From: Dmitry Ivankov Date: Sat, 24 Sep 2011 21:19:57 GMT Subject: Re: [PATCH v0] fast-import: Add drop command Message-ID: In-Reply-To: <20110924193733.GB10955@elie> On Sun, Sep 25, 2011 at 1:37 AM, Jonathan Nieder wrote: > Vitor Antunes wrote: > >> The drop command deletes the given branch reference, allowing >> fast-import to actively ignore it in the final checks. > > Thanks.  I must have missed the earlier discussion.  What are the > semantics of this command and its intended purpose? My guess is that if fast-import is used to manage a set of "remote" branches, it should be able to delete branches. Then, it should be allowed to do non-fastforward updates too (--force). Why can't it just ignore branches deletion (considering --force)? Random thoughts: 1. once 'drop' is executed, fast-import can't tell if the branch was actually deleted. And moreover any attempt to read this branch head becomes illegal (either it's missing in .git or fast-import is instructed to use a dropped branch). 2. 'reset' command is a bit like proposed 'drop' but it never deletes a branch ref. Consider following imports: 1) import branch topic 2) reset topic 3) import branch topic2 starting at topic (incorrect import) If 1-3) is done in one fast-import process, the error is reported. If 3) is done separately, it succeeds but the result is strange: topic2 isn't started from scratch but from old "erased" topic. So, maybe, reset should be fixed to erase branches on --force. One more scenario is: 1) import topic 2) reset topic 3) import topic If 1-3) go together - no error If 3) goes separate - no error, but non-fastforward update. Much more harmless, but still may look strange. > For example, what > happens if the branch already existed or if there is a checkpoint > (perhaps triggered by the impatient user sending SIGUSR1 to > fast-import) before the "drop" command is processed? I think that actual ref deletion should take place in update_branch(). So all the cases would be handled as usual. > Jonathan >