[Twisted-Python] Retry: Conch Issues

Robert DiFalco robert.difalco at gmail.com
Fri Sep 25 15:16:53 MDT 2020


My work around for the twisted/conch bug if anyone is interested.
FileTransferHandler was not handling closed connections properly. Btw, this
is with release version 20.3.0, which seems to be the latest version.
However, if I look in the Twisted repo it looks like someone is trying to
address this bug for the next release.

https://github.com/radifalco/conch_issues/commit/c25aa6bca20201f51d59c3a6dca4c1fb2aed2242?branch=c25aa6bca20201f51d59c3a6dca4c1fb2aed2242&diff=split

On Fri, Sep 25, 2020 at 7:42 AM Robert DiFalco <robert.difalco at gmail.com>
wrote:

> I agree it's a bug in conch and I believe my repo shows a reproducible
> example. Run the test, it never completes because the deferred from
> `makeDirectory` never fires. .
>
> On Fri, Sep 25, 2020 at 3:41 AM Jean-Paul Calderone <
> exarkun at twistedmatrix.com> wrote:
>
>> On Thu, Sep 24, 2020 at 8:54 PM Robert DiFalco <robert.difalco at gmail.com>
>> wrote:
>>
>>> Why exactly is makeDirectory not firing any callbacks or errbacks and
>>> what can I add at the Factory level to make it do so?
>>>
>>
>> class MySSHClientFactory(SSHClientFactory):
>>>     def clientConnectionLost(self, connector, reason):
>>>         self.op.addErrback(reason)
>>>
>>>     def makeDirectory(self, path, attrs):
>>>         self.op = Deferred()
>>>         def _cbSuccess(result):
>>>             self.op.callback(result)
>>>
>>>         return self.sftpClient.makeDirectory(path, attrs).addCallback(_cbSuccess)d
>>>
>>>
>> This code is wrong.  It takes what *may* be a perfectly good Deferred
>> from makeDirectory and breaks the error chain off of it.  The correct way
>> to do this would be more like `makeDirectory(...).chainDeferred(self.op)`.
>> However, `self.op` and `_cbSuccess` are doing nothing useful here so you
>> may as well just delete all that and return the `makeDirectory(...)`
>> Deferred.
>>
>> If *that* Deferred doesn't fire its errback chain when the connection is
>> closed, that's a bug in Conch.  If you can put together a minimal example
>> and file a ticket, that would be wonderful and perhaps someone can get it
>> fixed for you.
>>
>> Jean-Paul
>> _______________________________________________
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>> Twisted-Python at twistedmatrix.com
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>>
>
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