Mercurial > hg
view tests/test-push-checkheads-unpushed-D6.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> |
---|---|
date | Fri, 13 Apr 2018 11:02:34 -0700 |
parents | 4441705b7111 |
children | 34a46d48d24e |
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==================================== Testing head checking code: Case D-6 ==================================== Mercurial checks for the introduction of new heads on push. Evolution comes into play to detect if existing branches on the server are being replaced by some of the new one we push. This case is part of a series of tests checking this behavior. Category D: remote head is "obs-affected" locally, but result is not part of the push TestCase 6: single changeset, superseeded then pruned (on a new changeset unpushed) changeset This is a partial push variation of case B-6 .. old-state: .. .. * 1 changeset branch .. .. new-state: .. .. * old branch is rewritten onto another one, .. * the new version is then pruned. .. .. expected-result: .. .. * push denied .. .. graph-summary: .. .. A ø⇠⊗ A' .. | | .. C ◔ | ○ B .. \|/ .. ● $ . $TESTDIR/testlib/push-checkheads-util.sh Test setup ---------- $ mkdir D6 $ cd D6 $ setuprepos creating basic server and client repo updating to branch default 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cd client $ hg up 0 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ mkcommit B0 created new head $ mkcommit A1 $ hg up '0' 0 files updated, 0 files merged, 2 files removed, 0 files unresolved $ mkcommit C0 created new head $ hg debugobsolete `getid "desc(A0)"` `getid "desc(A1)"` obsoleted 1 changesets $ hg debugobsolete --record-parents `getid "desc(A1)"` obsoleted 1 changesets $ hg log -G --hidden @ 0f88766e02d6 (draft): C0 | | x ba93660aff8d (draft): A1 | | | o 74ff5441d343 (draft): B0 |/ | x 8aaa48160adc (draft): A0 |/ o 1e4be0697311 (public): root Actual testing -------------- $ hg push --rev 'desc(C0)' pushing to $TESTTMP/D6/server searching for changes abort: push creates new remote head 0f88766e02d6! (merge or see 'hg help push' for details about pushing new heads) [255] $ cd ../..