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Merged
icewind1991 merged 2 commits into from
Aug 7, 2025
Merged

spread out debouce times per-connection #636

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278f92f
store max-debounce-time in sendqueue
icewind1991 Aug 5, 2025
9fe46cb
spread out debouce times per-connection
icewind1991 Aug 5, 2025
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16 changes: 10 additions & 6 deletions src/connection.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -12,7 +12,7 @@ use crate::{App, UserId};
use dashmap::mapref::entry::Entry;
use dashmap::DashMap;
use futures::{future::select, pin_mut, SinkExt, StreamExt};
use rand::{Rng, SeedableRng};
use rand::{thread_rng, Rng, SeedableRng};
use std::net::IpAddr;
use std::num::NonZeroUsize;
use std::sync::atomic::{AtomicBool, AtomicUsize, Ordering};
Expand Down Expand Up @@ -131,11 +131,15 @@ pub async fn handle_user_socket(
let expect_pong = &expect_pong;

let transmit = async {
// Use faster random generator for generating ping messages, they dont need to be
// cryptographically secure. It is also OK to use same sequence for every connection.
let mut rng = rand::rngs::SmallRng::seed_from_u64(0);
// Use faster random generator for generating ping messages and time smearthey dont need to be
// cryptographically secure.
let mut rng =
rand::rngs::SmallRng::from_rng(thread_rng()).expect("Failed to initialize rng");

let mut send_queue = SendQueue::default();
// for each connection we randomize the max debounce time to remove the chance that many connections
// get messages at the same time and cause load peaks
let debounce_factor = rng.gen_range(0.5..1.5);
let mut send_queue = SendQueue::new(opts.max_debounce_time, debounce_factor);

let mut reset = app.reset_rx();

Expand All @@ -162,7 +166,7 @@ pub async fn handle_user_socket(
break 'tx_loop;
}

for msg in send_queue.drain(now, METRICS.active_connection_count() + 50000, opts.max_debounce_time) {
for msg in send_queue.drain(now, METRICS.active_connection_count()) {
last_send = now;
METRICS.add_message(msg.message_type());
log::debug!(target: "notify_push::send", "Sending debounced {msg} to {user_id}");
Expand Down
69 changes: 44 additions & 25 deletions src/message.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -59,13 +59,21 @@ impl PushMessage {
}
}

pub fn debounce_time(&self, connection_count: usize, max_debounce_time: usize) -> Duration {
pub fn debounce_time(
&self,
connection_count: usize,
max_debounce_time: usize,
debounce_factor: f32,
) -> Duration {
// scale the debounce time between 1s and 15s based on the number of active connections
// this provide a decent balance between performance and load
let time = max(1, min(connection_count / 10, max_debounce_time));
// this provides a decent balance between performance and load.
// Additionally, each connection will have a random debounce_factor between 0.5 and 1.5
// to spread out the load of notifications.
let time = max(1, min(connection_count / 10, max_debounce_time)) as f32;
let time = time * debounce_factor;
match self {
PushMessage::File(_) => Duration::from_secs(time as u64),
PushMessage::Activity => Duration::from_secs(time as u64),
PushMessage::File(_) => Duration::from_secs_f32(time),
PushMessage::Activity => Duration::from_secs_f32(time),
PushMessage::Notification => Duration::from_secs(1),
PushMessage::Custom(..) => Duration::from_millis(1), // no debouncing for custom messages
}
Expand Down Expand Up @@ -132,14 +140,23 @@ impl Default for SendQueueItem {
}
}

#[derive(Default, Debug)]
/// Queue for sending outgoing messages to a user for debounce
///
/// The server maintains once queue per connection
#[derive(Debug)]
pub struct SendQueue {
max_debounce_time: usize,
debounce_factor: f32,
items: [SendQueueItem; 3],
}

impl SendQueue {
pub fn new() -> Self {
SendQueue::default()
pub fn new(max_debounce_time: usize, debounce_factor: f32) -> Self {
SendQueue {
max_debounce_time,
debounce_factor,
items: Default::default(),
}
}

fn item_mut(&mut self, message: &PushMessage) -> Option<&mut SendQueueItem> {
Expand Down Expand Up @@ -177,13 +194,15 @@ impl SendQueue {
&mut self,
now: Instant,
connection_count: usize,
max_debounce_time: usize,
) -> impl Iterator<Item = PushMessage> + '_ {
let max_debounce_time = self.max_debounce_time;
let debounce_factor = self.debounce_factor;
self.items.iter_mut().filter_map(move |item| {
let debounce_time = item
.message
.as_ref()?
.debounce_time(connection_count, max_debounce_time);
let debounce_time = item.message.as_ref()?.debounce_time(
connection_count,
max_debounce_time,
debounce_factor,
);
if now.duration_since(item.sent) > debounce_time {
if now.duration_since(item.received) > Duration::from_millis(100) {
item.sent = now;
Expand All @@ -201,7 +220,7 @@ impl SendQueue {
#[test]
fn test_send_queue_100() {
let base_time = Instant::now();
let mut queue = SendQueue::new();
let mut queue = SendQueue::new(15, 1.0);
queue.push(PushMessage::Activity, base_time);
queue.push(
PushMessage::File(UpdatedFiles::Known(vec![1].into())),
Expand All @@ -216,7 +235,7 @@ fn test_send_queue_100() {
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_millis(20), 100, 15)
.drain(base_time + Duration::from_millis(20), 100)
.collect::<Vec<_>>()
);

Expand All @@ -227,7 +246,7 @@ fn test_send_queue_100() {
PushMessage::Activity
],
queue
.drain(base_time + Duration::from_millis(200), 100, 15)
.drain(base_time + Duration::from_millis(200), 100)
.collect::<Vec<_>>()
);

Expand All @@ -243,31 +262,31 @@ fn test_send_queue_100() {
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_secs(10), 100, 15)
.drain(base_time + Duration::from_secs(10), 100)
.collect::<Vec<_>>()
);

// after debounce time we get the merged messages from the timeframe
assert_eq!(
vec![PushMessage::File(UpdatedFiles::Known(vec![3, 4].into()))],
queue
.drain(base_time + Duration::from_secs(70), 100, 15)
.drain(base_time + Duration::from_secs(70), 100)
.collect::<Vec<_>>()
);

// nothing left
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_secs(300), 100, 15)
.drain(base_time + Duration::from_secs(300), 100)
.collect::<Vec<_>>()
);
}

#[test]
fn test_send_queue_1() {
let base_time = Instant::now();
let mut queue = SendQueue::new();
let mut queue = SendQueue::new(15, 1.0);
queue.push(PushMessage::Activity, base_time);
queue.push(
PushMessage::File(UpdatedFiles::Known(vec![1].into())),
Expand All @@ -282,7 +301,7 @@ fn test_send_queue_1() {
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_millis(20), 1, 15)
.drain(base_time + Duration::from_millis(20), 1)
.collect::<Vec<_>>()
);

Expand All @@ -293,7 +312,7 @@ fn test_send_queue_1() {
PushMessage::Activity
],
queue
.drain(base_time + Duration::from_millis(200), 1, 15)
.drain(base_time + Duration::from_millis(200), 1)
.collect::<Vec<_>>()
);

Expand All @@ -309,23 +328,23 @@ fn test_send_queue_1() {
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_secs(1), 1, 15)
.drain(base_time + Duration::from_secs(1), 1)
.collect::<Vec<_>>()
);

// after debounce time we get the merged messages from the timeframe
assert_eq!(
vec![PushMessage::File(UpdatedFiles::Known(vec![3, 4].into()))],
queue
.drain(base_time + Duration::from_secs(3), 1, 15)
.drain(base_time + Duration::from_secs(3), 1)
.collect::<Vec<_>>()
);

// nothing left
assert_eq!(
Vec::<PushMessage>::new(),
queue
.drain(base_time + Duration::from_secs(5), 1, 15)
.drain(base_time + Duration::from_secs(5), 1)
.collect::<Vec<_>>()
);
}