diff rust/hg-core/src/dagops.rs @ 41717:9060af281be7

rust: itering less on MissingAncestors.bases for max()

Instead of iterating on the whole `self.bases` each time to find
its max, we keep the latter in a separate member attribute and
keep it up to date in `add_bases()`

On a perfdiscovery done on PyPy, with repos prepared with
`contrib/discovery-helper.sh 50 100`, this gives a slight
improvement (around 0.5% on wall time, but 10% on CPU)

before:
! wall 0.172801 comb 0.180000 user 0.180000 sys 0.000000 (median of 541)
after:
! wall 0.171798 comb 0.160000 user 0.160000 sys 0.000000 (median of 551)

(perf command run time upped because of bigger variability during this test).

Differential Revision: https://phab.mercurial-scm.org/D5945

--- a/rust/hg-core/src/dagops.rs	Tue Feb 05 10:28:32 2019 +0100
+++ b/rust/hg-core/src/dagops.rs	Mon Feb 04 19:46:57 2019 +0100
@@ -46,7 +46,9 @@
     let mut heads: HashSet<Revision> = iter_revs.clone().cloned().collect();
     heads.remove(&NULL_REVISION);
     for rev in iter_revs {
-        remove_parents(graph, *rev, &mut heads)?;
+        if *rev != NULL_REVISION {
+            remove_parents(graph, *rev, &mut heads)?;
+        }
     }
     Ok(heads)
 }
@@ -71,7 +73,9 @@
     // mutating
     let as_vec: Vec<Revision> = revs.iter().cloned().collect();
     for rev in as_vec {
-        remove_parents(graph, rev, revs)?;
+        if rev != NULL_REVISION {
+            remove_parents(graph, rev, revs)?;
+        }
     }
     Ok(())
 }