dirstate-v2: Use attributes as intended instead of properties in v2_data() The property return other integer values instead of None, so `is not None` does not work. This fixes test-dirstate-race.t in pure-Python mode, which currently fails on the default branch. Differential Revision: https://phab.mercurial-scm.org/D11660

dirstate: Remove unused variable This fixes test-check-pyflakes.t which is currently failing on the default branch. Differential Revision: https://phab.mercurial-scm.org/D11658

rust: Reformat source code This fixes test-check-rust-format.t which is currently failing on the default branch. Differential Revision: https://phab.mercurial-scm.org/D11657

rhg: do not try to open a nodemap for an inline index This saves an [open] system call per file, which is a small saving, but it showed up in the profile at large file counts (it accounted for 30ms out of 400ms needed for catting 10000 files, on a ZFS filesystem on Linux, so ~3us per syscall). Differential Revision: https://phab.mercurial-scm.org/D11659

rhg: stop manifest traversal when no more files are needed Stopping the traversal early can skip a significant part of the manifest traversal, to avoid some of its cost. The worst-case benchmarks are favorable, as well. Running [hg cat] on the last file in the manifest of a large repo, I'm seeing a ~4ms improvement (150ms -> 146ms), so this time is now almost indistinguishable from the baseline ("brute force") implementation. Running [hg cat] on ~220 files together with the last file of the repo is further improved by ~5ms or so. I suspect the raw performance improvements are caused by splitting the manifest search and the file data access into separate phases, instead of interleaving them. Differential Revision: https://phab.mercurial-scm.org/D11616

rhg: faster hg cat when many files are requested With this patch I'm seeing a ~39ms improvement (220ms -> 181ms) when running [hg cat] on ~220 files in a ~260k-file repo. The timing for [hg cat] on an individual file becomes slightly worse (losing 5ms: 145ms -> 150ms). A follow-up commit is intended to improve that. Differential Revision: https://phab.mercurial-scm.org/D11615

dirstate-v2: Add support when Rust is not enabled This wires into `dirstatemap` the parser and serializer added in previous changesets. The memory representation is still the same, with a flat `dict` for `DirstateItem`s and another one for copy sources. Serialization always creates a new dirstate-v2 data file and does not support (when Rust is not enabled) appending to an existing one, since we don’t keep track of which tree nodes are new or modified. Instead the tree is reconstructed during serialization. Differential Revision: https://phab.mercurial-scm.org/D11520

dirstate-v2: Initial Python serializer This adds code seralizing a `map` and `copy_map` dicts into dirstate-v2 file formate. This is not used yet. Differential Revision: https://phab.mercurial-scm.org/D11519

dirstate-v2: initial Python parser The dirstate-v2 file format should be supported even if Rust extensions are not enabled. This changeset adds parsing code that is not used yet. Differential Revision: https://phab.mercurial-scm.org/D11518

dirstate: Move more methods to the _dirstatemapcommon base class This reduces duplication slightly and will help with supporting dirstate-v2 when Rust is not enabled. Differential Revision: https://phab.mercurial-scm.org/D11621