branchcache: skip entries that are topological heads in the on disk file In the majority of cases, topological heads are also branch heads. We have efficient way to get the topological heads and efficient way to retrieve their branch information. So there is little value in putting them in the branch cache file explicitly. On the contrary, writing them explicitly tend to create very large cache file that are inefficient to read and update. So the branch cache v3 format is no longer including them. This changeset focus on the format aspect and have no focus on the performance aspect. We will cover that later.

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https://bz.mercurial-scm.org/612

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  $ hg init repo

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  $ cd repo

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  $ mkdir src

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  $ echo a > src/a.c

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  $ hg ci -Ama

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  adding src/a.c

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  $ hg mv src source

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  moving src/a.c to source/a.c

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  $ hg ci -Ammove

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  $ hg co -C 0

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

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  $ echo new > src/a.c

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  $ echo compiled > src/a.o

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  $ hg ci -mupdate

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  created new head

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  $ hg status

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  ? src/a.o

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  $ hg merge

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  merging src/a.c and source/a.c to source/a.c

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

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  (branch merge, don't forget to commit)

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  $ hg status

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  M source/a.c

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  R src/a.c

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  ? src/a.o

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