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|
use std::future;
use axum::extract::State;
use axum_extra::extract::Query;
use futures::stream::{self, StreamExt as _};
use crate::{
event::{routes::get, Sequenced as _},
test::fixtures::{self, future::Expect as _},
};
#[tokio::test]
async fn resume() {
// Set up the environment
let app = fixtures::scratch_app().await;
let channel = fixtures::channel::create(&app, &fixtures::now()).await;
let sender = fixtures::login::create(&app, &fixtures::now()).await;
let initial_message = fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await;
let later_messages = vec![
fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
fixtures::message::send(&app, &channel, &sender, &fixtures::now()).await,
];
// Call the endpoint
let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
let resume_at = {
// First subscription
let get::Response(events) = get::handler(
State(app.clone()),
subscriber.clone(),
None,
Query::default(),
)
.await
.expect("subscribe never fails");
let event = events
.filter_map(fixtures::event::message)
.filter_map(fixtures::event::message::sent)
.filter(|event| future::ready(event.message == initial_message))
.next()
.expect_some("delivered event for initial message")
.await;
event.sequence()
};
// Resume after disconnect
let get::Response(resumed) = get::handler(
State(app),
subscriber,
Some(resume_at.into()),
Query::default(),
)
.await
.expect("subscribe never fails");
// Verify final events
let mut events = resumed
.filter_map(fixtures::event::message)
.filter_map(fixtures::event::message::sent)
.zip(stream::iter(later_messages));
while let Some((event, message)) = events.next().expect_ready("event ready").await {
assert_eq!(message, event.message);
}
}
// This test verifies a real bug I hit developing the vector-of-sequences
// approach to resuming events. A small omission caused the event IDs in a
// resumed stream to _omit_ channels that were in the original stream until
// those channels also appeared in the resumed stream.
//
// Clients would see something like
// * In the original stream, Cfoo=5,Cbar=8
// * In the resumed stream, Cfoo=6 (no Cbar sequence number)
//
// Disconnecting and reconnecting a second time, using event IDs from that
// initial period of the first resume attempt, would then cause the second
// resume attempt to restart all other channels from the beginning, and not
// from where the first disconnection happened.
//
// As we have switched to a single global event sequence number, this scenario
// can no longer arise, but this test is preserved because the actual behaviour
// _is_ a valid way for clients to behave, and should work. We might as well
// keep testing it.
#[tokio::test]
async fn serial_resume() {
// Set up the environment
let app = fixtures::scratch_app().await;
let sender = fixtures::login::create(&app, &fixtures::now()).await;
let channel_a = fixtures::channel::create(&app, &fixtures::now()).await;
let channel_b = fixtures::channel::create(&app, &fixtures::now()).await;
// Call the endpoint
let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
let resume_at = {
let initial_messages = [
fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
fixtures::message::send(&app, &channel_b, &sender, &fixtures::now()).await,
];
// First subscription
let get::Response(events) = get::handler(
State(app.clone()),
subscriber.clone(),
None,
Query::default(),
)
.await
.expect("subscribe never fails");
// Check for expected events
let events = events
.filter_map(fixtures::event::message)
.filter_map(fixtures::event::message::sent)
.zip(stream::iter(initial_messages))
.collect::<Vec<_>>()
.expect_ready("zipping a finite list of events is ready immediately")
.await;
assert!(events
.iter()
.all(|(event, message)| message == &event.message));
let (event, _) = events.last().expect("this vec is non-empty");
// Take the last one's resume point
event.sequence()
};
// Resume after disconnect
let resume_at = {
let resume_messages = [
// Note that channel_b does not appear here. The buggy behaviour
// would be masked if channel_b happened to send a new message
// into the resumed event stream.
fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
];
// Second subscription
let get::Response(events) = get::handler(
State(app.clone()),
subscriber.clone(),
Some(resume_at.into()),
Query::default(),
)
.await
.expect("subscribe never fails");
// Check for expected events
let events = events
.filter_map(fixtures::event::message)
.filter_map(fixtures::event::message::sent)
.zip(stream::iter(resume_messages))
.collect::<Vec<_>>()
.expect_ready("zipping a finite list of events is ready immediately")
.await;
assert!(events
.iter()
.all(|(event, message)| message == &event.message));
let (event, _) = events.last().expect("this vec is non-empty");
// Take the last one's resume point
event.sequence()
};
// Resume after disconnect a second time
{
// At this point, we can send on either channel and demonstrate the
// problem. The resume point should before both of these messages, but
// after _all_ prior messages.
let final_messages = [
fixtures::message::send(&app, &channel_a, &sender, &fixtures::now()).await,
fixtures::message::send(&app, &channel_b, &sender, &fixtures::now()).await,
];
// Third subscription
let get::Response(events) = get::handler(
State(app.clone()),
subscriber.clone(),
Some(resume_at.into()),
Query::default(),
)
.await
.expect("subscribe never fails");
// Check for expected events
let events = events
.filter_map(fixtures::event::message)
.filter_map(fixtures::event::message::sent)
.zip(stream::iter(final_messages))
.collect::<Vec<_>>()
.expect_ready("zipping a finite list of events is ready immediately")
.await;
assert!(events
.iter()
.all(|(event, message)| message == &event.message));
};
}
|
