view tests/test-issue586.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

Issue586: removing remote files after merge appears to corrupt the
dirstate

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg ci -Ama
  adding a

  $ hg init ../b
  $ cd ../b
  $ echo b > b
  $ hg ci -Amb
  adding b

  $ hg pull -f ../a
  pulling from ../a
  searching for changes
  warning: repository is unrelated
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets cb9a9f314b8b
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ hg rm -f a
  $ hg ci -Amc

  $ hg st -A
  C b
  $ cd ..

Issue1433: Traceback after two unrelated pull, two move, a merge and
a commit (related to issue586)

create test repos

  $ hg init repoa
  $ touch repoa/a
  $ hg -R repoa ci -Am adda
  adding a

  $ hg init repob
  $ touch repob/b
  $ hg -R repob ci -Am addb
  adding b

  $ hg init repoc
  $ cd repoc
  $ hg pull ../repoa
  pulling from ../repoa
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 7132ab4568ac
  (run 'hg update' to get a working copy)
  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ mkdir tst
  $ hg mv * tst
  $ hg ci -m "import a in tst"
  $ hg pull -f ../repob
  pulling from ../repob
  searching for changes
  warning: repository is unrelated
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets 5ddceb349652
  (run 'hg heads' to see heads, 'hg merge' to merge)

merge both repos

  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)
  $ mkdir src

move b content

  $ hg mv b src
  $ hg ci -m "import b in src"
  $ hg manifest
  src/b
  tst/a

  $ cd ..