test: use vectored impl for singular gets in tests

.github/workflows/build_and_test.yml

@@ -477,6 +477,7 @@ jobs:
           BUILD_TAG: ${{ needs.tag.outputs.build-tag }}
           PAGESERVER_VIRTUAL_FILE_IO_ENGINE: tokio-epoll-uring
           PAGESERVER_GET_VECTORED_IMPL: vectored
+          PAGESERVER_GET_IMPL: vectored
 
       # Temporary disable this step until we figure out why it's so flaky
       # Ref https://github.com/neondatabase/neon/issues/4540

control_plane/src/local_env.rs

@@ -129,6 +129,7 @@ pub struct PageServerConf {
 
     pub(crate) virtual_file_io_engine: Option<String>,
     pub(crate) get_vectored_impl: Option<String>,
+    pub(crate) get_impl: Option<String>,
 }
 
 impl Default for PageServerConf {
@@ -141,6 +142,7 @@ impl Default for PageServerConf {
             http_auth_type: AuthType::Trust,
             virtual_file_io_engine: None,
             get_vectored_impl: None,
+            get_impl: None,
         }
     }
 }

control_plane/src/pageserver.rs

@@ -92,6 +92,7 @@ impl PageServerNode {
             http_auth_type,
             virtual_file_io_engine,
             get_vectored_impl,
+            get_impl,
         } = &self.conf;
 
         let id = format!("id={}", id);
@@ -111,6 +112,11 @@ impl PageServerNode {
         } else {
             String::new()
         };
+        let get_impl = if let Some(get_impl) = get_impl {
+            format!("get_impl='{get_impl}'")
+        } else {
+            String::new()
+        };
 
         let broker_endpoint_param = format!("broker_endpoint='{}'", self.env.broker.client_url());
 
@@ -124,6 +130,7 @@ impl PageServerNode {
             broker_endpoint_param,
             virtual_file_io_engine,
             get_vectored_impl,
+            get_impl,
         ];
 
         if let Some(control_plane_api) = &self.env.control_plane_api {

test_runner/fixtures/neon_fixtures.py

@@ -507,6 +507,11 @@ class NeonEnvBuilder:
             self.pageserver_get_vectored_impl = "vectored"
             log.debug('Overriding pageserver get_vectored_impl config to "vectored"')
 
+        self.pageserver_get_impl: Optional[str] = None
+        if os.getenv("PAGESERVER_GET_IMPL", "") == "vectored":
+            self.pageserver_get_impl = "vectored"
+            log.debug('Overriding pageserver get_impl config to "vectored"')
+
         assert test_name.startswith(
             "test_"
         ), "Unexpectedly instantiated from outside a test function"
@@ -1078,6 +1083,8 @@ class NeonEnv:
                 ps_cfg["virtual_file_io_engine"] = self.pageserver_virtual_file_io_engine
             if config.pageserver_get_vectored_impl is not None:
                 ps_cfg["get_vectored_impl"] = config.pageserver_get_vectored_impl
+            if config.pageserver_get_impl is not None:
+                ps_cfg["get_impl"] = config.pageserver_get_impl
 
             # Create a corresponding NeonPageserver object
             self.pageservers.append(