Junio C Hamano <gitster@xxxxxxxxx> writes: > If you are trying to do "branch --with $commit", what you would want > is not exactly "paint-down-to-common(all branches, $commit)", but > something that paints down to $commit from all branches, with an > optimization that cuts off the traversal at a commit that is > reachable from $commit. If a traversal from branch B reached such a > commit that is reachable from $commit, you can stop the traversal > because propagating the bit for B further down to its parents will > not reach the $commit you are interested in. I forgot about the other direction, i.e. "branch --merged $commit". Since I do "git branch --no-merged pu" fairly often, I care about its performance ;-) We paint $commit as Left, and tips of all the branches as Right. We try to paint down from $commit but the traversal cannot terminate if it reaches a commit that is reachable from one Right ref---we may find that we can reach more Right refs by following its ancestor. We can stop when we paint Right bits fully, of course, but I wonder if we can do better than that. Suppose we just painted a commit with L and Rn bit (i.e. the commit is a common ancestor of the $commit and one branch). We know that traversing down from there will never reach the tip of the branch whose color is Rn (otherwise we will have a cycle from that commit back to the tip of the branch), so if the reason we are continuing the traversal is to prove that the tip of the branch Rn is reachable (or unreachable) from $commit, there is no reason to continue digging from there. Can we exploit that to terminate the traversal earlier? When we encounter a new commit that is painted with L bit and some but not necessarily all R bits, we propagate the bits and check the R bits. Some of the commits in Right set that correspond to R bits may have been painted in L (i.e. we found branches that are merged to $commit), and digging further from this commit will not give us any new information. Other commits are not painted in L (i.e. we do not yet know if $commit merges these branches), so we may need to keep digging. So perhaps we can stop if a commit is painted in L and also has all the R bits that correspond to Right commits that are not yet proven reachable from $commit (i.e. not painted in L)? -- 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