fix: fix the usage of service_engine::get_all_nodes()

src/replica/storage/simple_kv/test/checker.cpp

@@ -173,8 +173,8 @@ bool test_checker::init(const std::string &name, const std::vector<service_app *
         }
     }
 
-    auto nodes = ::dsn::service_engine::instance().get_all_nodes();
-    for (auto &node : nodes) {
+    const auto &nodes = dsn::service_engine::instance().get_all_nodes();
+    for (const auto &node : nodes) {
         int id = node.second->id();
         std::string name = node.second->full_name();
         rpc_address paddr = node.second->rpc()->primary_address();

src/runtime/service_api_c.cpp

@@ -208,8 +208,8 @@ DSN_API bool dsn_mimic_app(const char *app_role, int index)
         }
     }
 
-    auto nodes = ::dsn::service_engine::instance().get_all_nodes();
-    for (auto &n : nodes) {
+    const auto &nodes = dsn::service_engine::instance().get_all_nodes();
+    for (const auto &n : nodes) {
         if (n.second->spec().role_name == std::string(app_role) &&
             n.second->spec().index == index) {
             ::dsn::task::set_tls_dsn_context(n.second.get(), nullptr);
@@ -508,7 +508,7 @@ bool run(const char *config_file,
         }
     }
 
-    if (::dsn::service_engine::instance().get_all_nodes().size() == 0) {
+    if (dsn::service_engine::instance().get_all_nodes().size() == 0) {
         printf("no app are created, usually because \n"
                "app_name is not specified correctly, should be 'xxx' in [apps.xxx]\n"
                "or app_index (1-based) is greater than specified count in config file\n");

src/runtime/tool_api.cpp

@@ -80,8 +80,8 @@ tool_app::tool_app(const char *name) : tool_base(name) {}
 
 void tool_app::start_all_apps()
 {
-    auto apps = service_engine::instance().get_all_nodes();
-    for (auto &kv : apps) {
+    const auto &apps = service_engine::instance().get_all_nodes();
+    for (const auto &kv : apps) {
         task *t = new service_control_task(kv.second.get(), true);
         t->set_delay(1000 * kv.second.get()->spec().delay_seconds);
         t->enqueue();
@@ -90,8 +90,8 @@ void tool_app::start_all_apps()
 
 void tool_app::stop_all_apps(bool cleanup)
 {
-    auto apps = service_engine::instance().get_all_nodes();
-    for (auto &kv : apps) {
+    const auto &apps = service_engine::instance().get_all_nodes();
+    for (const auto &kv : apps) {
         task *t = new service_control_task(kv.second.get(), false, cleanup);
         t->enqueue();
     }