queries in 31.053461ms (mean 310ns) To be fair, even between bench runs, results tend to depend whether the file is still in kernel caches, and it's not so easy to get back to a real cold start. The worst we've seen was in the 50us ballpark. In any busy server setting, the pages would always be in RAM. We hope it's good enough not to be significantly slower on any concrete Mercurial operation than the C nodetree when fully in RAM, and of course this implementation has the serious headstart advantage of persistence. Differential Revision: https://phab.mercurial-scm.org/D7797

rust-nodemap: input/output primitives These allow to initiate a `NodeTree` from an immutable opaque sequence of bytes, which could be passed over from Python (extracted from a `PyBuffer`) or directly mmapped from a file. Conversely, we can consume a `NodeTree`, extracting the bytes that express what has been added to the immutable part, together with the original immutable part. This gives callers the choice to start a new Nodetree. After writing to disk, some would prefer to reread for best guarantees (very cheap if mmapping), some others will find it more convenient to grow the memory that was considered immutable in the `NodeTree` and continue from there. This is enough to build examples running on real data and start gathering performance hints. Differential Revision: https://phab.mercurial-scm.org/D7796

pyoxidizer: allow extensions to be loaded from the file system It seems that setting this config is all that's needed to be able to load extensions from the file system (which we clearly want). Thanks for making this work, Gregory Szorc!. Differential Revision: https://phab.mercurial-scm.org/D8122

graft: always allow hg graft --base . (issue6248) `hg graft --base . -r abc` is rejected before this change with a "nothing to merge" error, if `abc` does not descend from `.`. This looks like an artifact of the implementation rather than intended behavior. It makes perfect sense to apply the diff between `.` and `abc` to the working copy (i.e. degenerate into `hg revert`), regardless of what `abc` is. Differential Revision: https://phab.mercurial-scm.org/D8127

revlog-compression: update the config to be a list format.revlog-compression is now a list of engine, the first supported one is to be used. Doing this have several benefits: 1) this is fully backward compatible, config using a single entry will be read as a single item list, not changing any behavior. 2) This open the way to use zstd by default without impacting platform were it is not available. This will be done in a later changesets. Using zstd provide a significant performance boost explained in : bb271ec2fbfb. However zstd is not available in some cases, A notable example is the `--pure` version of Mercurial which doesn't come with zstd support. Differential Revision: https://phab.mercurial-scm.org/D8148

remotefilelog: add 'changelog' arg to shallowcg1packer.generate (issue6269) This cause traceback on widening using narrow extension when remotefilelog is enabled. Differential Revision: https://phab.mercurial-scm.org/D8134

drawdag: abide by new createmarkers() API The `obsolete.createmarkers()` API was changed in 6335c0de80fa (obsolete: allow multiple predecessors in createmarkers, 2018-09-22) to prefer its precursors input to be a tuple instead of a single precursor. Let's fix `drawdag.py` to comply. Differential Revision: https://phab.mercurial-scm.org/D8149

lfutil: provide a hint if the largefiles/lfs cache path cannot be determined A coworker hit this error using an LFS repo in a stripped down environment, and didn't know how to resolve it. The final conditional is a bit fast and loose, but there is currently no 'posix' test in hghave, and it doesn't seem like it's worth adding for this since I think Windows is the only non-POSIX platform we run tests on. Differential Revision: https://phab.mercurial-scm.org/D8145

setup: exclude the __index__ module from itself when generating This module is generated on Windows to hold all of the extension names and the help summaries, so that they are discoverable inside the py2exe zipfile. The problem is this file is generated by dumping the disabled list, and that list comes from walking the filesystem. So once an install from source into a virtualenv created this module, then next build from source from that virtualenv would also see __index__.py in the filesystem, and include it. Clearly that's wrong because this isn't a real extension, so just filter it from the list when generating it. The Mercurial installer was unaffected by this, but the TortoiseHg package was. In the final package, `hg help -v extensions` and the panel of extensions both showed it. Differential Revision: https://phab.mercurial-scm.org/D8142

tests: stabilize test-amend.t on Windows If $TESTTMP isn't quoted in this context, it ends up like `C:Temphgtests.pikkoxchild1test-amend.t-obsstore-off`. Differential Revision: https://phab.mercurial-scm.org/D8144