fake_resolver.h

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//
// Copyright 2016 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 GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FAKE_FAKE_RESOLVER_H
#define GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FAKE_FAKE_RESOLVER_H
 
#include <grpc/support/port_platform.h>
 
#include "absl/base/thread_annotations.h"
 
#include <grpc/impl/codegen/grpc_types.h>
 
#include "src/core/lib/gprpp/ref_counted.h"
#include "src/core/lib/gprpp/ref_counted_ptr.h"
#include "src/core/lib/gprpp/sync.h"
#include "src/core/lib/resolver/resolver.h"
 
#define GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR \
  "grpc.fake_resolver.response_generator"
 
namespace grpc_core {
 
class FakeResolver;
 
// TODO(roth): I would ideally like this to be InternallyRefCounted
// instead of RefCounted, but external refs are currently needed to
// encode this in channel args.  Once channel_args are converted to C++,
// see if we can find a way to fix this.
class FakeResolverResponseGenerator
    : public RefCounted<FakeResolverResponseGenerator> {
 public:
  static const grpc_arg_pointer_vtable kChannelArgPointerVtable;
 
  FakeResolverResponseGenerator();
  ~FakeResolverResponseGenerator() override;
 
  // Instructs the fake resolver associated with the response generator
  // instance to trigger a new resolution with the specified result. If the
  // resolver is not available yet, delays response setting until it is. This
  // can be called at most once before the resolver is available.
  void SetResponse(Resolver::Result result);
 
  // Sets the re-resolution response, which is returned by the fake resolver
  // when re-resolution is requested (via \a RequestReresolutionLocked()).
  // The new re-resolution response replaces any previous re-resolution
  // response that may have been set by a previous call.
  void SetReresolutionResponse(Resolver::Result result);
 
  // Unsets the re-resolution response.  After this, the fake resolver will
  // not return anything when \a RequestReresolutionLocked() is called.
  void UnsetReresolutionResponse();
 
  // Tells the resolver to return a transient failure.
  void SetFailure();
 
  // Same as SetFailure(), but instead of returning the error
  // immediately, waits for the next call to RequestReresolutionLocked().
  void SetFailureOnReresolution();
 
  // Returns a channel arg containing \a generator.
  // TODO(roth): When we have time, make this a non-static method.
  static grpc_arg MakeChannelArg(FakeResolverResponseGenerator* generator);
 
  // Returns the response generator in \a args, or null if not found.
  static RefCountedPtr<FakeResolverResponseGenerator> GetFromArgs(
      const grpc_channel_args* args);
 
 private:
  friend class FakeResolver;
  // Set the corresponding FakeResolver to this generator.
  void SetFakeResolver(RefCountedPtr<FakeResolver> resolver);
 
  // Mutex protecting the members below.
  Mutex mu_;
  RefCountedPtr<FakeResolver> resolver_ ABSL_GUARDED_BY(mu_);
  Resolver::Result result_ ABSL_GUARDED_BY(mu_);
  bool has_result_ ABSL_GUARDED_BY(mu_) = false;
};
 
}  // namespace grpc_core
 
#endif  // GRPC_CORE_EXT_FILTERS_CLIENT_CHANNEL_RESOLVER_FAKE_FAKE_RESOLVER_H