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      1 /* Copyright 2016 The TensorFlow Authors. All Rights Reserved.
      2 
      3 Licensed under the Apache License, Version 2.0 (the "License");
      4 you may not use this file except in compliance with the License.
      5 You may obtain a copy of the License at
      6 
      7     http://www.apache.org/licenses/LICENSE-2.0
      8 
      9 Unless required by applicable law or agreed to in writing, software
     10 distributed under the License is distributed on an "AS IS" BASIS,
     11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 See the License for the specific language governing permissions and
     13 limitations under the License.
     14 ==============================================================================*/
     15 
     16 #ifndef TENSORFLOW_CORE_DISTRIBUTED_RUNTIME_RPC_GRPC_SERVER_LIB_H_
     17 #define TENSORFLOW_CORE_DISTRIBUTED_RUNTIME_RPC_GRPC_SERVER_LIB_H_
     18 
     19 #include <memory>
     20 
     21 #include "grpc++/grpc++.h"
     22 #include "grpc++/security/credentials.h"
     23 
     24 #include "tensorflow/core/common_runtime/process_util.h"
     25 #include "tensorflow/core/distributed_runtime/master_env.h"
     26 #include "tensorflow/core/distributed_runtime/rpc/async_service_interface.h"
     27 #include "tensorflow/core/distributed_runtime/rpc/grpc_channel.h"
     28 #include "tensorflow/core/distributed_runtime/server_lib.h"
     29 #include "tensorflow/core/distributed_runtime/session_mgr.h"
     30 #include "tensorflow/core/distributed_runtime/worker_env.h"
     31 #include "tensorflow/core/framework/op.h"
     32 #include "tensorflow/core/platform/env.h"
     33 
     34 namespace tensorflow {
     35 
     36 class GrpcWorker;
     37 class Master;
     38 
     39 // function that creates a RendezvousMgr.
     40 typedef std::function<RendezvousMgrInterface*(const WorkerEnv*)>
     41     RendezvousMgrCreationFunction;
     42 
     43 // function that registers a service to the server. The service needs to
     44 // be registered before builder.BuildAndStart().
     45 typedef std::function<void(const WorkerEnv*, ::grpc::ServerBuilder*)>
     46     ServiceInitFunction;
     47 
     48 // function that creates a grpc based worker implementation.
     49 typedef std::function<std::unique_ptr<GrpcWorker>(WorkerEnv*)>
     50     WorkerCreationFunction;
     51 
     52 class GrpcServer : public ServerInterface {
     53  protected:
     54   GrpcServer(const ServerDef& server_def, Env* env);
     55 
     56  public:
     57   static Status Create(const ServerDef& server_def, Env* env,
     58                        std::unique_ptr<ServerInterface>* out_server);
     59 
     60   // Destruction is only supported in the factory method. Clean
     61   // shutdown is not currently implemented for this server type.
     62   virtual ~GrpcServer();
     63 
     64   // Implementations of ServerInterface methods.
     65   Status Start() override;
     66   Status Stop() override;
     67   Status Join() override;
     68   const string target() const override;
     69 
     70  protected:
     71   Status Init(ServiceInitFunction service_func,
     72               const RendezvousMgrCreationFunction& rendezvous_mgr_func,
     73               const WorkerCreationFunction& worker_func);
     74 
     75   Status Init(ServiceInitFunction service_func,
     76               const RendezvousMgrCreationFunction& rendezvous_mgr_func);
     77 
     78   Status Init();
     79 
     80   // A subclass can override this method to support secure credentials.
     81   virtual std::shared_ptr<::grpc::ServerCredentials> GetServerCredentials(
     82       const ServerDef& server_def) const;
     83 
     84   virtual ChannelCreationFunction GetChannelCreationFunction() const;
     85 
     86   virtual std::unique_ptr<Master> CreateMaster(MasterEnv* master_env);
     87 
     88   // Creates a WorkerCacheInterface for a session.
     89   Status WorkerCacheFactory(const WorkerCacheFactoryOptions& options,
     90                             WorkerCacheInterface** worker_cache);
     91 
     92   // Parses a WorkerCacheFactoryOptions into a GrpcChannelSpec.
     93   Status ParseChannelSpec(const WorkerCacheFactoryOptions& options,
     94                           GrpcChannelSpec* channel_spec);
     95 
     96   // Returns the port to which this server is bound.
     97   // This method may only be called after `this->Init()` returns successfully.
     98   int bound_port() const { return bound_port_; }
     99 
    100   WorkerEnv* worker_env() { return &worker_env_; }
    101 
    102   const ServerDef& server_def() const { return server_def_; }
    103 
    104  private:
    105   // The overall server configuration.
    106   const ServerDef server_def_;
    107   Env* env_;
    108 
    109   // The port to which this server is bound.
    110   int bound_port_ = 0;
    111 
    112   // Guards state transitions.
    113   mutex mu_;
    114 
    115   // Represents the current state of the server, which changes as follows:
    116   //
    117   //                 Join()            Join()
    118   //                  ___               ___
    119   //      Start()     \ /    Stop()     \ /
    120   // NEW ---------> STARTED --------> STOPPED
    121   //   \                          /
    122   //    \________________________/
    123   //            Stop(), Join()
    124   enum State { NEW, STARTED, STOPPED };
    125   State state_ GUARDED_BY(mu_);
    126 
    127   // Implementation of a TensorFlow master, and RPC polling thread.
    128   MasterEnv master_env_;
    129   std::unique_ptr<Master> master_impl_;
    130   AsyncServiceInterface* master_service_ = nullptr;
    131   std::unique_ptr<Thread> master_thread_ GUARDED_BY(mu_);
    132 
    133   // Implementation of a TensorFlow worker, and RPC polling thread.
    134   WorkerEnv worker_env_;
    135   std::unique_ptr<GrpcWorker> worker_impl_;
    136   AsyncServiceInterface* worker_service_ = nullptr;
    137   std::unique_ptr<Thread> worker_thread_ GUARDED_BY(mu_);
    138 
    139   std::unique_ptr<::grpc::Server> server_ GUARDED_BY(mu_);
    140 };
    141 
    142 }  // namespace tensorflow
    143 
    144 #endif  // TENSORFLOW_CORE_DISTRIBUTED_RUNTIME_RPC_GRPC_SERVER_LIB_H_
    145