io.grpc.internal.InUseStateAggregator Maven / Gradle / Ivy
/*
* Copyright 2016, gRPC Authors All rights reserved.
*
* 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.internal;
import java.util.HashSet;
import javax.annotation.concurrent.NotThreadSafe;
/**
* Aggregates the in-use state of a set of objects.
*/
@NotThreadSafe
abstract class InUseStateAggregator {
private final HashSet inUseObjects = new HashSet();
/**
* Update the in-use state of an object. Initially no object is in use.
*
* This may call into {@link #handleInUse} or {@link #handleNotInUse} when appropriate.
*/
final void updateObjectInUse(T object, boolean inUse) {
int origSize = inUseObjects.size();
if (inUse) {
inUseObjects.add(object);
if (origSize == 0) {
handleInUse();
}
} else {
boolean removed = inUseObjects.remove(object);
if (removed && origSize == 1) {
handleNotInUse();
}
}
}
final boolean isInUse() {
return !inUseObjects.isEmpty();
}
/**
* Called when the aggregated in-use state has changed to true, which means at least one object is
* in use.
*/
abstract void handleInUse();
/**
* Called when the aggregated in-use state has changed to false, which means no object is in use.
*/
abstract void handleNotInUse();
}