On Sun, Apr 22, 2012 at 20:59, <gst...@apache.org> wrote: > Author: gstein > Date: Mon Apr 23 00:59:46 2012 > New Revision: 1329015 > > URL: http://svn.apache.org/viewvc?rev=1329015&view=rev > Log: > Provide a first pass at (private) APIs to fetch an EV2-based commit > editor from the RA layers. Some of this is based on Hyrum's work on > the ev2-exports branch (see editor.c below). > > If an RA layer supports this new API, then it is used. Otherwise, an > Ev2 shim is inserted over its Ev1-based commit editor and returned.
The concept here is that we'll provide *two* commit editors out of the RA layers. The existing Ev1-based editor, and the new Ev2-based editor. Both are provided during the transition period. The Ev1 API will need to stick around for compatibility purposes, so I don't think we're really losing much by creating a second (Ev2-based) path. At some point in the future, we can simply deprecate the Ev1 version (as if we had moved from get_commit_editor3() to get_commit_editor4()). This is a different strategy from Hyrum's branch, where get_commit_editor3() has been deprecated in favor of an Ev2 version (ie. only one "valid" path). For now, the Ev2-based APIs are all private. Once we're comfortable with them, then we can make them public. Third parties can continue to use the Ev1-based commit editor. The Ev2-based commit editor can be built incrementally. For example, it could support *just* add_directory() and then we switch the 'svn mkdir URL' code over to use the Ev2 interface. Even if that gets run against an "old" RA layer and an Ev2/Ev2 shim is interposed, the shim won't create much of a problem since you're only operating on one (or a few) target paths. (the shims buffer all modified paths, basically, so we want to avoid them in "unbounded" commit sequences) Since a shim is used when needed, we can also implement the Ev2 APIs on one RA layer at a time. We don't have to code them all at once. Only when we want to avoid the Ev2/Ev1 shim and its overhead. Lastly: note that these are not bounded by any conditional compilation. This is unrelated to the ENABLE_EV2_SHIMS code, which interposes an Ev1/Ev2 and an Ev2/Ev1 shim around each delta (Ev1) editor created. This is true Ev2 work, only pending code that will make use of it. Cheers, -g
