server_impl.h

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/*
 *
 * Copyright 2015 gRPC authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

#ifndef GRPCPP_SERVER_IMPL_H
#define GRPCPP_SERVER_IMPL_H

#include <condition_variable>
#include <list>
#include <memory>
#include <mutex>
#include <vector>

#include <grpc/compression.h>
#include <grpc/support/atm.h>
#include <grpcpp/channel.h>
#include <grpcpp/completion_queue.h>
#include <grpcpp/health_check_service_interface.h>
#include <grpcpp/impl/call.h>
#include <grpcpp/impl/codegen/client_interceptor.h>
#include <grpcpp/impl/codegen/grpc_library.h>
#include <grpcpp/impl/codegen/server_interface.h>
#include <grpcpp/impl/rpc_service_method.h>
#include <grpcpp/security/server_credentials.h>
#include <grpcpp/support/channel_arguments.h>
#include <grpcpp/support/config.h>
#include <grpcpp/support/status.h>

struct grpc_server;

namespace grpc {
class AsyncGenericService;

namespace internal {
class ExternalConnectionAcceptorImpl;
}  // namespace internal

}  // namespace grpc

namespace grpc_impl {
class HealthCheckServiceInterface;
class ServerContext;
class ServerInitializer;

class Server : public grpc::ServerInterface, private grpc::GrpcLibraryCodegen {
 public:
  ~Server();

  void Wait() override;

  class GlobalCallbacks {
   public:
    virtual ~GlobalCallbacks() {}
    virtual void UpdateArguments(grpc::ChannelArguments* args) {}
    virtual void PreSynchronousRequest(grpc_impl::ServerContext* context) = 0;
    virtual void PostSynchronousRequest(grpc_impl::ServerContext* context) = 0;
    virtual void PreServerStart(Server* server) {}
    virtual void AddPort(Server* server, const grpc::string& addr,
                         grpc::ServerCredentials* creds, int port) {}
  };
  static void SetGlobalCallbacks(GlobalCallbacks* callbacks);

  grpc_server* c_server();

  grpc::HealthCheckServiceInterface* GetHealthCheckService() const {
    return health_check_service_.get();
  }

  std::shared_ptr<::grpc::Channel> InProcessChannel(
      const grpc::ChannelArguments& args);

  class experimental_type {
   public:
    explicit experimental_type(Server* server) : server_(server) {}

    std::shared_ptr<::grpc::Channel> InProcessChannelWithInterceptors(
        const grpc::ChannelArguments& args,
        std::vector<std::unique_ptr<
            grpc::experimental::ClientInterceptorFactoryInterface>>
            interceptor_creators);

   private:
    Server* server_;
  };

  experimental_type experimental() { return experimental_type(this); }

 protected:
  bool RegisterService(const grpc::string* host,
                       grpc::Service* service) override;

  int AddListeningPort(const grpc::string& addr,
                       grpc::ServerCredentials* creds) override;

  Server(
      int max_message_size, grpc::ChannelArguments* args,
      std::shared_ptr<std::vector<std::unique_ptr<grpc::ServerCompletionQueue>>>
          sync_server_cqs,
      int min_pollers, int max_pollers, int sync_cq_timeout_msec,
      std::vector<
          std::shared_ptr<grpc::internal::ExternalConnectionAcceptorImpl>>
          acceptors,
      grpc_resource_quota* server_rq = nullptr,
      std::vector<std::unique_ptr<
          grpc::experimental::ServerInterceptorFactoryInterface>>
          interceptor_creators = std::vector<std::unique_ptr<
              grpc::experimental::ServerInterceptorFactoryInterface>>());

  void Start(grpc::ServerCompletionQueue** cqs, size_t num_cqs) override;

  grpc_server* server() override { return server_; }

 protected:
  void set_health_check_service(
      std::unique_ptr<grpc::HealthCheckServiceInterface> service) {
    health_check_service_ = std::move(service);
  }

  bool health_check_service_disabled() const {
    return health_check_service_disabled_;
  }

 private:
  std::vector<
      std::unique_ptr<grpc::experimental::ServerInterceptorFactoryInterface>>*
  interceptor_creators() override {
    return &interceptor_creators_;
  }

  friend class grpc::AsyncGenericService;
  friend class grpc_impl::ServerBuilder;
  friend class grpc_impl::ServerInitializer;

  class SyncRequest;
  class CallbackRequestBase;
  template <class ServerContextType>
  class CallbackRequest;
  class UnimplementedAsyncRequest;
  class UnimplementedAsyncResponse;

  class SyncRequestThreadManager;

  void RegisterAsyncGenericService(grpc::AsyncGenericService* service) override;

  class experimental_registration_type final
      : public experimental_registration_interface {
   public:
    explicit experimental_registration_type(Server* server) : server_(server) {}
    void RegisterCallbackGenericService(
        grpc::experimental::CallbackGenericService* service) override {
      server_->RegisterCallbackGenericService(service);
    }

   private:
    Server* server_;
  };

  void RegisterCallbackGenericService(
      grpc::experimental::CallbackGenericService* service);

  experimental_registration_interface* experimental_registration() override {
    return &experimental_registration_;
  }

  void PerformOpsOnCall(grpc::internal::CallOpSetInterface* ops,
                        grpc::internal::Call* call) override;

  void ShutdownInternal(gpr_timespec deadline) override;

  int max_receive_message_size() const override {
    return max_receive_message_size_;
  }

  grpc::CompletionQueue* CallbackCQ() override;

  grpc_impl::ServerInitializer* initializer();

  std::vector<std::shared_ptr<grpc::internal::ExternalConnectionAcceptorImpl>>
      acceptors_;

  // A vector of interceptor factory objects.
  // This should be destroyed after health_check_service_ and this requirement
  // is satisfied by declaring interceptor_creators_ before
  // health_check_service_. (C++ mandates that member objects be destroyed in
  // the reverse order of initialization.)
  std::vector<
      std::unique_ptr<grpc::experimental::ServerInterceptorFactoryInterface>>
      interceptor_creators_;

  const int max_receive_message_size_;

  std::shared_ptr<std::vector<std::unique_ptr<grpc::ServerCompletionQueue>>>
      sync_server_cqs_;

  std::vector<std::unique_ptr<SyncRequestThreadManager>> sync_req_mgrs_;

  // Outstanding unmatched callback requests, indexed by method.
  // NOTE: Using a gpr_atm rather than atomic_int because atomic_int isn't
  //       copyable or movable and thus will cause compilation errors. We
  //       actually only want to extend the vector before the threaded use
  //       starts, but this is still a limitation.
  std::vector<gpr_atm> callback_unmatched_reqs_count_;

  // List of callback requests to start when server actually starts.
  std::list<CallbackRequestBase*> callback_reqs_to_start_;

  // For registering experimental callback generic service; remove when that
  // method longer experimental
  experimental_registration_type experimental_registration_{this};

  // Server status
  grpc::internal::Mutex mu_;
  bool started_;
  bool shutdown_;
  bool shutdown_notified_;  // Was notify called on the shutdown_cv_

  grpc::internal::CondVar shutdown_cv_;

  // It is ok (but not required) to nest callback_reqs_mu_ under mu_ .
  // Incrementing callback_reqs_outstanding_ is ok without a lock but it must be
  // decremented under the lock in case it is the last request and enables the
  // server shutdown. The increment is performance-critical since it happens
  // during periods of increasing load; the decrement happens only when memory
  // is maxed out, during server shutdown, or (possibly in a future version)
  // during decreasing load, so it is less performance-critical.
  grpc::internal::Mutex callback_reqs_mu_;
  grpc::internal::CondVar callback_reqs_done_cv_;
  std::atomic_int callback_reqs_outstanding_{0};

  std::shared_ptr<GlobalCallbacks> global_callbacks_;

  std::vector<grpc::string> services_;
  bool has_async_generic_service_{false};
  bool has_callback_generic_service_{false};

  // Pointer to the wrapped grpc_server.
  grpc_server* server_;

  std::unique_ptr<grpc_impl::ServerInitializer> server_initializer_;

  std::unique_ptr<grpc::HealthCheckServiceInterface> health_check_service_;
  bool health_check_service_disabled_;

  // When appropriate, use a default callback generic service to handle
  // unimplemented methods
  std::unique_ptr<grpc::experimental::CallbackGenericService>
      unimplemented_service_;

  // A special handler for resource exhausted in sync case
  std::unique_ptr<grpc::internal::MethodHandler> resource_exhausted_handler_;

  // Handler for callback generic service, if any
  std::unique_ptr<grpc::internal::MethodHandler> generic_handler_;

  // callback_cq_ references the callbackable completion queue associated
  // with this server (if any). It is set on the first call to CallbackCQ().
  // It is _not owned_ by the server; ownership belongs with its internal
  // shutdown callback tag (invoked when the CQ is fully shutdown).
  // It is protected by mu_
  grpc::CompletionQueue* callback_cq_ = nullptr;
};

}  // namespace grpc_impl

#endif  // GRPCPP_SERVER_IMPL_H