server.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_H
#define GRPCPP_SERVER_H

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

#include <grpc/compression.h>
#include <grpc/support/atm.h>
#include <grpcpp/completion_queue.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;
class HealthCheckServiceInterface;
class ServerContext;
class ServerInitializer;

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

  void Wait() override;

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

  grpc_server* c_server();

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

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

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

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

   private:
    Server* server_;
  };

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

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

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

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

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

  grpc_server* server() override { return server_; }

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

  friend class AsyncGenericService;
  friend class ServerBuilder;
  friend class ServerInitializer;

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

  class SyncRequestThreadManager;

  void RegisterAsyncGenericService(AsyncGenericService* service) override;

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

   private:
    Server* server_;
  };

  void RegisterCallbackGenericService(
      experimental::CallbackGenericService* service);

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

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

  void ShutdownInternal(gpr_timespec deadline) override;

  int max_receive_message_size() const override {
    return max_receive_message_size_;
  }

  CompletionQueue* CallbackCQ() override;

  ServerInitializer* initializer();

  // 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<experimental::ServerInterceptorFactoryInterface>>
      interceptor_creators_;

  const int max_receive_message_size_;

  std::shared_ptr<std::vector<std::unique_ptr<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
  std::mutex mu_;
  bool started_;
  bool shutdown_;
  bool shutdown_notified_;  // Was notify called on the shutdown_cv_

  std::condition_variable 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.
  std::mutex callback_reqs_mu_;
  std::condition_variable 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<ServerInitializer> server_initializer_;

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

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

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

  // Handler for callback generic service, if any
  std::unique_ptr<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_
  CompletionQueue* callback_cq_ = nullptr;
};

}  // namespace grpc

#endif  // GRPCPP_SERVER_H