Repository Hints and Rewriting Commits

Phabricator User Documentation (Field Manuals)

Dealing with rewrites of published repositories and other unusual problems.

Overview

Some repositories have unusual commits. You can provide "hints" to Phabricator about these commits to improve behavior.

Supported hints are:

• Rewritten Commits: If you have rewritten the history of a published repository, you can provide hints about the mapping from old commits to new commits so it can redirect users who visit old pages to the proper new pages.
• Unreadable Commits: If some commits are not readable (which is rare, but can happen in some cases if they are generated with an external tool) you can provide hints so that Phabricator doesn't try to read them.

The remainder of this document explains how to create and remove hints, and how to specify each type of hint.

Creating Hints

To create hints, pipe a JSON list of hints to bin/repository hint:

phabricator/ $ cat hints.json | ./bin/repository hint

The hints should be a list of objects like this:

[
  ...
  {
    "repository": "XYZ",
    "hint": "...",
    "old": "abcdef1234abcdef1234abcdef1234abcdef1234",
    "new": "..."
  }
  ...
]

Each hint may have these keys:

• repository: A repository identifier (ID, PHID, callsign or short name).
• hint: The hint type, see below.
• old: The full identifier or commit hash of the commit you want to provide a hint for.
• new: For hints which specify a new commit, the full identifier or commit hash of the new commit.

See below for exactly how to specify each type of hint.

Removing Hints

To remove a hint, create a hint of type "none". This will remove any existing hint.

For example, use a hint specification like this:

[
  {
    "repository": "XYZ",
    "hint": "none",
    "old": "abcdef1234abcdef1234abcdef1234abcdef1234"
  }
]

Phabricator won't treat commits without any hint specially.

Hint: Rewritten Commits

The "rewritten" hint allows you to redirect old commits to new commits after a rewrite of published history. You should normally avoid rewriting published commits, but sometimes this is necessary: for example, if a repository has become unwieldy because it contains large binaries, you may strip them from history.

To provide this kind of hint, pass the "old" commit hash (from before the rewrite) and the "new" commit hash (from after the rewrite).

For example, a hint might look like this:

[
  {
    "repository": "XYZ",
    "hint": "rewritten",
    "old": "abcdef1234abcdef1234abcdef1234abcdef1234",
    "new": "098765ffaabbccdd4680098765ffaabbccdd4680"
  }
]

Phabricator will show users that the commit was rewritten in the web UI.

Hint: Unreadable Commits

The "unreadable" hint allows you to tell Phabricator that it should not bother trying to read the changes associated with a particular commit. In some rare cases, repositories can contain commits which aren't readable (for example, if they were created by external tools during an import or merge process).

To provide this kind of hint, pass the "old" commit which is affected.

For example, a hint might look like this:

[
  {
    "repository": "XYZ",
    "hint": "unreadable",
    "old": "abcdef1234abcdef1234abcdef1234abcdef1234"
  }
]

Phabricator won't try to read, parse, import, or display the changes associated with this commit.