The C based gRPC (C++, Python, Ruby, Objective-C, PHP, C#) https://grpc.io/
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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.
*
*/
/// A ClientContext allows the person implementing a service client to:
///
/// - Add custom metadata key-value pairs that will propagated to the server
/// side.
/// - Control call settings such as compression and authentication.
/// - Initial and trailing metadata coming from the server.
/// - Get performance metrics (ie, census).
///
/// Context settings are only relevant to the call they are invoked with, that
/// is to say, they aren't sticky. Some of these settings, such as the
/// compression options, can be made persistent at channel construction time
/// (see \a grpc::CreateCustomChannel).
///
/// \warning ClientContext instances should \em not be reused across rpcs.
#ifndef GRPCPP_CLIENT_CONTEXT_H
#define GRPCPP_CLIENT_CONTEXT_H
#include <map>
#include <memory>
#include <string>
#include <grpc/impl/codegen/compression_types.h>
#include <grpc/impl/codegen/propagation_bits.h>
#include <grpcpp/impl/codegen/core_codegen_interface.h>
#include <grpcpp/impl/codegen/create_auth_context.h>
#include <grpcpp/impl/codegen/metadata_map.h>
#include <grpcpp/impl/codegen/sync.h>
#include <grpcpp/impl/rpc_method.h>
#include <grpcpp/security/auth_context.h>
#include <grpcpp/support/client_interceptor.h>
#include <grpcpp/support/config.h>
#include <grpcpp/support/slice.h>
#include <grpcpp/support/status.h>
#include <grpcpp/support/string_ref.h>
#include <grpcpp/support/time.h>
struct census_context;
struct grpc_call;
namespace grpc {
class ServerContext;
class ServerContextBase;
class CallbackServerContext;
namespace internal {
template <class InputMessage, class OutputMessage>
class CallbackUnaryCallImpl;
template <class Request, class Response>
class ClientCallbackReaderWriterImpl;
template <class Response>
class ClientCallbackReaderImpl;
template <class Request>
class ClientCallbackWriterImpl;
class ClientCallbackUnaryImpl;
class ClientContextAccessor;
class ClientAsyncResponseReaderHelper;
} // namespace internal
template <class R>
class ClientReader;
template <class W>
class ClientWriter;
template <class W, class R>
class ClientReaderWriter;
template <class R>
class ClientAsyncReader;
template <class W>
class ClientAsyncWriter;
template <class W, class R>
class ClientAsyncReaderWriter;
template <class R>
class ClientAsyncResponseReader;
namespace testing {
class InteropClientContextInspector;
class ClientContextTestPeer;
} // namespace testing
namespace internal {
class RpcMethod;
template <class InputMessage, class OutputMessage>
class BlockingUnaryCallImpl;
class CallOpClientRecvStatus;
class CallOpRecvInitialMetadata;
class ServerContextImpl;
template <class InputMessage, class OutputMessage>
class CallbackUnaryCallImpl;
template <class Request, class Response>
class ClientCallbackReaderWriterImpl;
template <class Response>
class ClientCallbackReaderImpl;
template <class Request>
class ClientCallbackWriterImpl;
class ClientCallbackUnaryImpl;
class ClientContextAccessor;
} // namespace internal
class CallCredentials;
class Channel;
class ChannelInterface;
class CompletionQueue;
/// Options for \a ClientContext::FromServerContext specifying which traits from
/// the \a ServerContext to propagate (copy) from it into a new \a
/// ClientContext.
///
/// \see ClientContext::FromServerContext
class PropagationOptions {
public:
PropagationOptions() : propagate_(GRPC_PROPAGATE_DEFAULTS) {}
PropagationOptions& enable_deadline_propagation() {
propagate_ |= GRPC_PROPAGATE_DEADLINE;
return *this;
}
PropagationOptions& disable_deadline_propagation() {
propagate_ &= ~GRPC_PROPAGATE_DEADLINE;
return *this;
}
PropagationOptions& enable_census_stats_propagation() {
propagate_ |= GRPC_PROPAGATE_CENSUS_STATS_CONTEXT;
return *this;
}
PropagationOptions& disable_census_stats_propagation() {
propagate_ &= ~GRPC_PROPAGATE_CENSUS_STATS_CONTEXT;
return *this;
}
PropagationOptions& enable_census_tracing_propagation() {
propagate_ |= GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT;
return *this;
}
PropagationOptions& disable_census_tracing_propagation() {
propagate_ &= ~GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT;
return *this;
}
PropagationOptions& enable_cancellation_propagation() {
propagate_ |= GRPC_PROPAGATE_CANCELLATION;
return *this;
}
PropagationOptions& disable_cancellation_propagation() {
propagate_ &= ~GRPC_PROPAGATE_CANCELLATION;
return *this;
}
uint32_t c_bitmask() const { return propagate_; }
private:
uint32_t propagate_;
};
/// A ClientContext allows the person implementing a service client to:
///
/// - Add custom metadata key-value pairs that will propagated to the server
/// side.
/// - Control call settings such as compression and authentication.
/// - Initial and trailing metadata coming from the server.
/// - Get performance metrics (ie, census).
///
/// Context settings are only relevant to the call they are invoked with, that
/// is to say, they aren't sticky. Some of these settings, such as the
/// compression options, can be made persistent at channel construction time
/// (see \a grpc::CreateCustomChannel).
///
/// \warning ClientContext instances should \em not be reused across rpcs.
/// \warning The ClientContext instance used for creating an rpc must remain
/// alive and valid for the lifetime of the rpc.
class ClientContext {
public:
ClientContext();
~ClientContext();
/// Create a new \a ClientContext as a child of an incoming server call,
/// according to \a options (\see PropagationOptions).
///
/// \param server_context The source server context to use as the basis for
/// constructing the client context.
/// \param options The options controlling what to copy from the \a
/// server_context.
///
/// \return A newly constructed \a ClientContext instance based on \a
/// server_context, with traits propagated (copied) according to \a options.
static std::unique_ptr<ClientContext> FromServerContext(
const grpc::ServerContextBase& server_context,
PropagationOptions options = PropagationOptions());
static std::unique_ptr<ClientContext> FromCallbackServerContext(
const grpc::CallbackServerContext& server_context,
PropagationOptions options = PropagationOptions());
/// Add the (\a meta_key, \a meta_value) pair to the metadata associated with
/// a client call. These are made available at the server side by the \a
/// grpc::ServerContext::client_metadata() method.
///
/// \warning This method should only be called before invoking the rpc.
///
/// \param meta_key The metadata key. If \a meta_value is binary data, it must
/// end in "-bin".
/// \param meta_value The metadata value. If its value is binary, the key name
/// must end in "-bin".
///
/// Metadata must conform to the following format:
/**
\verbatim
Custom-Metadata -> Binary-Header / ASCII-Header
Binary-Header -> {Header-Name "-bin" } {binary value}
ASCII-Header -> Header-Name ASCII-Value
Header-Name -> 1*( %x30-39 / %x61-7A / "_" / "-" / ".") ; 0-9 a-z _ - .
ASCII-Value -> 1*( %x20-%x7E ) ; space and printable ASCII
Custom-Metadata -> Binary-Header / ASCII-Header
\endverbatim
**/
void AddMetadata(const std::string& meta_key, const std::string& meta_value);
/// Return a collection of initial metadata key-value pairs. Note that keys
/// may happen more than once (ie, a \a std::multimap is returned).
///
/// \warning This method should only be called after initial metadata has been
/// received. For streaming calls, see \a
/// ClientReaderInterface::WaitForInitialMetadata().
///
/// \return A multimap of initial metadata key-value pairs from the server.
const std::multimap<grpc::string_ref, grpc::string_ref>&
GetServerInitialMetadata() const {
GPR_CODEGEN_ASSERT(initial_metadata_received_);
return *recv_initial_metadata_.map();
}
/// Return a collection of trailing metadata key-value pairs. Note that keys
/// may happen more than once (ie, a \a std::multimap is returned).
///
/// \warning This method is only callable once the stream has finished.
///
/// \return A multimap of metadata trailing key-value pairs from the server.
const std::multimap<grpc::string_ref, grpc::string_ref>&
GetServerTrailingMetadata() const {
// TODO(yangg) check finished
return *trailing_metadata_.map();
}
/// Set the deadline for the client call.
///
/// \warning This method should only be called before invoking the rpc.
///
/// \param deadline the deadline for the client call. Units are determined by
/// the type used. The deadline is an absolute (not relative) time.
template <typename T>
void set_deadline(const T& deadline) {
grpc::TimePoint<T> deadline_tp(deadline);
deadline_ = deadline_tp.raw_time();
}
/// Trigger wait-for-ready or not on this request.
/// See https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md.
/// If set, if an RPC is made when a channel's connectivity state is
/// TRANSIENT_FAILURE or CONNECTING, the call will not "fail fast",
/// and the channel will wait until the channel is READY before making the
/// call.
void set_wait_for_ready(bool wait_for_ready) {
wait_for_ready_ = wait_for_ready;
wait_for_ready_explicitly_set_ = true;
}
/// DEPRECATED: Use set_wait_for_ready() instead.
void set_fail_fast(bool fail_fast) { set_wait_for_ready(!fail_fast); }
/// Return the deadline for the client call.
std::chrono::system_clock::time_point deadline() const {
return grpc::Timespec2Timepoint(deadline_);
}
/// Return a \a gpr_timespec representation of the client call's deadline.
gpr_timespec raw_deadline() const { return deadline_; }
/// Set the per call authority header (see
/// https://tools.ietf.org/html/rfc7540#section-8.1.2.3).
void set_authority(const std::string& authority) { authority_ = authority; }
/// Return the authentication context for the associated client call.
/// It is only valid to call this during the lifetime of the client call.
///
/// \see grpc::AuthContext.
std::shared_ptr<const grpc::AuthContext> auth_context() const {
if (auth_context_ == nullptr) {
auth_context_ = grpc::CreateAuthContext(call_);
}
return auth_context_;
}
/// Set credentials for the client call.
///
/// A credentials object encapsulates all the state needed by a client to
/// authenticate with a server and make various assertions, e.g., about the
/// client’s identity, role, or whether it is authorized to make a particular
/// call.
///
/// It is legal to call this only before initial metadata is sent.
///
/// \see https://grpc.io/docs/guides/auth.html
void set_credentials(const std::shared_ptr<grpc::CallCredentials>& creds);
/// EXPERIMENTAL debugging API
///
/// Returns the credentials for the client call. This should be used only in
/// tests and for diagnostic purposes, and should not be used by application
/// logic.
std::shared_ptr<grpc::CallCredentials> credentials() { return creds_; }
/// Return the compression algorithm the client call will request be used.
/// Note that the gRPC runtime may decide to ignore this request, for example,
/// due to resource constraints.
grpc_compression_algorithm compression_algorithm() const {
return compression_algorithm_;
}
/// Set \a algorithm to be the compression algorithm used for the client call.
///
/// \param algorithm The compression algorithm used for the client call.
void set_compression_algorithm(grpc_compression_algorithm algorithm);
/// Flag whether the initial metadata should be \a corked
///
/// If \a corked is true, then the initial metadata will be coalesced with the
/// write of first message in the stream. As a result, any tag set for the
/// initial metadata operation (starting a client-streaming or bidi-streaming
/// RPC) will not actually be sent to the completion queue or delivered
/// via Next.
///
/// \param corked The flag indicating whether the initial metadata is to be
/// corked or not.
void set_initial_metadata_corked(bool corked) {
initial_metadata_corked_ = corked;
}
/// Return the peer uri in a string.
/// It is only valid to call this during the lifetime of the client call.
///
/// \warning This value is never authenticated or subject to any security
/// related code. It must not be used for any authentication related
/// functionality. Instead, use auth_context.
///
/// \return The call's peer URI.
std::string peer() const;
/// Sets the census context.
/// It is only valid to call this before the client call is created. A common
/// place of setting census context is from within the DefaultConstructor
/// method of GlobalCallbacks.
void set_census_context(struct census_context* ccp) { census_context_ = ccp; }
/// Returns the census context that has been set, or nullptr if not set.
struct census_context* census_context() const { return census_context_; }
/// Send a best-effort out-of-band cancel on the call associated with
/// this client context. The call could be in any stage; e.g., if it is
/// already finished, it may still return success.
///
/// There is no guarantee the call will be cancelled.
///
/// Note that TryCancel() does not change any of the tags that are pending
/// on the completion queue. All pending tags will still be delivered
/// (though their ok result may reflect the effect of cancellation).
///
/// This method is thread-safe, and can be called multiple times from any
/// thread.
void TryCancel();
/// Global Callbacks
///
/// Can be set exactly once per application to install hooks whenever
/// a client context is constructed and destructed.
class GlobalCallbacks {
public:
virtual ~GlobalCallbacks() {}
virtual void DefaultConstructor(ClientContext* context) = 0;
virtual void Destructor(ClientContext* context) = 0;
};
static void SetGlobalCallbacks(GlobalCallbacks* callbacks);
/// Should be used for framework-level extensions only.
/// Applications never need to call this method.
grpc_call* c_call() { return call_; }
/// EXPERIMENTAL debugging API
///
/// if status is not ok() for an RPC, this will return a detailed string
/// of the gRPC Core error that led to the failure. It should not be relied
/// upon for anything other than gaining more debug data in failure cases.
std::string debug_error_string() const { return debug_error_string_; }
private:
// Disallow copy and assign.
ClientContext(const ClientContext&);
ClientContext& operator=(const ClientContext&);
friend class grpc::testing::InteropClientContextInspector;
friend class grpc::testing::ClientContextTestPeer;
friend class grpc::internal::CallOpClientRecvStatus;
friend class grpc::internal::CallOpRecvInitialMetadata;
friend class grpc::Channel;
template <class R>
friend class grpc::ClientReader;
template <class W>
friend class grpc::ClientWriter;
template <class W, class R>
friend class grpc::ClientReaderWriter;
template <class R>
friend class grpc::ClientAsyncReader;
template <class W>
friend class grpc::ClientAsyncWriter;
template <class W, class R>
friend class grpc::ClientAsyncReaderWriter;
template <class R>
friend class grpc::ClientAsyncResponseReader;
friend class grpc::internal::ClientAsyncResponseReaderHelper;
template <class InputMessage, class OutputMessage>
friend class grpc::internal::BlockingUnaryCallImpl;
template <class InputMessage, class OutputMessage>
friend class grpc::internal::CallbackUnaryCallImpl;
template <class Request, class Response>
friend class grpc::internal::ClientCallbackReaderWriterImpl;
template <class Response>
friend class grpc::internal::ClientCallbackReaderImpl;
template <class Request>
friend class grpc::internal::ClientCallbackWriterImpl;
friend class grpc::internal::ClientCallbackUnaryImpl;
friend class grpc::internal::ClientContextAccessor;
// Used by friend class CallOpClientRecvStatus
void set_debug_error_string(const std::string& debug_error_string) {
debug_error_string_ = debug_error_string;
}
grpc_call* call() const { return call_; }
void set_call(grpc_call* call, const std::shared_ptr<grpc::Channel>& channel);
grpc::experimental::ClientRpcInfo* set_client_rpc_info(
const char* method, const char* suffix_for_stats,
grpc::internal::RpcMethod::RpcType type, grpc::ChannelInterface* channel,
const std::vector<std::unique_ptr<
grpc::experimental::ClientInterceptorFactoryInterface>>& creators,
size_t interceptor_pos) {
rpc_info_ = grpc::experimental::ClientRpcInfo(this, type, method,
suffix_for_stats, channel);
rpc_info_.RegisterInterceptors(creators, interceptor_pos);
return &rpc_info_;
}
uint32_t initial_metadata_flags() const {
return (wait_for_ready_ ? GRPC_INITIAL_METADATA_WAIT_FOR_READY : 0) |
(wait_for_ready_explicitly_set_
? GRPC_INITIAL_METADATA_WAIT_FOR_READY_EXPLICITLY_SET
: 0);
}
std::string authority() { return authority_; }
void SendCancelToInterceptors();
static std::unique_ptr<ClientContext> FromInternalServerContext(
const grpc::ServerContextBase& server_context,
PropagationOptions options);
bool initial_metadata_received_;
bool wait_for_ready_;
bool wait_for_ready_explicitly_set_;
std::shared_ptr<grpc::Channel> channel_;
grpc::internal::Mutex mu_;
grpc_call* call_;
bool call_canceled_;
gpr_timespec deadline_;
grpc::string authority_;
std::shared_ptr<grpc::CallCredentials> creds_;
mutable std::shared_ptr<const grpc::AuthContext> auth_context_;
struct census_context* census_context_;
std::multimap<std::string, std::string> send_initial_metadata_;
mutable grpc::internal::MetadataMap recv_initial_metadata_;
mutable grpc::internal::MetadataMap trailing_metadata_;
grpc_call* propagate_from_call_;
PropagationOptions propagation_options_;
grpc_compression_algorithm compression_algorithm_;
bool initial_metadata_corked_;
std::string debug_error_string_;
grpc::experimental::ClientRpcInfo rpc_info_;
};
} // namespace grpc
#endif // GRPCPP_CLIENT_CONTEXT_H