Use neon.primary_is_running GUC for replica startup

control_plane/src/endpoint.rs

@@ -307,6 +307,9 @@ impl Endpoint {
         // Load the 'neon' extension
         conf.append("shared_preload_libraries", "neon");
 
+		// It is only for testing, in real environment this GUC is passed by control plane
+		conf.append("neon.primary_is_running", "on");
+
         conf.append_line("");
         // Replication-related configurations, such as WAL sending
         match &self.mode {

pgxn/neon/neon.c

@@ -30,6 +30,8 @@
 PG_MODULE_MAGIC;
 void		_PG_init(void);
 
+bool primary_is_running = false;
+
 void
 _PG_init(void)
 {
@@ -48,6 +50,16 @@ _PG_init(void)
 
 	pg_init_extension_server();
 
+	DefineCustomBoolVariable(
+		"neon.primary_is_running",
+		"For replica it is true, if primary is running, false otherwise",
+		NULL,
+		&primary_is_running,
+		false,
+		PGC_POSTMASTER,
+		0,
+		NULL, NULL, NULL);
+
 	/*
 	 * Important: This must happen after other parts of the extension are
 	 * loaded, otherwise any settings to GUCs that were set before the

vendor/revisions.json

@@ -1,5 +1,5 @@
 {
-    "postgres-v16": "0d4eb408a1242f8564ba2bfa57a1ea601dc99a4c",
-    "postgres-v15": "d4d552ce42e40f29909f1c6613c57ecda6ea6933",
-    "postgres-v14": "23a19fe0a4f6e56f4540afabe6825281c9d02cd1"
+    "postgres-v16": "3f96a5b0c70e48b9142f0c9b496c7c04c93bec8b",
+    "postgres-v15": "e2a0a8aa75ff2fa70af87cb86ba6fb7f575e3155",
+    "postgres-v14": "7eb44da047e68cf6785d27388c482abd02fe2a2d"
 }