There is some possibility that this save() could race, if two workers are parsing different commits by the same author:

• Both look for the Identity and don't find it.
• Both build a new Identity and save it.
• Whichever one is slower loses.

In this case, the slower INSERT will hit AphrontDuplicateKeyQueryException when the second row collides with the first row on the UNIQUE KEY on nameHash.

I don't have a great solution for this. Where it comes up elsewhere, I think we usually use this pattern:

thing = load(id);
if (!thing) {
  thing = new(id);
  try {
    thing->save();
  } catch (duplicate) {
    thing = load(id);
    if (!thing) {
      throw new Exception("Raced and lost, then failed to load the object we lost the race to? Very confusing.");
    }
  }
}

This doesn't feel very elegant, but should survive anything reasonable.