src/cpp/client/channel_cc.cc

   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 #include <grpcpp/channel.h>
  20
  21 #include <cstring>
  22 #include <memory>
  23 #include <mutex>
  24
  25 #include <grpc/grpc.h>
  26 #include <grpc/slice.h>
  27 #include <grpc/support/alloc.h>
  28 #include <grpc/support/log.h>
  29 #include <grpc/support/sync.h>
  30 #include <grpc/support/time.h>
  31 #include <grpcpp/client_context.h>
  32 #include <grpcpp/completion_queue.h>
  33 #include <grpcpp/impl/call.h>
  34 #include <grpcpp/impl/codegen/call_op_set.h>
  35 #include <grpcpp/impl/codegen/completion_queue_tag.h>
  36 #include <grpcpp/impl/grpc_library.h>
  37 #include <grpcpp/impl/rpc_method.h>
  38 #include <grpcpp/security/credentials.h>
  39 #include <grpcpp/support/channel_arguments.h>
  40 #include <grpcpp/support/config.h>
  41 #include <grpcpp/support/status.h>
  42 #include "src/core/lib/gpr/string.h"
  43 #include "src/core/lib/surface/completion_queue.h"
  44
  45 void ::grpc::experimental::ChannelResetConnectionBackoff(Channel* channel) {
  46   grpc_impl::experimental::ChannelResetConnectionBackoff(channel);
  47 }
  48
  49 namespace grpc_impl {
  50
  51 static ::grpc::internal::GrpcLibraryInitializer g_gli_initializer;
  52 Channel::Channel(const grpc::string& host, grpc_channel* channel,
  53                  std::vector<std::unique_ptr<
  54                      ::grpc::experimental::ClientInterceptorFactoryInterface>>
  55                      interceptor_creators)
  56     : host_(host), c_channel_(channel) {
  57   interceptor_creators_ = std::move(interceptor_creators);
  58   g_gli_initializer.summon();
  59 }
  60
  61 Channel::~Channel() {
  62   grpc_channel_destroy(c_channel_);
  63   if (callback_cq_ != nullptr) {
  64     callback_cq_->Shutdown();
  65   }
  66 }
  67
  68 namespace {
  69
  70 inline grpc_slice SliceFromArray(const char* arr, size_t len) {
  71   return ::grpc::g_core_codegen_interface->grpc_slice_from_copied_buffer(arr,
  72                                                                          len);
  73 }
  74
  75 grpc::string GetChannelInfoField(grpc_channel* channel,
  76                                  grpc_channel_info* channel_info,
  77                                  char*** channel_info_field) {
  78   char* value = nullptr;
  79   memset(channel_info, 0, sizeof(*channel_info));
  80   *channel_info_field = &value;
  81   grpc_channel_get_info(channel, channel_info);
  82   if (value == nullptr) return "";
  83   grpc::string result = value;
  84   gpr_free(value);
  85   return result;
  86 }
  87
  88 }  // namespace
  89
  90 grpc::string Channel::GetLoadBalancingPolicyName() const {
  91   grpc_channel_info channel_info;
  92   return GetChannelInfoField(c_channel_, &channel_info,
  93                              &channel_info.lb_policy_name);
  94 }
  95
  96 grpc::string Channel::GetServiceConfigJSON() const {
  97   grpc_channel_info channel_info;
  98   return GetChannelInfoField(c_channel_, &channel_info,
  99                              &channel_info.service_config_json);
 100 }
 101
 102 namespace experimental {
 103
 104 void ChannelResetConnectionBackoff(Channel* channel) {
 105   grpc_channel_reset_connect_backoff(channel->c_channel_);
 106 }
 107
 108 }  // namespace experimental
 109
 110 ::grpc::internal::Call Channel::CreateCallInternal(
 111     const ::grpc::internal::RpcMethod& method, ::grpc::ClientContext* context,
 112     ::grpc::CompletionQueue* cq, size_t interceptor_pos) {
 113   const bool kRegistered = method.channel_tag() && context->authority().empty();
 114   grpc_call* c_call = nullptr;
 115   if (kRegistered) {
 116     c_call = grpc_channel_create_registered_call(
 117         c_channel_, context->propagate_from_call_,
 118         context->propagation_options_.c_bitmask(), cq->cq(),
 119         method.channel_tag(), context->raw_deadline(), nullptr);
 120   } else {
 121     const ::grpc::string* host_str = nullptr;
 122     if (!context->authority_.empty()) {
 123       host_str = &context->authority_;
 124     } else if (!host_.empty()) {
 125       host_str = &host_;
 126     }
 127     grpc_slice method_slice =
 128         SliceFromArray(method.name(), strlen(method.name()));
 129     grpc_slice host_slice;
 130     if (host_str != nullptr) {
 131       host_slice = ::grpc::SliceFromCopiedString(*host_str);
 132     }
 133     c_call = grpc_channel_create_call(
 134         c_channel_, context->propagate_from_call_,
 135         context->propagation_options_.c_bitmask(), cq->cq(), method_slice,
 136         host_str == nullptr ? nullptr : &host_slice, context->raw_deadline(),
 137         nullptr);
 138     grpc_slice_unref(method_slice);
 139     if (host_str != nullptr) {
 140       grpc_slice_unref(host_slice);
 141     }
 142   }
 143   grpc_census_call_set_context(c_call, context->census_context());
 144
 145   // ClientRpcInfo should be set before call because set_call also checks
 146   // whether the call has been cancelled, and if the call was cancelled, we
 147   // should notify the interceptors too.
 148   auto* info =
 149       context->set_client_rpc_info(method.name(), method.method_type(), this,
 150                                    interceptor_creators_, interceptor_pos);
 151   context->set_call(c_call, shared_from_this());
 152
 153   return ::grpc::internal::Call(c_call, this, cq, info);
 154 }
 155
 156 ::grpc::internal::Call Channel::CreateCall(
 157     const ::grpc::internal::RpcMethod& method, ::grpc::ClientContext* context,
 158     CompletionQueue* cq) {
 159   return CreateCallInternal(method, context, cq, 0);
 160 }
 161
 162 void Channel::PerformOpsOnCall(::grpc::internal::CallOpSetInterface* ops,
 163                                ::grpc::internal::Call* call) {
 164   ops->FillOps(
 165       call);  // Make a copy of call. It's fine since Call just has pointers
 166 }
 167
 168 void* Channel::RegisterMethod(const char* method) {
 169   return grpc_channel_register_call(
 170       c_channel_, method, host_.empty() ? nullptr : host_.c_str(), nullptr);
 171 }
 172
 173 grpc_connectivity_state Channel::GetState(bool try_to_connect) {
 174   return grpc_channel_check_connectivity_state(c_channel_, try_to_connect);
 175 }
 176
 177 namespace {
 178
 179 class TagSaver final : public ::grpc::internal::CompletionQueueTag {
 180  public:
 181   explicit TagSaver(void* tag) : tag_(tag) {}
 182   ~TagSaver() override {}
 183   bool FinalizeResult(void** tag, bool* status) override {
 184     *tag = tag_;
 185     delete this;
 186     return true;
 187   }
 188
 189  private:
 190   void* tag_;
 191 };
 192
 193 }  // namespace
 194
 195 void Channel::NotifyOnStateChangeImpl(grpc_connectivity_state last_observed,
 196                                       gpr_timespec deadline,
 197                                       ::grpc::CompletionQueue* cq, void* tag) {
 198   TagSaver* tag_saver = new TagSaver(tag);
 199   grpc_channel_watch_connectivity_state(c_channel_, last_observed, deadline,
 200                                         cq->cq(), tag_saver);
 201 }
 202
 203 bool Channel::WaitForStateChangeImpl(grpc_connectivity_state last_observed,
 204                                      gpr_timespec deadline) {
 205   ::grpc::CompletionQueue cq;
 206   bool ok = false;
 207   void* tag = nullptr;
 208   NotifyOnStateChangeImpl(last_observed, deadline, &cq, nullptr);
 209   cq.Next(&tag, &ok);
 210   GPR_ASSERT(tag == nullptr);
 211   return ok;
 212 }
 213
 214 namespace {
 215 class ShutdownCallback : public grpc_experimental_completion_queue_functor {
 216  public:
 217   ShutdownCallback() { functor_run = &ShutdownCallback::Run; }
 218   // TakeCQ takes ownership of the cq into the shutdown callback
 219   // so that the shutdown callback will be responsible for destroying it
 220   void TakeCQ(::grpc::CompletionQueue* cq) { cq_ = cq; }
 221
 222   // The Run function will get invoked by the completion queue library
 223   // when the shutdown is actually complete
 224   static void Run(grpc_experimental_completion_queue_functor* cb, int) {
 225     auto* callback = static_cast<ShutdownCallback*>(cb);
 226     delete callback->cq_;
 227     delete callback;
 228   }
 229
 230  private:
 231   ::grpc::CompletionQueue* cq_ = nullptr;
 232 };
 233 }  // namespace
 234
 235 ::grpc::CompletionQueue* Channel::CallbackCQ() {
 236   // TODO(vjpai): Consider using a single global CQ for the default CQ
 237   // if there is no explicit per-channel CQ registered
 238   grpc::internal::MutexLock l(&mu_);
 239   if (callback_cq_ == nullptr) {
 240     auto* shutdown_callback = new ShutdownCallback;
 241     callback_cq_ = new ::grpc::CompletionQueue(grpc_completion_queue_attributes{
 242         GRPC_CQ_CURRENT_VERSION, GRPC_CQ_CALLBACK, GRPC_CQ_DEFAULT_POLLING,
 243         shutdown_callback});
 244
 245     // Transfer ownership of the new cq to its own shutdown callback
 246     shutdown_callback->TakeCQ(callback_cq_);
 247   }
 248   return callback_cq_;
 249 }
 250
 251 }  // namespace grpc_impl