view tests/test-bad-extension.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

ensure that failing ui.atexit handlers report sensibly

  $ cat > $TESTTMP/bailatexit.py <<EOF
  > from mercurial import util
  > def bail():
  >     raise RuntimeError('ui.atexit handler exception')
  > 
  > def extsetup(ui):
  >     ui.atexit(bail)
  > EOF
  $ hg -q --config extensions.bailatexit=$TESTTMP/bailatexit.py \
  >  help help
  hg help [-ecks] [TOPIC]
  
  show help for a given topic or a help overview
  error in exit handlers:
  Traceback (most recent call last):
    File "*/mercurial/dispatch.py", line *, in _runexithandlers (glob)
      func(*args, **kwargs)
    File "$TESTTMP/bailatexit.py", line *, in bail (glob)
      raise RuntimeError('ui.atexit handler exception')
  RuntimeError: ui.atexit handler exception
  [255]

  $ rm $TESTTMP/bailatexit.py

another bad extension

  $ echo 'raise Exception("bit bucket overflow")' > badext.py
  $ abspathexc=`pwd`/badext.py

  $ cat >baddocext.py <<EOF
  > """
  > baddocext is bad
  > """
  > EOF
  $ abspathdoc=`pwd`/baddocext.py

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > gpg =
  > hgext.gpg =
  > badext = $abspathexc
  > baddocext = $abspathdoc
  > badext2 =
  > EOF

  $ hg -q help help 2>&1 |grep extension
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  *** failed to import extension badext2: No module named badext2

show traceback

  $ hg -q help help --traceback 2>&1 | egrep ' extension|^Exception|Traceback|ImportError'
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  Traceback (most recent call last):
  Exception: bit bucket overflow
  *** failed to import extension badext2: No module named badext2
  Traceback (most recent call last):
  ImportError: No module named badext2

names of extensions failed to load can be accessed via extensions.notloaded()

  $ cat <<EOF > showbadexts.py
  > from mercurial import commands, extensions, registrar
  > cmdtable = {}
  > command = registrar.command(cmdtable)
  > @command(b'showbadexts', norepo=True)
  > def showbadexts(ui, *pats, **opts):
  >     ui.write('BADEXTS: %s\n' % ' '.join(sorted(extensions.notloaded())))
  > EOF
  $ hg --config extensions.badexts=showbadexts.py showbadexts 2>&1 | grep '^BADEXTS'
  BADEXTS: badext badext2

#if no-extraextensions
show traceback for ImportError of hgext.name if devel.debug.extensions is set

  $ (hg help help --traceback --debug --config devel.debug.extensions=yes 2>&1) \
  > | grep -v '^ ' \
  > | egrep 'extension..[^p]|^Exception|Traceback|ImportError|not import'
  debug.extensions: loading extensions
  debug.extensions: - processing 5 entries
  debug.extensions:   - loading extension: 'gpg'
  debug.extensions:   > 'gpg' extension loaded in * (glob)
  debug.extensions:     - validating extension tables: 'gpg'
  debug.extensions:     - invoking registered callbacks: 'gpg'
  debug.extensions:     > callbacks completed in * (glob)
  debug.extensions:   - loading extension: 'badext'
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  Traceback (most recent call last):
  Exception: bit bucket overflow
  debug.extensions:   - loading extension: 'baddocext'
  debug.extensions:   > 'baddocext' extension loaded in * (glob)
  debug.extensions:     - validating extension tables: 'baddocext'
  debug.extensions:     - invoking registered callbacks: 'baddocext'
  debug.extensions:     > callbacks completed in * (glob)
  debug.extensions:   - loading extension: 'badext2'
  debug.extensions:     - could not import hgext.badext2 (No module named badext2): trying hgext3rd.badext2
  Traceback (most recent call last):
  ImportError: No module named *badext2 (glob)
  debug.extensions:     - could not import hgext3rd.badext2 (No module named badext2): trying badext2
  Traceback (most recent call last):
  ImportError: No module named *badext2 (glob)
  *** failed to import extension badext2: No module named badext2
  Traceback (most recent call last):
  ImportError: No module named badext2
  debug.extensions: > loaded 2 extensions, total time * (glob)
  debug.extensions: - loading configtable attributes
  debug.extensions: - executing uisetup hooks
  debug.extensions:   - running uisetup for 'gpg'
  debug.extensions:   > uisetup for 'gpg' took * (glob)
  debug.extensions:   - running uisetup for 'baddocext'
  debug.extensions:   > uisetup for 'baddocext' took * (glob)
  debug.extensions: > all uisetup took * (glob)
  debug.extensions: - executing extsetup hooks
  debug.extensions:   - running extsetup for 'gpg'
  debug.extensions:   > extsetup for 'gpg' took * (glob)
  debug.extensions:   - running extsetup for 'baddocext'
  debug.extensions:   > extsetup for 'baddocext' took * (glob)
  debug.extensions: > all extsetup took * (glob)
  debug.extensions: - executing remaining aftercallbacks
  debug.extensions: > remaining aftercallbacks completed in * (glob)
  debug.extensions: - loading extension registration objects
  debug.extensions: > extension registration object loading took * (glob)
  debug.extensions: > extension baddocext take a total of * to load (glob)
  debug.extensions: > extension gpg take a total of * to load (glob)
  debug.extensions: extension loading complete
#endif

confirm that there's no crash when an extension's documentation is bad

  $ hg help --keyword baddocext
  *** failed to import extension badext from $TESTTMP/badext.py: bit bucket overflow
  *** failed to import extension badext2: No module named badext2
  Topics:
  
   extensions Using Additional Features