Generate ref updates in Mercurial hooks
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Authored by epriestley on Dec 13 2013, 12:06 AM.

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Reviewers

btrahan

Maniphest Tasks

T4195: Implement pre-commit Herald rules

Commits

Restricted Diffusion Commit
rP6f3a99eb392e: Generate ref updates in Mercurial hooks

Summary

Ref T4195. Mercurial is not my favorite VCS.

Test Plan

Hit the split branches case:

>>> orbital ~/repos/INIH $ hg push --force
pushing to ssh://dweller@local.aphront.com/diffusion/INIH
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 2 changesets with 2 changes to 1 files (+1 heads)
remote: +---------------------------------------------------------------+
remote: |      * * * PUSH REJECTED BY EVIL DRAGON BUREAUCRATS * * *     |
remote: +---------------------------------------------------------------+
remote:             \
remote:              \                    ^    /^
remote:               \                  / \  // \
remote:                \   |\___/|      /   \//  .\
remote:                 \  /V  V  \__  /    //  | \ \           *----*
remote:                   /     /  \/_/    //   |  \  \          \   |
remote:                   @___@`    \/_   //    |   \   \         \/\ \
remote:                  0/0/|       \/_ //     |    \    \         \  \
remote:              0/0/0/0/|        \///      |     \     \       |  |
remote:           0/0/0/0/0/_|_ /   (  //       |      \     _\     |  /
remote:        0/0/0/0/0/0/`/,_ _ _/  ) ; -.    |    _ _\.-~       /   /
remote:                    ,-}        _      *-.|.-~-.           .~    ~
remote:   \     \__/        `/\      /                 ~-. _ .-~      /
remote:    \____(Oo)           *.   }            {                   /
remote:    (    (--)          .----~-.\        \-`                 .~
remote:    //__\\  \ DENIED!  ///.----..<        \             _ -~
remote:   //    \\               ///-._ _ _ _ _ _ _{^ - - - - ~
remote: 
remote: 
remote: DANGEROUS CHANGE: The change you're attempting to push splits the head of branch 'default' into multiple heads: 802c785c3dd9, e73400db39b0. This is inadvisable and dangerous.
remote: Dangerous change protection is enabled for this repository.
remote: Edit the repository configuration before making dangerous changes.
remote: 
remote: transaction abort!
remote: rollback completed
remote: abort: pretxnchangegroup.phabricator hook exited with status 1

Hit the divergent heads case:

>>> orbital ~/repos/INIH $ hg push --force
pushing to ssh://dweller@local.aphront.com/diffusion/INIH
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files (+1 heads)
remote: +---------------------------------------------------------------+
remote: |      * * * PUSH REJECTED BY EVIL DRAGON BUREAUCRATS * * *     |
remote: +---------------------------------------------------------------+
remote:             \
remote:              \                    ^    /^
remote:               \                  / \  // \
remote:                \   |\___/|      /   \//  .\
remote:                 \  /V  V  \__  /    //  | \ \           *----*
remote:                   /     /  \/_/    //   |  \  \          \   |
remote:                   @___@`    \/_   //    |   \   \         \/\ \
remote:                  0/0/|       \/_ //     |    \    \         \  \
remote:              0/0/0/0/|        \///      |     \     \       |  |
remote:           0/0/0/0/0/_|_ /   (  //       |      \     _\     |  /
remote:        0/0/0/0/0/0/`/,_ _ _/  ) ; -.    |    _ _\.-~       /   /
remote:                    ,-}        _      *-.|.-~-.           .~    ~
remote:   \     \__/        `/\      /                 ~-. _ .-~      /
remote:    \____(Oo)           *.   }            {                   /
remote:    (    (--)          .----~-.\        \-`                 .~
remote:    //__\\  \ DENIED!  ///.----..<        \             _ -~
remote:   //    \\               ///-._ _ _ _ _ _ _{^ - - - - ~
remote: 
remote: 
remote: DANGEROUS CHANGE: The change you're attempting to push creates new, divergent heads for the branch 'default': f56af4232aa9. This is inadvisable and dangerous.
remote: Dangerous change protection is enabled for this repository.
remote: Edit the repository configuration before making dangerous changes.
remote: 
remote: transaction abort!
remote: rollback completed
remote: abort: pretxnchangegroup.phabricator hook exited with status 1

Did a bunch of good/bad pushes:

{F89300}

Diff Detail

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Unit

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Event Timeline

This is pretty gross. Basically, in Mercurial you can't ever delete or overwrite a branch, but you can push a new branch head with hg push --force, so then "master" has, like, an arbitrarily large number of heads. We detect creating more heads on some branch than already exist in the repository and reject it as dangerous. Otherwise, we create update refs for all the heads, keeping track of which ones were appended to and which ones are new.