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/*
* Copyright 2015 Open Networking Laboratory
*
* 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 org.onosproject.store.consistent.impl;
import org.onosproject.store.service.AtomicValue;
import org.onosproject.store.service.AtomicValueEvent;
import org.onosproject.store.service.AtomicValueEventListener;
import org.onosproject.store.service.ConsistentMap;
import org.onosproject.store.service.MapEvent;
import org.onosproject.store.service.MapEventListener;
import org.onosproject.store.service.Serializer;
import org.onosproject.store.service.Versioned;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArraySet;
/**
* Default implementation of AtomicValue.
*
* @param <V> value type
*/
public class DefaultAtomicValue<V> implements AtomicValue<V> {
private final Set<AtomicValueEventListener<V>> listeners = new CopyOnWriteArraySet<>();
private final ConsistentMap<String, byte[]> valueMap;
private final String name;
private final Serializer serializer;
private final MapEventListener<String, byte[]> mapEventListener = new InternalMapEventListener();
private final MeteringAgent monitor;
private static final String COMPONENT_NAME = "atomicValue";
private static final String GET = "get";
private static final String GET_AND_SET = "getAndSet";
private static final String COMPARE_AND_SET = "compareAndSet";
public DefaultAtomicValue(ConsistentMap<String, byte[]> valueMap,
String name,
boolean meteringEnabled,
Serializer serializer) {
this.valueMap = valueMap;
this.name = name;
this.serializer = serializer;
this.monitor = new MeteringAgent(COMPONENT_NAME, name, meteringEnabled);
}
@Override
public boolean compareAndSet(V expect, V update) {
final MeteringAgent.Context newTimer = monitor.startTimer(COMPARE_AND_SET);
try {
if (expect == null) {
if (update == null) {
return true;
}
return valueMap.putIfAbsent(name, serializer.encode(update)) == null;
} else {
if (update == null) {
return valueMap.remove(name, serializer.encode(expect));
}
return valueMap.replace(name, serializer.encode(expect), serializer.encode(update));
}
} finally {
newTimer.stop(null);
}
}
@Override
public V get() {
final MeteringAgent.Context newTimer = monitor.startTimer(GET);
try {
Versioned<byte[]> rawValue = valueMap.get(name);
return rawValue == null ? null : serializer.decode(rawValue.value());
} finally {
newTimer.stop(null);
}
}
@Override
public V getAndSet(V value) {
final MeteringAgent.Context newTimer = monitor.startTimer(GET_AND_SET);
try {
Versioned<byte[]> previousValue = value == null ?
valueMap.remove(name) : valueMap.put(name, serializer.encode(value));
return previousValue == null ? null : serializer.decode(previousValue.value());
} finally {
newTimer.stop(null);
}
}
@Override
public void set(V value) {
getAndSet(value);
}
@Override
public void addListener(AtomicValueEventListener<V> listener) {
synchronized (listeners) {
if (listeners.add(listener)) {
if (listeners.size() == 1) {
valueMap.addListener(mapEventListener);
}
}
}
}
@Override
public void removeListener(AtomicValueEventListener<V> listener) {
synchronized (listeners) {
if (listeners.remove(listener)) {
if (listeners.size() == 0) {
valueMap.removeListener(mapEventListener);
}
}
}
}
private class InternalMapEventListener implements MapEventListener<String, byte[]> {
@Override
public void event(MapEvent<String, byte[]> mapEvent) {
V newValue = mapEvent.type() == MapEvent.Type.REMOVE ? null : serializer.decode(mapEvent.value().value());
AtomicValueEvent<V> atomicValueEvent = new AtomicValueEvent<>(name, AtomicValueEvent.Type.UPDATE, newValue);
listeners.forEach(l -> l.event(atomicValueEvent));
}
}
}
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