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Resolve pubsub future only when nothing can happen anymore #72

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Resolve pubsub future only when nothing can happen anymore #72

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3467a85
Resolve pubsub future only when nothing can happen anymore
dippi Jul 3, 2021
36bf772
Add tests to cover new pubsub completion policy
dippi Jul 4, 2021
b51f99f
Add a note on PubsubStream about the assumptions made
dippi Jul 4, 2021
26e1362
Reword expect in tests
dippi Jul 4, 2021
23a85ec
Add comment referencing the issue #50
dippi Jul 4, 2021
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136 changes: 79 additions & 57 deletions src/client/pubsub.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -131,7 +131,7 @@ impl PubsubConnectionInner {
}
}

fn handle_message(&mut self, msg: resp::RespValue) -> Result<bool, error::Error> {
fn handle_message(&mut self, msg: resp::RespValue) -> Result<(), error::Error> {
let (message_type, topic, msg) = match msg {
resp::RespValue::Array(mut messages) => match (
messages.pop(),
Expand Down Expand Up @@ -193,38 +193,28 @@ impl PubsubConnectionInner {
)));
}
},
b"unsubscribe" => {
match self.subscriptions.entry(topic) {
Entry::Occupied(entry) => {
entry.remove_entry();
}
Entry::Vacant(vacant) => {
return Err(error::internal(format!(
"Unexpected unsubscribe message: {}",
vacant.key()
)));
}
b"unsubscribe" => match self.subscriptions.entry(topic) {
Entry::Occupied(entry) => {
entry.remove_entry();
}
if self.subscriptions.is_empty() {
return Ok(false);
Entry::Vacant(vacant) => {
return Err(error::internal(format!(
"Unexpected unsubscribe message: {}",
vacant.key()
)));
}
}
b"punsubscribe" => {
match self.psubscriptions.entry(topic) {
Entry::Occupied(entry) => {
entry.remove_entry();
}
Entry::Vacant(vacant) => {
return Err(error::internal(format!(
"Unexpected unsubscribe message: {}",
vacant.key()
)));
}
},
b"punsubscribe" => match self.psubscriptions.entry(topic) {
Entry::Occupied(entry) => {
entry.remove_entry();
}
if self.psubscriptions.is_empty() {
return Ok(false);
Entry::Vacant(vacant) => {
return Err(error::internal(format!(
"Unexpected unsubscribe message: {}",
vacant.key()
)));
}
}
},
b"message" => match self.subscriptions.get(&topic) {
Some(sender) => {
if let Err(error) = sender.unbounded_send(Ok(msg)) {
Expand Down Expand Up @@ -263,39 +253,32 @@ impl PubsubConnectionInner {
}
}

Ok(true)
Ok(())
}

/// Returns true, if there are still valid subscriptions at the end, or false if not, i.e. the whole thing can be dropped.
fn handle_messages(&mut self, cx: &mut Context) -> Result<bool, error::Error> {
fn handle_messages(&mut self, cx: &mut Context) -> Result<(), error::Error> {
loop {
match self.connection.poll_next_unpin(cx) {
Poll::Pending => return Ok(true),
Poll::Pending => return Ok(()),
Poll::Ready(None) => {
if self.subscriptions.is_empty() {
return Ok(false);
} else {
// This can only happen if the connection is closed server-side
for sub in self.subscriptions.values() {
sub.unbounded_send(Err(error::Error::Connection(
ConnectionReason::NotConnected,
)))
.unwrap();
}
for psub in self.psubscriptions.values() {
psub.unbounded_send(Err(error::Error::Connection(
ConnectionReason::NotConnected,
)))
.unwrap();
}
return Err(error::Error::Connection(ConnectionReason::NotConnected));
// This can only happen if the connection is closed server-side
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@dippi dippi Jul 4, 2021 •
edited
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Here I removed the handling of the special case, because I couldn't think of a reason to keep it. Am I missing anything?

for sub in self.subscriptions.values() {
sub.unbounded_send(Err(error::Error::Connection(
ConnectionReason::NotConnected,
)))
.unwrap();
}
for psub in self.psubscriptions.values() {
psub.unbounded_send(Err(error::Error::Connection(
ConnectionReason::NotConnected,
)))
.unwrap();
}
return Err(error::Error::Connection(ConnectionReason::NotConnected));
}
Poll::Ready(Some(Ok(message))) => {
let message_result = self.handle_message(message)?;
if !message_result {
return Ok(false);
}
self.handle_message(message)?;
}
Poll::Ready(Some(Err(e))) => {
for sub in self.subscriptions.values() {
Expand Down Expand Up @@ -326,11 +309,11 @@ impl Future for PubsubConnectionInner {
let this_self = self.get_mut();
this_self.handle_new_subs(cx)?;
this_self.do_flush(cx)?;
let cont = this_self.handle_messages(cx)?;
if cont {
Poll::Pending
} else {
this_self.handle_messages(cx)?;
if this_self.out_rx.is_done() {
Poll::Ready(Ok(()))
} else {
Poll::Pending
}
}
}
Expand Down Expand Up @@ -456,6 +439,8 @@ impl PubsubConnection {
pub struct PubsubStream {
topic: String,
underlying: PubsubStreamInner,
// Note that, to keep the Future running, PubsubConnectionInner relies on PubsubStream to hold
// a reference to the connection. If that's ever changed remember to adapt the readiness check.
con: PubsubConnection,
}

Expand Down Expand Up @@ -540,4 +525,41 @@ mod test {
assert_eq!(result[1], "test-message-2".into());
assert_eq!(result[2], "test-message-3".into());
}

#[tokio::test]
/// Regression test for https://github.com/benashford/redis-async-rs/issues/50
async fn test_connection_remains_open_after_unsubscription() {
let addr = "127.0.0.1:6379".parse().unwrap();
let pubsub = super::pubsub_connect(addr)
.await
.expect("Cannot connect to Redis");

let topic_messages = pubsub
.subscribe("test-topic")
.await
.expect("Cannot subscribe to topic");
drop(topic_messages);

pubsub
.subscribe("test-topic")
.await
.expect("Cannot subscribe to topic");
}
}

#[tokio::test]
async fn test_connection_is_closed_after_channel_is_dropped() {
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I had to do this test outside the test module, to have access to the private types. Is there a better way?

let addr = "127.0.0.1:6379".parse().unwrap();
let connection = connect_with_auth(&addr, None, None)
.await
.expect("Cannot connect to Redis");
let (out_tx, out_rx) = mpsc::unbounded();
let handle = tokio::spawn(async {
match PubsubConnectionInner::new(connection, out_rx).await {
Ok(_) => (),
Err(e) => log::error!("Pub/Sub error: {:?}", e),
}
});
drop(out_tx);
handle.await.expect("Error waiting on the JoinHandle");
}