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/*
* ============LICENSE_START====================================
* DCAEGEN2-SERVICES-SDK
* =========================================================
* Copyright (C) 2019 Nokia. 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.
* ============LICENSE_END=====================================
*/
package org.onap.dcaegen2.services.sdk.rest.services.cbs.client.api.listener;
import io.vavr.collection.List;
import io.vavr.control.Option;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import reactor.core.Disposable;
import reactor.core.publisher.Flux;
/**
* @author <a href="mailto:piotr.jaszczyk@nokia.com">Piotr Jaszczyk</a>
* @since 1.1.2
*/
public class ListenableCbsConfig {
private MerkleTree<String> tree = MerkleTree.emptyWithDefaultDigest(String::getBytes);
private final Map<List<String>, CompositeTreeChangeListener<String>> pathListeners = new HashMap<>();
private final Object listenersUpdateMonitor = new Object();
private final Object treeUpdateMonitor = new Object();
public void listen(List<String> path, TreeChangeListener<String> listener) {
synchronized (listenersUpdateMonitor) {
CompositeTreeChangeListener<String> compositeListener = pathListeners
.computeIfAbsent(path, p -> new CompositeTreeChangeListener<>());
compositeListener.addListener(listener);
}
}
public void cancel(List<String> path, TreeChangeListener<String> listener) {
synchronized (listenersUpdateMonitor) {
CompositeTreeChangeListener<String> compositeListener = pathListeners.get(path);
if (compositeListener != null) {
compositeListener.removeListener(listener);
}
}
}
public Flux<Option<MerkleTree<String>>> subtreeChanges(List<String> path) {
return Flux.create(sink -> {
final TreeChangeListener<String> listener = sink::next;
sink.onDispose(() -> cancel(path, listener));
listen(path, listener);
});
}
public Disposable subscribeForUpdates(Flux<MerkleTree<String>> updates) {
return updates.subscribe(this::update);
}
public void update(MerkleTree<String> newTree) {
final MerkleTree<String> oldTree;
synchronized (treeUpdateMonitor) {
oldTree = tree;
tree = newTree;
}
for (Map.Entry<List<String>, CompositeTreeChangeListener<String>> entry : pathListeners.entrySet()) {
final List<String> path = entry.getKey();
final CompositeTreeChangeListener<String> listeners = entry.getValue();
if (!newTree.isSame(path, oldTree)) {
listeners.accept(newTree, path);
}
}
}
private static class CompositeTreeChangeListener<V> implements TreeChangeListener<V> {
private final Collection<TreeChangeListener<V>> listeners = new HashSet<>();
void addListener(TreeChangeListener<V> listener) {
listeners.add(listener);
}
void removeListener(TreeChangeListener<V> listener) {
listeners.remove(listener);
}
@Override
public void accept(Option<MerkleTree<V>> updatedSubtree) {
for (TreeChangeListener<V> listener : listeners) {
listener.accept(updatedSubtree);
}
}
}
}
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