Remove "final" keyword and make methods protected.

This adds extensibility to the API and makes custom implementation
of the server possible.

include/grpcpp/impl/codegen/completion_queue.h

@@ -165,7 +165,7 @@ class CompletionQueue : private GrpcLibraryCodegen {
   ///
   /// \return true if got an event, false if the queue is fully drained and
   ///         shut down.
-  bool Next(void** tag, bool* ok) {
+  virtual bool Next(void** tag, bool* ok) {
     return (AsyncNextInternal(tag, ok,
                               g_core_codegen_interface->gpr_inf_future(
                                   GPR_CLOCK_REALTIME)) != SHUTDOWN);
@@ -365,9 +365,7 @@ class ServerCompletionQueue : public CompletionQueue {
  public:
   bool IsFrequentlyPolled() { return polling_type_ != GRPC_CQ_NON_LISTENING; }
 
- private:
-  grpc_cq_polling_type polling_type_;
-  friend class ServerBuilder;
+ protected:
   /// \param is_frequently_polled Informs the GRPC library about whether the
   /// server completion queue would be actively polled (by calling Next() or
   /// AsyncNext()). By default all server completion queues are assumed to be
@@ -376,6 +374,10 @@ class ServerCompletionQueue : public CompletionQueue {
       : CompletionQueue(grpc_completion_queue_attributes{
             GRPC_CQ_CURRENT_VERSION, GRPC_CQ_NEXT, polling_type}),
         polling_type_(polling_type) {}
+
+ private:
+  grpc_cq_polling_type polling_type_;
+  friend class ServerBuilder;
 };
 
 }  // namespace grpc

include/grpcpp/server.h

@@ -49,7 +49,7 @@ class ServerInitializer;
 ///
 /// Use a \a grpc::ServerBuilder to create, configure, and start
 /// \a Server instances.
-class Server final : public ServerInterface, private GrpcLibraryCodegen {
+class Server : public ServerInterface, private GrpcLibraryCodegen {
  public:
   ~Server();
 
@@ -98,24 +98,26 @@ class Server final : public ServerInterface, private GrpcLibraryCodegen {
   /// Establish a channel for in-process communication
   std::shared_ptr<Channel> InProcessChannel(const ChannelArguments& args);
 
- private:
-  friend class AsyncGenericService;
-  friend class ServerBuilder;
-  friend class ServerInitializer;
-
-  class SyncRequest;
-  class AsyncRequest;
-  class ShutdownRequest;
-
-  /// SyncRequestThreadManager is an implementation of ThreadManager. This class
-  /// is responsible for polling for incoming RPCs and calling the RPC handlers.
-  /// This is only used in case of a Sync server (i.e a server exposing a sync
-  /// interface)
-  class SyncRequestThreadManager;
+protected:
+  /// Register a service. This call does not take ownership of the service.
+  /// The service must exist for the lifetime of the Server instance.
+  bool RegisterService(const grpc::string* host, Service* service) override;
 
-  class UnimplementedAsyncRequestContext;
-  class UnimplementedAsyncRequest;
-  class UnimplementedAsyncResponse;
+  /// Try binding the server to the given \a addr endpoint
+  /// (port, and optionally including IP address to bind to).
+  ///
+  /// It can be invoked multiple times. Should be used before
+  /// starting the server.
+  ///
+  /// \param addr The address to try to bind to the server (eg, localhost:1234,
+  /// 192.168.1.1:31416, [::1]:27182, etc.).
+  /// \param creds The credentials associated with the server.
+  ///
+  /// \return bound port number on success, 0 on failure.
+  ///
+  /// \warning It is an error to call this method on an already started server.
+  int AddListeningPort(const grpc::string& addr,
+                       ServerCredentials* creds) override;
 
   /// Server constructors. To be used by \a ServerBuilder only.
   ///
@@ -143,30 +145,6 @@ class Server final : public ServerInterface, private GrpcLibraryCodegen {
              sync_server_cqs,
          int min_pollers, int max_pollers, int sync_cq_timeout_msec);
 
-  /// Register a service. This call does not take ownership of the service.
-  /// The service must exist for the lifetime of the Server instance.
-  bool RegisterService(const grpc::string* host, Service* service) override;
-
-  /// Register a generic service. This call does not take ownership of the
-  /// service. The service must exist for the lifetime of the Server instance.
-  void RegisterAsyncGenericService(AsyncGenericService* service) override;
-
-  /// Try binding the server to the given \a addr endpoint
-  /// (port, and optionally including IP address to bind to).
-  ///
-  /// It can be invoked multiple times. Should be used before
-  /// starting the server.
-  ///
-  /// \param addr The address to try to bind to the server (eg, localhost:1234,
-  /// 192.168.1.1:31416, [::1]:27182, etc.).
-  /// \param creds The credentials associated with the server.
-  ///
-  /// \return bound port number on success, 0 on failure.
-  ///
-  /// \warning It is an error to call this method on an already started server.
-  int AddListeningPort(const grpc::string& addr,
-                       ServerCredentials* creds) override;
-
   /// Start the server.
   ///
   /// \param cqs Completion queues for handling asynchronous services. The
@@ -175,6 +153,35 @@ class Server final : public ServerInterface, private GrpcLibraryCodegen {
   /// \param num_cqs How many completion queues does \a cqs hold.
   void Start(ServerCompletionQueue** cqs, size_t num_cqs) override;
 
+  // Pointer to the wrapped grpc_server.
+  grpc_server* server_;
+
+  // Server status
+  bool started_;
+
+ private:
+  friend class AsyncGenericService;
+  friend class ServerBuilder;
+  friend class ServerInitializer;
+
+  class SyncRequest;
+  class AsyncRequest;
+  class ShutdownRequest;
+
+  /// SyncRequestThreadManager is an implementation of ThreadManager. This class
+  /// is responsible for polling for incoming RPCs and calling the RPC handlers.
+  /// This is only used in case of a Sync server (i.e a server exposing a sync
+  /// interface)
+  class SyncRequestThreadManager;
+
+  class UnimplementedAsyncRequestContext;
+  class UnimplementedAsyncRequest;
+  class UnimplementedAsyncResponse;
+
+  /// Register a generic service. This call does not take ownership of the
+  /// service. The service must exist for the lifetime of the Server instance.
+  void RegisterAsyncGenericService(AsyncGenericService* service) override;
+
   void PerformOpsOnCall(internal::CallOpSetInterface* ops,
                         internal::Call* call) override;
 
@@ -200,9 +207,8 @@ class Server final : public ServerInterface, private GrpcLibraryCodegen {
   /// the \a sync_server_cqs)
   std::vector<std::unique_ptr<SyncRequestThreadManager>> sync_req_mgrs_;
 
-  // Sever status
+  // Server status
   std::mutex mu_;
-  bool started_;
   bool shutdown_;
   bool shutdown_notified_;  // Was notify called on the shutdown_cv_
 
@@ -213,9 +219,6 @@ class Server final : public ServerInterface, private GrpcLibraryCodegen {
   std::vector<grpc::string> services_;
   bool has_generic_service_;
 
-  // Pointer to the wrapped grpc_server.
-  grpc_server* server_;
-
   std::unique_ptr<ServerInitializer> server_initializer_;
 
   std::unique_ptr<HealthCheckServiceInterface> health_check_service_;

include/grpcpp/server_builder.h

@@ -52,7 +52,7 @@ class ServerBuilderPluginTest;
 class ServerBuilder {
  public:
   ServerBuilder();
-  ~ServerBuilder();
+  virtual ~ServerBuilder();
 
   //////////////////////////////////////////////////////////////////////////////
   // Primary API's
@@ -65,7 +65,7 @@ class ServerBuilder {
   ///     traffic (via AddListeningPort)
   ///  3. [for async api only] completion queues have been added via
   ///     AddCompletionQueue
-  std::unique_ptr<Server> BuildAndStart();
+  virtual std::unique_ptr<Server> BuildAndStart();
 
   /// Register a service. This call does not take ownership of the service.
   /// The service must exist for the lifetime of the \a Server instance returned
@@ -210,15 +210,29 @@ class ServerBuilder {
   /// doc/workarounds.md.
   ServerBuilder& EnableWorkaround(grpc_workaround_list id);
 
- private:
-  friend class ::grpc::testing::ServerBuilderPluginTest;
-
+ protected:
   struct Port {
     grpc::string addr;
     std::shared_ptr<ServerCredentials> creds;
     int* selected_port;
   };
 
+  typedef std::unique_ptr<grpc::string> HostString;
+  struct NamedService {
+    explicit NamedService(Service* s) : service(s) {}
+    NamedService(const grpc::string& h, Service* s)
+        : host(new grpc::string(h)), service(s) {}
+    HostString host;
+    Service* service;
+  };
+
+  std::vector<std::unique_ptr<ServerBuilderOption>> options_;
+  std::vector<std::unique_ptr<NamedService>> services_;
+  std::vector<Port> ports_;
+
+ private:
+  friend class ::grpc::testing::ServerBuilderPluginTest;
+
   struct SyncServerSettings {
     SyncServerSettings()
         : num_cqs(1), min_pollers(1), max_pollers(2), cq_timeout_msec(10000) {}
@@ -238,20 +252,8 @@ class ServerBuilder {
     int cq_timeout_msec;
   };
 
-  typedef std::unique_ptr<grpc::string> HostString;
-  struct NamedService {
-    explicit NamedService(Service* s) : service(s) {}
-    NamedService(const grpc::string& h, Service* s)
-        : host(new grpc::string(h)), service(s) {}
-    HostString host;
-    Service* service;
-  };
-
   int max_receive_message_size_;
   int max_send_message_size_;
-  std::vector<std::unique_ptr<ServerBuilderOption>> options_;
-  std::vector<std::unique_ptr<NamedService>> services_;
-  std::vector<Port> ports_;
 
   SyncServerSettings sync_server_settings_;
 

src/cpp/server/server_cc.cc

@@ -368,13 +368,13 @@ Server::Server(
     std::shared_ptr<std::vector<std::unique_ptr<ServerCompletionQueue>>>
         sync_server_cqs,
     int min_pollers, int max_pollers, int sync_cq_timeout_msec)
-    : max_receive_message_size_(max_receive_message_size),
-      sync_server_cqs_(sync_server_cqs),
+    : server_(nullptr),
       started_(false),
+      max_receive_message_size_(max_receive_message_size),
+      sync_server_cqs_(sync_server_cqs),
       shutdown_(false),
       shutdown_notified_(false),
       has_generic_service_(false),
-      server_(nullptr),
       server_initializer_(new ServerInitializer(this)),
       health_check_service_disabled_(false) {
   g_gli_initializer.summon();
@@ -382,11 +382,13 @@ Server::Server(
   global_callbacks_ = g_callbacks;
   global_callbacks_->UpdateArguments(args);
 
-  for (auto it = sync_server_cqs_->begin(); it != sync_server_cqs_->end();
-       it++) {
-    sync_req_mgrs_.emplace_back(new SyncRequestThreadManager(
-        this, (*it).get(), global_callbacks_, min_pollers, max_pollers,
-        sync_cq_timeout_msec));
+  if (sync_server_cqs_ != nullptr) {
+    for (auto it = sync_server_cqs_->begin(); it != sync_server_cqs_->end();
+         it++) {
+      sync_req_mgrs_.emplace_back(new SyncRequestThreadManager(
+          this, (*it).get(), global_callbacks_, min_pollers, max_pollers,
+          sync_cq_timeout_msec));
+    }
   }
 
   grpc_channel_args channel_args;
@@ -525,7 +527,7 @@ void Server::Start(ServerCompletionQueue** cqs, size_t num_cqs) {
   // explicit one.
   if (health_check_service_ == nullptr && !health_check_service_disabled_ &&
       DefaultHealthCheckServiceEnabled()) {
-    if (sync_server_cqs_->empty()) {
+    if (sync_server_cqs_ == nullptr || sync_server_cqs_->empty()) {
       gpr_log(GPR_INFO,
               "Default health check service disabled at async-only server.");
     } else {