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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 GRPC_SRC_CORE_LIB_RESOLVER_RESOLVER_REGISTRY_H
#define GRPC_SRC_CORE_LIB_RESOLVER_RESOLVER_REGISTRY_H
#include <grpc/support/port_platform.h>
#include <map>
#include <memory>
#include <util/generic/string.h>
#include <util/string/cast.h>
#include <utility>
#include "y_absl/strings/string_view.h"
#include "src/core/lib/channel/channel_args.h"
#include "src/core/lib/gprpp/orphanable.h"
#include "src/core/lib/iomgr/iomgr_fwd.h"
#include "src/core/lib/resolver/resolver.h"
#include "src/core/lib/resolver/resolver_factory.h"
#include "src/core/lib/uri/uri_parser.h"
namespace grpc_core {
class ResolverRegistry {
private:
// Forward declaration needed to use this in Builder.
struct State {
std::map<y_absl::string_view, std::unique_ptr<ResolverFactory>> factories;
TString default_prefix;
};
public:
/// Methods used to create and populate the ResolverRegistry.
/// NOT THREAD SAFE -- to be used only during global gRPC
/// initialization and shutdown.
class Builder {
public:
Builder();
/// Sets the default URI prefix to \a default_prefix.
void SetDefaultPrefix(TString default_prefix);
/// Registers a resolver factory. The factory will be used to create a
/// resolver for any URI whose scheme matches that of the factory.
void RegisterResolverFactory(std::unique_ptr<ResolverFactory> factory);
/// Returns true iff scheme already has a registered factory.
bool HasResolverFactory(y_absl::string_view scheme) const;
/// Wipe everything in the registry and reset to empty.
void Reset();
ResolverRegistry Build();
private:
ResolverRegistry::State state_;
};
ResolverRegistry(const ResolverRegistry&) = delete;
ResolverRegistry& operator=(const ResolverRegistry&) = delete;
ResolverRegistry(ResolverRegistry&&) noexcept;
ResolverRegistry& operator=(ResolverRegistry&&) noexcept;
/// Checks whether the user input \a target is valid to create a resolver.
bool IsValidTarget(y_absl::string_view target) const;
/// Creates a resolver given \a target.
/// First tries to parse \a target as a URI. If this succeeds, tries
/// to locate a registered resolver factory based on the URI scheme.
/// If parsing fails or there is no factory for the URI's scheme,
/// prepends default_prefix to target and tries again.
/// If a resolver factory is found, uses it to instantiate a resolver and
/// returns it; otherwise, returns nullptr.
/// \a args, \a pollset_set, and \a work_serializer are passed to the
/// factory's \a CreateResolver() method. \a args are the channel args to be
/// included in resolver results. \a pollset_set is used to drive I/O in the
/// name resolution process. \a work_serializer is the work_serializer under
/// which all resolver calls will be run. \a result_handler is used to return
/// results from the resolver.
OrphanablePtr<Resolver> CreateResolver(
y_absl::string_view target, const ChannelArgs& args,
grpc_pollset_set* pollset_set,
std::shared_ptr<WorkSerializer> work_serializer,
std::unique_ptr<Resolver::ResultHandler> result_handler) const;
/// Returns the default authority to pass from a client for \a target.
TString GetDefaultAuthority(y_absl::string_view target) const;
/// Returns \a target with the default prefix prepended, if needed.
TString AddDefaultPrefixIfNeeded(y_absl::string_view target) const;
/// Returns the resolver factory for \a scheme.
/// Caller does NOT own the return value.
ResolverFactory* LookupResolverFactory(y_absl::string_view scheme) const;
private:
explicit ResolverRegistry(State state) : state_(std::move(state)) {}
// TODO(ctiller): fix callers such that the canonical_target argument can be
// removed, and replaced with uri.ToString().
ResolverFactory* FindResolverFactory(y_absl::string_view target, URI* uri,
TString* canonical_target) const;
State state_;
};
} // namespace grpc_core
#endif // GRPC_SRC_CORE_LIB_RESOLVER_RESOLVER_REGISTRY_H
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