io.grpc.xds.client.ReferenceCounted Maven / Gradle / Ivy
/*
* Copyright 2020 The 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.
*/
package io.grpc.xds.client;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
/**
* A reference count wrapper for objects. This class does not take the ownership for the object,
* but only provides usage counting. The real owner of the wrapped object is responsible for
* managing the lifecycle of the object.
*
* Intended for a container class to keep track of lifecycle for elements it contains. This
* wrapper itself should never be returned to the consumers of the elements to avoid reference
* counts being leaked.
*/
// TODO(chengyuanzhang): move this class into LoadStatsManager2.
final class ReferenceCounted {
private final T instance;
private int refs;
private ReferenceCounted(T instance) {
this.instance = instance;
}
static ReferenceCounted wrap(T instance) {
checkNotNull(instance, "instance");
return new ReferenceCounted<>(instance);
}
void retain() {
refs++;
}
void release() {
checkState(refs > 0, "reference reached 0");
refs--;
}
int getReferenceCount() {
return refs;
}
T get() {
return instance;
}
}