ok op, tracey

Throwing this into the mix for a while, we can always get rid of it again if it becomes annoying. No objections from stsp@

ok stsp@

This allows the main process to avoid looping over all object IDs again in case the pack file used for enumeration is complete. ok op@

The problem that was found in the earlier version has been fixed. ok op@

This implementation marked commits and trees as enumerated before all trees which they depend on were enumerated. This behaviour leads to incomplete pack files when a tree is only partially packed and got-read-pack hits a missing tree entry as a result. The algorithm must be reworked such that packed leave nodes are marked enumerated first, then bubble-up. Found by op@

pointed out by op@

ok op@

The 'nskip' variable is supposed to reflect commits which are waiting on the queue and have the 'skip' color. Only increment 'nskip' when adding such commits to the queue. Problem observed with got send -T and a tag pointing to a deleted branch. Test to reproduce the bug written by op@.

change the three hardcoded seeds to fresh ones generated on demand via arc4random. Suggested/fixed by and ok stsp@

This flag can be expressed as m->reused_delta_offset != 0 because all deltas in valid pack files will be written at a non-zero offset. We allocate a huge number of these structs during packing, so every little bit helps.

With files sorted properly for deltification we produce better deltas but end up consuming more memory and risk running into OpenBSD ulimits during packing. To compensate, reduce the threshold for the amount of delta data we store in memory, spooling more deltas into the cache file. ok op@

This reduces memory use by gotadmin pack. The goal is to sort files which share a path next to each other for deltification. A hash of the path is good enough for this purpose and consumes less memory than a verbatim copy of the path. Git does something similar. ok op@

The old code was broken and stored an empty path or filenames, instead of a repository-relative path. Which means we didn't sort files for deltification as was intended. Fixing this provides much better deltas in large pack files written by gotadmin pack -a. In my test case, pack size changed from 2GB to 1.5GB. ok op@

with a fix from + ok op@

reported by jrick and op

This significantly speeds up the deltification step of packing by avoiding imsg traffic. gotadmin no longer requests individual raw deltas from got-read-pack to check whether it can reuse them. Instead, got-read-pack obtains a list of objects we want to pack, and hands back the list of all deltas in its pack file which can be reused. Messages are now batched such that imsg buffers are filled as much as possible. Another advantage is that deltas we are not going to reuse will no longer be written to the delta cache file, saving disk space. Before this patch, any raw delta candidate was written to the delta cache file by got-read-pack, and the decision whether to reuse the delta happened afterwards in the gotadmin process. Code for reading individual raw deltas is now unused and could be removed at some point. ok op@

ok op@

ok op@

This reduces memory and disk space consumption during packing. with tweaks + memleak on error fix from op@ ok op@

tweak + ok tb@