view tests/test-pull-r.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

  $ hg init repo
  $ cd repo
  $ echo foo > foo
  $ hg ci -qAm 'add foo'
  $ echo >> foo
  $ hg ci -m 'change foo'
  $ hg up -qC 0
  $ echo bar > bar
  $ hg ci -qAm 'add bar'

  $ hg log
  changeset:   2:effea6de0384
  tag:         tip
  parent:      0:bbd179dfa0a7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add bar
  
  changeset:   1:ed1b79f46b9a
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change foo
  
  changeset:   0:bbd179dfa0a7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add foo
  
  $ cd ..

don't show "(+1 heads)" message when pulling closed head

  $ hg clone -q repo repo2
  $ hg clone -q repo2 repo3
  $ cd repo2
  $ hg up -q 0
  $ echo hello >> foo
  $ hg ci -mx1
  created new head
  $ hg ci -mx2 --close-branch
  $ cd ../repo3
  $ hg heads -q --closed
  2:effea6de0384
  1:ed1b79f46b9a
  $ hg pull
  pulling from $TESTTMP/repo2
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 1 changes to 1 files
  new changesets 8c900227dd5d:00cfe9073916
  (run 'hg update' to get a working copy)
  $ hg heads -q --closed
  4:00cfe9073916
  2:effea6de0384
  1:ed1b79f46b9a

  $ cd ..

  $ hg init copy
  $ cd copy

Pull a missing revision:

  $ hg pull -qr missing ../repo
  abort: unknown revision 'missing'!
  [255]

Pull multiple revisions with update:

  $ hg pull -qu -r 0 -r 1 ../repo
  $ hg -q parents
  0:bbd179dfa0a7
  $ hg rollback
  repository tip rolled back to revision -1 (undo pull)
  working directory now based on revision -1

  $ hg pull -qr 0 ../repo
  $ hg log
  changeset:   0:bbd179dfa0a7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add foo
  
  $ hg pull -qr 1 ../repo
  $ hg log
  changeset:   1:ed1b79f46b9a
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change foo
  
  changeset:   0:bbd179dfa0a7
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add foo
  

This used to abort: received changelog group is empty:

  $ hg pull -qr 1 ../repo

Test race condition with -r and -U (issue4707)

We pull '-U -r <name>' and the name change right after/during the changegroup emission.
We use http because http is better is our racy-est option.


  $ echo babar > ../repo/jungle
  $ cat <<EOF > ../repo/.hg/hgrc
  > [hooks]
  > outgoing.makecommit = hg ci -Am 'racy commit'; echo committed in pull-race
  > EOF
  $ hg serve -R ../repo -p $HGPORT2 -d --pid-file=../repo.pid
  $ cat ../repo.pid >> $DAEMON_PIDS
  $ hg pull --rev default --update http://localhost:$HGPORT2/
  pulling from http://localhost:$HGPORT2/
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets effea6de0384
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G
  @  changeset:   2:effea6de0384
  |  tag:         tip
  |  parent:      0:bbd179dfa0a7
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     add bar
  |
  | o  changeset:   1:ed1b79f46b9a
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     change foo
  |
  o  changeset:   0:bbd179dfa0a7
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     add foo
  

  $ cd ..
  $ killdaemons.py