2 // Copyright 2016 gRPC authors.
4 // Licensed under the Apache License, Version 2.0 (the "License");
5 // you may not use this file except in compliance with the License.
6 // You may obtain a copy of the License at
8 // http://www.apache.org/licenses/LICENSE-2.0
10 // Unless required by applicable law or agreed to in writing, software
11 // distributed under the License is distributed on an "AS IS" BASIS,
12 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 // See the License for the specific language governing permissions and
14 // limitations under the License.
17 // This is similar to the sockaddr resolver, except that it supports a
18 // bunch of query args that are useful for dependency injection in tests.
20 #include <grpc/support/port_platform.h>
28 #include <grpc/support/alloc.h>
29 #include <grpc/support/string_util.h>
31 #include "src/core/ext/filters/client_channel/resolver_registry.h"
32 #include "src/core/ext/filters/client_channel/server_address.h"
33 #include "src/core/lib/channel/channel_args.h"
34 #include "src/core/lib/gpr/string.h"
35 #include "src/core/lib/gpr/useful.h"
36 #include "src/core/lib/iomgr/closure.h"
37 #include "src/core/lib/iomgr/parse_address.h"
38 #include "src/core/lib/iomgr/resolve_address.h"
39 #include "src/core/lib/iomgr/unix_sockets_posix.h"
40 #include "src/core/lib/iomgr/work_serializer.h"
41 #include "src/core/lib/slice/slice_internal.h"
42 #include "src/core/lib/slice/slice_string_helpers.h"
44 #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
48 // This cannot be in an anonymous namespace, because it is a friend of
49 // FakeResolverResponseGenerator.
50 class FakeResolver : public Resolver {
52 explicit FakeResolver(ResolverArgs args);
54 void StartLocked() override;
56 void RequestReresolutionLocked() override;
59 friend class FakeResolverResponseGenerator;
60 friend class FakeResolverResponseSetter;
62 virtual ~FakeResolver();
64 void ShutdownLocked() override;
66 void MaybeSendResultLocked();
68 void ReturnReresolutionResult();
70 // passed-in parameters
71 grpc_channel_args* channel_args_ = nullptr;
72 RefCountedPtr<FakeResolverResponseGenerator> response_generator_;
73 // If has_next_result_ is true, next_result_ is the next resolution result
75 bool has_next_result_ = false;
77 // Result to use for the pretended re-resolution in
78 // RequestReresolutionLocked().
79 bool has_reresolution_result_ = false;
80 Result reresolution_result_;
81 // True after the call to StartLocked().
82 bool started_ = false;
83 // True after the call to ShutdownLocked().
84 bool shutdown_ = false;
85 // if true, return failure
86 bool return_failure_ = false;
87 // pending re-resolution
88 bool reresolution_closure_pending_ = false;
91 FakeResolver::FakeResolver(ResolverArgs args)
92 : Resolver(std::move(args.work_serializer), std::move(args.result_handler)),
94 FakeResolverResponseGenerator::GetFromArgs(args.args)) {
95 // Channels sharing the same subchannels may have different resolver response
96 // generators. If we don't remove this arg, subchannel pool will create new
97 // subchannels for the same address instead of reusing existing ones because
98 // of different values of this channel arg.
99 const char* args_to_remove[] = {GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR};
100 channel_args_ = grpc_channel_args_copy_and_remove(
101 args.args, args_to_remove, GPR_ARRAY_SIZE(args_to_remove));
102 if (response_generator_ != nullptr) {
103 response_generator_->SetFakeResolver(Ref());
107 FakeResolver::~FakeResolver() { grpc_channel_args_destroy(channel_args_); }
109 void FakeResolver::StartLocked() {
111 MaybeSendResultLocked();
114 void FakeResolver::RequestReresolutionLocked() {
115 if (has_reresolution_result_ || return_failure_) {
116 next_result_ = reresolution_result_;
117 has_next_result_ = true;
118 // Return the result in a different closure, so that we don't call
119 // back into the LB policy while it's still processing the previous
121 if (!reresolution_closure_pending_) {
122 reresolution_closure_pending_ = true;
123 Ref().release(); // ref held by closure
124 work_serializer()->Run([this]() { ReturnReresolutionResult(); },
130 void FakeResolver::ShutdownLocked() {
132 if (response_generator_ != nullptr) {
133 response_generator_->SetFakeResolver(nullptr);
134 response_generator_.reset();
138 void FakeResolver::MaybeSendResultLocked() {
139 if (!started_ || shutdown_) return;
140 if (return_failure_) {
141 // TODO(roth): Change resolver result generator to be able to inject
142 // the error to be returned.
143 result_handler()->ReturnError(grpc_error_set_int(
144 GRPC_ERROR_CREATE_FROM_STATIC_STRING("Resolver transient failure"),
145 GRPC_ERROR_INT_GRPC_STATUS, GRPC_STATUS_UNAVAILABLE));
146 return_failure_ = false;
147 } else if (has_next_result_) {
149 result.addresses = std::move(next_result_.addresses);
150 result.service_config = std::move(next_result_.service_config);
151 // TODO(roth): Use std::move() once grpc_error is converted to C++.
152 result.service_config_error = next_result_.service_config_error;
153 next_result_.service_config_error = GRPC_ERROR_NONE;
154 // When both next_results_ and channel_args_ contain an arg with the same
155 // name, only the one in next_results_ will be kept since next_results_ is
156 // before channel_args_.
157 result.args = grpc_channel_args_union(next_result_.args, channel_args_);
158 result_handler()->ReturnResult(std::move(result));
159 has_next_result_ = false;
163 void FakeResolver::ReturnReresolutionResult() {
164 reresolution_closure_pending_ = false;
165 MaybeSendResultLocked();
169 class FakeResolverResponseSetter {
171 explicit FakeResolverResponseSetter(RefCountedPtr<FakeResolver> resolver,
172 Resolver::Result result,
173 bool has_result = false,
174 bool immediate = true)
175 : resolver_(std::move(resolver)),
176 result_(std::move(result)),
177 has_result_(has_result),
178 immediate_(immediate) {}
179 void SetResponseLocked();
180 void SetReresolutionResponseLocked();
181 void SetFailureLocked();
184 RefCountedPtr<FakeResolver> resolver_;
185 Resolver::Result result_;
190 // Deletes object when done
191 void FakeResolverResponseSetter::SetReresolutionResponseLocked() {
192 if (!resolver_->shutdown_) {
193 resolver_->reresolution_result_ = std::move(result_);
194 resolver_->has_reresolution_result_ = has_result_;
199 // Deletes object when done
200 void FakeResolverResponseSetter::SetResponseLocked() {
201 if (!resolver_->shutdown_) {
202 resolver_->next_result_ = std::move(result_);
203 resolver_->has_next_result_ = true;
204 resolver_->MaybeSendResultLocked();
209 // Deletes object when done
210 void FakeResolverResponseSetter::SetFailureLocked() {
211 if (!resolver_->shutdown_) {
212 resolver_->return_failure_ = true;
213 if (immediate_) resolver_->MaybeSendResultLocked();
219 // FakeResolverResponseGenerator
222 FakeResolverResponseGenerator::FakeResolverResponseGenerator() {}
224 FakeResolverResponseGenerator::~FakeResolverResponseGenerator() {}
226 void FakeResolverResponseGenerator::SetResponse(Resolver::Result result) {
227 RefCountedPtr<FakeResolver> resolver;
229 MutexLock lock(&mu_);
230 if (resolver_ == nullptr) {
232 result_ = std::move(result);
235 resolver = resolver_->Ref();
237 FakeResolverResponseSetter* arg =
238 new FakeResolverResponseSetter(resolver, std::move(result));
239 resolver->work_serializer()->Run([arg]() { arg->SetResponseLocked(); },
243 void FakeResolverResponseGenerator::SetReresolutionResponse(
244 Resolver::Result result) {
245 RefCountedPtr<FakeResolver> resolver;
247 MutexLock lock(&mu_);
248 GPR_ASSERT(resolver_ != nullptr);
249 resolver = resolver_->Ref();
251 FakeResolverResponseSetter* arg = new FakeResolverResponseSetter(
252 resolver, std::move(result), true /* has_result */);
253 resolver->work_serializer()->Run(
254 [arg]() { arg->SetReresolutionResponseLocked(); }, DEBUG_LOCATION);
257 void FakeResolverResponseGenerator::UnsetReresolutionResponse() {
258 RefCountedPtr<FakeResolver> resolver;
260 MutexLock lock(&mu_);
261 GPR_ASSERT(resolver_ != nullptr);
262 resolver = resolver_->Ref();
264 FakeResolverResponseSetter* arg =
265 new FakeResolverResponseSetter(resolver, Resolver::Result());
266 resolver->work_serializer()->Run(
267 [arg]() { arg->SetReresolutionResponseLocked(); }, DEBUG_LOCATION);
270 void FakeResolverResponseGenerator::SetFailure() {
271 RefCountedPtr<FakeResolver> resolver;
273 MutexLock lock(&mu_);
274 GPR_ASSERT(resolver_ != nullptr);
275 resolver = resolver_->Ref();
277 FakeResolverResponseSetter* arg =
278 new FakeResolverResponseSetter(resolver, Resolver::Result());
279 resolver->work_serializer()->Run([arg]() { arg->SetFailureLocked(); },
283 void FakeResolverResponseGenerator::SetFailureOnReresolution() {
284 RefCountedPtr<FakeResolver> resolver;
286 MutexLock lock(&mu_);
287 GPR_ASSERT(resolver_ != nullptr);
288 resolver = resolver_->Ref();
290 FakeResolverResponseSetter* arg = new FakeResolverResponseSetter(
291 resolver, Resolver::Result(), false /* has_result */,
292 false /* immediate */);
293 resolver->work_serializer()->Run([arg]() { arg->SetFailureLocked(); },
297 void FakeResolverResponseGenerator::SetFakeResolver(
298 RefCountedPtr<FakeResolver> resolver) {
299 MutexLock lock(&mu_);
300 resolver_ = std::move(resolver);
301 if (resolver_ == nullptr) return;
303 FakeResolverResponseSetter* arg =
304 new FakeResolverResponseSetter(resolver_, std::move(result_));
305 resolver_->work_serializer()->Run([arg]() { arg->SetResponseLocked(); },
313 static void* response_generator_arg_copy(void* p) {
314 FakeResolverResponseGenerator* generator =
315 static_cast<FakeResolverResponseGenerator*>(p);
316 // TODO(roth): We currently deal with this ref manually. Once the
317 // new channel args code is converted to C++, find a way to track this ref
319 RefCountedPtr<FakeResolverResponseGenerator> copy = generator->Ref();
324 static void response_generator_arg_destroy(void* p) {
325 FakeResolverResponseGenerator* generator =
326 static_cast<FakeResolverResponseGenerator*>(p);
330 static int response_generator_cmp(void* a, void* b) { return GPR_ICMP(a, b); }
332 static const grpc_arg_pointer_vtable response_generator_arg_vtable = {
333 response_generator_arg_copy, response_generator_arg_destroy,
334 response_generator_cmp};
338 grpc_arg FakeResolverResponseGenerator::MakeChannelArg(
339 FakeResolverResponseGenerator* generator) {
341 arg.type = GRPC_ARG_POINTER;
342 arg.key = (char*)GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR;
343 arg.value.pointer.p = generator;
344 arg.value.pointer.vtable = &response_generator_arg_vtable;
348 RefCountedPtr<FakeResolverResponseGenerator>
349 FakeResolverResponseGenerator::GetFromArgs(const grpc_channel_args* args) {
350 const grpc_arg* arg =
351 grpc_channel_args_find(args, GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR);
352 if (arg == nullptr || arg->type != GRPC_ARG_POINTER) return nullptr;
353 return static_cast<FakeResolverResponseGenerator*>(arg->value.pointer.p)
363 class FakeResolverFactory : public ResolverFactory {
365 bool IsValidUri(const grpc_uri* /*uri*/) const override { return true; }
367 OrphanablePtr<Resolver> CreateResolver(ResolverArgs args) const override {
368 return MakeOrphanable<FakeResolver>(std::move(args));
371 const char* scheme() const override { return "fake"; }
376 } // namespace grpc_core
378 void grpc_resolver_fake_init() {
379 grpc_core::ResolverRegistry::Builder::RegisterResolverFactory(
380 absl::make_unique<grpc_core::FakeResolverFactory>());
383 void grpc_resolver_fake_shutdown() {}