view tests/test-stream-bundle-v2.t @ 37631:2f626233859b

wireproto: implement batching on peer executor interface

This is a bit more complicated than non-batch requests because we
need to buffer sends until the last request arrives *and* we need
to support resolving futures as data arrives from the remote.

In a classical concurrent.futures executor model, the future
"starts" as soon as it is submitted. However, we have nothing to
start until the last command is submitted.

If we did nothing, calling result() would deadlock, since the future
hasn't "started." So in the case where we queue the command, we return
a special future type whose result() will trigger sendcommands().
This eliminates the deadlock potential. It also serves as a check
against callers who may be calling result() prematurely, as it will
prevent any subsequent callcommands() from working. This behavior
is slightly annoying and a bit restrictive. But it's the world
that half duplex connections forces on us.

In order to support streaming responses, we were previously using
a generator. But with a futures-based API, we're using futures
and not generators. So in order to get streaming, we need a
background thread to read data from the server.

The approach taken in this patch is to leverage the ThreadPoolExecutor
from concurrent.futures for managing a background thread. We create
an executor and future that resolves when all response data is
processed (or an error occurs). When exiting the context manager,
we wait on that background reading before returning.

I was hoping we could manually spin up a threading.Thread and this
would be simple. But I ran into a few deadlocks when implementing.
After looking at the source code to concurrent.futures, I figured
it would just be easier to use a ThreadPoolExecutor than implement
all the code needed to manually manage a thread.

To prove this works, a use of the batch API in discovery has been
updated.

Differential Revision: https://phab.mercurial-scm.org/D3269

#require no-reposimplestore

Test creating a consuming stream bundle v2

  $ getmainid() {
  >    hg -R main log --template '{node}\n' --rev "$1"
  > }

  $ cp $HGRCPATH $TESTTMP/hgrc.orig

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > evolution.createmarkers=True
  > evolution.exchange=True
  > bundle2-output-capture=True
  > [ui]
  > ssh="$PYTHON" "$TESTDIR/dummyssh"
  > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}
  > [web]
  > push_ssl = false
  > allow_push = *
  > [phases]
  > publish=False
  > [extensions]
  > drawdag=$TESTDIR/drawdag.py
  > clonebundles=
  > EOF

The extension requires a repo (currently unused)

  $ hg init main
  $ cd main

  $ hg debugdrawdag <<'EOF'
  > E
  > |
  > D
  > |
  > C
  > |
  > B
  > |
  > A
  > EOF

  $ hg bundle -a --type="none-v2;stream=v2" bundle.hg
  $ hg debugbundle bundle.hg
  Stream params: {}
  stream2 -- {bytecount: 1693, filecount: 11, requirements: dotencode%2Cfncache%2Cgeneraldelta%2Crevlogv1%2Cstore}
  $ hg debugbundle --spec bundle.hg
  none-v2;stream=v2;requirements%3Ddotencode%2Cfncache%2Cgeneraldelta%2Crevlogv1%2Cstore

Test that we can apply the bundle as a stream clone bundle

  $ cat > .hg/clonebundles.manifest << EOF
  > http://localhost:$HGPORT1/bundle.hg BUNDLESPEC=`hg debugbundle --spec bundle.hg`
  > EOF

  $ hg serve -d -p $HGPORT --pid-file hg.pid --accesslog access.log
  $ cat hg.pid >> $DAEMON_PIDS

  $ "$PYTHON" $TESTDIR/dumbhttp.py -p $HGPORT1 --pid http.pid
  $ cat http.pid >> $DAEMON_PIDS

  $ cd ..
  $ hg clone http://localhost:$HGPORT streamv2-clone-implicit --debug
  using http://localhost:$HGPORT/
  sending capabilities command
  sending clonebundles command
  applying clone bundle from http://localhost:$HGPORT1/bundle.hg
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "stream2" (params: 3 mandatory) supported
  applying stream bundle
  11 files to transfer, 1.65 KB of data
  starting 4 threads for background file closing (?)
  starting 4 threads for background file closing (?)
  adding [s] data/A.i (66 bytes)
  adding [s] data/B.i (66 bytes)
  adding [s] data/C.i (66 bytes)
  adding [s] data/D.i (66 bytes)
  adding [s] data/E.i (66 bytes)
  adding [s] 00manifest.i (584 bytes)
  adding [s] 00changelog.i (595 bytes)
  adding [s] phaseroots (43 bytes)
  adding [c] branch2-served (94 bytes)
  adding [c] rbc-names-v1 (7 bytes)
  adding [c] rbc-revs-v1 (40 bytes)
  transferred 1.65 KB in \d\.\d seconds \(.*/sec\) (re)
  bundle2-input-part: total payload size 1840
  bundle2-input-bundle: 0 parts total
  finished applying clone bundle
  query 1; heads
  sending batch command
  searching for changes
  all remote heads known locally
  no changes found
  sending getbundle command
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "listkeys" (params: 1 mandatory) supported
  bundle2-input-part: "phase-heads" supported
  bundle2-input-part: total payload size 24
  bundle2-input-bundle: 1 parts total
  checking for updated bookmarks
  updating to branch default
  resolving manifests
   branchmerge: False, force: False, partial: False
   ancestor: 000000000000, local: 000000000000+, remote: 9bc730a19041
   A: remote created -> g
  getting A
   B: remote created -> g
  getting B
   C: remote created -> g
  getting C
   D: remote created -> g
  getting D
   E: remote created -> g
  getting E
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg clone --stream http://localhost:$HGPORT streamv2-clone-explicit --debug
  using http://localhost:$HGPORT/
  sending capabilities command
  sending clonebundles command
  applying clone bundle from http://localhost:$HGPORT1/bundle.hg
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "stream2" (params: 3 mandatory) supported
  applying stream bundle
  11 files to transfer, 1.65 KB of data
  starting 4 threads for background file closing (?)
  starting 4 threads for background file closing (?)
  adding [s] data/A.i (66 bytes)
  adding [s] data/B.i (66 bytes)
  adding [s] data/C.i (66 bytes)
  adding [s] data/D.i (66 bytes)
  adding [s] data/E.i (66 bytes)
  adding [s] 00manifest.i (584 bytes)
  adding [s] 00changelog.i (595 bytes)
  adding [s] phaseroots (43 bytes)
  adding [c] branch2-served (94 bytes)
  adding [c] rbc-names-v1 (7 bytes)
  adding [c] rbc-revs-v1 (40 bytes)
  transferred 1.65 KB in *.* seconds (*/sec) (glob)
  bundle2-input-part: total payload size 1840
  bundle2-input-bundle: 0 parts total
  finished applying clone bundle
  query 1; heads
  sending batch command
  searching for changes
  all remote heads known locally
  no changes found
  sending getbundle command
  bundle2-input-bundle: with-transaction
  bundle2-input-part: "listkeys" (params: 1 mandatory) supported
  bundle2-input-part: "phase-heads" supported
  bundle2-input-part: total payload size 24
  bundle2-input-bundle: 1 parts total
  checking for updated bookmarks
  updating to branch default
  resolving manifests
   branchmerge: False, force: False, partial: False
   ancestor: 000000000000, local: 000000000000+, remote: 9bc730a19041
   A: remote created -> g
  getting A
   B: remote created -> g
  getting B
   C: remote created -> g
  getting C
   D: remote created -> g
  getting D
   E: remote created -> g
  getting E
  5 files updated, 0 files merged, 0 files removed, 0 files unresolved