changegroup: define linknodes callbacks in generatefiles() This is how it is done everywhere else. But the logic here is a bit more complex because shallow clone needs to reference the original linknode implementation. But at least now all function implementations are defined in the same place. Differential Revision: https://phab.mercurial-scm.org/D4191

changegroup: track changelog to manifest revision map explicitly Previously, self._nextclrevtolocalrev was only populated as part of the changelog lookup callback. But cgpacker._close() was looking at self._nextclrevtolocalrev on every invocation. Since self._nextclrevtolocalrev is for communicating the mapping of changelog revisions to manifest revisions, this commit refactors the code to make that explicit. The changelog state now stores this mapping. And after the changelog group is emitted, we update self._clrevtolocalrev with that dict. self._nextclrevtolocalrev is unused and has been deleted. Differential Revision: https://phab.mercurial-scm.org/D4190

changegroup: remove _clnodetorev cgpacker._clnodetorev is a glorified cache/index of changelog nodes to revision numbers. I'm not sure why it exists. Maybe performance? But its presence is making refactoring of this code more complicated than it needs to be. This commit removes the cache and replaces it with direct lookups against the changelog. If this cache was for performance reasons, we should be able to restore it easily enough... after the changegroup refactor is complete. Differential Revision: https://phab.mercurial-scm.org/D4189

changegroup: rename _fullnodes to _fullclnodes So it is obvious which nodes we are talking about. And sneak in a docs change to reflect that this variable is a set. Differential Revision: https://phab.mercurial-scm.org/D4188

changegroup: move part of _revisiondeltanarrow into group() Now all the logic for determining which delta generation code is called lives in a single function. Differential Revision: https://phab.mercurial-scm.org/D4187

changegroup: populate _clnodetorev as part of changelog linknode lookup The thing that matters is that self._clnodetorev is populated with changesets that are being sent. Back when this code was in an extension, it wasn't possible to monkeypatch the changelog lookup function. Now that the code is in core, we can move this code to where it logically belongs. Differential Revision: https://phab.mercurial-scm.org/D4186