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ZenGo-X / round-based-protocol

Driver for round-based protocols in Rust
Apache License 2.0
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fix: async protocol may stuck at the last round forever if messages n… #10

Closed BigMurry closed 1 year ago

BigMurry commented 1 year ago

When the incoming messages not coming by order, the async protocol may stuck at the last round forever.

For example, there is a protocol has 2 rounds, when the messages for the round 2 are coming first before the messages for round 1. All these messages will be saved in the message store inside the state machine. When the messages for round 1 are ready, the protocol will go to round 2. But at this time, the handle_incoming().await in the loop may never get the messages for the last round (round 2), cause they are already saved inside the state machine.

https://github.com/ZenGo-X/round-based-protocol/blob/149512bb0a32805fb0f460c690a35427f10bc0e1/src/async_runtime/mod.rs#L145

I found this issue, when I was debug a strange issue for multi-party-ecdsa. I found that when there was a lot messages and the message channels were busy, some of the async protocol may never finish the last round.

I've changed the proceed_if_needed method a little bit, make the state forward as much as it can to avoid the issue.

survived commented 1 year ago

Interesting, nice catch! Thanks for your fix!