perf: add --reverse to perfrevlog It can be useful to know how fast we can read revisions from a revlog in reverse. This operation tends to occur in `hg log` commands, for example.

log: copy the way of ancestor traversal to --follow matcher (issue5376) We can't use fctx.linkrev() because follow() revset tries hard to simulate the traversal of changelog DAG, not filelog DAG. This patch fixes _makefollowlogfilematcher() to walk file ancestors in the same way as revset._follow(). I'll factor out a common function in future patches.

log: unroll loop that populates file paths for --patch --follow matcher We can't handle the first fctx in the same manner as its ancestors. Also, I think the original code was too tricky.

wireproto: rename argument to groupchunks() groupchunks() is a generic "turn a file object into a generator" function. It isn't limited to changegroups. Rename the argument and update the docstring to reflect this.

tests: actually test non-generaldelta variant for stream clones 608cabec1b15 accidentally made both tests test generaldelta repos. Restore the test for a non-gd repo.

revlog: document high frequency of code execution Recording my notes while working on performance optimization.