Coordinator: spawn async task for expensive hash work

Author: DAlperin

src/adapter/src/coord/command_handler.rs

@@ -544,15 +544,20 @@ impl Coordinator {
             }
             if let Some(auth) = self.catalog().try_get_role_auth_by_id(&role.id) {
                 if let Some(hash) = &auth.password_hash {
-                    let _ = match mz_auth::hash::scram256_verify(&password, hash) {
-                        Ok(_) => tx.send(Ok(AuthResponse {
-                            role_id: role.id,
-                            superuser: role.attributes.superuser.unwrap_or(false),
-                        })),
-                        Err(_) => tx.send(Err(AdapterError::AuthenticationError(
-                            AuthenticationError::InvalidCredentials,
-                        ))),
-                    };
+                    let hash = hash.clone();
+                    let role_id = role.id;
+                    let superuser = role.attributes.superuser.unwrap_or(false);
+                    task::spawn_blocking(
+                        || "auth-check-hash",
+                        move || {
+                            let _ = match mz_auth::hash::scram256_verify(&password, &hash) {
+                                Ok(_) => tx.send(Ok(AuthResponse { role_id, superuser })),
+                                Err(_) => tx.send(Err(AdapterError::AuthenticationError(
+                                    AuthenticationError::InvalidCredentials,
+                                ))),
+                            };
+                        },
+                    );
                     return;
                 }
             }