speed up initial stage of packing by adding a "skip" commit color The skip color marks boundary commits and their ancestors. Boundary commits are reachable both via references which we want to exclude from the pack, and via references which we want to include in the pack. We continue processing commit history up to the point we are left with only skip commits on the queue. This can speed up findtwixt() significantly and avoids wrong results produced by the old algorithm which made no distinction between "drop" and "skip". This idea was first implemented by Michael Forney for git9: https://git.9front.org/plan9front/plan9front/2e47badb88312c5c045a8042dc2ef80148e5ab47/commit.html Michael's log message for git9 is reproduced below: git/query: refactor graph painting algorithm (findtwixt, lca) We now keep track of 3 sets during traversal: - keep: commits we've reached from head commits - drop: commits we've reached from tail commits - skip: ancestors of commits in both 'keep' and 'drop' Commits in 'keep' and/or 'drop' may be added later to the 'skip' set if we discover later that they are part of a common subgraph of the head and tail commits. From these sets we can calculate the commits we are interested in: lca commits are those in 'keep' and 'drop', but not in 'skip'. findtwixt commits are those in 'keep', but not in 'drop' or 'skip'. The "LCA" commit returned is a common ancestor such that there are no other common ancestors that can reach that commit. Although there can be multiple commits that meet this criteria, where one is technically lower on the commit-graph than the other, these cases only happen in complex merge arrangements and any choice is likely a decent merge base. Repainting is now done in paint() directly. When we find a boundary commit, we switch our paint color to 'skip'. 'skip' painting does not stop when it hits another color; we continue until we are left with only 'skip' commits on the queue. This fixes several mishandled cases in the current algorithm: 1. If we hit the common subgraph from tail commits first (if the tail commit was newer than the head commit), we ended up traversing the entire commit graph. This is because we couldn't distinguish between 'drop' commits that were part of the common subgraph, and those that were still looking for it. 2. If we traversed through an initial part of the common subgraph from head commits before reaching it from tail commits, these commits were returned from findtwixt even though they were also reachable from tail commits. 3. In the same case as 2, we might end up choosing an incorrect commit as the LCA, which is an ancestor of the real LCA.

check return value of RB_INSERT; ok + memleak fix by op@

make sure callers of got_object_idset_add() free data.

fix a double-free in an error case of cmd_checkout()

sort references by date for packing; newer commits should be processed first

add a -q (quiet) option to 'gotadmin pack'

revert 03c03172 "drop a commit right away if it matches an excluded commit" This change resulted in a full history walk even when no objects will be added to the pack file. Fix this regression by reverting the change.

for clarity, move the coloring loop from findtwixt() into a separate function

remove a pointless object-id dup/free dance in findtwixt()

don't forget to call the cancel callback while coloring commits in findtwixt()

in findtwixt(), drop a commit right away if it matches an excluded commit

the obj_types array in pack_create.c is no longer useful, remove it

make 'got tag' unlock the work tree earlier when creating tags The work tree was only held open in order to find its got.conf file since this file could contain a tagger name to use. Read the tagger name earlier. Once the tagger name is known we can close the work tree already.

make 'got tag -l' unlock the work tree earlier to allow other parallel commands

make 'got cat' not search for a work tree if the -r option is used Fixes failures in our test suite if 'got tag -l | less' is used in the work tree while cmdline tests are running.