On Thu, Feb 11, 2016 at 2:42 PM, Andrew Ardill <andrew.ardill@xxxxxxxxx> wrote: > On 12 February 2016 at 09:06, Junio C Hamano <gitster@xxxxxxxxx> wrote: >> >> To realize this, there are low-hanging-fruit building blocks that >> are trivial: >> >> - Such an annotation can be made as a note attached to the commit >> in question; >> >> - Such a check can be done in pre-commit hook; >> >> - Such a pre-commit hook can iterate over this set of commits >> >> DIFF=$(git rev-list --left-right HEAD...MERGE_HEAD) >> >> collect these Merge Gate annotations from the commit appears on >> the left hand side (e.g. only exists on the trunk that a side >> branch is about to be merged in), and run them. >> >> But the last one feels very costly, and I suspect that there must be >> a better way to do this. I do not think we want the "what to do" >> part (i.e. checking new lines for __attribute__ in the first >> example, or rewriting new lines that has __attribute_ in the second >> example) to be in git-core; that clearly is outside the scope of the >> plumbing. But the part that finds these "annotations", especially >> if we can come up with a fast implementation that may be hard to >> script, may be a good addition to the plumbing command set. >> >> Thoughts? > > What is the benefit in doing this in notes vs having the tests in the > working tree? > > Pros: > > - merge-gates can be added after the commit, but will stick with the > commit if it moves around (as opposed to creating a second commit to > add the merge-gate to the working tree) > > - cross repository standards can be established that allow > merge-gates to be detected and run automatically (arguably could be > done with a standardised folder structure too, but that is more > disruptive) > > - can view the relevant merge-gates in git log against each commit > that they are protecting > > Cons: > > - difficult to see the current complete set of merge-gates > > - difficult to make changes to a number of merge-gates at the same time > > - poorly defined behaviour when multiple merge-gates overlap in > functionality. Which gates execute first? What if I reorder the > commits? The way I could imagine "merge gates" currently: * they are some kind of invariant to be checked, or an action performed, an event * they can be introduced by a commit X. * they can be turned off by a commit Y * an offspring commit inherits all "merge gates" from its parents (in order of the parents So the event for one merge gate is in effect iff you merge one commit from X..Y Now we want to know for a given commit C, which merge gates are there? To find all events we would need to walk the whole history of C and record all found events, which are not turned off. So I'd think that could be accelerated with event bitmaps (which work similar to the reachability bitmaps, but having a different goal and record which events are alive for certain commits, such that you only need to walk a bounded set of commits to find out. When first reading this email I thought this is a typical maintainers problem, so it should happen all the time in larger projects, such as linux, how do they handle system wide refactorings? > > > My practical knowledge of notes is severely lacking so excuse me if I > missed anything obvious. > > Regards, > > Andrew Ardill > > (sorry for the double post Junio, gmail ate my plain text encoding at > some point...) > -- > To unsubscribe from this list: send the line "unsubscribe git" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html