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return none if subscription returns early #250

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Merged
ascjones merged 4 commits into from
Mar 22, 2021
Merged

return none if subscription returns early #250

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132e78a
return none if subscription returns early
gregdhill Mar 15, 2021
e36114c
add comment on subscription close
gregdhill Mar 15, 2021
cde426d
Merge remote-tracking branch 'origin/master' into none-on-sub-exit
gregdhill Mar 17, 2021
17217da
no need for jsonrpsee error enum
gregdhill Mar 17, 2021
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24 changes: 8 additions & 16 deletions src/subscription.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,6 @@
// 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_types::error::Error as RpcError;
use jsonrpsee_ws_client::WsSubscription as Subscription;
use sp_core::{
storage::{
Expand Down Expand Up @@ -95,14 +94,8 @@ impl<'a, T: Runtime> EventSubscription<'a, T> {
if self.finished {
return None
}
let change_set = match self.subscription.next().await {
Some(c) => c,
None => {
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@niklasad1 niklasad1 Mar 15, 2021

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The proper action should be to indicate that the subscription is dropped and need to restarted because after it returns None it shouldn't be polled anymore because the channel has been terminated.

If you poll if after None it will panic

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@gregdhill gregdhill Mar 15, 2021

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Which is exactly why I would expect it to return None, to indicate the stream has closed (much like with StreamExt).

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@niklasad1 niklasad1 Mar 15, 2021

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Alright, that makes sense to me but perhaps we should document it because it's not obvious to me ^^

return Some(Err(
RpcError::Custom("RPC subscription dropped".into()).into()
))
}
};
// always return None if subscription has closed
let change_set = self.subscription.next().await?;
if let Some(hash) = self.block.as_ref() {
if &change_set.block == hash {
self.finished = true;
Expand Down Expand Up @@ -184,13 +177,12 @@ impl<T: Runtime> FinalizedEventStorageSubscription<T> {
return Some(storage_change)
}
let header: T::Header = self.subscription.next().await?;
if let Ok(storage_changes) = self
.rpc
.query_storage_at(&[self.storage_key.clone()], Some(header.hash()))
.await
{
self.storage_changes.extend(storage_changes);
}
self.storage_changes.extend(
self.rpc
.query_storage_at(&[self.storage_key.clone()], Some(header.hash()))
.await
.ok()?,
);
}
}
}
Expand Down