view tests/test-convert-p4.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 p4

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert = " >> $HGRCPATH

create p4 depot
  $ P4ROOT=`pwd`/depot; export P4ROOT
  $ P4AUDIT=$P4ROOT/audit; export P4AUDIT
  $ P4JOURNAL=$P4ROOT/journal; export P4JOURNAL
  $ P4LOG=$P4ROOT/log; export P4LOG
  $ P4PORT=localhost:$HGPORT; export P4PORT
  $ P4DEBUG=1; export P4DEBUG

start the p4 server
  $ [ ! -d $P4ROOT ] && mkdir $P4ROOT
  $ p4d -f -J off >$P4ROOT/stdout 2>$P4ROOT/stderr &
  $ echo $! >> $DAEMON_PIDS
  $ trap "echo stopping the p4 server ; p4 admin stop" EXIT

  $ # wait for the server to initialize
  $ while ! p4 ; do
  >    sleep 1
  > done >/dev/null 2>/dev/null

create a client spec
  $ P4CLIENT=hg-p4-import; export P4CLIENT
  $ DEPOTPATH=//depot/test-mercurial-import/...
  $ p4 client -o | sed '/^View:/,$ d' >p4client
  $ echo View: >>p4client
  $ echo " $DEPOTPATH //$P4CLIENT/..." >>p4client
  $ p4 client -i <p4client
  Client hg-p4-import saved.

populate the depot
  $ echo a > a
  $ mkdir b
  $ echo c > b/c
  $ p4 add a b/c
  //depot/test-mercurial-import/a#1 - opened for add
  //depot/test-mercurial-import/b/c#1 - opened for add
  $ p4 submit -d initial
  Submitting change 1.
  Locking 2 files ...
  add //depot/test-mercurial-import/a#1
  add //depot/test-mercurial-import/b/c#1
  Change 1 submitted.

change some files
  $ p4 edit a
  //depot/test-mercurial-import/a#1 - opened for edit
  $ echo aa >> a
  $ p4 submit -d "change a"
  Submitting change 2.
  Locking 1 files ...
  edit //depot/test-mercurial-import/a#2
  Change 2 submitted.

  $ p4 edit b/c
  //depot/test-mercurial-import/b/c#1 - opened for edit
  $ echo cc >> b/c
  $ p4 submit -d "change b/c"
  Submitting change 3.
  Locking 1 files ...
  edit //depot/test-mercurial-import/b/c#2
  Change 3 submitted.

convert
  $ hg convert -s p4 $DEPOTPATH dst
  initializing destination dst repository
  scanning source...
  reading p4 views
  collecting p4 changelists
  1 initial
  2 change a
  3 change b/c
  sorting...
  converting...
  2 initial
  1 change a
  0 change b/c
  $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n'
  rev=2 desc="change b/c" tags="tip" files="b/c"
  rev=1 desc="change a" tags="" files="a"
  rev=0 desc="initial" tags="" files="a b/c"

change some files
  $ p4 edit a b/c
  //depot/test-mercurial-import/a#2 - opened for edit
  //depot/test-mercurial-import/b/c#2 - opened for edit
  $ echo aaa >> a
  $ echo ccc >> b/c
  $ p4 submit -d "change a b/c"
  Submitting change 4.
  Locking 2 files ...
  edit //depot/test-mercurial-import/a#3
  edit //depot/test-mercurial-import/b/c#3
  Change 4 submitted.

convert again
  $ hg convert -s p4 $DEPOTPATH dst
  scanning source...
  reading p4 views
  collecting p4 changelists
  4 change a b/c
  sorting...
  converting...
  0 change a b/c
  $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n'
  rev=3 desc="change a b/c" tags="tip" files="a b/c"
  rev=2 desc="change b/c" tags="" files="b/c"
  rev=1 desc="change a" tags="" files="a"
  rev=0 desc="initial" tags="" files="a b/c"

interesting names
  $ echo dddd > "d d"
  $ mkdir " e"
  $ echo fff >" e/ f"
  $ p4 add "d d" " e/ f"
  //depot/test-mercurial-import/d d#1 - opened for add
  //depot/test-mercurial-import/ e/ f#1 - opened for add
  $ p4 submit -d "add d e f"
  Submitting change 5.
  Locking 2 files ...
  add //depot/test-mercurial-import/ e/ f#1
  add //depot/test-mercurial-import/d d#1
  Change 5 submitted.

convert again
  $ hg convert -s p4 $DEPOTPATH dst
  scanning source...
  reading p4 views
  collecting p4 changelists
  5 add d e f
  sorting...
  converting...
  0 add d e f
  $ hg -R dst log --template 'rev={rev} desc="{desc}" tags="{tags}" files="{files}"\n'
  rev=4 desc="add d e f" tags="tip" files=" e/ f d d"
  rev=3 desc="change a b/c" tags="" files="a b/c"
  rev=2 desc="change b/c" tags="" files="b/c"
  rev=1 desc="change a" tags="" files="a"
  rev=0 desc="initial" tags="" files="a b/c"

empty commit message
  $ p4 edit a
  //depot/test-mercurial-import/a#3 - opened for edit
  $ echo aaaaa >> a
  $ p4 submit -d ""
  Submitting change 6.
  Locking 1 files ...
  edit //depot/test-mercurial-import/a#4
  Change 6 submitted.
  $ hg convert -s p4 $DEPOTPATH dst
  scanning source...
  reading p4 views
  collecting p4 changelists
  6 **empty changelist description**
  sorting...
  converting...
  0 

exit trap:
  stopping the p4 server