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