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view tests/test-issue1306.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
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Fri, 13 Apr 2018 11:02:34 -0700 |
parents | eb586ed5d8ce |
children |
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https://bz.mercurial-scm.org/1306 Initialize remote repo with branches: $ hg init remote $ cd remote $ echo a > a $ hg ci -Ama adding a $ hg branch br marked working directory as branch br (branches are permanent and global, did you want a bookmark?) $ hg ci -Amb $ echo c > c $ hg ci -Amc adding c $ hg log changeset: 2:ae3d9c30ec50 branch: br tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c changeset: 1:3f7f930ca414 branch: br user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a $ cd .. Try cloning -r branch: $ hg clone -rbr remote local1 adding changesets adding manifests adding file changes added 3 changesets with 2 changes to 2 files new changesets cb9a9f314b8b:ae3d9c30ec50 updating to branch br 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg -R local1 parents changeset: 2:ae3d9c30ec50 branch: br tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: c Try cloning -rother clone#branch: $ hg clone -r0 remote#br local2 adding changesets adding manifests adding file changes added 3 changesets with 2 changes to 2 files new changesets cb9a9f314b8b:ae3d9c30ec50 updating to branch default 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg -R local2 parents changeset: 0:cb9a9f314b8b user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: a Try cloning -r1 clone#branch: $ hg clone -r1 remote#br local3 adding changesets adding manifests adding file changes added 3 changesets with 2 changes to 2 files new changesets cb9a9f314b8b:ae3d9c30ec50 updating to branch br 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg -R local3 parents changeset: 1:3f7f930ca414 branch: br user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: b