dirstate: use visitchildrenset in traverse This speeds up `hg status` a fair amount when there is a very large directory and narrow is in use. Timing numbers according to command: hyperfine --warmup 1 'hg status' HGRCPATH points to a file with the following contents: [extensions] narrow = mozilla-unified (called m-u below) was at revision #468856. regular hash: eb39298e432d treemanifests hash: 0553b7f29eaf large-dir-repo (called l-d-r below) was generated with the following script: #!/bin/bash hg init large-dir-repo mkdir -p large-dir-repo/third_party/rust/log touch large-dir-repo/third_party/rust/log/foo.txt for i in $(seq 1 30000); do d=$(mktemp -d large-dir-repo/third_party/XXXXXXXXX) touch $d/file.txt done hg -R large-dir-repo ci -Am 'rev0' --user test --date '0 0' for repos that use narrow, the narrowspec was this: [includes] rootfilesin:third_party/rust/log [excludes] This narrowspec was chosen due to the size of the third_party/rust directory; this directory was *not* modified in revision #468856 in mozilla-unified. Importantly, when using narrow, these repos had everything checked out (in the case of large-dir-repo, that means all 30,001 directories), *before* adding the narrowspec. This is to simulate the behavior when using a virtual filesystem that shows everything for the user even if they haven't added it to the narrowspec yet. This is not a supported configuration, and `hg update` will not really do the "correct" thing, but non-mutating commands should behave correctly. There are two repos below that do not follow the setup above, 'citc1' and 'citc2', which are using a virtual filesystem and can not be reproduced upstream; these numbers are here mostly to indicate that these performance improvements are not hypothetical, and show the benefits we're hoping to achieve on our real workloads. 'citc1' is closest to large-dir-repo with one of our pathological cases, 'citc2' is an arbitrary repo and closer to "average". I'm not claiming anything less than a 5% speed win as improvements due to this change; these are probably eiter measurement artifacts or constant time improvements. The numbers that aren't changing are shown primarily to prove that this doesn't make anything worse in any case I plan on testing during this series. 'before' is hg from commit c83ad576. 'N' indicates narrow in use, 'T' indicates treemanifest in use. hg status: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 2.284 s +- 0.022 s | 2.274 s +- 0.021 s | 99.6% m-u | | x | 2.289 s +- 0.008 s | 2.284 s +- 0.028 s | 99.8% m-u | x | | 430.8 ms +- 3.1 ms | 424.5 ms +- 3.2 ms | 98.5% m-u | x | x | 429.8 ms +- 2.5 ms | 425.8 ms +- 3.7 ms | 99.1% l-d-r | | | 681.3 ms +- 5.5 ms | 689.6 ms +- 8.0 ms | 101.2% l-d-r | | x | 666.8 ms +- 21.8 ms | 672.5 ms +- 14.9 ms | 100.9% l-d-r | x | | 282.6 ms +- 1.8 ms | 203.0 ms +- 1.2 ms | 71.8% <-- l-d-r | x | x | 275.2 ms +- 3.9 ms | 199.3 ms +- 3.5 ms | 72.4% <-- citc1 | x | x | 1.023 s +- 0.011 s | 398.6 ms +- 9.2 ms | 39.0% <-- citc2 | x | x | 297.9 ms +- 4.4 ms | 289.6 ms +- 4.2 ms | 97.2% hg status --change .: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 478.2 ms +- 2.0 ms | 476.9 ms +- 3.7 ms | 99.7% m-u | | x | 169.5 ms +- 2.7 ms | 169.5 ms +- 2.5 ms | 100.0% m-u | x | | 477.0 ms +- 2.4 ms | 476.1 ms +- 1.4 ms | 99.8% m-u | x | x | 124.7 ms +- 1.9 ms | 124.2 ms +- 3.3 ms | 99.6% l-d-r | | | 97.4 ms +- 1.2 ms | 96.5 ms +- 1.2 ms | 99.1% l-d-r | | x | 4.778 s +- 0.018 s | 4.774 s +- 0.011 s | 99.9% l-d-r | x | | 99.9 ms +- 1.1 ms | 98.8 ms +- 1.3 ms | 98.9% l-d-r | x | x | 848.7 ms +- 7.1 ms | 849.4 ms +- 6.5 ms | 100.1% citc1 | x | x | 4.250 s +- 0.051 s | 4.283 s +- 0.042 s | 100.8% citc2 | x | x | 341.5 ms +- 4.7 ms | 341.5 ms +- 4.1 ms | 100.0% hg update $rev^; hg update $rev: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 4.357 s +- 0.032 s | 4.312 s +- 0.093 s | 99.0% m-u | | x | 3.599 s +- 0.061 s | 3.592 s +- 0.071 s | 99.8% m-u | x | | 1.815 s +- 0.012 s | 1.816 s +- 0.013 s | 100.1% m-u | x | x | 1.110 s +- 0.009 s | 1.106 s +- 0.005 s | 99.6% l-d-r | | | 527.1 ms +- 7.8 ms | 523.3 ms +- 6.5 ms | 99.3% l-d-r | | x | 8.835 s +- 0.067 s | 8.825 s +- 0.064 s | 99.9% l-d-r | x | | 313.0 ms +- 2.2 ms | 312.1 ms +- 1.2 ms | 99.7% l-d-r | x | x | 1.780 s +- 0.011 s | 1.799 s +- 0.013 s | 101.1% citc1 | x | x | 6.825 s +- 0.262 s | 6.707 s +- 0.353 s | 98.3% citc2 | x | x | 776.4 ms +- 4.5 ms | 781.3 ms +- 6.3 ms | 100.6% hg diff: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+------------------------+-----------------------+------------ m-u | | | 1.519 s +- 0.015 s | 1.525 s +- 0.017 s | 100.4% m-u | | x | 1.512 s +- 0.010 s | 1.517 s +- 0.027 s | 100.3% m-u | x | | 420.0 ms +- 3.2 ms | 417.1 ms +- 1.9 ms | 99.3% m-u | x | x | 415.0 ms +- 3.8 ms | 415.7 ms +- 2.7 ms | 100.2% l-d-r | | | 220.8 ms +- 4.0 ms | 220.8 ms +- 3.7 ms | 100.0% l-d-r | | x | 216.6 ms +- 7.5 ms | 211.4 ms +- 2.1 ms | 97.6% l-d-r | x | | 111.9 ms +- 1.8 ms | 112.0 ms +- 1.5 ms | 100.1% l-d-r | x | x | 111.4 ms +- 1.4 ms | 110.2 ms +- 1.0 ms | 98.9% citc1 | x | x | 268.7 ms +- 2.3 ms | 269.6 ms +- 2.8 ms | 100.3% citc2 | x | x | 273.5 ms +- 5.5 ms | 273.9 ms +- 3.7 ms | 100.1% hg diff -c .: repo | N | T | before (mean +- stdev) | after (mean +- stdev) | % of before ------+---+---+--------------------------+-----------------------+---------- m-u | | | 497.1 ms +- 1.4 ms | 500.1 ms +- 2.4 ms | 100.6% m-u | | x | 195.3 ms +- 13.2 ms | 191.6 ms +- 3.0 ms | 98.1% m-u | x | | 476.8 ms +- 1.9 ms | 476.7 ms +- 2.3 ms | 100.0% m-u | x | x | 122.8 ms +- 2.1 ms | 122.9 ms +- 2.0 ms | 100.1% l-d-r | | | 99.3 ms +- 2.3 ms | 98.8 ms +- 1.7 ms | 99.5% l-d-r | | x | 4.875 s +- 0.041 s | 4.847 s +- 0.038 s | 99.4% l-d-r | x | | 98.5 ms +- 1.2 ms | 98.9 ms +- 1.3 ms | 100.4% l-d-r | x | x | 864.6 ms +- 7.4 ms | 855.4 ms +- 6.6 ms | 98.9% citc1 | x | x | 4.505 s +- 0.060 s | 4.466 s +- 0.036 s | 99.1% citc2 | x | x | 368.0 ms +- 4.0 ms | 365.5 ms +- 6.3 ms | 99.3% Differential Revision: https://phab.mercurial-scm.org/D4131