swarm/: Limit negotiating inbound substreams per connection #2697
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This limit is shared across all `ConnectionHandler`s on a single connection. It only enforces a limit on the number of negotiating substreams. Once negotiated a `ConnectionHandler` manages the lifecycle of the substream and has to enforce limits themselves.
thomaseizinger
approved these changes
Jun 7, 2022
| @@ -243,6 +247,11 @@ where | |||
| ) { | |||
| match endpoint { | |||
| SubstreamEndpoint::Listener => { | |||
| if self.negotiating_in.len() == MAX_NUM_NEGOTIATING_IN { | |||
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Instead of doing this check here, we could create a wrapper around FuturesUnordered that enforces a limit on the number of concurrent futures. This would foster reuse and actually enforce this limit. At the moment, there is a risk that this check is circumvented in case the FuturesUnordered is modified in a different place without this check.
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👍 for the reusable abstraction, though I would much rather like to remove the entire upgrade mechanism for substreams in the future.
| @@ -35,6 +35,10 @@ use libp2p_core::{ | |||
| }; | |||
| use std::{error, fmt, pin::Pin, task::Context, task::Poll, time::Duration}; | |||
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| /// The maximum number of incoming streams concurrently negotiated. Streams are | |||
| /// dropped and thus reset. | |||
| const MAX_NUM_NEGOTIATING_IN: usize = 128; | |||
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How was this number chosen?
mxinden
commented
Jun 8, 2022
1 task
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Description
This limit is shared across all
ConnectionHandlers on a single connection. Itonly enforces a limit on the number of negotiating substreams. Once negotiated a
ConnectionHandlermanages the lifecycle of the substream and has to enforcelimits themselves.
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