perf: extract the timing of a section in a context manager This makes it easier to reuse it in other (future) part of the code that requires their own time management.

pref: support negative indexing in perfrevlogrevisions This is useful to check for a consistent final slice in multiple different repositories.

perf: accept formatter option for perfmanifest

perf: fix -T json The previous code was mixing formatting and data, breaking `-T json` with unexpected data. We fix the issue and add a test to prevent future regression.

formatter: more details on assertion failure This is useful when the assertion fails.

wireprotov2: raise ProgrammingError on unknown action Suggested by @durin42 in review of D4923. Differential Revision: https://phab.mercurial-scm.org/D4935

wireprotov2: send content encoded frames from server Now that we have support for negotiating encodings and configuring an encoder, we can start sending content encoded frames from the server. This commit teaches the wireprotov2 server code to send content encoded frames. On the mozilla-unified repository with zstd enabled peers, this change reduces the total amount of data transferred from server to client drastically: befor: 7,190,995,812 bytes after: 1,605,508,691 bytes Differential Revision: https://phab.mercurial-scm.org/D4927

wireprotov2: raise exception in objects() if future has been resolved Differential Revision: https://phab.mercurial-scm.org/D4926

wireprotov2: don't emit empty frames Staring at logs revealed the presence of empty frames that should have contained payload. Let's stop that from happening. Differential Revision: https://phab.mercurial-scm.org/D4925

wireprotov2: remove functions for creating response frames from bytes All code in the actual server uses oncommandresponsereadyobjects(). Test code was ported to that method. This resulted in a handful of subtle test changes. Differential Revision: https://phab.mercurial-scm.org/D4924