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view tests/sslcerts/pub.pem @ 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 | 9d02bed8477b |
children |
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-----BEGIN CERTIFICATE----- MIIDNTCCAh2gAwIBAgIJAJ12yUL2zGhzMA0GCSqGSIb3DQEBCwUAMDExEjAQBgNV BAMMCWxvY2FsaG9zdDEbMBkGCSqGSIb3DQEJARYMaGdAbG9jYWxob3N0MB4XDTE2 MDcxMzA0MTcxMloXDTQxMDMwNDA0MTcxMlowMTESMBAGA1UEAwwJbG9jYWxob3N0 MRswGQYJKoZIhvcNAQkBFgxoZ0Bsb2NhbGhvc3QwggEiMA0GCSqGSIb3DQEBAQUA A4IBDwAwggEKAoIBAQDZSC3uNCsP674m0h9dmlV6nM4C59xfgIygdX3mpldmaXaO 4anHdPvCNA8H8g+g6lEb0KgJp6Qor5sipBfWo26JRrYKypyE1By5raOzkNO22ZFg L5/AdpBzRRjVAp7/Svw0VfVeh4hZ+4v7RQARGgjXOaG72nHnfboLs+jIE8i5tPR6 MtUt9yIWDIcOaq9ga7pxQGk0WsCLxyw80ZzKJ7UDGHTBn/2O8d036IaZpX0Zk5sa /QZmltaUmbx8b6YfWowVgDqaeSclsQEFOdXQhZ0YlqUafP7kZ8K+HHNhwRaYsN47 /sU2tYxVP0vwrLrlzKAJ4niURbVcHXD/qtBiNpKfAgMBAAGjUDBOMB0GA1UdDgQW BBT6fA08JcG+SWBN9Y+p575xcFfIVjAfBgNVHSMEGDAWgBT6fA08JcG+SWBN9Y+p 575xcFfIVjAMBgNVHRMEBTADAQH/MA0GCSqGSIb3DQEBCwUAA4IBAQCzJhM/OBoS JXnjfLhZqi6hTmx1XC7MR05z4fWdyBhZx8PwSDEjxAj/omAm2RMEx/Fv1a7FO6hd ClYsxxSfWJO7NQ3V4YLn9AvNr5gcxuXV/4bTtEFNebuzhV06u5nH7pGbHbkxCI+u QekmRTvKIojr8F44cyszEk+MZQ5bFBElByjVzgXNvAaDP0ryUL5eQhLrkuwbNFLQ mFf7EaerMuM28x1knhiH/39s7t92CJgm9+D60TmJ4XXwue1gZ0v9MVS18iOuWyio BklppJsdtDLxHTHGNlBeHdam5VejbXRo7s0y5OfuATwlgcaCMYC/68hVJYwl/GZ7 3YpdNpMshSaE -----END CERTIFICATE-----