cluster: create constants for default config values

Author: muzarski

scylla-rust-wrapper/src/cluster.rs

@@ -26,6 +26,12 @@ use std::time::Duration;
 
 include!(concat!(env!("OUT_DIR"), "/cppdriver_compression_types.rs"));
 
+// According to `cassandra.h` the default CPP driver's
+// - consistency for statements is LOCAL_ONE,
+// - request client timeout is 12000 millis.
+const DEFAULT_CONSISTENCY: Consistency = Consistency::LocalOne;
+const DEFAULT_REQUEST_TIMEOUT_MILLIS: u64 = 12000;
+
 #[derive(Clone, Debug)]
 pub(crate) struct LoadBalancingConfig {
     pub(crate) token_awareness_enabled: bool,
@@ -115,12 +121,9 @@ pub fn build_session_builder(
 
 #[no_mangle]
 pub unsafe extern "C" fn cass_cluster_new() -> *mut CassCluster {
-    // According to `cassandra.h` the default CPP driver's
-    // - consistency for statements is LOCAL_ONE,
-    // - request client timeout is 12000 millis.
     let default_execution_profile_builder = ExecutionProfileBuilder::default()
-        .consistency(Consistency::LocalOne)
-        .request_timeout(Some(Duration::from_millis(12000)));
+        .consistency(DEFAULT_CONSISTENCY)
+        .request_timeout(Some(Duration::from_millis(DEFAULT_REQUEST_TIMEOUT_MILLIS)));
 
     Box::into_raw(Box::new(CassCluster {
         session_builder: SessionBuilder::new(),