Strict reliability with limited history

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Mon, 12/14/2020 - 06:48
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borlec
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Strict reliability with limited history

Hello,

My need in a few words is:

  • strict reliability
  • limited history (N samples)
  • non blocking writer

My detailed need:

A late joining reader shall read only the last N written samples. Once these history samples read, the reader shall not lose any sample.

I don't mind if the writer consume as memory as it need to store samples that are not yet acked by the yet connected reader(s).

But I don't want the writer to store all the samples for the late joining readers (just the last N).

 

To achieve that, I set:

  • KEEP_ALL for both reader and writer (strict reliability)
  • No sample limitation on writer side (non blocking writer)

But can you help me on how to have a limited history on the writer side for the late joining readers ?

 

Thanks in advance.

Boris.

 

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Mon, 12/14/2020 - 07:28
erin
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Posts: 28

Hi Boris, 

Our upcoming release (end of Q1 next year) will add a new QoS Durability.writer_depth that will allow you to configure how many samples per instance are sent to late joiners, while still allowing you to configure strict reliability using the History QoS KEEP_ALL setting. 

In the currently available releases this is not possible. Will you be able to update your Connext DDS version next year and take advantage of the new QoS?

- Erin

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Mon, 01/04/2021 - 04:36
borlec
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Posts: 22

Yes, I will.

Thanks for your answer.

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