rpc v2: rely backpressure for chainHead_v1_storage #5741
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niklasad1
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Sep 17, 2024
substrate/client/rpc-spec-v2/src/chain_head/chain_head_storage.rs
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niklasad1
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Sep 17, 2024
substrate/client/rpc-spec-v2/src/chain_head/chain_head_storage.rs
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niklasad1
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Sep 17, 2024
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The CI pipeline was cancelled due to failure one of the required jobs. |
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Storage::query_iter
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niklasad1
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Sep 19, 2024
substrate/client/rpc-spec-v2/src/chain_head/subscription/inner.rs
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substrate/client/rpc-spec-v2/src/chain_head/subscription/inner.rs
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niklasad1
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Sep 19, 2024
| @@ -272,15 +221,15 @@ impl RegisteredOperation { | |||
| /// Returns the number of reserved elements for this permit. | |||
| /// | |||
| /// This can be smaller than the number of items requested via [`LimitOperations::reserve()`]. | |||
| #[allow(unused)] | |||
niklasad1
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Sep 19, 2024
| impl OperationState { | ||
| pub fn stop(&mut self) { | ||
| if !self.stop.is_stopped() { | ||
| self.operations.lock().remove(&self.operation_id); |
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annoying to lock the mutex here instead of AtomicBool but this is needed to have an async notification when operation is stopped.
couldn't find a better way for this
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Close #5589
This PR makes it possible for
rpc_v2::Storage::query_iter_paginatedto be "backpressured" which is achieved by having a channel where the result is sent back and when this channel is "full" we pause the iteration.The chainHead_follow has an internal channel which doesn't represent the actual connection and that is set to a very small number (16). Recall that the JSON-RPC server has a dedicate buffer for each connection by default of 64.
One additional thiny is that
chainHead_v1_continueis just no-op and returns Ok(()) because WaitingForContinue is never emitted anymore.Notes
archive_storagealso depends onrpc_v2::Storage::query_iter_paginatedI had to tweak the method to support limits as well. The reason is that archive_storage won't get backpressured properly because it's not an subscription. (it would much easier if it would be a subscription in rpc v2 spec because nothing against querying huge amount storage keys)query_iter_paginateddoesn't necessarily return the storage "in order" such asquery_iter_paginated(vec![("key1", hash), ("key2", value)], ...)could return them in arbitrary order because it's wrapped in FuturesUnordered but I could change that if we want to process it inorder (it's slower)Benchmarks using subxt on localhost
The reason for this is because as Josep explained in the issue is that one is only allowed query five storage items per call and clients has make lots of calls to drive it forward..