RequestStrategy with possible interruption or not

TODO

@@ -12,10 +12,6 @@ Membership: keep IP addresses of failed nodes and try to reping them regularly
 
 RPC client/server: do not go through the serialization+HTTP+TLS+deserialization when doing a request to ourself.
 
-RPC requests: unify quorum + timeout in a "RequestStrategy" class,
-and add to the request strategy whether or not the request should continue in the background
-once `quorum` valid responses have been received
-
 
 Attaining S3 compatibility
 --------------------------

src/block.rs

@@ -317,7 +317,7 @@ impl BlockManager {
 								e
 							)));
 						}
-						_ => {
+						Ok(_) => {
 							return Err(Error::Message(format!(
 								"Unexpected response to NeedBlockQuery RPC"
 							)));
@@ -327,13 +327,14 @@ impl BlockManager {
 
 				if need_nodes.len() > 0 {
 					let put_block_message = self.read_block(hash).await?;
-					let put_responses = self
-						.rpc_client
-						.call_many(&need_nodes[..], put_block_message, BLOCK_RW_TIMEOUT)
-						.await;
-					for resp in put_responses {
-						resp?;
-					}
+					self.rpc_client
+						.try_call_many(
+							&need_nodes[..],
+							put_block_message,
+							RequestStrategy::with_quorum(need_nodes.len())
+								.with_timeout(BLOCK_RW_TIMEOUT),
+						)
+						.await?;
 				}
 			}
 			fs::remove_file(path).await?;
@@ -354,19 +355,22 @@ impl BlockManager {
 	pub async fn rpc_get_block(&self, hash: &Hash) -> Result<Vec<u8>, Error> {
 		let ring = self.system.ring.borrow().clone();
 		let who = ring.walk_ring(&hash, self.system.config.data_replication_factor);
-		let msg = Arc::new(Message::GetBlock(*hash));
-		let mut resp_stream = who
-			.iter()
-			.map(|to| self.rpc_client.call(to, msg.clone(), BLOCK_RW_TIMEOUT))
-			.collect::<FuturesUnordered<_>>();
+		let resps = self
+			.rpc_client
+			.try_call_many(
+				&who[..],
+				Message::GetBlock(*hash),
+				RequestStrategy::with_quorum(1)
+					.with_timeout(BLOCK_RW_TIMEOUT)
+					.interrupt_after_quorum(true),
+			)
+			.await?;
 
-		while let Some(resp) = resp_stream.next().await {
-			if let Ok(Message::PutBlock(msg)) = resp {
-				if data::hash(&msg.data[..]) == *hash {
+		for resp in resps {
+			if let Message::PutBlock(msg) = resp {
 				return Ok(msg.data);
 			}
 		}
-		}
 		Err(Error::Message(format!(
 			"Unable to read block {:?}: no valid blocks returned",
 			hash
@@ -380,8 +384,8 @@ impl BlockManager {
 			.try_call_many(
 				&who[..],
 				Message::PutBlock(PutBlockMessage { hash, data }),
-				(self.system.config.data_replication_factor + 1) / 2,
-				BLOCK_RW_TIMEOUT,
+				RequestStrategy::with_quorum((self.system.config.data_replication_factor + 1) / 2)
+					.with_timeout(BLOCK_RW_TIMEOUT),
 			)
 			.await?;
 		Ok(())

src/rpc_client.rs

@@ -20,6 +20,33 @@ use crate::rpc_server::RpcMessage;
 use crate::server::TlsConfig;
 use crate::tls_util;
 
+const DEFAULT_TIMEOUT: Duration = Duration::from_secs(10);
+
+#[derive(Copy, Clone)]
+pub struct RequestStrategy {
+	pub rs_timeout: Duration,
+	pub rs_quorum: usize,
+	pub rs_interrupt_after_quorum: bool,
+}
+
+impl RequestStrategy {
+	pub fn with_quorum(quorum: usize) -> Self {
+		RequestStrategy {
+			rs_timeout: DEFAULT_TIMEOUT,
+			rs_quorum: quorum,
+			rs_interrupt_after_quorum: false,
+		}
+	}
+	pub fn with_timeout(mut self, timeout: Duration) -> Self {
+		self.rs_timeout = timeout;
+		self
+	}
+	pub fn interrupt_after_quorum(mut self, interrupt: bool) -> Self {
+		self.rs_interrupt_after_quorum = interrupt;
+		self
+	}
+}
+
 pub struct RpcClient<M: RpcMessage> {
 	status: watch::Receiver<Arc<Status>>,
 	background: Arc<BackgroundRunner>,
@@ -83,9 +110,10 @@ impl<M: RpcMessage + 'static> RpcClient<M> {
 		self: &Arc<Self>,
 		to: &[UUID],
 		msg: M,
-		stop_after: usize,
-		timeout: Duration,
+		strategy: RequestStrategy,
 	) -> Result<Vec<M>, Error> {
+		let timeout = strategy.rs_timeout;
+
 		let msg = Arc::new(msg);
 		let mut resp_stream = to
 			.to_vec()
@@ -104,7 +132,7 @@ impl<M: RpcMessage + 'static> RpcClient<M> {
 			match resp {
 				Ok(msg) => {
 					results.push(msg);
-					if results.len() >= stop_after {
+					if results.len() >= strategy.rs_quorum {
 						break;
 					}
 				}
@@ -114,16 +142,15 @@ impl<M: RpcMessage + 'static> RpcClient<M> {
 			}
 		}
 
-		if results.len() >= stop_after {
-			// Continue requests in background
-			// TODO: make this optionnal (only usefull for write requests)
-
+		if results.len() >= strategy.rs_quorum {
+			// Continue requests in background.
 			// Continue the remaining requests immediately using tokio::spawn
 			// but enqueue a task in the background runner
 			// to ensure that the process won't exit until the requests are done
 			// (if we had just enqueued the resp_stream.collect directly in the background runner,
 			// the requests might have been put on hold in the background runner's queue,
 			// in which case they might timeout or otherwise fail)
+			if !strategy.rs_interrupt_after_quorum {
 				let wait_finished_fut = tokio::spawn(async move {
 					resp_stream.collect::<Vec<_>>().await;
 					Ok(())
@@ -131,6 +158,7 @@ impl<M: RpcMessage + 'static> RpcClient<M> {
 				self.clone().background.spawn(wait_finished_fut.map(|x| {
 					x.unwrap_or_else(|e| Err(Error::Message(format!("Await failed: {}", e))))
 				}));
+			}
 
 			Ok(results)
 		} else {

src/table.rs

@@ -179,8 +179,8 @@ where
 			.try_call_many(
 				&who[..],
 				rpc,
-				self.replication.write_quorum(),
-				TABLE_RPC_TIMEOUT,
+				RequestStrategy::with_quorum(self.replication.write_quorum())
+					.with_timeout(TABLE_RPC_TIMEOUT),
 			)
 			.await?;
 		Ok(())
@@ -237,8 +237,9 @@ where
 			.try_call_many(
 				&who[..],
 				rpc,
-				self.replication.read_quorum(),
-				TABLE_RPC_TIMEOUT,
+				RequestStrategy::with_quorum(self.replication.read_quorum())
+					.with_timeout(TABLE_RPC_TIMEOUT)
+					.interrupt_after_quorum(true),
 			)
 			.await?;
 
@@ -292,8 +293,9 @@ where
 			.try_call_many(
 				&who[..],
 				rpc,
-				self.replication.read_quorum(),
-				TABLE_RPC_TIMEOUT,
+				RequestStrategy::with_quorum(self.replication.read_quorum())
+					.with_timeout(TABLE_RPC_TIMEOUT)
+					.interrupt_after_quorum(true),
 			)
 			.await?;
 
@@ -347,8 +349,7 @@ where
 			.try_call_many(
 				&who[..],
 				TableRPC::<F>::Update(vec![what_enc]),
-				who.len(),
-				TABLE_RPC_TIMEOUT,
+				RequestStrategy::with_quorum(who.len()).with_timeout(TABLE_RPC_TIMEOUT),
 			)
 			.await?;
 		Ok(())