view tests/test-mq-qclone-http.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 killdaemons

hide outer repo
  $ hg init

  $ echo "[extensions]" >> $HGRCPATH
  $ echo "mq=" >> $HGRCPATH
  $ mkdir webdir
  $ cd webdir
  $ hg init a
  $ hg --cwd a qinit -c
  $ echo a > a/a
  $ hg --cwd a ci -A -m a
  adding a
  $ echo b > a/b
  $ hg --cwd a addremove
  adding b
  $ hg --cwd a qnew -f b.patch
  $ hg --cwd a qcommit -m b.patch
  $ hg --cwd a log --template "{desc}\n"
  [mq]: b.patch
  a
  $ hg --cwd a/.hg/patches log --template "{desc}\n"
  b.patch
  $ root=`pwd`
  $ cd ..

test with recursive collection

  $ cat > collections.conf <<EOF
  > [paths]
  > /=$root/**
  > EOF
  $ hg serve -p $HGPORT -d --pid-file=hg.pid --webdir-conf collections.conf \
  >     -A access-paths.log -E error-paths-1.log
  $ cat hg.pid >> $DAEMON_PIDS
  $ get-with-headers.py localhost:$HGPORT '?style=raw'
  200 Script output follows
  
  
  /a/
  /a/.hg/patches/
  
  $ hg qclone http://localhost:$HGPORT/a b
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:184916345baa
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets 4052ceaa8c4e
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --cwd b log --template "{desc}\n"
  a
  $ hg --cwd b qpush -a
  applying b.patch
  now at: b.patch
  $ hg --cwd b log --template "{desc}\n"
  imported patch b.patch
  a

test with normal collection

  $ cat > collections1.conf <<EOF
  > [paths]
  > /=$root/*
  > EOF
  $ hg serve -p $HGPORT1 -d --pid-file=hg.pid --webdir-conf collections1.conf \
  >     -A access-paths.log -E error-paths-1.log
  $ cat hg.pid >> $DAEMON_PIDS
  $ get-with-headers.py localhost:$HGPORT1 '?style=raw'
  200 Script output follows
  
  
  /a/
  /a/.hg/patches/
  
  $ hg qclone http://localhost:$HGPORT1/a c
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:184916345baa
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets 4052ceaa8c4e
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --cwd c log --template "{desc}\n"
  a
  $ hg --cwd c qpush -a
  applying b.patch
  now at: b.patch
  $ hg --cwd c log --template "{desc}\n"
  imported patch b.patch
  a

test with old-style collection

  $ cat > collections2.conf <<EOF
  > [collections]
  > $root=$root
  > EOF
  $ hg serve -p $HGPORT2 -d --pid-file=hg.pid --webdir-conf collections2.conf \
  >     -A access-paths.log -E error-paths-1.log
  $ cat hg.pid >> $DAEMON_PIDS
  $ get-with-headers.py localhost:$HGPORT2 '?style=raw'
  200 Script output follows
  
  
  /a/
  /a/.hg/patches/
  
  $ hg qclone http://localhost:$HGPORT2/a d
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:184916345baa
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 3 changes to 3 files
  new changesets 4052ceaa8c4e
  updating to branch default
  3 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg --cwd d log --template "{desc}\n"
  a
  $ hg --cwd d qpush -a
  applying b.patch
  now at: b.patch
  $ hg --cwd d log --template "{desc}\n"
  imported patch b.patch
  a

test --mq works and uses correct repository config

  $ hg --cwd d outgoing --mq
  comparing with http://localhost:$HGPORT2/a/.hg/patches
  searching for changes
  no changes found
  [1]
  $ hg --cwd d log --mq --template '{rev} {desc|firstline}\n'
  0 b.patch

  $ killdaemons.py