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/// A ClientContext allows the person implementing a service client to:
20///
21/// - Add custom metadata key-value pairs that will propagated to the server
22/// side.
23/// - Control call settings such as compression and authentication.
24/// - Initial and trailing metadata coming from the server.
25/// - Get performance metrics (ie, census).
26///
27/// Context settings are only relevant to the call they are invoked with, that
28/// is to say, they aren't sticky. Some of these settings, such as the
29/// compression options, can be made persistent at channel construction time
30/// (see \a grpc::CreateCustomChannel).
31///
32/// \warning ClientContext instances should \em not be reused across rpcs.
33
34#ifndef GRPCPP_CLIENT_CONTEXT_H
35#define GRPCPP_CLIENT_CONTEXT_H
36
37#include <map>
38#include <memory>
39#include <string>
40
41#include <grpc/impl/codegen/compression_types.h>
42#include <grpc/impl/codegen/propagation_bits.h>
43#include <grpcpp/impl/codegen/core_codegen_interface.h>
44#include <grpcpp/impl/codegen/create_auth_context.h>
45#include <grpcpp/impl/codegen/metadata_map.h>
46#include <grpcpp/impl/codegen/sync.h>
47#include <grpcpp/impl/rpc_method.h>
48#include <grpcpp/security/auth_context.h>
49#include <grpcpp/support/client_interceptor.h>
50#include <grpcpp/support/config.h>
51#include <grpcpp/support/slice.h>
52#include <grpcpp/support/status.h>
53#include <grpcpp/support/string_ref.h>
54#include <grpcpp/support/time.h>
55
56struct census_context;
57struct grpc_call;
58
59namespace grpc {
60class ServerContext;
61class ServerContextBase;
62class CallbackServerContext;
63
64namespace internal {
65template <class InputMessage, class OutputMessage>
66class CallbackUnaryCallImpl;
67template <class Request, class Response>
68class ClientCallbackReaderWriterImpl;
69template <class Response>
70class ClientCallbackReaderImpl;
71template <class Request>
72class ClientCallbackWriterImpl;
73class ClientCallbackUnaryImpl;
74class ClientContextAccessor;
75class ClientAsyncResponseReaderHelper;
76} // namespace internal
77
78template <class R>
79class ClientReader;
80template <class W>
81class ClientWriter;
82template <class W, class R>
83class ClientReaderWriter;
84template <class R>
85class ClientAsyncReader;
86template <class W>
87class ClientAsyncWriter;
88template <class W, class R>
89class ClientAsyncReaderWriter;
90template <class R>
91class ClientAsyncResponseReader;
92
93namespace testing {
94class InteropClientContextInspector;
95class ClientContextTestPeer;
96} // namespace testing
97
98namespace internal {
99class RpcMethod;
100template <class InputMessage, class OutputMessage>
101class BlockingUnaryCallImpl;
102class CallOpClientRecvStatus;
103class CallOpRecvInitialMetadata;
104class ServerContextImpl;
105template <class InputMessage, class OutputMessage>
106class CallbackUnaryCallImpl;
107template <class Request, class Response>
108class ClientCallbackReaderWriterImpl;
109template <class Response>
110class ClientCallbackReaderImpl;
111template <class Request>
112class ClientCallbackWriterImpl;
113class ClientCallbackUnaryImpl;
114class ClientContextAccessor;
115} // namespace internal
116
117class CallCredentials;
118class Channel;
119class ChannelInterface;
120class CompletionQueue;
121
122/// Options for \a ClientContext::FromServerContext specifying which traits from
123/// the \a ServerContext to propagate (copy) from it into a new \a
124/// ClientContext.
125///
126/// \see ClientContext::FromServerContext
127class PropagationOptions {
128 public:
129 PropagationOptions() : propagate_(GRPC_PROPAGATE_DEFAULTS) {}
130
131 PropagationOptions& enable_deadline_propagation() {
132 propagate_ |= GRPC_PROPAGATE_DEADLINE;
133 return *this;
134 }
135
136 PropagationOptions& disable_deadline_propagation() {
137 propagate_ &= ~GRPC_PROPAGATE_DEADLINE;
138 return *this;
139 }
140
141 PropagationOptions& enable_census_stats_propagation() {
142 propagate_ |= GRPC_PROPAGATE_CENSUS_STATS_CONTEXT;
143 return *this;
144 }
145
146 PropagationOptions& disable_census_stats_propagation() {
147 propagate_ &= ~GRPC_PROPAGATE_CENSUS_STATS_CONTEXT;
148 return *this;
149 }
150
151 PropagationOptions& enable_census_tracing_propagation() {
152 propagate_ |= GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT;
153 return *this;
154 }
155
156 PropagationOptions& disable_census_tracing_propagation() {
157 propagate_ &= ~GRPC_PROPAGATE_CENSUS_TRACING_CONTEXT;
158 return *this;
159 }
160
161 PropagationOptions& enable_cancellation_propagation() {
162 propagate_ |= GRPC_PROPAGATE_CANCELLATION;
163 return *this;
164 }
165
166 PropagationOptions& disable_cancellation_propagation() {
167 propagate_ &= ~GRPC_PROPAGATE_CANCELLATION;
168 return *this;
169 }
170
171 uint32_t c_bitmask() const { return propagate_; }
172
173 private:
174 uint32_t propagate_;
175};
176
177/// A ClientContext allows the person implementing a service client to:
178///
179/// - Add custom metadata key-value pairs that will propagated to the server
180/// side.
181/// - Control call settings such as compression and authentication.
182/// - Initial and trailing metadata coming from the server.
183/// - Get performance metrics (ie, census).
184///
185/// Context settings are only relevant to the call they are invoked with, that
186/// is to say, they aren't sticky. Some of these settings, such as the
187/// compression options, can be made persistent at channel construction time
188/// (see \a grpc::CreateCustomChannel).
189///
190/// \warning ClientContext instances should \em not be reused across rpcs.
191/// \warning The ClientContext instance used for creating an rpc must remain
192/// alive and valid for the lifetime of the rpc.
193class ClientContext {
194 public:
195 ClientContext();
196 ~ClientContext();
197
198 /// Create a new \a ClientContext as a child of an incoming server call,
199 /// according to \a options (\see PropagationOptions).
200 ///
201 /// \param server_context The source server context to use as the basis for
202 /// constructing the client context.
203 /// \param options The options controlling what to copy from the \a
204 /// server_context.
205 ///
206 /// \return A newly constructed \a ClientContext instance based on \a
207 /// server_context, with traits propagated (copied) according to \a options.
208 static std::unique_ptr<ClientContext> FromServerContext(
209 const grpc::ServerContextBase& server_context,
210 PropagationOptions options = PropagationOptions());
211 static std::unique_ptr<ClientContext> FromCallbackServerContext(
212 const grpc::CallbackServerContext& server_context,
213 PropagationOptions options = PropagationOptions());
214
215 /// Add the (\a meta_key, \a meta_value) pair to the metadata associated with
216 /// a client call. These are made available at the server side by the \a
217 /// grpc::ServerContext::client_metadata() method.
218 ///
219 /// \warning This method should only be called before invoking the rpc.
220 ///
221 /// \param meta_key The metadata key. If \a meta_value is binary data, it must
222 /// end in "-bin".
223 /// \param meta_value The metadata value. If its value is binary, the key name
224 /// must end in "-bin".
225 ///
226 /// Metadata must conform to the following format:
227 /**
228 \verbatim
229 Custom-Metadata -> Binary-Header / ASCII-Header
230 Binary-Header -> {Header-Name "-bin" } {binary value}
231 ASCII-Header -> Header-Name ASCII-Value
232 Header-Name -> 1*( %x30-39 / %x61-7A / "_" / "-" / ".") ; 0-9 a-z _ - .
233 ASCII-Value -> 1*( %x20-%x7E ) ; space and printable ASCII
234 Custom-Metadata -> Binary-Header / ASCII-Header
235 \endverbatim
236 **/
237 void AddMetadata(const std::string& meta_key, const std::string& meta_value);
238
239 /// Return a collection of initial metadata key-value pairs. Note that keys
240 /// may happen more than once (ie, a \a std::multimap is returned).
241 ///
242 /// \warning This method should only be called after initial metadata has been
243 /// received. For streaming calls, see \a
244 /// ClientReaderInterface::WaitForInitialMetadata().
245 ///
246 /// \return A multimap of initial metadata key-value pairs from the server.
247 const std::multimap<grpc::string_ref, grpc::string_ref>&
248 GetServerInitialMetadata() const {
249 GPR_CODEGEN_ASSERT(initial_metadata_received_);
250 return *recv_initial_metadata_.map();
251 }
252
253 /// Return a collection of trailing metadata key-value pairs. Note that keys
254 /// may happen more than once (ie, a \a std::multimap is returned).
255 ///
256 /// \warning This method is only callable once the stream has finished.
257 ///
258 /// \return A multimap of metadata trailing key-value pairs from the server.
259 const std::multimap<grpc::string_ref, grpc::string_ref>&
260 GetServerTrailingMetadata() const {
261 // TODO(yangg) check finished
262 return *trailing_metadata_.map();
263 }
264
265 /// Set the deadline for the client call.
266 ///
267 /// \warning This method should only be called before invoking the rpc.
268 ///
269 /// \param deadline the deadline for the client call. Units are determined by
270 /// the type used. The deadline is an absolute (not relative) time.
271 template <typename T>
272 void set_deadline(const T& deadline) {
273 grpc::TimePoint<T> deadline_tp(deadline);
274 deadline_ = deadline_tp.raw_time();
275 }
276
277 /// Trigger wait-for-ready or not on this request.
278 /// See https://github.com/grpc/grpc/blob/master/doc/wait-for-ready.md.
279 /// If set, if an RPC is made when a channel's connectivity state is
280 /// TRANSIENT_FAILURE or CONNECTING, the call will not "fail fast",
281 /// and the channel will wait until the channel is READY before making the
282 /// call.
283 void set_wait_for_ready(bool wait_for_ready) {
284 wait_for_ready_ = wait_for_ready;
285 wait_for_ready_explicitly_set_ = true;
286 }
287
288 /// DEPRECATED: Use set_wait_for_ready() instead.
289 void set_fail_fast(bool fail_fast) { set_wait_for_ready(!fail_fast); }
290
291 /// Return the deadline for the client call.
292 std::chrono::system_clock::time_point deadline() const {
293 return grpc::Timespec2Timepoint(t: deadline_);
294 }
295
296 /// Return a \a gpr_timespec representation of the client call's deadline.
297 gpr_timespec raw_deadline() const { return deadline_; }
298
299 /// Set the per call authority header (see
300 /// https://tools.ietf.org/html/rfc7540#section-8.1.2.3).
301 void set_authority(const std::string& authority) { authority_ = authority; }
302
303 /// Return the authentication context for the associated client call.
304 /// It is only valid to call this during the lifetime of the client call.
305 ///
306 /// \see grpc::AuthContext.
307 std::shared_ptr<const grpc::AuthContext> auth_context() const {
308 if (auth_context_ == nullptr) {
309 auth_context_ = grpc::CreateAuthContext(call: call_);
310 }
311 return auth_context_;
312 }
313
314 /// Set credentials for the client call.
315 ///
316 /// A credentials object encapsulates all the state needed by a client to
317 /// authenticate with a server and make various assertions, e.g., about the
318 /// client’s identity, role, or whether it is authorized to make a particular
319 /// call.
320 ///
321 /// It is legal to call this only before initial metadata is sent.
322 ///
323 /// \see https://grpc.io/docs/guides/auth.html
324 void set_credentials(const std::shared_ptr<grpc::CallCredentials>& creds);
325
326 /// EXPERIMENTAL debugging API
327 ///
328 /// Returns the credentials for the client call. This should be used only in
329 /// tests and for diagnostic purposes, and should not be used by application
330 /// logic.
331 std::shared_ptr<grpc::CallCredentials> credentials() { return creds_; }
332
333 /// Return the compression algorithm the client call will request be used.
334 /// Note that the gRPC runtime may decide to ignore this request, for example,
335 /// due to resource constraints.
336 grpc_compression_algorithm compression_algorithm() const {
337 return compression_algorithm_;
338 }
339
340 /// Set \a algorithm to be the compression algorithm used for the client call.
341 ///
342 /// \param algorithm The compression algorithm used for the client call.
343 void set_compression_algorithm(grpc_compression_algorithm algorithm);
344
345 /// Flag whether the initial metadata should be \a corked
346 ///
347 /// If \a corked is true, then the initial metadata will be coalesced with the
348 /// write of first message in the stream. As a result, any tag set for the
349 /// initial metadata operation (starting a client-streaming or bidi-streaming
350 /// RPC) will not actually be sent to the completion queue or delivered
351 /// via Next.
352 ///
353 /// \param corked The flag indicating whether the initial metadata is to be
354 /// corked or not.
355 void set_initial_metadata_corked(bool corked) {
356 initial_metadata_corked_ = corked;
357 }
358
359 /// Return the peer uri in a string.
360 /// It is only valid to call this during the lifetime of the client call.
361 ///
362 /// \warning This value is never authenticated or subject to any security
363 /// related code. It must not be used for any authentication related
364 /// functionality. Instead, use auth_context.
365 ///
366 /// \return The call's peer URI.
367 std::string peer() const;
368
369 /// Sets the census context.
370 /// It is only valid to call this before the client call is created. A common
371 /// place of setting census context is from within the DefaultConstructor
372 /// method of GlobalCallbacks.
373 void set_census_context(struct census_context* ccp) { census_context_ = ccp; }
374
375 /// Returns the census context that has been set, or nullptr if not set.
376 struct census_context* census_context() const { return census_context_; }
377
378 /// Send a best-effort out-of-band cancel on the call associated with
379 /// this client context. The call could be in any stage; e.g., if it is
380 /// already finished, it may still return success.
381 ///
382 /// There is no guarantee the call will be cancelled.
383 ///
384 /// Note that TryCancel() does not change any of the tags that are pending
385 /// on the completion queue. All pending tags will still be delivered
386 /// (though their ok result may reflect the effect of cancellation).
387 ///
388 /// This method is thread-safe, and can be called multiple times from any
389 /// thread.
390 void TryCancel();
391
392 /// Global Callbacks
393 ///
394 /// Can be set exactly once per application to install hooks whenever
395 /// a client context is constructed and destructed.
396 class GlobalCallbacks {
397 public:
398 virtual ~GlobalCallbacks() {}
399 virtual void DefaultConstructor(ClientContext* context) = 0;
400 virtual void Destructor(ClientContext* context) = 0;
401 };
402 static void SetGlobalCallbacks(GlobalCallbacks* callbacks);
403
404 /// Should be used for framework-level extensions only.
405 /// Applications never need to call this method.
406 grpc_call* c_call() { return call_; }
407
408 /// EXPERIMENTAL debugging API
409 ///
410 /// if status is not ok() for an RPC, this will return a detailed string
411 /// of the gRPC Core error that led to the failure. It should not be relied
412 /// upon for anything other than gaining more debug data in failure cases.
413 std::string debug_error_string() const { return debug_error_string_; }
414
415 private:
416 // Disallow copy and assign.
417 ClientContext(const ClientContext&);
418 ClientContext& operator=(const ClientContext&);
419
420 friend class grpc::testing::InteropClientContextInspector;
421 friend class grpc::testing::ClientContextTestPeer;
422 friend class grpc::internal::CallOpClientRecvStatus;
423 friend class grpc::internal::CallOpRecvInitialMetadata;
424 friend class grpc::Channel;
425 template <class R>
426 friend class grpc::ClientReader;
427 template <class W>
428 friend class grpc::ClientWriter;
429 template <class W, class R>
430 friend class grpc::ClientReaderWriter;
431 template <class R>
432 friend class grpc::ClientAsyncReader;
433 template <class W>
434 friend class grpc::ClientAsyncWriter;
435 template <class W, class R>
436 friend class grpc::ClientAsyncReaderWriter;
437 template <class R>
438 friend class grpc::ClientAsyncResponseReader;
439 friend class grpc::internal::ClientAsyncResponseReaderHelper;
440 template <class InputMessage, class OutputMessage>
441 friend class grpc::internal::BlockingUnaryCallImpl;
442 template <class InputMessage, class OutputMessage>
443 friend class grpc::internal::CallbackUnaryCallImpl;
444 template <class Request, class Response>
445 friend class grpc::internal::ClientCallbackReaderWriterImpl;
446 template <class Response>
447 friend class grpc::internal::ClientCallbackReaderImpl;
448 template <class Request>
449 friend class grpc::internal::ClientCallbackWriterImpl;
450 friend class grpc::internal::ClientCallbackUnaryImpl;
451 friend class grpc::internal::ClientContextAccessor;
452
453 // Used by friend class CallOpClientRecvStatus
454 void set_debug_error_string(const std::string& debug_error_string) {
455 debug_error_string_ = debug_error_string;
456 }
457
458 grpc_call* call() const { return call_; }
459 void set_call(grpc_call* call, const std::shared_ptr<grpc::Channel>& channel);
460
461 grpc::experimental::ClientRpcInfo* set_client_rpc_info(
462 const char* method, const char* suffix_for_stats,
463 grpc::internal::RpcMethod::RpcType type, grpc::ChannelInterface* channel,
464 const std::vector<std::unique_ptr<
465 grpc::experimental::ClientInterceptorFactoryInterface>>& creators,
466 size_t interceptor_pos) {
467 rpc_info_ = grpc::experimental::ClientRpcInfo(this, type, method,
468 suffix_for_stats, channel);
469 rpc_info_.RegisterInterceptors(creators, interceptor_pos);
470 return &rpc_info_;
471 }
472
473 uint32_t initial_metadata_flags() const {
474 return (wait_for_ready_ ? GRPC_INITIAL_METADATA_WAIT_FOR_READY : 0) |
475 (wait_for_ready_explicitly_set_
476 ? GRPC_INITIAL_METADATA_WAIT_FOR_READY_EXPLICITLY_SET
477 : 0);
478 }
479
480 std::string authority() { return authority_; }
481
482 void SendCancelToInterceptors();
483
484 static std::unique_ptr<ClientContext> FromInternalServerContext(
485 const grpc::ServerContextBase& server_context,
486 PropagationOptions options);
487
488 bool initial_metadata_received_;
489 bool wait_for_ready_;
490 bool wait_for_ready_explicitly_set_;
491 std::shared_ptr<grpc::Channel> channel_;
492 grpc::internal::Mutex mu_;
493 grpc_call* call_;
494 bool call_canceled_;
495 gpr_timespec deadline_;
496 grpc::string authority_;
497 std::shared_ptr<grpc::CallCredentials> creds_;
498 mutable std::shared_ptr<const grpc::AuthContext> auth_context_;
499 struct census_context* census_context_;
500 std::multimap<std::string, std::string> send_initial_metadata_;
501 mutable grpc::internal::MetadataMap recv_initial_metadata_;
502 mutable grpc::internal::MetadataMap trailing_metadata_;
503
504 grpc_call* propagate_from_call_;
505 PropagationOptions propagation_options_;
506
507 grpc_compression_algorithm compression_algorithm_;
508 bool initial_metadata_corked_;
509
510 std::string debug_error_string_;
511
512 grpc::experimental::ClientRpcInfo rpc_info_;
513};
514
515} // namespace grpc
516
517#endif // GRPCPP_CLIENT_CONTEXT_H
518

source code of include/grpcpp/client_context.h