acks: send sequence-0 ack for 0-window batches #479
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Ensures that at least one ACK is sent in reply to each window, including those with 0-length, by emitting an empty batch when we receive a 0-window frame and sending a sequence-0 ACK in reply when we process an empty batch. This enables upstream users of the protocol to (ab)use a 0-length window frame and an _ensured_ in-protocol response to validate that we are alive. Note: 0-sequence ACKs are already used as application-level keep-alives between when the `ConnectionHandler` receives bytes and when `BeatsHandler` finishes processing a batch, and therefore should already be handled gracefully by any existing clients.
yaauie
commented
Sep 6, 2023
| @@ -5,6 +5,7 @@ env | |||
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| set -ex | |||
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| bundle exec rake test:java | |||
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review note: java unit tests were not being triggered as part of the build 🤦🏼
jsvd
approved these changes
Sep 6, 2023
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LGTM, I tested locally with a modified lumberjack client. I could observe that with this patch the client immediately received an ack after sending an zero window frame, instead of waiting a long time for the ack from the idlestatehandler.
The script used, that takes code from the original lumberjack ruby client, can be found here: https://gist.github.com/jsvd/b86ea9d2f16a868c1460d4e12145a35f#file-beats_empty_writer-rb
fbacchella
added a commit
to fbacchella/netty-beats
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Sep 27, 2023
…b.com> acks: send sequence-0 ack for 0-window batches (logstash-plugins#479) * acks: send sequence-0 ack for 0-window batches Ensures that at least one ACK is sent in reply to each window, including those with 0-length, by emitting an empty batch when we receive a 0-window frame and sending a sequence-0 ACK in reply when we process an empty batch. This enables upstream users of the protocol to (ab)use a 0-length window frame and an _ensured_ in-protocol response to validate that we are alive. Note: 0-sequence ACKs are already used as application-level keep-alives between when the `ConnectionHandler` receives bytes and when `BeatsHandler` finishes processing a batch, and therefore should already be handled gracefully by any existing clients.
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Ensures that at least one ACK is sent in reply to each window, including those with 0-length, by emitting an empty batch when we receive a 0-window frame and sending a sequence-0 ACK in reply when we process an empty batch.
This enables upstream users of the protocol to (ab)use a 0-length window frame and an ensured in-protocol response to validate that we are alive.
Note: 0-sequence ACKs are already used as application-level keep-alives between when the
ConnectionHandlerreceives bytes and whenBeatsHandlerfinishes processing a batch, and therefore should already be handled gracefully by any existing clients.Thanks for contributing to Logstash! If you haven't already signed our CLA, here's a handy link: https://www.elastic.co/contributor-agreement/