status: prefer relative paths in Rust code … when the repository root is under the current directory, so the kernel needs to traverse fewer directory in every call to `read_dir` or `symlink_metadata`. Better yet would be to use libc functions like `openat` and `fstatat` to remove such repeated traversals entirely, but the standard library does not provide APIs based on those. Maybe with a crate like https://crates.io/crates/openat instead? Benchmarks of `rhg status` show that this patch is neutral in some configurations, and makes the command up to ~20% faster in others. Below is semi-arbitrary subset of results. The four numeric columns are: time (in seconds) with this changeset’s parent, time with this changeset, time difference (negative is better), time ratio (less than 1 is better). ``` mercurial-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.0061 -> 0.0059: -0.0002 (0.97) mercurial-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0029 -> 0.0028: -0.0001 (0.97) mozilla-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.2110 -> 0.2102: -0.0007 (1.00) mozilla-dirstate-v2 | default-copies-clean.ignored.pbr | 0.0489 -> 0.0401: -0.0088 (0.82) mozilla-dirstate-v2 | default-copies-clean.no-iu.pbr | 0.0479 -> 0.0393: -0.0085 (0.82) mozilla-dirstate-v2 | default-copies-large.all.pbr | 0.1262 -> 0.1210: -0.0051 (0.96) mozilla-dirstate-v2 | default-copies-small.ignored-unknown.pbr | 0.1262 -> 0.1200: -0.0062 (0.95) mozilla-dirstate-v2 | default-copies-small.ignored.pbr | 0.0536 -> 0.0417: -0.0119 (0.78) mozilla-dirstate-v2 | default-copies-small.no-iu.pbr | 0.0482 -> 0.0393: -0.0089 (0.81) mozilla-dirstate-v2 | default-plain-clean.ignored.pbr | 0.0518 -> 0.0402: -0.0116 (0.78) mozilla-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0481 -> 0.0392: -0.0088 (0.82) mozilla-dirstate-v2 | default-plain-large.all.pbr | 0.1271 -> 0.1218: -0.0052 (0.96) mozilla-dirstate-v2 | default-plain-small.ignored-unknown.pbr | 0.1225 -> 0.1202: -0.0022 (0.98) mozilla-dirstate-v2 | default-plain-small.ignored.pbr | 0.0510 -> 0.0418: -0.0092 (0.82) mozilla-dirstate-v2 | default-plain-small.no-iu.pbr | 0.0480 -> 0.0394: -0.0086 (0.82) netbeans-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.1442 -> 0.1422: -0.0020 (0.99) netbeans-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0325 -> 0.0282: -0.0043 (0.87) ``` Differential Revision: https://phab.mercurial-scm.org/D12175

     1

% removeancestorsfrom(), example 1

     2

remaining (sorted): [5, 6, 8, 9]

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% removeancestorsfrom(), example 2

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remaining (sorted): [11, 12, 13, 14]

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% removeancestorsfrom(), example 3

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remaining (sorted): [3, 5]

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% missingancestors(), example 1

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return [3, 7, 11]

     9

% missingancestors(), example 2

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return [5, 10]

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% missingancestors(), example 3

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return [3, 6, 9, 11]

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% removeancestorsfrom(), bigger graph

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Ok

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% lazy ancestor set for [], stoprev = 0, inclusive = False

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membership: []

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iteration:  []

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% lazy ancestor set for [11, 13], stoprev = 0, inclusive = False

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membership: [7, 8, 3, 4, 1, 0]

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iteration:  [8, 7, 4, 3, 2, 1, 0]

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% lazy ancestor set for [1, 3], stoprev = 0, inclusive = False

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membership: [1, 0]

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iteration:  [1, 0]

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% lazy ancestor set for [11, 13], stoprev = 0, inclusive = True

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membership: [11, 13, 7, 8, 3, 4, 1, 0]

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iteration:  [13, 11, 8, 7, 4, 3, 2, 1, 0]

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% lazy ancestor set for [11, 13], stoprev = 6, inclusive = False

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membership: [7, 8]

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iteration:  [8, 7]

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% lazy ancestor set for [11, 13], stoprev = 6, inclusive = True

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membership: [11, 13, 7, 8]

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iteration:  [13, 11, 8, 7]

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% lazy ancestor set for [11, 13], stoprev = 11, inclusive = True

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membership: [11, 13]

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iteration:  [13, 11]

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% lazy ancestor set for [11, 13], stoprev = 12, inclusive = True

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membership: [13]

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iteration:  [13]

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% lazy ancestor set for [10, 1], stoprev = 0, inclusive = True

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membership: [2, 10, 4, 5, 0, 1]

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iteration:  [10, 5, 4, 2, 1, 0]