Increase priority of timer over txpool event (#2345)

If TxPool has a lot of events, it will interrupt the work of the timer.

### Before requesting review
- [x] I have reviewed the code myself

---------

Co-authored-by: AurelienFT <32803821+AurelienFT@users.noreply.github.com>
Co-authored-by: AurelienFT <aurefook@gmail.com>

CHANGELOG.md

@@ -8,8 +8,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Added
 - [2350](https://github.com/FuelLabs/fuel-core/pull/2350): Added a new CLI flag `graphql-number-of-threads` to limit the number of threads used by the GraphQL service. The default value is `2`, `0` enables the old behavior.
 
-### Changed
+### Fixed
+- [2345](https://github.com/FuelLabs/fuel-core/pull/2345): In PoA increase priority of block creation timer trigger compare to txpool event management
 
+### Changed
 - [2334](https://github.com/FuelLabs/fuel-core/pull/2334): Prepare the GraphQL service for the switching to `async` methods.
 - [2350](https://github.com/FuelLabs/fuel-core/pull/2350): Limited the number of threads used by the GraphQL service.
 

crates/services/consensus_module/poa/src/service.rs

@@ -573,10 +573,6 @@ where
                     should_continue = false;
                 }
             }
-            _ = self.new_txs_watcher.changed() => {
-                self.on_txpool_event().await.context("While processing txpool event")?;
-                should_continue = true;
-            }
             _ = next_block_production => {
                 match self.on_timer().await.context("While processing timer event") {
                     Ok(()) => should_continue = true,
@@ -587,6 +583,10 @@ where
                     }
                 };
             }
+            _ = self.new_txs_watcher.changed() => {
+                self.on_txpool_event().await.context("While processing txpool event")?;
+                should_continue = true;
+            }
         }
 
         Ok(should_continue)

crates/services/consensus_module/poa/src/service_test/trigger_tests.rs

@@ -478,3 +478,32 @@ async fn interval_trigger_produces_blocks_in_the_future_when_time_rewinds() {
     // similarly to how it works when time is lagging.
     assert_eq!(second_block_time, start_time + block_time.as_secs() * 2);
 }
+
+#[tokio::test]
+async fn interval_trigger_even_if_queued_tx_events() {
+    let block_time = Duration::from_secs(2);
+    let mut ctx = DefaultContext::new(Config {
+        trigger: Trigger::Interval { block_time },
+        signer: SignMode::Key(test_signing_key()),
+        metrics: false,
+        ..Default::default()
+    })
+    .await;
+    let block_creation_notifier = Arc::new(Notify::new());
+    tokio::task::spawn({
+        let notifier = ctx.new_txs_notifier.clone();
+        async move {
+            loop {
+                time::sleep(Duration::from_nanos(10)).await;
+                notifier.send_replace(());
+            }
+        }
+    });
+    let block_creation_waiter = block_creation_notifier.clone();
+    tokio::task::spawn(async move {
+        ctx.block_import.recv().await.unwrap();
+        dbg!("First block produced");
+        block_creation_notifier.notify_waiters();
+    });
+    block_creation_waiter.notified().await;
+}