Additional docs for hanging sockets & shared futures/promises #2030
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Added documentation for how to use shared_future/shared_promise
arkocetu
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doc/hanging-socket.md
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| ``` | ||
| In this example, the next step after read, will never happen, and we'll never reach the "end" state. | ||
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| A simple solution for this case might be to add a timeout on the read operation, in the case the client doesn't do any progress, for instance |
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Please mention that it's wrong up-front, before people (or copilot) starts copy'n'pasting it.
doc/hanging-socket.md
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| }); | ||
| }); |
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Better to rewrite the examples are coroutines, nobody should be using continuations in 2024.
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All examples are written with coroutine.
doc/hanging-socket.md
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| }).handle_exception_type([&s] (const seastar::timed_out_error &err) { | ||
| // Will resolve the currently waiting futures, with an exception | ||
| s.shutdown_input(); | ||
| // Allows to wait untill the inputs are actually closed |
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Well this is also wrong, since the original continuation escapes. Maybe it works for the example, but for the general case, it's problematic.
The correct approach is to have a separate monitoring fiber issue the shutdown when it wants. Then the original write() just terminates with an exception. It's also more efficient as we don't wrap everything with with_timeout wrappers.
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What can be a good approach for such handling, for example, if we set operation counter, and in the monitor fiber, we just verify that the counter changing in between a specified timeout for example?
Because otherwise I don't see a way to see if the socket is actually making any progress.
Or maybe you can suggest a better approach? If possible
The docs currently lacking some explanation how to deal with clients/servers that don't send any data, and how to close them correctly.
Added additional explanation about shared futures/promises which aren't documented under the tutorial, and only can be found in the reference.