From 2d570f01e4fe8b491514e10d04a189cb101a321f Mon Sep 17 00:00:00 2001
From: Morgan Mccauley <morgan@mccauley.co.nz>
Date: Mon, 4 Dec 2023 13:56:50 +1300
Subject: [PATCH] fix: Prevent duplicate block streams from starting

---
 .../src/server/block_streamer_service.rs      | 26 ++++++++++++-------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/block-streamer/src/server/block_streamer_service.rs b/block-streamer/src/server/block_streamer_service.rs
index 4e9cbe67c..79fd1b541 100644
--- a/block-streamer/src/server/block_streamer_service.rs
+++ b/block-streamer/src/server/block_streamer_service.rs
@@ -45,6 +45,14 @@ impl BlockStreamerService {
             block_streams: Mutex::new(HashMap::new()),
         }
     }
+
+    fn get_block_streams_lock(
+        &self,
+    ) -> Result<std::sync::MutexGuard<HashMap<String, block_stream::BlockStream>>, Status> {
+        self.block_streams
+            .lock()
+            .map_err(|err| Status::internal(format!("Failed to acquire lock: {}", err)))
+    }
 }
 
 #[tonic::async_trait]
@@ -98,6 +106,12 @@ impl blockstreamer::block_streamer_server::BlockStreamer for BlockStreamerServic
             indexer_rule: filter_rule,
         };
 
+        let lock = self.get_block_streams_lock()?;
+        match lock.get(&indexer_config.get_hash_id()) {
+            Some(_) => return Err(Status::already_exists("Block stream already exists")),
+            None => drop(lock),
+        }
+
         let mut block_stream =
             block_stream::BlockStream::new(indexer_config.clone(), self.chain_id.clone());
 
@@ -107,12 +121,9 @@ impl blockstreamer::block_streamer_server::BlockStreamer for BlockStreamerServic
                 self.redis_connection_manager.clone(),
                 self.delta_lake_client.clone(),
             )
-            .map_err(|_| Status::already_exists("Block stream already exists"))?;
+            .map_err(|_| Status::internal("Failed to start block stream"))?;
 
-        let mut lock = self
-            .block_streams
-            .lock()
-            .map_err(|err| Status::internal(format!("Failed to acquire lock: {}", err)))?;
+        let mut lock = self.get_block_streams_lock()?;
         lock.insert(indexer_config.get_hash_id(), block_stream);
 
         Ok(Response::new(blockstreamer::StartStreamResponse {
@@ -129,10 +140,7 @@ impl blockstreamer::block_streamer_server::BlockStreamer for BlockStreamerServic
         let stream_id = request.stream_id;
 
         let exising_block_stream = {
-            let mut lock = self
-                .block_streams
-                .lock()
-                .map_err(|err| Status::internal(format!("Failed to acquire lock: {}", err)))?;
+            let mut lock = self.get_block_streams_lock()?;
             lock.remove(&stream_id)
         };