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//
// Copyright 2021 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.
//
#include <grpc/support/port_platform.h>
#include "src/core/ext/xds/xds_client.h"
#include "src/core/ext/xds/xds_resource_type.h"
#ifndef GRPC_CORE_EXT_XDS_XDS_RESOURCE_TYPE_IMPL_H
#define GRPC_CORE_EXT_XDS_XDS_RESOURCE_TYPE_IMPL_H
namespace grpc_core {
// Base class for XdsResourceType implementations.
// Handles all down-casting logic for a particular resource type struct.
template <typename Subclass, typename ResourceTypeStruct>
class XdsResourceTypeImpl : public XdsResourceType {
public:
struct ResourceDataSubclass : public ResourceData {
ResourceTypeStruct resource;
};
// XdsClient watcher that handles down-casting.
class WatcherInterface : public XdsClient::ResourceWatcherInterface {
public:
virtual void OnResourceChanged(ResourceTypeStruct listener) = 0;
private:
// Get result from XdsClient generic watcher interface, perform
// down-casting, and invoke the caller's OnListenerChanged() method.
void OnGenericResourceChanged(
const XdsResourceType::ResourceData* resource) override {
OnResourceChanged(
static_cast<const ResourceDataSubclass*>(resource)->resource);
}
};
static const Subclass* Get() {
static const Subclass* g_instance = new Subclass();
return g_instance;
}
// Convenient wrappers around XdsClient generic watcher API that provide
// type-safety.
static void StartWatch(XdsClient* xds_client, absl::string_view resource_name,
RefCountedPtr<WatcherInterface> watcher) {
xds_client->WatchResource(Get(), resource_name, std::move(watcher));
}
static void CancelWatch(XdsClient* xds_client,
absl::string_view resource_name,
WatcherInterface* watcher,
bool delay_unsubscription = false) {
xds_client->CancelResourceWatch(Get(), resource_name, watcher,
delay_unsubscription);
}
bool ResourcesEqual(const ResourceData* r1,
const ResourceData* r2) const override {
return static_cast<const ResourceDataSubclass*>(r1)->resource ==
static_cast<const ResourceDataSubclass*>(r2)->resource;
}
std::unique_ptr<ResourceData> CopyResource(
const ResourceData* resource) const override {
auto* resource_copy = new ResourceDataSubclass();
resource_copy->resource =
static_cast<const ResourceDataSubclass*>(resource)->resource;
return std::unique_ptr<ResourceData>(resource_copy);
}
};
} // namespace grpc_core
#endif // GRPC_CORE_EXT_XDS_XDS_RESOURCE_TYPE_IMPL_H
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