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docker / libchan

Like Go channels over the network
Apache License 2.0
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Clarify channel semantics #22

Closed aphyr closed 10 years ago

aphyr commented 10 years ago

The readme says:

network services communicate in the same way that goroutines communicate using channels:

And the Golang spec, regarding asynchronous channels, says:

elements are received in the order they are sent

How does libchan enforce the ordering/delivery properties of golang channels when the underlying transport is disrupted--e.g., when re-establishing a TCP link that dropped, how does the channel state machine negotiate redelivery of incomplete in-flight messages? Do libchan channels yield at-least-once delivery? At-most-once? Exactly once? Are there any ordering invariants, or can messages be arbitrarily reordered? If ordering is preserved, what are the space costs on both sides of the network?

pnasrat commented 10 years ago

@aphyr thanks for your interesting questions - I am not the maintainer, so don't have answers for you. I would emphasize that libchan is pretty early and rough. @shykes has been travelling but hopefully he can respond with some detail here.

shykes commented 10 years ago

Hi @aphyr, libchan relies on the underlying transport to guarantee ordering (either SOCK_STREAM unix sockets, spdy/tls sessions or actual golang channels). When the underlying connection/session/channel is closed, that must result in the libchan channels closing as well. Then it's up to the application to re-open.

In short: there is no magic here.

aphyr commented 10 years ago

Cool cool. Might want to document that these don't have the delivery semantics of Go channels, then. :)

shykes commented 10 years ago

Sure. We welcome pull requests :)

On Monday, June 16, 2014, Kyle Kingsbury notifications@github.com wrote:

Cool cool. Might want to document that these don't have the delivery semantics of Go channels, then. :)

— Reply to this email directly or view it on GitHub https://github.com/docker/libchan/issues/22#issuecomment-46201311.

pnasrat commented 10 years ago

Triage this can be closed - @aphyr I think you should be able to do this, or @shykes

cpuguy83 commented 10 years ago

Closed by #26