copies-rust: start recording overwrite as they happens

If a revision has information overwriting data from another revision, the
overwriting revision is a descendant of the overwritten one. So we could warm
the Oracle cache with such information to avoid potential future `is_ancestors`
call.

This provide us with a large speedup in the most expensive cases:

Repo            Case                                  Source-Rev   Dest-Rev      # of revisions  old time      new time      Difference    Factor    time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs,  41.113063 s,  36.001255 s,  -5.111808 s, × 0.8757,   157 µs/rev
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 : 382065 revs,  27.891612 s,  14.340641 s, -13.550971 s, × 0.5142,    37 µs/rev




Full comparison below:

Repo            Case                                  Source-Rev   Dest-Rev      # of revisions  old time      new time      Difference    Factor    time per rev
---------------------------------------------------------------------------------------------------------------------------------------------------------------
mercurial       x_revs_x_added_0_copies               ad6b123de1c7 39cfcef4f463 :      1 revs,   0.000042 s,   0.000042 s,  +0.000000 s, × 1.0000,    42 µs/rev
mercurial       x_revs_x_added_x_copies               2b1c78674230 0c1d10351869 :      6 revs,   0.000114 s,   0.000109 s,  -0.000005 s, × 0.9561,    18 µs/rev
mercurial       x000_revs_x000_added_x_copies         81f8ff2a9bf2 dd3267698d84 :   1032 revs,   0.004934 s,   0.004953 s,  +0.000019 s, × 1.0039,     4 µs/rev
pypy            x_revs_x_added_0_copies               aed021ee8ae8 099ed31b181b :      9 revs,   0.000195 s,   0.000237 s,  +0.000042 s, × 1.2154,    26 µs/rev
pypy            x_revs_x000_added_0_copies            4aa4e1f8e19a 359343b9ac0e :      1 revs,   0.000050 s,   0.000050 s,  +0.000000 s, × 1.0000,    50 µs/rev
pypy            x_revs_x_added_x_copies               ac52eb7bbbb0 72e022663155 :      7 revs,   0.000113 s,   0.000113 s,  +0.000000 s, × 1.0000,    16 µs/rev
pypy            x_revs_x00_added_x_copies             c3b14617fbd7 ace7255d9a26 :      1 revs,   0.6f1f4a s,   0.6f1f4a s,  +0.000000 s, × 1.0000,   322 µs/rev
pypy            x_revs_x000_added_x000_copies         df6f7a526b60 a83dc6a2d56f :      6 revs,   0.010788 s,   0.010702 s,  -0.000086 s, × 0.9920,  1783 µs/rev
pypy            x000_revs_xx00_added_0_copies         89a76aede314 2f22446ff07e :   4785 revs,   0.050880 s,   0.050504 s,  -0.000376 s, × 0.9926,    10 µs/rev
pypy            x000_revs_x000_added_x_copies         8a3b5bfd266e 2c68e87c3efe :   6780 revs,   0.081760 s,   0.080159 s,  -0.001601 s, × 0.9804,    11 µs/rev
pypy            x000_revs_x000_added_x000_copies      89a76aede314 7b3dda341c84 :   5441 revs,   0.061382 s,   0.060058 s,  -0.001324 s, × 0.9784,    11 µs/rev
pypy            x0000_revs_x_added_0_copies           d1defd0dc478 c9cb1334cc78 :  43645 revs,   0.585802 s,   0.536950 s,  -0.048852 s, × 0.9166,    12 µs/rev
pypy            x0000_revs_xx000_added_0_copies       bf2c629d0071 4ffed77c095c :      2 revs,   0.012803 s,   0.012868 s,  +0.000065 s, × 1.0051,  6434 µs/rev
pypy            x0000_revs_xx000_added_x000_copies    08ea3258278e d9fa043f30c0 :  11316 revs,   0.113558 s,   0.112806 s,  -0.000752 s, × 0.9934,     9 µs/rev
netbeans        x_revs_x_added_0_copies               fb0955ffcbcd a01e9239f9e7 :      2 revs,   0.000085 s,   0.000084 s,  -0.000001 s, × 0.9882,    42 µs/rev
netbeans        x_revs_x000_added_0_copies            6f360122949f 20eb231cc7d0 :      2 revs,   0.000106 s,   0.000106 s,  +0.000000 s, × 1.0000,    53 µs/rev
netbeans        x_revs_x_added_x_copies               1ada3faf6fb6 5a39d12eecf4 :      3 revs,   0.000175 s,   0.000174 s,  -0.000001 s, × 0.9943,    58 µs/rev
netbeans        x_revs_x00_added_x_copies             35be93ba1e2c 9eec5e90c05f :      9 revs,   0.000721 s,   0.000726 s,  +0.000005 s, × 1.0069,    80 µs/rev
netbeans        x000_revs_xx00_added_0_copies         eac3045b4fdd 51d4ae7f1290 :   1421 revs,   0.010127 s,   0.010105 s,  -0.000022 s, × 0.9978,     7 µs/rev
netbeans        x000_revs_x000_added_x_copies         e2063d266acd 6081d72689dc :   1533 revs,   0.015616 s,   0.015748 s,  +0.000132 s, × 1.0085,    10 µs/rev
netbeans        x000_revs_x000_added_x000_copies      ff453e9fee32 411350406ec2 :   5750 revs,   0.061341 s,   0.060357 s,  -0.000984 s, × 0.9840,    10 µs/rev
netbeans        x0000_revs_xx000_added_x000_copies    588c2d1ced70 1aad62e59ddd :  66949 revs,   0.542214 s,   0.499356 s,  -0.042858 s, × 0.9210,     7 µs/rev
mozilla-central x_revs_x_added_0_copies               3697f962bb7b 7015fcdd43a2 :      2 revs,   0.000089 s,   0.000092 s,  +0.000003 s, × 1.0337,    46 µs/rev
mozilla-central x_revs_x000_added_0_copies            dd390860c6c9 40d0c5bed75d :      8 revs,   0.000279 s,   0.000279 s,  +0.000000 s, × 1.0000,    34 µs/rev
mozilla-central x_revs_x_added_x_copies               8d198483ae3b 14207ffc2b2f :      9 revs,   0.000184 s,   0.000186 s,  +0.000002 s, × 1.0109,    20 µs/rev
mozilla-central x_revs_x00_added_x_copies             98cbc58cc6bc 446a150332c3 :      7 revs,   0.000661 s,   0.000660 s,  -0.000001 s, × 0.9985,    94 µs/rev
mozilla-central x_revs_x000_added_x000_copies         3c684b4b8f68 0a5e72d1b479 :      3 revs,   0.003377 s,   0.003372 s,  -0.000005 s, × 0.9985,  1124 µs/rev
mozilla-central x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :      6 revs,   0.070508 s,   0.070294 s,  -0.000214 s, × 0.9970, 11715 µs/rev
mozilla-central x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   1593 revs,   0.006576 s,   0.006545 s,  -0.000031 s, × 0.9953,     4 µs/rev
mozilla-central x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :     41 revs,   0.004809 s,   0.004998 s,  +0.000189 s, × 1.0393,   121 µs/rev
mozilla-central x000_revs_x000_added_x000_copies      7c97034feb78 4407bd0c6330 :   7839 revs,   0.064872 s,   0.063348 s,  -0.001524 s, × 0.9765,     8 µs/rev
mozilla-central x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :    615 revs,   0.026142 s,   0.026154 s,  +0.000012 s, × 1.0005,    42 µs/rev
mozilla-central x0000_revs_xx000_added_x000_copies    f78c615a656c 96a38b690156 :  30263 revs,   0.203956 s,   0.199063 s,  -0.004893 s, × 0.9760,     6 µs/rev
mozilla-central x00000_revs_x0000_added_x0000_copies  6832ae71433c 4c222a1d9a00 : 153721 revs,   1.763853 s,   1.277320 s,  -0.486533 s, × 0.7242,     8 µs/rev
mozilla-central x00000_revs_x00000_added_x000_copies  76caed42cf7c 1daa622bbe42 : 204976 revs,   2.609761 s,   1.698794 s,  -0.910967 s, × 0.6509,     8 µs/rev
mozilla-try     x_revs_x_added_0_copies               aaf6dde0deb8 9790f499805a :      2 revs,   0.000847 s,   0.000842 s,  -0.000005 s, × 0.9941,   421 µs/rev
mozilla-try     x_revs_x000_added_0_copies            d8d0222927b4 5bb8ce8c7450 :      2 revs,   0.000867 s,   0.000865 s,  -0.000002 s, × 0.9977,   432 µs/rev
mozilla-try     x_revs_x_added_x_copies               092fcca11bdb 936255a0384a :      4 revs,   0.000161 s,   0.000160 s,  -0.000001 s, × 0.9938,    40 µs/rev
mozilla-try     x_revs_x00_added_x_copies             b53d2fadbdb5 017afae788ec :      2 revs,   0.001131 s,   0.001122 s,  -0.000009 s, × 0.9920,   561 µs/rev
mozilla-try     x_revs_x000_added_x000_copies         20408ad61ce5 6f0ee96e21ad :      1 revs,   0.033114 s,   0.032743 s,  -0.000371 s, × 0.9888, 32743 µs/rev
mozilla-try     x_revs_x0000_added_x0000_copies       effb563bb7e5 c07a39dc4e80 :      6 revs,   0.071092 s,   0.071529 s,  +0.000437 s, × 1.0061, 11921 µs/rev
mozilla-try     x000_revs_xx00_added_0_copies         6100d773079a 04a55431795e :   1593 revs,   0.006554 s,   0.006593 s,  +0.000039 s, × 1.0060,     4 µs/rev
mozilla-try     x000_revs_x000_added_x_copies         9f17a6fc04f9 2d37b966abed :     41 revs,   0.005160 s,   0.005311 s,  +0.000151 s, × 1.0293,   129 µs/rev
mozilla-try     x000_revs_x000_added_x000_copies      1346fd0130e4 4c65cbdabc1f :   6657 revs,   0.065063 s,   0.063063 s,  -0.002000 s, × 0.9693,     9 µs/rev
mozilla-try     x0000_revs_x_added_0_copies           63519bfd42ee a36a2a865d92 :  40314 revs,   0.297118 s,   0.312363 s,  +0.015245 s, × 1.0513,     7 µs/rev
mozilla-try     x0000_revs_x_added_x_copies           9fe69ff0762d bcabf2a78927 :  38690 revs,   0.284002 s,   0.283106 s,  -0.000896 s, × 0.9968,     7 µs/rev
mozilla-try     x0000_revs_xx000_added_x_copies       156f6e2674f2 4d0f2c178e66 :   8598 revs,   0.086311 s,   0.083817 s,  -0.002494 s, × 0.9711,     9 µs/rev
mozilla-try     x0000_revs_xx000_added_0_copies       9eec5917337d 67118cc6dcad :    615 revs,   0.026738 s,   0.026516 s,  -0.000222 s, × 0.9917,    43 µs/rev
mozilla-try     x0000_revs_xx000_added_x000_copies    89294cd501d9 7ccb2fc7ccb5 :  97052 revs,   1.514270 s,   1.304865 s,  -0.209405 s, × 0.8617,    13 µs/rev
mozilla-try     x0000_revs_x0000_added_x0000_copies   e928c65095ed e951f4ad123a :  52031 revs,   0.735875 s,   0.681088 s,  -0.054787 s, × 0.9255,    13 µs/rev
mozilla-try     x00000_revs_x_added_0_copies          6a320851d377 1ebb79acd503 : 363753 revs,   4.843329 s,   4.454320 s,  -0.389009 s, × 0.9197,    12 µs/rev
mozilla-try     x00000_revs_x00000_added_0_copies     dc8a3ca7010e d16fde900c9c :  34414 revs,   0.591752 s,   0.567913 s,  -0.023839 s, × 0.9597,    16 µs/rev
mozilla-try     x00000_revs_x_added_x_copies          5173c4b6f97c 95d83ee7242d : 362229 revs,   4.760563 s,   4.547043 s,  -0.213520 s, × 0.9551,    12 µs/rev
mozilla-try     x00000_revs_x000_added_x_copies       9126823d0e9c ca82787bb23c : 359344 revs,   4.751942 s,   4.378579 s,  -0.373363 s, × 0.9214,    12 µs/rev
mozilla-try     x00000_revs_x0000_added_x0000_copies  8d3fafa80d4b eb884023b810 : 192665 revs,   2.605014 s,   1.703622 s,  -0.901392 s, × 0.6540,     8 µs/rev
mozilla-try     x00000_revs_x00000_added_x0000_copies 1b661134e2ca 1ae03d022d6d : 228985 revs,  41.113063 s,  36.001255 s,  -5.111808 s, × 0.8757,   157 µs/rev
mozilla-try     x00000_revs_x00000_added_x000_copies  9b2a99adc05e 8e29777b48e6 : 382065 revs,  27.891612 s,  14.340641 s, -13.550971 s, × 0.5142,    37 µs/rev

Differential Revision: https://phab.mercurial-scm.org/D9497

rust/hg-core/src/copy_tracing.rs

@@ -243,6 +243,10 b" impl<'a, A: Fn(Revision, Revision) -> bo"
         }
     }
 
+    fn record_overwrite(&mut self, anc: Revision, desc: Revision) {
+        self.pairs.insert((anc, desc), true);
+    }
+
     /// returns `true` if `anc` is an ancestors of `desc`, `false` otherwise
     fn is_overwrite(&mut self, anc: Revision, desc: Revision) -> bool {
         if anc > desc {
@@ -390,6 +394,7 b' pub fn combine_changeset_copies<A: Fn(Re'
                 // combine it with data for that revision
                 let vertex_copies = add_from_changes(
                     &mut path_map,
+                    &mut oracle,
                     &parent_copies,
                     &changes,
                     Parent::FirstParent,
@@ -410,6 +415,7 b' pub fn combine_changeset_copies<A: Fn(Re'
                 // combine it with data for that revision
                 let vertex_copies = add_from_changes(
                     &mut path_map,
+                    &mut oracle,
                     &parent_copies,
                     &changes,
                     Parent::SecondParent,
@@ -485,8 +491,9 b' fn get_and_clean_parent_copies('
 
 /// Combine ChangedFiles with some existing PathCopies information and return
 /// the result
-fn add_from_changes(
+fn add_from_changes<A: Fn(Revision, Revision) -> bool>(
     path_map: &mut TwoWayPathMap,
+    oracle: &mut AncestorOracle<A>,
     base_copies: &TimeStampedPathCopies,
     changes: &ChangedFiles,
     parent: Parent,
@@ -521,6 +528,7 b' fn add_from_changes('
                     }
                     Entry::Occupied(mut slot) => {
                         let mut ttpc = slot.get_mut();
+                        oracle.record_overwrite(ttpc.rev, current_rev);
                         ttpc.rev = current_rev;
                         ttpc.path = entry;
                     }
@@ -534,6 +542,7 b' fn add_from_changes('
                 // TimeStampedPathCopies object.
                 let deleted = path_map.tokenize(deleted_path);
                 copies.entry(deleted).and_modify(|old| {
+                    oracle.record_overwrite(old.rev, current_rev);
                     old.rev = current_rev;
                     old.path = None;
                 });