From 2e0f8138e2e343fbd302a64ff3ef7cb9f5ad7bca Mon Sep 17 00:00:00 2001
From: Luke Parker <lukeparker5132@gmail.com>
Date: Tue, 26 Sep 2023 23:28:05 -0400
Subject: [PATCH] Update the coordinator to not handle a processor message
 multiple times

---
 coordinator/src/db.rs   | 10 ++++++++++
 coordinator/src/main.rs | 12 ++++++++++--
 2 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/coordinator/src/db.rs b/coordinator/src/db.rs
index 67566e53..43bd4cb0 100644
--- a/coordinator/src/db.rs
+++ b/coordinator/src/db.rs
@@ -16,6 +16,16 @@ impl<'a, D: Db> MainDb<'a, D> {
     D::key(b"coordinator_main", dst, key)
   }
 
+  fn handled_message_key(id: u64) -> Vec<u8> {
+    Self::main_key(b"handled_message", id.to_le_bytes())
+  }
+  pub fn save_handled_message(txn: &mut D::Transaction<'_>, id: u64) {
+    txn.put(Self::handled_message_key(id), []);
+  }
+  pub fn handled_message<G: Get>(getter: &G, id: u64) -> bool {
+    getter.get(Self::handled_message_key(id)).is_some()
+  }
+
   fn acive_tributaries_key() -> Vec<u8> {
     Self::main_key(b"active_tributaries", [])
   }
diff --git a/coordinator/src/main.rs b/coordinator/src/main.rs
index 0a75c16d..d08a43d1 100644
--- a/coordinator/src/main.rs
+++ b/coordinator/src/main.rs
@@ -524,6 +524,7 @@ pub async fn handle_processors<D: Db, Pro: Processors, P: P2p>(
 
   let channels = Arc::new(RwLock::new(HashMap::new()));
   tokio::spawn({
+    let db = db.clone();
     let processors = processors.clone();
     let channels = channels.clone();
     async move {
@@ -849,6 +850,11 @@ pub async fn handle_processors<D: Db, Pro: Processors, P: P2p>(
                 }
               }
 
+              // TODO: Consider a global txn for this message?
+              let mut txn = db.txn();
+              MainDb::<'static, D>::save_handled_message(&mut txn, msg.id);
+              txn.commit();
+
               processors.ack(msg).await;
             }
           }
@@ -864,9 +870,11 @@ pub async fn handle_processors<D: Db, Pro: Processors, P: P2p>(
     // Modify message-queue to offer per-sender queues, not per-receiver.
     // Alternatively, a peek method with local delineation of handled messages would work.
 
-    // TODO: Do we handle having handled a message, by DB, yet having rebooted before `ack`ing it?
-    // Does the processor?
     let msg = processors.recv().await;
+    if MainDb::<'static, D>::handled_message(&db, msg.id) {
+      processors.ack(msg).await;
+      continue;
+    }
     if last_msg == Some(msg.id) {
       sleep(Duration::from_secs(1)).await;
       continue;