view tests/test-convert-cvsnt-mergepoints.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 cvs

  $ filterpath()
  > {
  >     eval "$@" | sed "s:$CVSROOT:*REPO*:g"
  > }
  $ cvscall()
  > {
  >     cvs -f "$@"
  > }

output of 'cvs ci' varies unpredictably, so discard most of it
-- just keep the part that matters

  $ cvsci()
  > {
  >     cvs -f ci -f "$@" > /dev/null
  > }
  $ hgcat()
  > {
  >     hg --cwd src-hg cat -r tip "$1"
  > }
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "convert = " >> $HGRCPATH

create cvs repository

  $ mkdir cvsmaster
  $ cd cvsmaster
  $ CVSROOT=`pwd`
  $ export CVSROOT
  $ CVS_OPTIONS=-f
  $ export CVS_OPTIONS
  $ cd ..
  $ rmdir cvsmaster
  $ filterpath cvscall -Q -d "$CVSROOT" init

checkout #1: add foo.txt

  $ cvscall -Q checkout -d cvsworktmp .
  $ cd cvsworktmp
  $ mkdir foo
  $ cvscall -Q add foo
  $ cd foo
  $ echo foo > foo.txt
  $ cvscall -Q add foo.txt
  $ cvsci -m "add foo.txt" foo.txt
  $ cd ../..
  $ rm -rf cvsworktmp

checkout #2: create MYBRANCH1 and modify foo.txt on it

  $ cvscall -Q checkout -d cvswork foo
  $ cd cvswork
  $ cvscall -q rtag -b -R MYBRANCH1 foo
  $ cvscall -Q update -P -r MYBRANCH1
  $ echo bar > foo.txt
  $ cvsci -m "bar" foo.txt
  $ echo baz > foo.txt
  $ cvsci -m "baz" foo.txt

create MYBRANCH1_2 and modify foo.txt some more

  $ cvscall -q rtag -b -R -r MYBRANCH1 MYBRANCH1_2 foo
  $ cvscall -Q update -P -r MYBRANCH1_2
  $ echo bazzie > foo.txt
  $ cvsci -m "bazzie" foo.txt

create MYBRANCH1_1 and modify foo.txt yet again

  $ cvscall -q rtag -b -R MYBRANCH1_1 foo
  $ cvscall -Q update -P -r MYBRANCH1_1
  $ echo quux > foo.txt
  $ cvsci -m "quux" foo.txt

merge MYBRANCH1 to MYBRANCH1_1

  $ filterpath cvscall -Q update -P -jMYBRANCH1
  rcsmerge: warning: conflicts during merge
  RCS file: *REPO*/foo/foo.txt,v
  retrieving revision 1.1
  retrieving revision 1.1.2.2
  Merging differences between 1.1 and 1.1.2.2 into foo.txt

carefully placed sleep to dodge cvs bug (optimization?) where it
sometimes ignores a "commit" command if it comes too fast (the -f
option in cvsci seems to work for all the other commits in this
script)

  $ sleep 1
  $ echo xyzzy > foo.txt
  $ cvsci -m "merge1+clobber" foo.txt

#if unix-permissions

return to trunk and merge MYBRANCH1_2

  $ cvscall -Q update -P -A
  $ filterpath cvscall -Q update -P -jMYBRANCH1_2
  RCS file: *REPO*/foo/foo.txt,v
  retrieving revision 1.1
  retrieving revision 1.1.2.2.2.1
  Merging differences between 1.1 and 1.1.2.2.2.1 into foo.txt
  $ cvsci -m "merge2" foo.txt
  $ REALCVS=`which cvs`
  $ echo "for x in \$*; do if [ \"\$x\" = \"rlog\" ]; then echo \"RCS file: $CVSROOT/foo/foo.txt,v\"; cat \"$TESTDIR/test-convert-cvsnt-mergepoints.rlog\"; exit 0; fi; done; $REALCVS \$*" > ../cvs
  $ chmod +x ../cvs
  $ PATH=..:${PATH} hg debugcvsps --parents foo
  collecting CVS rlog
  7 log entries
  creating changesets
  7 changeset entries
  ---------------------
  PatchSet 1 
  Date: * (glob)
  Author: user
  Branch: HEAD
  Tag: (none) 
  Branchpoints: MYBRANCH1, MYBRANCH1_1 
  Log:
  foo.txt
  
  Members: 
  	foo.txt:INITIAL->1.1 
  
  ---------------------
  PatchSet 2 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1
  Tag: (none) 
  Parent: 1
  Log:
  bar
  
  Members: 
  	foo.txt:1.1->1.1.2.1 
  
  ---------------------
  PatchSet 3 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1
  Tag: (none) 
  Branchpoints: MYBRANCH1_2 
  Parent: 2
  Log:
  baz
  
  Members: 
  	foo.txt:1.1.2.1->1.1.2.2 
  
  ---------------------
  PatchSet 4 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_1
  Tag: (none) 
  Parent: 1
  Log:
  quux
  
  Members: 
  	foo.txt:1.1->1.1.4.1 
  
  ---------------------
  PatchSet 5 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_2
  Tag: (none) 
  Parent: 3
  Log:
  bazzie
  
  Members: 
  	foo.txt:1.1.2.2->1.1.2.2.2.1 
  
  ---------------------
  PatchSet 6 
  Date: * (glob)
  Author: user
  Branch: HEAD
  Tag: (none) 
  Parents: 1,5
  Log:
  merge
  
  Members: 
  	foo.txt:1.1->1.2 
  
  ---------------------
  PatchSet 7 
  Date: * (glob)
  Author: user
  Branch: MYBRANCH1_1
  Tag: (none) 
  Parents: 4,3
  Log:
  merge
  
  Members: 
  	foo.txt:1.1.4.1->1.1.4.2 
  
#endif

  $ cd ..