view tests/test-debugbundle.t @ 37054:40206e227412

wireproto: define and implement protocol for issuing requests

The existing HTTP and SSH wire protocols suffer from a host of flaws
and shortcomings. I've been wanting to rewrite the protocol for a while
now. Supporting partial clone - which will require new wire protocol
commands and capabilities - and other advanced server functionality
will be much easier if we start from a clean slate and don't have
to be constrained by limitations of the existing wire protocol.

This commit starts to introduce a new data exchange format for
use over the wire protocol.

The new protocol is built on top of "frames," which are atomic
units of metadata + data. Frames will make it easier to implement
proxies and other mechanisms that want to inspect data without
having to maintain state. The existing frame metadata is very
minimal and it will evolve heavily. (We will eventually support
things like concurrent requests, out-of-order responses,
compression, side-channels for status updates, etc. Some of
these will require additions to the frame header.)

Another benefit of frames is that all reads are of a fixed size.
A reader works by consuming a frame header, extracting the payload
length, then reading that many bytes. No lookahead, buffering, or
memory reallocations are needed.

The new protocol attempts to be transport agnostic. I want all that's
required to use the new protocol to be a pair of unidirectional,
half-duplex pipes. (Yes, we will eventually make use of full-duplex
pipes, but that's for another commit.) Notably, when the SSH
transport switches to this new protocol, stderr will be unused.
This is by design: the lack of stderr on HTTP harms protocol
behavior there. By shoehorning everything into a pair of pipes,
we can have more consistent behavior across transports.

We currently only define the client side parts of the new protocol,
specifically the bits for requesting that a command run. This keeps
the new code and feature small and somewhat easy to review.

We add support to `hg debugwireproto` for writing frames into
HTTP request bodies. Our tests that issue commands to the new
HTTP endpoint have been updated to transmit frames. The server
bits haven't been touched to consume the frames yet. This will
occur in the next commit...

Astute readers may notice that the command name is transmitted in
both the HTTP request URL and the command request frame. This is
partially a kludge from me initially implementing the frame-based
protocol for SSH first. But it is also a feature: I intend to
eventually support issuing multiple commands per HTTP request. This
will allow us to replace the abomination that is the "batch" wire
protocol command with a protocol-level mechanism for performing
multi-dispatch. Because I want the frame-based protocol to be
as similar as possible across transports, I'd rather we (redundantly)
include the command name in the frame than differ behavior between
transports that have out-of-band routing information (like HTTP)
readily available.

Differential Revision: https://phab.mercurial-scm.org/D2851

Create a test repository:

  $ hg init repo
  $ cd repo
  $ touch a ; hg add a ; hg ci -ma
  $ touch b ; hg add b ; hg ci -mb
  $ touch c ; hg add c ; hg ci -mc
  $ hg bundle --base 0 --rev tip bundle.hg -v --type v1
  2 changesets found
  uncompressed size of bundle content:
       332 (changelog)
       282 (manifests)
        93  b
        93  c
  $ hg bundle --base 0 --rev tip bundle2.hg -v --type none-v2
  2 changesets found
  uncompressed size of bundle content:
       344 (changelog)
       322 (manifests)
       113  b
       113  c

Terse output:

  $ hg debugbundle bundle.hg
  0e067c57feba1a5694ca4844f05588bb1bf82342
  991a3460af53952d10ec8a295d3d2cc2e5fa9690

Terse output:

  $ hg debugbundle bundle2.hg
  Stream params: {}
  changegroup -- {nbchanges: 2, version: 02}
      0e067c57feba1a5694ca4844f05588bb1bf82342
      991a3460af53952d10ec8a295d3d2cc2e5fa9690
  cache:rev-branch-cache -- {}

Quiet output

  $ hg debugbundle --quiet bundle2.hg
  Stream params: {}
  changegroup -- {nbchanges: 2, version: 02}
  cache:rev-branch-cache -- {}

Verbose output:

  $ hg debugbundle --all bundle.hg
  format: id, p1, p2, cset, delta base, len(delta)
  
  changelog
  0e067c57feba1a5694ca4844f05588bb1bf82342 3903775176ed42b1458a6281db4a0ccf4d9f287a 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 3903775176ed42b1458a6281db4a0ccf4d9f287a 80
  991a3460af53952d10ec8a295d3d2cc2e5fa9690 0e067c57feba1a5694ca4844f05588bb1bf82342 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 0e067c57feba1a5694ca4844f05588bb1bf82342 80
  
  manifest
  686dbf0aeca417636fa26a9121c681eabbb15a20 8515d4bfda768e04af4c13a69a72e28c7effbea7 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 8515d4bfda768e04af4c13a69a72e28c7effbea7 55
  ae25a31b30b3490a981e7b96a3238cc69583fda1 686dbf0aeca417636fa26a9121c681eabbb15a20 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 686dbf0aeca417636fa26a9121c681eabbb15a20 55
  
  b
  b80de5d138758541c5f05265ad144ab9fa86d1db 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 0000000000000000000000000000000000000000 0
  
  c
  b80de5d138758541c5f05265ad144ab9fa86d1db 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 0000000000000000000000000000000000000000 0

  $ hg debugbundle --all bundle2.hg
  Stream params: {}
  changegroup -- {nbchanges: 2, version: 02}
      format: id, p1, p2, cset, delta base, len(delta)
  
      changelog
      0e067c57feba1a5694ca4844f05588bb1bf82342 3903775176ed42b1458a6281db4a0ccf4d9f287a 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 0000000000000000000000000000000000000000 66
      991a3460af53952d10ec8a295d3d2cc2e5fa9690 0e067c57feba1a5694ca4844f05588bb1bf82342 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 0000000000000000000000000000000000000000 66
  
      manifest
      686dbf0aeca417636fa26a9121c681eabbb15a20 8515d4bfda768e04af4c13a69a72e28c7effbea7 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 8515d4bfda768e04af4c13a69a72e28c7effbea7 55
      ae25a31b30b3490a981e7b96a3238cc69583fda1 686dbf0aeca417636fa26a9121c681eabbb15a20 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 686dbf0aeca417636fa26a9121c681eabbb15a20 55
  
      b
      b80de5d138758541c5f05265ad144ab9fa86d1db 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 0e067c57feba1a5694ca4844f05588bb1bf82342 0000000000000000000000000000000000000000 0
  
      c
      b80de5d138758541c5f05265ad144ab9fa86d1db 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 991a3460af53952d10ec8a295d3d2cc2e5fa9690 0000000000000000000000000000000000000000 0
  cache:rev-branch-cache -- {}

  $ cd ..