1/*
2 *
3 * Copyright 2015 gRPC authors.
4 *
5 * Licensed under the Apache License, Version 2.0 (the "License");
6 * you may not use this file except in compliance with the License.
7 * You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 *
17 */
18
19#ifndef GRPCPP_CHANNEL_H
20#define GRPCPP_CHANNEL_H
21
22#include <memory>
23
24#include <grpc/grpc.h>
25#include <grpcpp/completion_queue.h>
26#include <grpcpp/impl/call.h>
27#include <grpcpp/impl/channel_interface.h>
28#include <grpcpp/impl/codegen/grpc_library.h>
29#include <grpcpp/impl/codegen/sync.h>
30#include <grpcpp/support/client_interceptor.h>
31#include <grpcpp/support/config.h>
32
33struct grpc_channel;
34
35namespace grpc {
36namespace testing {
37class ChannelTestPeer;
38} // namespace testing
39
40std::shared_ptr<Channel> CreateChannelInternal(
41 const std::string& host, grpc_channel* c_channel,
42 std::vector<
43 std::unique_ptr<experimental::ClientInterceptorFactoryInterface>>
44 interceptor_creators);
45
46namespace experimental {
47/// Resets the channel's connection backoff.
48/// TODO(roth): Once we see whether this proves useful, either create a gRFC
49/// and change this to be a method of the Channel class, or remove it.
50void ChannelResetConnectionBackoff(Channel* channel);
51} // namespace experimental
52
53/// Channels represent a connection to an endpoint. Created by \a CreateChannel.
54class Channel final : public grpc::ChannelInterface,
55 public grpc::internal::CallHook,
56 public std::enable_shared_from_this<Channel>,
57 private grpc::GrpcLibraryCodegen {
58 public:
59 ~Channel() override;
60
61 /// Get the current channel state. If the channel is in IDLE and
62 /// \a try_to_connect is set to true, try to connect.
63 grpc_connectivity_state GetState(bool try_to_connect) override;
64
65 /// Returns the LB policy name, or the empty string if not yet available.
66 std::string GetLoadBalancingPolicyName() const;
67
68 /// Returns the service config in JSON form, or the empty string if
69 /// not available.
70 std::string GetServiceConfigJSON() const;
71
72 private:
73 template <class InputMessage, class OutputMessage>
74 friend class grpc::internal::BlockingUnaryCallImpl;
75 friend class grpc::testing::ChannelTestPeer;
76 friend void experimental::ChannelResetConnectionBackoff(Channel* channel);
77 friend std::shared_ptr<Channel> grpc::CreateChannelInternal(
78 const std::string& host, grpc_channel* c_channel,
79 std::vector<std::unique_ptr<
80 grpc::experimental::ClientInterceptorFactoryInterface>>
81 interceptor_creators);
82 friend class grpc::internal::InterceptedChannel;
83 Channel(const std::string& host, grpc_channel* c_channel,
84 std::vector<std::unique_ptr<
85 grpc::experimental::ClientInterceptorFactoryInterface>>
86 interceptor_creators);
87
88 grpc::internal::Call CreateCall(const grpc::internal::RpcMethod& method,
89 grpc::ClientContext* context,
90 grpc::CompletionQueue* cq) override;
91 void PerformOpsOnCall(grpc::internal::CallOpSetInterface* ops,
92 grpc::internal::Call* call) override;
93 void* RegisterMethod(const char* method) override;
94
95 void NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
96 gpr_timespec deadline, grpc::CompletionQueue* cq,
97 void* tag) override;
98 bool WaitForStateChangeImpl(grpc_connectivity_state last_observed,
99 gpr_timespec deadline) override;
100
101 grpc::CompletionQueue* CallbackCQ() override;
102
103 grpc::internal::Call CreateCallInternal(
104 const grpc::internal::RpcMethod& method, grpc::ClientContext* context,
105 grpc::CompletionQueue* cq, size_t interceptor_pos) override;
106
107 const std::string host_;
108 grpc_channel* const c_channel_; // owned
109
110 // mu_ protects callback_cq_ (the per-channel callbackable completion queue)
111 grpc::internal::Mutex mu_;
112
113 // callback_cq_ references the callbackable completion queue associated
114 // with this channel (if any). It is set on the first call to CallbackCQ().
115 // It is _not owned_ by the channel; ownership belongs with its internal
116 // shutdown callback tag (invoked when the CQ is fully shutdown).
117 std::atomic<CompletionQueue*> callback_cq_{nullptr};
118
119 std::vector<
120 std::unique_ptr<grpc::experimental::ClientInterceptorFactoryInterface>>
121 interceptor_creators_;
122};
123
124} // namespace grpc
125
126#endif // GRPCPP_CHANNEL_H
127

source code of include/grpcpp/channel.h