view tests/test-extensions-afterloaded.t @ 39561:d06834e0f48e

wireprotov2peer: stream decoded responses

Previously, wire protocol version 2 would buffer all response data.
Only once all data was received did we CBOR decode it and resolve
the future associated with the command. This was obviously not
desirable. In future commits that introduce large response payloads,
this caused significant memory bloat and slowed down client
operations due to waiting on the server.

This commit refactors the response handling code so that response
data can be streamed.

Command response objects now contain a buffered CBOR decoder. As
new data arrives, it is fed into the decoder. Decoded objects are
made available to the generator as they are decoded.

Because there is a separate thread processing incoming frames and
feeding data into the response object, there is the potential for
race conditions when mutating response objects. So a lock has been
added to guard access to critical state variables.

Because the generator emitting decoded objects needs to wait on
those objects to become available, we've added an Event for the
generator to wait on so it doesn't busy loop. This does mean
there is the potential for deadlocks. And I'm pretty sure they can
occur in some scenarios. We already have a handful of TODOs around
this. But I've added some more. Fixing this will likely require
moving the background thread receiving frames into clienthandler.
We likely would have done this anyway when implementing the client
bits for the SSH transport.

Test output changes because the initial CBOR map holding the overall
response state is now always handled internally by the response
object.

Differential Revision: https://phab.mercurial-scm.org/D4474

Test the extensions.afterloaded() function

  $ cat > foo.py <<EOF
  > from mercurial import extensions
  > def uisetup(ui):
  >     ui.write(b"foo.uisetup\\n")
  >     ui.flush()
  >     def bar_loaded(loaded):
  >         ui.write(b"foo: bar loaded: %r\\n" % (loaded,))
  >         ui.flush()
  >     extensions.afterloaded(b'bar', bar_loaded)
  > EOF
  $ cat > bar.py <<EOF
  > def uisetup(ui):
  >     ui.write(b"bar.uisetup\\n")
  >     ui.flush()
  > EOF
  $ basepath=`pwd`

  $ hg init basic
  $ cd basic
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> .hg/hgrc
  $ echo "foo = $basepath/foo.py" >> .hg/hgrc
  $ echo "bar = $basepath/bar.py" >> .hg/hgrc
  $ hg log -r. -T'{rev}\n'
  foo.uisetup
  foo: bar loaded: True
  bar.uisetup
  0

Test afterloaded with the opposite extension load order

  $ cd ..
  $ hg init basic_reverse
  $ cd basic_reverse
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> .hg/hgrc
  $ echo "bar = $basepath/bar.py" >> .hg/hgrc
  $ echo "foo = $basepath/foo.py" >> .hg/hgrc
  $ hg log -r. -T'{rev}\n'
  bar.uisetup
  foo.uisetup
  foo: bar loaded: True
  0

Test the extensions.afterloaded() function when the requested extension is not
loaded

  $ cd ..
  $ hg init notloaded
  $ cd notloaded
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> .hg/hgrc
  $ echo "foo = $basepath/foo.py" >> .hg/hgrc
  $ hg log -r. -T'{rev}\n'
  foo.uisetup
  foo: bar loaded: False
  0

Test the extensions.afterloaded() function when the requested extension is not
configured but fails the minimum version check

  $ cd ..
  $ cat > minvers.py <<EOF
  > minimumhgversion = b'9999.9999'
  > def uisetup(ui):
  >     ui.write(b"minvers.uisetup\\n")
  >     ui.flush()
  > EOF
  $ hg init minversion
  $ cd minversion
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> .hg/hgrc
  $ echo "foo = $basepath/foo.py" >> .hg/hgrc
  $ echo "bar = $basepath/minvers.py" >> .hg/hgrc
  $ hg log -r. -T'{rev}\n'
  (third party extension bar requires version 9999.9999 or newer of Mercurial; disabling)
  foo.uisetup
  foo: bar loaded: False
  0

Test the extensions.afterloaded() function when the requested extension is not
configured but fails the minimum version check, using the opposite load order
for the two extensions.

  $ cd ..
  $ hg init minversion_reverse
  $ cd minversion_reverse
  $ echo foo > file
  $ hg add file
  $ hg commit -m 'add file'

  $ echo '[extensions]' >> .hg/hgrc
  $ echo "bar = $basepath/minvers.py" >> .hg/hgrc
  $ echo "foo = $basepath/foo.py" >> .hg/hgrc
  $ hg log -r. -T'{rev}\n'
  (third party extension bar requires version 9999.9999 or newer of Mercurial; disabling)
  foo.uisetup
  foo: bar loaded: False
  0