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.

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  $ cat >> $HGRCPATH << EOF

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  > [extensions]

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  > absorb=

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  > EOF

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  $ hg init repo1

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  $ cd repo1

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Make some commits:

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  $ for i in 1 2 3; do

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  >   echo $i >> a

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  >   hg commit -A a -m "commit $i" -q

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  > done

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absorb --edit-lines will run the editor if filename is provided:

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  $ hg absorb --edit-lines

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  nothing applied

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  [1]

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  $ HGEDITOR=cat hg absorb --edit-lines a

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  HG: editing a

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  HG: "y" means the line to the right exists in the changeset to the top

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  HG:

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  HG: /---- 4ec16f85269a commit 1

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  HG: |/--- 5c5f95224a50 commit 2

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  HG: ||/-- 43f0a75bede7 commit 3

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  HG: |||

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      yyy : 1

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       yy : 2

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        y : 3

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  nothing applied

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  [1]

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Edit the file using --edit-lines:

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  $ cat > editortext << EOF

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  >       y : a

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  >      yy :  b

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  >      y  : c

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  >     yy  : d  

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  >     y y : e

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  >     y   : f

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  >     yyy : g

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  > EOF

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  $ HGEDITOR='cat editortext >' hg absorb -q --edit-lines a

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  $ hg cat -r 0 a

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  d  

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  e

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  f

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  g

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  $ hg cat -r 1 a

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   b

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  c

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  d  

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  g

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  $ hg cat -r 2 a

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  a

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   b

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  e

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  g