start federation based on latest id at the time

crates/federate/src/federation_queue_state.rs

@@ -17,7 +17,7 @@ pub struct FederationQueueState {
 }
 
 impl FederationQueueState {
-  /// load or return a default empty value
+  /// load state or return a default empty value
   pub async fn load(pool: &mut DbPool<'_>, domain_: &str) -> Result<FederationQueueState> {
     use lemmy_db_schema::schema::federation_queue_state::dsl::{domain, federation_queue_state};
     let conn = &mut get_conn(pool).await?;
@@ -32,7 +32,7 @@ impl FederationQueueState {
           domain: domain_.to_owned(),
           fail_count: 0,
           last_retry: Utc.timestamp_nanos(0),
-          last_successful_id: 0, // todo: start at current id not from beginning
+          last_successful_id: 0, // this value is set to the most current id for new instances
         }),
     )
   }

crates/federate/src/worker.rs

@@ -105,6 +105,13 @@ impl InstanceWorker {
   }
   async fn loop_batch(&mut self, pool: &mut DbPool<'_>) -> Result<()> {
     let latest_id = get_latest_activity_id(pool).await?;
+    if self.state.last_successful_id == 0 {
+      // this is the initial creation (instance first seen) of the federation queue for this instance
+      // skip all past activities:
+      self.state.last_successful_id = latest_id;
+      // save here to ensure it's not read as 0 again later if no activities have happened
+      self.save_and_send_state(pool).await?;
+    }
     let mut id = self.state.last_successful_id;
     if id == latest_id {
       // no more work to be done, wait before rechecking