view tests/svn/svndump-tags.sh @ 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

#!/bin/sh
#
# Use this script to generate tags.svndump
#

mkdir temp
cd temp

mkdir project-orig
cd project-orig
mkdir trunk
mkdir branches
mkdir tags
mkdir unrelated
cd ..

svnadmin create svn-repo
svnurl=file://`pwd`/svn-repo
svn import project-orig $svnurl -m "init projA"

svn co $svnurl project
cd project
echo a > trunk/a
svn add trunk/a
svn ci -m adda
echo a >> trunk/a
svn ci -m changea
echo a >> trunk/a
svn ci -m changea2
# Add an unrelated commit to test that tags are bound to the
# correct "from" revision and not a dummy one
echo a >> unrelated/dummy
svn add unrelated/dummy
svn ci -m unrelatedchange
# Tag current revision
svn up
svn copy trunk tags/trunk.v1
svn copy trunk tags/trunk.badtag
svn ci -m "tagging trunk.v1 trunk.badtag"
echo a >> trunk/a
svn ci -m changea3
# Fix the bad tag
# trunk.badtag should not show in converted tags
svn up
svn mv tags/trunk.badtag tags/trunk.goodtag
svn ci -m "fix trunk.badtag"
echo a >> trunk/a
svn ci -m changea
# Delete goodtag and recreate it, to test we pick the good one
svn rm tags/trunk.goodtag
svn ci -m removegoodtag
svn up
svn copy trunk tags/trunk.goodtag
svn ci -m recreategoodtag
cd ..

svnadmin dump svn-repo > ../tags.svndump