feat(coordinator): Notify traders after new funding rate is inserted

After an update to the `funding_rates` table, there is no guarantee
that the next funding rate has changed, but sending the message
unconditionally is simpler and should cause no problems.

Author: luckysori

coordinator/src/funding_fee.rs

@@ -18,18 +18,19 @@ use std::time::Duration;
 use time::ext::NumericalDuration;
 use time::format_description;
 use time::OffsetDateTime;
+use tokio::sync::broadcast;
 use tokio::task::block_in_place;
 use tokio_cron_scheduler::JobScheduler;
 use xxi_node::commons::ContractSymbol;
 use xxi_node::commons::Direction;
+use xxi_node::commons::FundingRate;
 use xxi_node::commons::Message;
 
 mod db;
 
 pub use db::get_funding_fee_events_for_active_trader_positions;
 pub use db::get_next_funding_rate;
 pub use db::get_outstanding_funding_fee_events;
-pub use db::insert_funding_rates;
 pub use db::insert_protocol_funding_fee_event;
 pub use db::mark_funding_fee_event_as_paid;
 
@@ -312,6 +313,26 @@ pub fn funding_fee_from_funding_fee_events(events: &[FundingFeeEvent]) -> Fundin
     }
 }
 
+pub fn insert_funding_rates(
+    conn: &mut PgConnection,
+    tx_orderbook_feed: broadcast::Sender<Message>,
+    funding_rates: &[FundingRate],
+) -> Result<()> {
+    db::insert_funding_rates(conn, funding_rates)?;
+
+    // There is no guarantee that the next funding rate has changed, but sending the message
+    // unconditionally is simpler and should cause no problems.
+    let next_funding_rate = get_next_funding_rate(conn)?;
+
+    if let Some(next_funding_rate) = next_funding_rate {
+        if let Err(e) = tx_orderbook_feed.send(Message::NextFundingRate(next_funding_rate)) {
+            tracing::error!("Failed to notify traders about next funding rate: {e}");
+        }
+    }
+
+    Ok(())
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

coordinator/src/routes/admin.rs

@@ -685,7 +685,7 @@ pub async fn post_funding_rates(
             .map(xxi_node::commons::FundingRate::from)
             .collect::<Vec<_>>();
 
-        insert_funding_rates(&mut conn, &funding_rates)
+        insert_funding_rates(&mut conn, state.tx_orderbook_feed.clone(), &funding_rates)
             .map_err(|e| AppError::BadRequest(format!("{e:#}")))?;
 
         Ok(())