grpc/include/grpc++/server.h

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#ifndef GRPCXX_SERVER_H
#define GRPCXX_SERVER_H

#include <list>
#include <memory>

#include <grpc++/completion_queue.h>
#include <grpc++/impl/call.h>
#include <grpc++/impl/grpc_library.h>
#include <grpc++/impl/sync.h>
#include <grpc++/security/server_credentials.h>
#include <grpc++/support/channel_arguments.h>
#include <grpc++/support/config.h>
#include <grpc++/support/status.h>
#include <grpc/compression.h>

struct grpc_server;

namespace grpc {

class AsynchronousService;
class GenericServerContext;
class AsyncGenericService;
class RpcService;
class RpcServiceMethod;
class ServerAsyncStreamingInterface;
class ServerContext;
class ThreadPoolInterface;

/// Models a gRPC server.
///
/// Servers are configured and started via \a grpc::ServerBuilder.
class Server GRPC_FINAL : public GrpcLibrary, private CallHook {
 public:
  ~Server();

  /// Shutdown the server, blocking until all rpc processing finishes.
  /// Forcefully terminate pending calls after \a deadline expires.
  ///
  /// \param deadline How long to wait until pending rpcs are forcefully
  /// terminated.
  template <class T>
  void Shutdown(const T& deadline) {
    ShutdownInternal(TimePoint<T>(deadline).raw_time());
  }

  /// Shutdown the server, waiting for all rpc processing to finish.
  void Shutdown() { ShutdownInternal(gpr_inf_future(GPR_CLOCK_MONOTONIC)); }

  /// Block waiting for all work to complete.
  ///
  /// \warning The server must be either shutting down or some other thread must
  /// call \a Shutdown for this function to ever return.
  void Wait();

  /// Global Callbacks
  ///
  /// Can be set exactly once per application to install hooks whenever
  /// a server event occurs
  class GlobalCallbacks {
   public:
    virtual ~GlobalCallbacks() {}
    /// Called before application callback for each synchronous server request
    virtual void PreSynchronousRequest(ServerContext* context) = 0;
    /// Called after application callback for each synchronous server request
    virtual void PostSynchronousRequest(ServerContext* context) = 0;
  };
  /// Set the global callback object. Can only be called once. Does not take
  /// ownership of callbacks, and expects the pointed to object to be alive
  /// until all server objects in the process have been destroyed.
  static void SetGlobalCallbacks(GlobalCallbacks* callbacks);

 private:
  friend class AsyncGenericService;
  friend class AsynchronousService;
  friend class ServerBuilder;

  class SyncRequest;
  class AsyncRequest;
  class ShutdownRequest;

  /// Server constructors. To be used by \a ServerBuilder only.
  ///
  /// \param thread_pool The threadpool instance to use for call processing.
  /// \param thread_pool_owned Does the server own the \a thread_pool instance?
  /// \param max_message_size Maximum message length that the channel can
  /// receive.
  Server(ThreadPoolInterface* thread_pool, bool thread_pool_owned,
         int max_message_size, const ChannelArguments& args);

  /// 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, RpcService* service);

  /// Register an asynchronous service. This call does not take ownership of the
  /// service. The service must exist for the lifetime of the Server instance.
  bool RegisterAsyncService(const grpc::string* host,
                            AsynchronousService* service);

  /// 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);

  /// Tries to bind \a server to the given \a addr.
  ///
  /// It can be invoked multiple times.
  ///
  /// \param addr The address to try to bind to the server (eg, localhost:1234,
  /// 192.168.1.1:31416, [::1]:27182, etc.).
  /// \params creds The credentials associated with the server.
  ///
  /// \return bound port number on sucess, 0 on failure.
  ///
  /// \warning It's an error to call this method on an already started server.
  int AddListeningPort(const grpc::string& addr, ServerCredentials* creds);

  /// Start the server.
  ///
  /// \param cqs Completion queues for handling asynchronous services. The
  /// caller is required to keep all completion queues live until the server is
  /// destroyed.
  /// \param num_cqs How many completion queues does \a cqs hold.
  ///
  /// \return true on a successful shutdown.
  bool Start(ServerCompletionQueue** cqs, size_t num_cqs);

  void HandleQueueClosed();

  /// Process one or more incoming calls.
  void RunRpc();

  /// Schedule \a RunRpc to run in the threadpool.
  void ScheduleCallback();

  void PerformOpsOnCall(CallOpSetInterface* ops, Call* call) GRPC_OVERRIDE;

  void ShutdownInternal(gpr_timespec deadline);

  class BaseAsyncRequest : public CompletionQueueTag {
   public:
    BaseAsyncRequest(Server* server, ServerContext* context,
                     ServerAsyncStreamingInterface* stream,
                     CompletionQueue* call_cq, void* tag,
                     bool delete_on_finalize);
    virtual ~BaseAsyncRequest();

    bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE;

   protected:
    Server* const server_;
    ServerContext* const context_;
    ServerAsyncStreamingInterface* const stream_;
    CompletionQueue* const call_cq_;
    void* const tag_;
    const bool delete_on_finalize_;
    grpc_call* call_;
    grpc_metadata_array initial_metadata_array_;
  };

  class RegisteredAsyncRequest : public BaseAsyncRequest {
   public:
    RegisteredAsyncRequest(Server* server, ServerContext* context,
                           ServerAsyncStreamingInterface* stream,
                           CompletionQueue* call_cq, void* tag);

    // uses BaseAsyncRequest::FinalizeResult

   protected:
    void IssueRequest(void* registered_method, grpc_byte_buffer** payload,
                      ServerCompletionQueue* notification_cq);
  };

  class NoPayloadAsyncRequest GRPC_FINAL : public RegisteredAsyncRequest {
   public:
    NoPayloadAsyncRequest(void* registered_method, Server* server,
                          ServerContext* context,
                          ServerAsyncStreamingInterface* stream,
                          CompletionQueue* call_cq,
                          ServerCompletionQueue* notification_cq, void* tag)
        : RegisteredAsyncRequest(server, context, stream, call_cq, tag) {
      IssueRequest(registered_method, nullptr, notification_cq);
    }

    // uses RegisteredAsyncRequest::FinalizeResult
  };

  template <class Message>
  class PayloadAsyncRequest GRPC_FINAL : public RegisteredAsyncRequest {
   public:
    PayloadAsyncRequest(void* registered_method, Server* server,
                        ServerContext* context,
                        ServerAsyncStreamingInterface* stream,
                        CompletionQueue* call_cq,
                        ServerCompletionQueue* notification_cq, void* tag,
                        Message* request)
        : RegisteredAsyncRequest(server, context, stream, call_cq, tag),
          request_(request) {
      IssueRequest(registered_method, &payload_, notification_cq);
    }

    bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE {
      bool serialization_status =
          *status && payload_ &&
          SerializationTraits<Message>::Deserialize(
              payload_, request_, server_->max_message_size_).ok();
      bool ret = RegisteredAsyncRequest::FinalizeResult(tag, status);
      *status = serialization_status&&* status;
      return ret;
    }

   private:
    grpc_byte_buffer* payload_;
    Message* const request_;
  };

  class GenericAsyncRequest : public BaseAsyncRequest {
   public:
    GenericAsyncRequest(Server* server, GenericServerContext* context,
                        ServerAsyncStreamingInterface* stream,
                        CompletionQueue* call_cq,
                        ServerCompletionQueue* notification_cq, void* tag,
                        bool delete_on_finalize);

    bool FinalizeResult(void** tag, bool* status) GRPC_OVERRIDE;

   private:
    grpc_call_details call_details_;
  };

  class UnimplementedAsyncRequestContext;
  class UnimplementedAsyncRequest;
  class UnimplementedAsyncResponse;

  template <class Message>
  void RequestAsyncCall(void* registered_method, ServerContext* context,
                        ServerAsyncStreamingInterface* stream,
                        CompletionQueue* call_cq,
                        ServerCompletionQueue* notification_cq, void* tag,
                        Message* message) {
    new PayloadAsyncRequest<Message>(registered_method, this, context, stream,
                                     call_cq, notification_cq, tag, message);
  }

  void RequestAsyncCall(void* registered_method, ServerContext* context,
                        ServerAsyncStreamingInterface* stream,
                        CompletionQueue* call_cq,
                        ServerCompletionQueue* notification_cq, void* tag) {
    new NoPayloadAsyncRequest(registered_method, this, context, stream, call_cq,
                              notification_cq, tag);
  }

  void RequestAsyncGenericCall(GenericServerContext* context,
                               ServerAsyncStreamingInterface* stream,
                               CompletionQueue* call_cq,
                               ServerCompletionQueue* notification_cq,
                               void* tag) {
    new GenericAsyncRequest(this, context, stream, call_cq, notification_cq,
                            tag, true);
  }

  const int max_message_size_;

  // Completion queue.
  CompletionQueue cq_;

  // Sever status
  grpc::mutex mu_;
  bool started_;
  bool shutdown_;
  // The number of threads which are running callbacks.
  int num_running_cb_;
  grpc::condition_variable callback_cv_;

  std::shared_ptr<GlobalCallbacks> global_callbacks_;

  std::list<SyncRequest>* sync_methods_;
  std::unique_ptr<RpcServiceMethod> unknown_method_;
  bool has_generic_service_;

  // Pointer to the c grpc server.
  grpc_server* const server_;

  ThreadPoolInterface* thread_pool_;
  // Whether the thread pool is created and owned by the server.
  bool thread_pool_owned_;
};

}  // namespace grpc

#endif  // GRPCXX_SERVER_H