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
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
>
> [alias]
> tglog = log -G --template "{rev}: {node|short} '{desc}'\n"
>
> [extensions]
> drawdag=$TESTDIR/drawdag.py
> EOF
Rebasing D onto B detaching from C (one commit):
$ hg init a1
$ cd a1
$ hg debugdrawdag <<EOF
> D
> |
> C B
> |/
> A
> EOF
$ hg phase --force --secret D
$ hg rebase -s D -d B
rebasing 3:e7b3f00ed42e "D" (D tip)
saved backup bundle to $TESTTMP/a1/.hg/strip-backup/e7b3f00ed42e-6f368371-rebase.hg
$ hg log -G --template "{rev}:{phase} '{desc}' {branches}\n"
o 3:secret 'D'
|
| o 2:draft 'C'
| |
o | 1:draft 'B'
|/
o 0:draft 'A'
$ hg manifest --rev tip
A
B
D
$ cd ..
Rebasing D onto B detaching from C (two commits):
$ hg init a2
$ cd a2
$ hg debugdrawdag <<EOF
> E
> |
> D
> |
> C B
> |/
> A
> EOF
$ hg rebase -s D -d B
rebasing 3:e7b3f00ed42e "D" (D)
rebasing 4:69a34c08022a "E" (E tip)
saved backup bundle to $TESTTMP/a2/.hg/strip-backup/e7b3f00ed42e-a2ec7cea-rebase.hg
$ hg tglog
o 4: ee79e0744528 'E'
|
o 3: 10530e1d72d9 'D'
|
| o 2: dc0947a82db8 'C'
| |
o | 1: 112478962961 'B'
|/
o 0: 426bada5c675 'A'
$ hg manifest --rev tip
A
B
D
E
$ cd ..
Rebasing C onto B using detach (same as not using it):
$ hg init a3
$ cd a3
$ hg debugdrawdag <<EOF
> D
> |
> C B
> |/
> A
> EOF
$ hg rebase -s C -d B
rebasing 2:dc0947a82db8 "C" (C)
rebasing 3:e7b3f00ed42e "D" (D tip)
saved backup bundle to $TESTTMP/a3/.hg/strip-backup/dc0947a82db8-b8481714-rebase.hg
$ hg tglog
o 3: 7375f3dbfb0f 'D'
|
o 2: bbfdd6cb49aa 'C'
|
o 1: 112478962961 'B'
|
o 0: 426bada5c675 'A'
$ hg manifest --rev tip
A
B
C
D
$ cd ..
Rebasing D onto B detaching from C and collapsing:
$ hg init a4
$ cd a4
$ hg debugdrawdag <<EOF
> E
> |
> D
> |
> C B
> |/
> A
> EOF
$ hg phase --force --secret E
$ hg rebase --collapse -s D -d B
rebasing 3:e7b3f00ed42e "D" (D)
rebasing 4:69a34c08022a "E" (E tip)
saved backup bundle to $TESTTMP/a4/.hg/strip-backup/e7b3f00ed42e-a2ec7cea-rebase.hg
$ hg log -G --template "{rev}:{phase} '{desc}' {branches}\n"
o 3:secret 'Collapsed revision
| * D
| * E'
| o 2:draft 'C'
| |
o | 1:draft 'B'
|/
o 0:draft 'A'
$ hg manifest --rev tip
A
B
D
E
$ cd ..
Rebasing across null as ancestor
$ hg init a5
$ cd a5
$ hg debugdrawdag <<EOF
> E
> |
> D
> |
> C
> |
> A B
> EOF
$ hg rebase -s C -d B
rebasing 2:dc0947a82db8 "C" (C)
rebasing 3:e7b3f00ed42e "D" (D)
rebasing 4:69a34c08022a "E" (E tip)
saved backup bundle to $TESTTMP/a5/.hg/strip-backup/dc0947a82db8-3eefec98-rebase.hg
$ hg tglog
o 4: e3d0c70d606d 'E'
|
o 3: e9153d36a1af 'D'
|
o 2: a7ac28b870a8 'C'
|
o 1: fc2b737bb2e5 'B'
o 0: 426bada5c675 'A'
$ hg rebase -d 1 -s 3
rebasing 3:e9153d36a1af "D"
rebasing 4:e3d0c70d606d "E" (tip)
saved backup bundle to $TESTTMP/a5/.hg/strip-backup/e9153d36a1af-db7388ed-rebase.hg
$ hg tglog
o 4: 2c24e540eccd 'E'
|
o 3: 73f786ed52ff 'D'
|
| o 2: a7ac28b870a8 'C'
|/
o 1: fc2b737bb2e5 'B'
o 0: 426bada5c675 'A'
$ cd ..
Verify that target is not selected as external rev (issue3085)
$ hg init a6
$ cd a6
$ hg debugdrawdag <<EOF
> H
> | G
> |/|
> F E
> |/
> A
> EOF
$ hg up -q G
$ echo "I" >> E
$ hg ci -m "I"
$ hg tag --local I
$ hg merge H
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg ci -m "Merge"
$ echo "J" >> F
$ hg ci -m "J"
$ hg tglog
@ 7: c6aaf0d259c0 'J'
|
o 6: 0cfbc7e8faaf 'Merge'
|\
| o 5: b92d164ad3cb 'I'
| |
o | 4: 4ea5b230dea3 'H'
| |
| o 3: c6001eacfde5 'G'
|/|
o | 2: 8908a377a434 'F'
| |
| o 1: 7fb047a69f22 'E'
|/
o 0: 426bada5c675 'A'
$ hg rebase -s I -d H --collapse --config ui.merge=internal:other
rebasing 5:b92d164ad3cb "I" (I)
rebasing 6:0cfbc7e8faaf "Merge"
rebasing 7:c6aaf0d259c0 "J" (tip)
saved backup bundle to $TESTTMP/a6/.hg/strip-backup/b92d164ad3cb-88fd7ab7-rebase.hg
$ hg tglog
@ 5: 65079693dac4 'Collapsed revision
| * I
| * Merge
| * J'
o 4: 4ea5b230dea3 'H'
|
| o 3: c6001eacfde5 'G'
|/|
o | 2: 8908a377a434 'F'
| |
| o 1: 7fb047a69f22 'E'
|/
o 0: 426bada5c675 'A'
$ hg log --rev tip
changeset: 5:65079693dac4
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Collapsed revision
$ cd ..
Ensure --continue restores a correct state (issue3046) and phase:
$ hg init a7
$ cd a7
$ hg debugdrawdag <<EOF
> C B
> |/
> A
> EOF
$ hg up -q C
$ echo 'B2' > B
$ hg ci -A -m 'B2'
adding B
$ hg phase --force --secret .
$ hg rebase -s . -d B --config ui.merge=internal:fail
rebasing 3:17b4880d2402 "B2" (tip)
merging B
warning: conflicts while merging B! (edit, then use 'hg resolve --mark')
unresolved conflicts (see hg resolve, then hg rebase --continue)
[1]
$ hg resolve --all -t internal:local
(no more unresolved files)
continue: hg rebase --continue
$ hg rebase -c
rebasing 3:17b4880d2402 "B2" (tip)
note: rebase of 3:17b4880d2402 created no changes to commit
saved backup bundle to $TESTTMP/a7/.hg/strip-backup/17b4880d2402-1ae1f6cc-rebase.hg
$ hg log -G --template "{rev}:{phase} '{desc}' {branches}\n"
o 2:draft 'C'
|
| @ 1:draft 'B'
|/
o 0:draft 'A'
$ cd ..