view tests/test-narrow-strip.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

#testcases flat tree

  $ . "$TESTDIR/narrow-library.sh"

#if tree
  $ cat << EOF >> $HGRCPATH
  > [experimental]
  > treemanifest = 1
  > EOF
#endif

create full repo

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [narrow]
  > serveellipses=True
  > EOF

  $ mkdir inside
  $ echo inside > inside/f1
  $ mkdir outside
  $ echo outside > outside/f1
  $ hg ci -Aqm 'initial'

  $ echo modified > inside/f1
  $ hg ci -qm 'modify inside'

  $ hg co -q 0
  $ echo modified > outside/f1
  $ hg ci -qm 'modify outside'

  $ echo modified again >> outside/f1
  $ hg ci -qm 'modify outside again'

  $ cd ..

  $ hg clone --narrow ssh://user@dummy/master narrow --include inside
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 1 files (+1 heads)
  new changesets *:* (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrow
  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > strip=
  > EOF

Can strip and recover changesets affecting only files within narrow spec

  $ hg co -r 'desc("modify inside")'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm -f .hg/strip-backup/*-backup.hg
  $ hg strip .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-backup.hg (glob)
  $ hg unbundle .hg/strip-backup/*-backup.hg
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets * (glob)
  (run 'hg heads' to see heads, 'hg merge' to merge)

Can strip and recover changesets affecting files outside of narrow spec

  $ hg co -r 'desc("modify outside")'
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G -T '{rev} {desc}\n'
  o  2 modify inside
  |
  | @  1 modify outside again
  |/
  o  0 initial
  
  $ hg debugdata -m 1
  inside/f1\x004d6a634d5ba06331a60c29ee0db8412490a54fcd (esc) (flat !)
  outside/f1\x0084ba604d54dee1f13310ce3d4ac2e8a36636691a (esc) (flat !)
  inside\x006a8bc41df94075d501f9740587a0c0e13c170dc5t (esc) (tree !)
  outside\x00255c2627ebdd3c7dcaa6945246f9b9f02bd45a09t (esc) (tree !)

  $ rm -f .hg/strip-backup/*-backup.hg
  $ hg strip .
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-backup.hg (glob)
  $ hg unbundle .hg/strip-backup/*-backup.hg
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (+1 heads)
  new changesets * (glob)
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg log -G -T '{rev} {desc}\n'
  o  2 modify outside again
  |
  | o  1 modify inside
  |/
  @  0 initial
  
Check that hash of file outside narrow spec got restored
  $ hg debugdata -m 2
  inside/f1\x004d6a634d5ba06331a60c29ee0db8412490a54fcd (esc) (flat !)
  outside/f1\x0084ba604d54dee1f13310ce3d4ac2e8a36636691a (esc) (flat !)
  inside\x006a8bc41df94075d501f9740587a0c0e13c170dc5t (esc) (tree !)
  outside\x00255c2627ebdd3c7dcaa6945246f9b9f02bd45a09t (esc) (tree !)

Also verify we can apply the bundle with 'hg pull':
  $ hg co -r 'desc("modify inside")'
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ rm .hg/strip-backup/*-backup.hg
  $ hg strip .
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-backup.hg (glob)
#if repobundlerepo
  $ hg pull .hg/strip-backup/*-backup.hg
  pulling from .hg/strip-backup/*-backup.hg (glob)
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files (+1 heads)
  new changesets * (glob)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ rm .hg/strip-backup/*-backup.hg
  $ hg strip 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  saved backup bundle to $TESTTMP/narrow/.hg/strip-backup/*-backup.hg (glob)

  $ hg incoming .hg/strip-backup/*-backup.hg
  comparing with .hg/strip-backup/*-backup.hg (glob)
  changeset:   0:* (glob)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     initial
  
  changeset:   1:9e48d953700d (flat !)
  changeset:   1:3888164bccf0 (tree !)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify outside again
  
  changeset:   2:f505d5e96aa8 (flat !)
  changeset:   2:40b66f95a209 (tree !)
  tag:         tip
  parent:      0:a99f4d53924d (flat !)
  parent:      0:c2a5fabcca3c (tree !)
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     modify inside
  
  $ hg pull .hg/strip-backup/*-backup.hg
  pulling from .hg/strip-backup/*-backup.hg (glob)
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 1 files (+1 heads)
  new changesets *:* (glob)
  (run 'hg heads' to see heads, 'hg merge' to merge)
#endif