view tests/test-pending.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

Verify that pending changesets are seen by pretxn* hooks but not by other
processes that access the destination repo while the hooks are running.

The hooks (python and external) both reject changesets after some think time,
during which another process runs pull.  Each hook creates a file ('notify') to
indicate to the controlling process that it is running; the process removes the
file to indicate the hook can terminate.

init env vars

  $ d=`pwd`
  $ maxwait=20

utility to run the test - start a push in the background and run pull

  $ dotest() {
  >     rm -f notify
  >     printf 'push '; hg -R child-push tip --template '{node}\n'
  >     hg -R child-push -q push > push.out 2>&1 &
  > 
  >     # wait for hook to create the notify file
  >     i=$maxwait
  >     while [ ! -f notify -a $i != 0 ]; do
  >         sleep 1
  >         i=`expr $i - 1`
  >     done
  > 
  >     # run pull
  >     hg -R child-pull -q pull
  >     rc=$?
  > 
  >     # tell hook to finish; notify should exist.
  >     rm notify
  >     wait
  > 
  >     cat push.out
  >     printf 'pull '; hg -R child-pull tip --template '{node}\n'
  >     return $rc
  > }

python hook

  $ cat <<EOF > reject.py
  > import os, time
  > from mercurial import ui, localrepo
  > def rejecthook(ui, repo, hooktype, node, **opts):
  >     ui.write(b'hook %s\\n' % repo[b'tip'].hex())
  >     # create the notify file so caller knows we're running
  >     fpath = os.path.join('$d', 'notify')
  >     f = open(fpath, 'w')
  >     f.close()
  >     # wait for ack - caller should delete the notify file
  >     i = $maxwait
  >     while os.path.exists(fpath) and i > 0:
  >         time.sleep(1)
  >         i -= 1
  >     return True # reject the changesets
  > EOF

external hook

  $ cat <<EOF > reject.sh
  > printf 'hook '; hg tip --template '{node}\\n'
  > # create the notify file so caller knows we're running
  > fpath=$d/notify
  > touch \$fpath
  > # wait for ack - caller should delete the notify file
  > i=$maxwait
  > while [ -f \$fpath -a \$i != 0 ]; do
  >     sleep 1
  >     i=\`expr \$i - 1\`
  > done
  > exit 1 # reject the changesets
  > EOF

create repos

  $ hg init parent
  $ hg clone -q parent child-push
  $ hg clone -q parent child-pull
  $ echo a > child-push/a
  $ hg -R child-push add child-push/a
  $ hg -R child-push commit -m a -d '1000000 0'

test python hook

  $ cat <<EOF > parent/.hg/hgrc
  > [extensions]
  > reject = $d/reject.py
  > [hooks]
  > pretxnchangegroup = python:reject.rejecthook
  > EOF

  $ dotest
  push 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
  hook 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
  transaction abort!
  rollback completed
  abort: pretxnchangegroup hook failed
  pull 0000000000000000000000000000000000000000

test external hook

  $ cat <<EOF > parent/.hg/hgrc
  > [hooks]
  > pretxnchangegroup = sh $d/reject.sh
  > EOF

  $ dotest
  push 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
  hook 29b62aeb769fdf78d8d9c5f28b017f76d7ef824b
  transaction abort!
  rollback completed
  abort: pretxnchangegroup hook exited with status 1
  pull 0000000000000000000000000000000000000000

Test that pending on transaction without changegroup see the normal changegroup(
(issue4609)

  $ cat <<EOF > parent/.hg/hgrc
  > [hooks]
  > pretxnchangegroup=
  > pretxnclose = hg tip -T "tip: {node|short}\n"
  > [phases]
  > publishing=False
  > EOF

setup

  $ cd parent
  $ echo a > a
  $ hg add a
  $ hg commit -m a
  tip: cb9a9f314b8b

actual test

  $ hg phase --public .
  tip: cb9a9f314b8b