protocol_server: add per-protocol is_server_running method

Change b0a2a97 broke
the generic api implementation of
is_native_transport_running that relied on
the addresses list being empty agter the server is stopped.

To fix that, this change introduces a pure virtual method:
protocol_server::is_server_running that can be implemented
by each derived class.

Test: unit(dev)
DTest: nodetool_additional_test.py:TestNodetool.binary_test

Signed-off-by: Benny Halevy <[email protected]>
Message-Id: <[email protected]>

alternator/controller.cc

@@ -68,6 +68,10 @@ std::vector<socket_address> controller::listen_addresses() const {
     return _listen_addresses;
 }
 
+bool controller::is_server_running() const {
+    return !_listen_addresses.empty();
+}
+
 future<> controller::start_server() {
     return seastar::async([this] {
         _listen_addresses.clear();

alternator/controller.hh

@@ -87,6 +87,7 @@ public:
     virtual sstring protocol() const override;
     virtual sstring protocol_version() const override;
     virtual std::vector<socket_address> listen_addresses() const override;
+    virtual bool is_server_running() const override;
     virtual future<> start_server() override;
     virtual future<> stop_server() override;
     virtual future<> request_stop_server() override;

api/storage_service.cc

@@ -183,7 +183,7 @@ void set_transport_controller(http_context& ctx, routes& r, cql_transport::contr
 
     ss::is_native_transport_running.set(r, [&ctl] (std::unique_ptr<request> req) {
         return smp::submit_to(0, [&] {
-            return !ctl.listen_addresses().empty();
+            return ctl.is_server_running();
         }).then([] (bool running) {
             return make_ready_future<json::json_return_type>(running);
         });

protocol_server.hh

@@ -37,6 +37,8 @@ public:
     virtual sstring protocol_version() const = 0;
     /// Addresses the server is listening on, should be empty when server is not running.
     virtual std::vector<socket_address> listen_addresses() const = 0;
+    /// Check if the server is running.
+    virtual bool is_server_running() const = 0;
     /// Start the server.
     /// Can be called multiple times, in any state of the server.
     virtual future<> start_server() = 0;

redis/service.cc

@@ -124,6 +124,10 @@ std::vector<socket_address> redis_service::listen_addresses() const {
     return _listen_addresses;
 }
 
+bool redis_service::is_server_running() const {
+    return !_listen_addresses.empty();
+}
+
 future<> redis_service::start_server()
 {
     // 1. Create keyspace/tables used by redis API if not exists.

redis/service.hh

@@ -85,6 +85,7 @@ public:
     virtual sstring protocol() const override;
     virtual sstring protocol_version() const override;
     virtual std::vector<socket_address> listen_addresses() const override;
+    virtual bool is_server_running() const override;
     virtual future<> start_server() override;
     virtual future<> stop_server() override;
     virtual future<> request_stop_server() override;

thrift/controller.cc

@@ -55,6 +55,10 @@ std::vector<socket_address> thrift_controller::listen_addresses() const {
     return {};
 }
 
+bool thrift_controller::is_server_running() const {
+    return bool(_server);
+}
+
 future<> thrift_controller::start_server() {
     if (!_ops_sem.try_wait()) {
         throw std::runtime_error(format("Thrift server is stopping, try again later"));

thrift/controller.hh

@@ -56,6 +56,7 @@ public:
     virtual sstring protocol() const override;
     virtual sstring protocol_version() const override;
     virtual std::vector<socket_address> listen_addresses() const override;
+    virtual bool is_server_running() const override;
     virtual future<> start_server() override;
     virtual future<> stop_server() override;
     virtual future<> request_stop_server() override;

transport/controller.cc

@@ -65,6 +65,10 @@ std::vector<socket_address> controller::listen_addresses() const {
     return _listen_addresses;
 }
 
+bool controller::is_server_running() const {
+    return bool(_server);
+}
+
 future<> controller::start_server() {
     if (!_ops_sem.try_wait()) {
         throw std::runtime_error(format("CQL server is stopping, try again later"));

transport/controller.hh

@@ -74,6 +74,7 @@ public:
     virtual sstring protocol() const override;
     virtual sstring protocol_version() const override;
     virtual std::vector<socket_address> listen_addresses() const override;
+    virtual bool is_server_running() const override;
     virtual future<> start_server() override;
     virtual future<> stop_server() override;
     virtual future<> request_stop_server() override;