push: rework the computation of fallbackheads to be correct The previous computation tried to be smart but ended up being wrong. This was caught by phase movement test while reworking the phase discovery logic to be faster. The previous logic was failing to catch case where the pushed set was not based on a common heads (i.e. when the discovery seemed to have "over discovered" content, outside the pushed set) In the following graph, `e` is a common head and we `hg push -r f`. We need to detect `c` as a fallback heads and we previous failed to do so:: e | d f |/ c | b | a The performance impact of the change seems minimal. On the most impacted repository at hand (mozilla-try), the slowdown seems mostly mixed in the overall noise `hg push` but seems to be in the hundred of milliseconds order of magnitude. When using rust, we seems to be a bit faster, probably because we leverage more accelaratd internals. I added a couple of performance related common for further investigation later on.

     1

  $ cat >> $HGRCPATH << EOF

     2

  > [extensions]

     3

  > strip=

     4

  > EOF

     5

     6

Setup repo

     7

     8

  $ hg init repo

     9

  $ cd repo

    10

    11

Test backups list and recover

    12

    13

  $ hg debugbackupbundle

    14

  no backup changesets found

    15

    16

  $ mkcommit() {

    17

  >    echo "$1" > "$1"

    18

  >    hg add "$1"

    19

  >    hg ci -l $1

    20

  > }

    21

  $ mkcommit a

    22

  $ mkcommit b

    23

  $ hg strip .

    24

  0 files updated, 0 files merged, 1 files removed, 0 files unresolved

    25

  saved backup bundle to $TESTTMP/repo/.hg/strip-backup/d2ae7f538514-2953539b-backup.hg

    26

  $ hg debugbackupbundle

    27

  Recover changesets using: hg debugbackupbundle --recover <changeset hash>

    28

    29

  Available backup changesets:

    30

  * (glob)

    31

  d2ae7f538514 b

    32

    33

  $ hg debugbackupbundle --recover d2ae7f538514

    34

  Unbundling d2ae7f538514

    35

  adding changesets

    36

  adding manifests

    37

  adding file changes

    38

  added 1 changesets with 1 changes to 1 files

    39

  new changesets d2ae7f538514 (1 drafts)