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Make event subscription logic more generic.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,121 @@ | ||
| // Copyright 2019-2020 Parity Technologies (UK) Ltd. | ||
| // This file is part of substrate-subxt. | ||
| // | ||
| // subxt is free software: you can redistribute it and/or modify | ||
| // it under the terms of the GNU General Public License as published by | ||
| // the Free Software Foundation, either version 3 of the License, or | ||
| // (at your option) any later version. | ||
| // | ||
| // subxt is distributed in the hope that it will be useful, | ||
| // but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| // GNU General Public License for more details. | ||
| // | ||
| // You should have received a copy of the GNU General Public License | ||
| // along with substrate-subxt. If not, see <http://www.gnu.org/licenses/>. | ||
|
|
||
| use jsonrpsee::client::Subscription; | ||
| use sp_core::storage::StorageChangeSet; | ||
| use std::collections::VecDeque; | ||
|
|
||
| use crate::{ | ||
| error::Error, | ||
| events::{ | ||
| EventsDecoder, | ||
| RawEvent, | ||
| }, | ||
| frame::{ | ||
| system::Phase, | ||
| Event, | ||
| }, | ||
| runtimes::Runtime, | ||
| }; | ||
|
|
||
| /// Event subscription simplifies filtering a storage change set stream for | ||
| /// events of interest. | ||
| pub struct EventSubscription<T: Runtime> { | ||
| subscription: Subscription<StorageChangeSet<T::Hash>>, | ||
| decoder: EventsDecoder<T>, | ||
| block: Option<T::Hash>, | ||
| extrinsic: Option<usize>, | ||
| event: Option<(&'static str, &'static str)>, | ||
| events: VecDeque<RawEvent>, | ||
| finished: bool, | ||
| } | ||
|
|
||
| impl<T: Runtime> EventSubscription<T> { | ||
| /// Creates a new event subscription. | ||
| pub fn new( | ||
| subscription: Subscription<StorageChangeSet<T::Hash>>, | ||
| decoder: EventsDecoder<T>, | ||
| ) -> Self { | ||
| Self { | ||
| subscription, | ||
| decoder, | ||
| block: None, | ||
| extrinsic: None, | ||
| event: None, | ||
| events: Default::default(), | ||
| finished: false, | ||
| } | ||
| } | ||
|
|
||
| /// Only returns events contained in the block with the given hash. | ||
| pub fn filter_block(&mut self, block: T::Hash) { | ||
| self.block = Some(block); | ||
| } | ||
|
|
||
| /// Only returns events from block emitted by extrinsic with index. | ||
| pub fn filter_extrinsic(&mut self, block: T::Hash, ext_index: usize) { | ||
| self.block = Some(block); | ||
| self.extrinsic = Some(ext_index); | ||
| } | ||
|
|
||
| /// Filters events by type. | ||
| pub fn filter_event<E: Event<T>>(&mut self) { | ||
| self.event = Some((E::MODULE, E::EVENT)); | ||
| } | ||
|
|
||
| /// Gets the next event. | ||
| pub async fn next(&mut self) -> Option<Result<RawEvent, Error>> { | ||
| loop { | ||
| if let Some(event) = self.events.pop_front() { | ||
| return Some(Ok(event)) | ||
| } | ||
| if self.finished { | ||
| return None | ||
| } | ||
| let change_set = self.subscription.next().await; | ||
| if let Some(hash) = self.block.as_ref() { | ||
| if &change_set.block == hash { | ||
| self.finished = true; | ||
| } else { | ||
| continue | ||
| } | ||
| } | ||
| for (_key, data) in change_set.changes { | ||
| if let Some(data) = data { | ||
| let raw_events = match self.decoder.decode_events(&mut &data.0[..]) { | ||
| Ok(events) => events, | ||
| Err(error) => return Some(Err(error)), | ||
| }; | ||
| for (phase, event) in raw_events { | ||
| if let Phase::ApplyExtrinsic(i) = phase { | ||
| if let Some(ext_index) = self.extrinsic { | ||
| if i as usize != ext_index { | ||
| continue | ||
| } | ||
| } | ||
| if let Some((module, variant)) = self.event { | ||
| if event.module != module || event.variant != variant { | ||
| continue | ||
| } | ||
| } | ||
| self.events.push_back(event); | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } | ||
| } |