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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_SUPPORT_CLIENT_INTERCEPTOR_H
#define GRPCPP_SUPPORT_CLIENT_INTERCEPTOR_H
#include <memory>
#include <vector>
#include <grpcpp/impl/rpc_method.h>
#include <grpcpp/support/interceptor.h>
#include <grpcpp/support/string_ref.h>
namespace grpc {
class Channel;
class ClientContext;
namespace internal {
class InterceptorBatchMethodsImpl;
}
namespace experimental {
class ClientRpcInfo;
// A factory interface for creation of client interceptors. A vector of
// factories can be provided at channel creation which will be used to create a
// new vector of client interceptors per RPC. Client interceptor authors should
// create a subclass of ClientInterceptorFactorInterface which creates objects
// of their interceptors.
class ClientInterceptorFactoryInterface {
public:
virtual ~ClientInterceptorFactoryInterface() {}
// Returns a pointer to an Interceptor object on successful creation, nullptr
// otherwise. If nullptr is returned, this server interceptor factory is
// ignored for the purposes of that RPC.
virtual Interceptor* CreateClientInterceptor(ClientRpcInfo* info) = 0;
};
} // namespace experimental
namespace internal {
extern experimental::ClientInterceptorFactoryInterface*
g_global_client_interceptor_factory;
}
/// ClientRpcInfo represents the state of a particular RPC as it
/// appears to an interceptor. It is created and owned by the library and
/// passed to the CreateClientInterceptor method of the application's
/// ClientInterceptorFactoryInterface implementation
namespace experimental {
class ClientRpcInfo {
public:
// TODO(yashykt): Stop default-constructing ClientRpcInfo and remove UNKNOWN
// from the list of possible Types.
/// Type categorizes RPCs by unary or streaming type
enum class Type {
UNARY,
CLIENT_STREAMING,
SERVER_STREAMING,
BIDI_STREAMING,
UNKNOWN // UNKNOWN is not API and will be removed later
};
~ClientRpcInfo() {}
// Delete copy constructor but allow default move constructor
ClientRpcInfo(const ClientRpcInfo&) = delete;
ClientRpcInfo(ClientRpcInfo&&) = default;
// Getter methods
/// Return the fully-specified method name
const char* method() const { return method_; }
/// Return an identifying suffix for the client stub, or nullptr if one wasn't
/// specified.
const char* suffix_for_stats() const { return suffix_for_stats_; }
/// Return a pointer to the channel on which the RPC is being sent
ChannelInterface* channel() { return channel_; }
/// Return a pointer to the underlying ClientContext structure associated
/// with the RPC to support features that apply to it
grpc::ClientContext* client_context() { return ctx_; }
/// Return the type of the RPC (unary or a streaming flavor)
Type type() const { return type_; }
private:
static_assert(Type::UNARY ==
static_cast<Type>(internal::RpcMethod::NORMAL_RPC),
"violated expectation about Type enum");
static_assert(Type::CLIENT_STREAMING ==
static_cast<Type>(internal::RpcMethod::CLIENT_STREAMING),
"violated expectation about Type enum");
static_assert(Type::SERVER_STREAMING ==
static_cast<Type>(internal::RpcMethod::SERVER_STREAMING),
"violated expectation about Type enum");
static_assert(Type::BIDI_STREAMING ==
static_cast<Type>(internal::RpcMethod::BIDI_STREAMING),
"violated expectation about Type enum");
// Default constructor should only be used by ClientContext
ClientRpcInfo() = default;
// Constructor will only be called from ClientContext
ClientRpcInfo(grpc::ClientContext* ctx, internal::RpcMethod::RpcType type,
const char* method, const char* suffix_for_stats,
grpc::ChannelInterface* channel)
: ctx_(ctx),
type_(static_cast<Type>(type)),
method_(method),
suffix_for_stats_(suffix_for_stats),
channel_(channel) {}
// Move assignment should only be used by ClientContext
// TODO(yashykt): Delete move assignment
ClientRpcInfo& operator=(ClientRpcInfo&&) = default;
// Runs interceptor at pos \a pos.
void RunInterceptor(
experimental::InterceptorBatchMethods* interceptor_methods, size_t pos) {
GPR_CODEGEN_ASSERT(pos < interceptors_.size());
interceptors_[pos]->Intercept(interceptor_methods);
}
void RegisterInterceptors(
const std::vector<std::unique_ptr<
experimental::ClientInterceptorFactoryInterface>>& creators,
size_t interceptor_pos) {
if (interceptor_pos > creators.size()) {
// No interceptors to register
return;
}
// NOTE: The following is not a range-based for loop because it will only
// iterate over a portion of the creators vector.
for (auto it = creators.begin() + interceptor_pos; it != creators.end();
++it) {
auto* interceptor = (*it)->CreateClientInterceptor(this);
if (interceptor != nullptr) {
interceptors_.push_back(
std::unique_ptr<experimental::Interceptor>(interceptor));
}
}
if (internal::g_global_client_interceptor_factory != nullptr) {
interceptors_.push_back(std::unique_ptr<experimental::Interceptor>(
internal::g_global_client_interceptor_factory
->CreateClientInterceptor(this)));
}
}
grpc::ClientContext* ctx_ = nullptr;
// TODO(yashykt): make type_ const once move-assignment is deleted
Type type_{Type::UNKNOWN};
const char* method_ = nullptr;
const char* suffix_for_stats_ = nullptr;
grpc::ChannelInterface* channel_ = nullptr;
std::vector<std::unique_ptr<experimental::Interceptor>> interceptors_;
bool hijacked_ = false;
size_t hijacked_interceptor_ = 0;
friend class internal::InterceptorBatchMethodsImpl;
friend class grpc::ClientContext;
};
// PLEASE DO NOT USE THIS. ALWAYS PREFER PER CHANNEL INTERCEPTORS OVER A GLOBAL
// INTERCEPTOR. IF USAGE IS ABSOLUTELY NECESSARY, PLEASE READ THE SAFETY NOTES.
// Registers a global client interceptor factory object, which is used for all
// RPCs made in this process. The application is responsible for maintaining the
// life of the object while gRPC operations are in progress. The global
// interceptor factory should only be registered once at the start of the
// process before any gRPC operations have begun.
void RegisterGlobalClientInterceptorFactory(
ClientInterceptorFactoryInterface* factory);
// For testing purposes only
void TestOnlyResetGlobalClientInterceptorFactory();
} // namespace experimental
} // namespace grpc
#endif // GRPCPP_SUPPORT_CLIENT_INTERCEPTOR_H
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