From 31f9a6812a20ebf8e18d721dfb06cab0fea5a12d Mon Sep 17 00:00:00 2001
From: Pierre Krieger <pierre.krieger1708@gmail.com>
Date: Wed, 25 Nov 2020 10:15:37 +0100
Subject: [PATCH] Fix notifications sometimes not being sent (#7594)
* Fix notifications sometimes not being sent
* Add comment
---
.../network/src/protocol/generic_proto/handler.rs | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/substrate/client/network/src/protocol/generic_proto/handler.rs b/substrate/client/network/src/protocol/generic_proto/handler.rs
index c8a76c1cc9a..42cf02f1b77 100644
--- a/substrate/client/network/src/protocol/generic_proto/handler.rs
+++ b/substrate/client/network/src/protocol/generic_proto/handler.rs
@@ -971,6 +971,16 @@ impl ProtocolsHandler for NotifsHandler {
if let Some(pos) = self.out_protocols.iter().position(|(n, _)| *n == protocol_name) {
if let Some(substream) = out_substreams[pos].as_mut() {
let _ = substream.start_send_unpin(message);
+ // Calling `start_send_unpin` only queues the message. Actually
+ // emitting the message is done with `poll_flush`. In order to
+ // not introduce too much complexity, this flushing is done earlier
+ // in the body of this `poll()` method. As such, we schedule a task
+ // wake-up now in order to guarantee that `poll()` will be called
+ // again and the flush happening.
+ // At the time of the writing of this comment, a rewrite of this
+ // code is being planned. If you find this comment in the wild and
+ // the rewrite didn't happen, please consider a refactor.
+ cx.waker().wake_by_ref();
continue 'poll_notifs_sink;
}
--
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