From f860086c7c28db71c610c6185ffd5b2c4e8900df Mon Sep 17 00:00:00 2001
From: samuel orji <awesomeorji@gmail.com>
Date: Tue, 17 Oct 2023 16:08:20 +0100
Subject: [PATCH] review feedback

---
 scylla-cql/src/errors.rs                       | 14 +++++++-------
 scylla/src/transport/load_balancing/default.rs |  2 +-
 scylla/src/transport/session.rs                | 12 ++++++++----
 scylla/src/transport/session_test.rs           |  5 +----
 4 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/scylla-cql/src/errors.rs b/scylla-cql/src/errors.rs
index 957696ed1d..b93d4520db 100644
--- a/scylla-cql/src/errors.rs
+++ b/scylla-cql/src/errors.rs
@@ -46,9 +46,9 @@ pub enum QueryError {
     #[error("Request timeout: {0}")]
     RequestTimeout(String),
 
-    /// No known node found to perform query
-    #[error("No known node found: {0}")]
-    NoKnownNodeFoundError(String),
+    /// Empty Query Plan
+    #[error("Load balancing policy returned empty query plan. It can happen when the driver is provided with non-existing datacenter name")]
+    EmptyQueryPlan,
 
     /// Address translation failed
     #[error("Address translation failed: {0}")]
@@ -408,9 +408,9 @@ pub enum NewSessionError {
     #[error("Client timeout: {0}")]
     RequestTimeout(String),
 
-    /// No known node found to perform query
-    #[error("No known node found: {0}")]
-    NoKnownNodeFoundError(String),
+    /// Empty Query Plan
+    #[error("Load balancing policy returned empty query plan. It can happen when the driver is provided with non-existing datacenter name")]
+    EmptyQueryPlan,
 
     /// Address translation failed
     #[error("Address translation failed: {0}")]
@@ -490,7 +490,7 @@ impl From<QueryError> for NewSessionError {
             QueryError::UnableToAllocStreamId => NewSessionError::UnableToAllocStreamId,
             QueryError::RequestTimeout(msg) => NewSessionError::RequestTimeout(msg),
             QueryError::TranslationError(e) => NewSessionError::TranslationError(e),
-            QueryError::NoKnownNodeFoundError(e) => NewSessionError::NoKnownNodeFoundError(e),
+            QueryError::EmptyQueryPlan => NewSessionError::EmptyQueryPlan,
         }
     }
 }
diff --git a/scylla/src/transport/load_balancing/default.rs b/scylla/src/transport/load_balancing/default.rs
index e125f0ce34..a915890c26 100644
--- a/scylla/src/transport/load_balancing/default.rs
+++ b/scylla/src/transport/load_balancing/default.rs
@@ -2414,7 +2414,7 @@ mod latency_awareness {
                 | QueryError::IoError(_)
                 | QueryError::ProtocolError(_)
                 | QueryError::TimeoutError
-                | QueryError::NoKnownNodeFoundError(_)
+                | QueryError::EmptyQueryPlan
                 | QueryError::RequestTimeout(_) => true,
             }
         }
diff --git a/scylla/src/transport/session.rs b/scylla/src/transport/session.rs
index cf66fda436..5a8670018b 100644
--- a/scylla/src/transport/session.rs
+++ b/scylla/src/transport/session.rs
@@ -1661,15 +1661,15 @@ impl Session {
         QueryFut: Future<Output = Result<ResT, QueryError>>,
         ResT: AllowedRunQueryResTType,
     {
-        // set default error as no known found as the query plan returns an empty iterator if there are no nodes in the plan
-        let mut last_error: Option<QueryError> = Some(QueryError::NoKnownNodeFoundError(
-            "Please confirm the supplied datacenters exists".to_string(),
-        ));
+        let mut last_error: Option<QueryError> = None;
         let mut current_consistency: Consistency = context
             .consistency_set_on_statement
             .unwrap_or(execution_profile.consistency);
 
+        let mut query_plan_is_empty = true;
+
         'nodes_in_plan: for node in query_plan {
+            query_plan_is_empty = false;
             let span = trace_span!("Executing query", node = %node.address);
             'same_node_retries: loop {
                 trace!(parent: &span, "Execution started");
@@ -1772,6 +1772,10 @@ impl Session {
             }
         }
 
+        if query_plan_is_empty {
+            return Some(Err(QueryError::EmptyQueryPlan));
+        }
+
         last_error.map(Result::Err)
     }
 
diff --git a/scylla/src/transport/session_test.rs b/scylla/src/transport/session_test.rs
index e2e7fc14b3..dcf8dce03e 100644
--- a/scylla/src/transport/session_test.rs
+++ b/scylla/src/transport/session_test.rs
@@ -2886,8 +2886,5 @@ async fn test_non_existent_dc_return_correct_error() {
     let ks_stmt = format!("CREATE KEYSPACE IF NOT EXISTS {} WITH replication = {{'class': 'NetworkTopologyStrategy', '{}': 1}}", ks, dc);
     let query_result = session.query(ks_stmt, &[]).await;
 
-    assert_matches!(
-        query_result.unwrap_err(),
-        QueryError::NoKnownNodeFoundError(_)
-    )
+    assert_matches!(query_result.unwrap_err(), QueryError::EmptyQueryPlan)
 }