hgext/git/TODO.md
author Pierre-Yves David <pierre-yves.david@octobus.net>
Thu, 07 Mar 2024 10:55:22 +0100
changeset 51531 f85f23f1479b
parent 44621 c5653cf2811d
permissions -rw-r--r--
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.
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
44477
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     1
Octopus Merge Support
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     2
=====================
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     3
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     4
This will be moderately complicated, as we'll need to synthesize phony
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     5
changeset entries to explode the octopus into "revisions" that only
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     6
have two parents each. For today, we can probably just do something like
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     7
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     8
    aaaaaaaaaaaaaaaaaaXX{20 bytes of exploded node's hex sha}
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
     9
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    10
where XX is a counter (so we could have as many as 255 parents in a
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    11
git commit - more than I think we'd ever see.) That means that we can
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    12
install some check in this extension to disallow checking out or
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    13
otherwise interacting with the `aaaaaaaaaaaaaaaaaa` revisions.
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    14
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    15
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    16
Interface Creation
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    17
====================
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    18
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    19
We at least need an interface definition for `changelog` in core that
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    20
this extension can satisfy, and again for `basicstore`.
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    21
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    22
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    23
Reason About Locking
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    24
====================
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    25
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    26
We should spend some time thinking hard about locking, especially on
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    27
.git/index etc. We're probably adequately locking the _git_
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    28
repository, but may not have enough locking correctness in places
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    29
where hg does locking that git isn't aware of (notably the working
ad718271a9eb git: skeleton of a new extension to _directly_ operate on git repos
Augie Fackler <augie@google.com>
parents:
diff changeset
    30
copy, which I believe Git does not lock.)