rhg: fix `hg cat` interaction with null revision Differential Revision: https://phab.mercurial-scm.org/D11664

dirstate-v2: add an option to prevent unintentional slow dirstate-v2 This is the project policy discussed in November 2020 and already put to use for the persistent nodemap. Differential Revision: https://phab.mercurial-scm.org/D11668

rhg: fix formatting error reported by test-check-format-rust.t Differential Revision: https://phab.mercurial-scm.org/D11670

chistedit: add option to show order of commits in opposite order Many users (including me) expect the order of commits in histedit to match the order in `hg log -G` and are confused because it doesnn't. This patch adds an option to show later commits first in the list. I've only added support for it in chistedit for now. As a consequence, I've marked the config option experimental (I think it should apply to both interfaces before it graduates). Differential Revision: https://phab.mercurial-scm.org/D11669

dirstate-v2: Separate HAS_FILE_MTIME and HAS_DIRECTORY_MTIME flags Previously the same flag was used, with its meaning based on whether the node otherwise identifies a file tracked anywhere. In addition to being more explicit, this enables storing a directory mtime if a given path used to be tracked in a parent commit (so the dirstate still has data about it) but became a directory in the working copy. (However this is not done yet as it would require a larger change, replacing the `dirstate_map::NodeData` enum with struct fields.) Differential Revision: https://phab.mercurial-scm.org/D11662

dirstate-v2: Extend node flags to 16 bits Only 7 out of 8 available bits are used right now. Reserve some more. Future versions of Mercurial may assign meaning to some of these bits, with the limitation that then-older versions will always reset those bits to unset when writing nodes. (A new node is written for any mutation in its subtree, leaving the bytes of the old node unreachable until the data file is rewritten entirely.) Differential Revision: https://phab.mercurial-scm.org/D11661

narrow: raise StateError when working copy is stale (for detailed exit code) Differential Revision: https://phab.mercurial-scm.org/D11663

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