Java tutorial
/* * Copyright 2008-2010 LinkedIn, Inc * * 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 voldemort.store.stats; import com.google.common.collect.Maps; import org.apache.log4j.Logger; import voldemort.VoldemortException; import voldemort.cluster.Cluster; import voldemort.cluster.Node; import java.util.Collections; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentMap; import java.util.concurrent.atomic.AtomicLong; /** * A thread-safe counter, that tracks per-node statistics and allows aggregation * by node and zone * */ public class ClusterWideCounter { private final static Logger logger = Logger.getLogger(ClusterWideCounter.class); private final Cluster cluster; private final ConcurrentMap<Integer, AtomicLong> values; public ClusterWideCounter(Cluster cluster) { this.cluster = cluster; this.values = new ConcurrentHashMap<Integer, AtomicLong>(cluster.getNumberOfNodes()); for (Node node : cluster.getNodes()) values.put(node.getId(), new AtomicLong(0L)); } public void incrementCount(int nodeId) { AtomicLong counter = values.get(nodeId); if (counter == null) { counter = new AtomicLong(0L); values.putIfAbsent(nodeId, counter); } counter.incrementAndGet(); } public void clearCount() { for (AtomicLong counter : values.values()) counter.set(0L); } public void clearCount(int nodeId) { AtomicLong counter = values.get(nodeId); if (counter == null) { counter = new AtomicLong(0L); values.put(nodeId, counter); } else counter.set(0L); } public void setCount(int nodeId, Long newValue) { AtomicLong counter = values.get(nodeId); if (counter == null) { counter = new AtomicLong(0L); values.putIfAbsent(nodeId, counter); } counter.set(newValue); } public void setAll(Map<Integer, Long> newValues) { for (Map.Entry<Integer, Long> entry : newValues.entrySet()) setCount(entry.getKey(), entry.getValue()); } public Map<Integer, Long> asMap() { Map<Integer, Long> map = Maps.newHashMapWithExpectedSize(values.size()); for (Map.Entry<Integer, AtomicLong> entry : values.entrySet()) map.put(entry.getKey(), entry.getValue().get()); return Collections.unmodifiableMap(map); } public Map<Integer, Long> byZone() { Map<Integer, Long> map = Maps.newHashMapWithExpectedSize(cluster.getNumberOfNodes()); for (Map.Entry<Integer, AtomicLong> entry : values.entrySet()) { try { Node node = cluster.getNodeById(entry.getKey()); int zoneId = node.getZoneId(); Long count = map.get(zoneId); if (count == null) count = 0L; count += entry.getValue().get(); map.put(zoneId, count); } catch (VoldemortException e) { logger.warn("Can't get zone information for node id " + entry.getKey(), e); } } return Collections.unmodifiableMap(map); } public Long getCount(int nodeId) { AtomicLong counter = values.get(nodeId); if (counter == null) throw new IllegalArgumentException("no value for " + nodeId); return counter.get(); } public Long getTotalCount() { long total = 0L; for (AtomicLong value : values.values()) total += value.get(); return total; } }