Added ReadOnly session attr

Author: chandr-andr

tokio-postgres/src/config.rs

@@ -34,6 +34,8 @@ pub enum TargetSessionAttrs {
     Any,
     /// The session must allow writes.
     ReadWrite,
+    /// The session allow only reads.
+    ReadOnly,
 }
 
 /// TLS configuration.
@@ -622,6 +624,7 @@ impl Config {
                 let target_session_attrs = match value {
                     "any" => TargetSessionAttrs::Any,
                     "read-write" => TargetSessionAttrs::ReadWrite,
+                    "read-only" => TargetSessionAttrs::ReadOnly,
                     _ => {
                         return Err(Error::config_parse(Box::new(InvalidValue(
                             "target_session_attrs",

tokio-postgres/tests/test/parse.rs

@@ -34,6 +34,14 @@ fn settings() {
             .keepalives_idle(Duration::from_secs(30))
             .target_session_attrs(TargetSessionAttrs::ReadWrite),
     );
+    check(
+        "connect_timeout=3 keepalives=0 keepalives_idle=30 target_session_attrs=read-only",
+        Config::new()
+            .connect_timeout(Duration::from_secs(3))
+            .keepalives(false)
+            .keepalives_idle(Duration::from_secs(30))
+            .target_session_attrs(TargetSessionAttrs::ReadOnly),
+    );
 }
 
 #[test]