Basic workflow for client PUT, next is do actual storage

src/rpc_client.rs

@@ -16,7 +16,6 @@ use crate::membership::System;
 pub async fn rpc_call_many(sys: Arc<System>,
 						   to: &[UUID],
 						   msg: &Message,
-						   stop_after: Option<usize>,
 						   timeout: Duration)
 	-> Vec<Result<Message, Error>>
 {
@@ -25,19 +24,49 @@ pub async fn rpc_call_many(sys: Arc<System>,
 		.collect::<FuturesUnordered<_>>();
 
 	let mut results = vec![];
-	let mut n_ok = 0;
 	while let Some(resp) = resp_stream.next().await {
-		if resp.is_ok() {
-			n_ok += 1
-		}
 		results.push(resp);
-		if let Some(n) = stop_after {
-			if n_ok >= n {
-				break
+	}
+	results
+}
+
+pub async fn rpc_try_call_many(sys: Arc<System>,
+						       to: &[UUID],
+						       msg: &Message,
+						       stop_after: usize,
+						       timeout: Duration)
+	-> Result<Vec<Message>, Error>
+{
+	let mut resp_stream = to.iter()
+		.map(|to| rpc_call(sys.clone(), to, msg, timeout))
+		.collect::<FuturesUnordered<_>>();
+
+	let mut results = vec![];
+	let mut errors = vec![];
+
+	while let Some(resp) = resp_stream.next().await {
+		match resp {
+			Ok(msg) => {
+				results.push(msg);
+				if results.len() >= stop_after {
+					break
+				}
+			}
+			Err(e) => {
+				errors.push(e);
 			}
 		}
 	}
-	results
+
+	if results.len() >= stop_after {
+		Ok(results)
+	} else {
+		let mut msg = "Too many failures:".to_string();
+		for e in errors {
+			msg += &format!("\n{}", e);
+		}
+		Err(Error::Message(msg))
+	}
 }
 
 pub async fn rpc_call(sys: Arc<System>,