view tests/test-convert-tagsbranch-topology.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

#require git

  $ echo "[core]" >> $HOME/.gitconfig
  $ echo "autocrlf = false" >> $HOME/.gitconfig
  $ echo "[core]" >> $HOME/.gitconfig
  $ echo "autocrlf = false" >> $HOME/.gitconfig
  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > convert =
  > [convert]
  > hg.usebranchnames = True
  > hg.tagsbranch = tags-update
  > EOF
  $ GIT_AUTHOR_NAME='test'; export GIT_AUTHOR_NAME
  $ GIT_AUTHOR_EMAIL='[e-mail]'; export GIT_AUTHOR_EMAIL
  $ GIT_AUTHOR_DATE="2007-01-01 00:00:00 +0000"; export GIT_AUTHOR_DATE
  $ GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"; export GIT_COMMITTER_NAME
  $ GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"; export GIT_COMMITTER_EMAIL
  $ GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"; export GIT_COMMITTER_DATE
  $ count=10
  $ action()
  > {
  >     GIT_AUTHOR_DATE="2007-01-01 00:00:$count +0000"
  >     GIT_COMMITTER_DATE="$GIT_AUTHOR_DATE"
  >     git "$@" >/dev/null 2>/dev/null || echo "git command error"
  >     count=`expr $count + 1`
  > }
  $ glog()
  > {
  >     hg log -G --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
  > }
  $ convertrepo()
  > {
  >     hg convert --datesort git-repo hg-repo
  > }

Build a GIT repo with at least 1 tag

  $ mkdir git-repo
  $ cd git-repo
  $ git init >/dev/null 2>&1
  $ echo a > a
  $ git add a
  $ action commit -m "rev1"
  $ action tag -m "tag1" tag1
  $ cd ..

Convert without tags

  $ hg convert git-repo hg-repo --config convert.skiptags=True
  initializing destination hg-repo repository
  scanning source...
  sorting...
  converting...
  0 rev1
  updating bookmarks
  $ hg -R hg-repo tags
  tip                                0:d98c8ad3a4cf
  $ rm -rf hg-repo

Do a first conversion

  $ convertrepo
  initializing destination hg-repo repository
  scanning source...
  sorting...
  converting...
  0 rev1
  updating tags
  updating bookmarks

Simulate upstream  updates after first conversion

  $ cd git-repo
  $ echo b > a
  $ git add a
  $ action commit -m "rev2"
  $ action tag -m "tag2" tag2
  $ cd ..

Perform an incremental conversion

  $ convertrepo
  scanning source...
  sorting...
  converting...
  0 rev2
  updating tags
  updating bookmarks

Print the log

  $ cd hg-repo
  $ glog
  o  3 "update tags" files: .hgtags
  |
  | o  2 "rev2" files: a
  | |
  o |  1 "update tags" files: .hgtags
   /
  o  0 "rev1" files: a
  

  $ cd ..