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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.clustercontroller.core;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.logging.Logger;
import com.yahoo.log.LogLevel;
/**
* A class that stores stats about outstanding merge operations for
* the current cluster state version, and exports metrics about these.
*
* Each distributor reports outstanding merge operations for the different
* storage nodes. These reports arrive with getnodestate RPC calls,
* and eventually ends up as calls to updateForDistributor().
* No assumptions are made on the sequence of getnodestate calls.
* For instance, it's perfectly fine for the calls to arrive in the
* following order:
* distributor 0
* distributor 1
* distributor 1
* distributor 0
* distributor 2
* ... etc
*
* Whereas the metrics we want, is how many merge operations are outstanding
* for a given storage nodes. So we need to keep track of the latest info
* from each distributor.
*
* @author hakonhall
* @since 5.34
*/
public class ClusterStatsAggregator {
private static Logger log = Logger.getLogger(ClusterStatsAggregator.class.getName());
private final Set<Integer> distributors;
private final MetricUpdater updater;
// Maps the distributor node index to a map of storage node index to the
// storage node's merge stats.
private final Map<Integer, StorageMergeStats> distributorToStats = new HashMap<>();
// This is only needed as an optimization. should just be the sum of distributorToStats' StorageMergeStats.
// Maps the storage node index to the aggregate merge stats for that storage node.
// This MUST be kept up-to-date with distributorToStats;
private final StorageMergeStats aggregatedStats;
private int hostToStatsMapHashCode = 0;
ClusterStatsAggregator(Set<Integer> distributors, Set<Integer> storageNodes, MetricUpdater updater) {
this.distributors = distributors;
aggregatedStats = new StorageMergeStats(storageNodes);
this.updater = updater;
}
/**
* Update the aggregator with the newest available stats from a distributor.
* Will update metrics if necessary.
*/
void updateForDistributor(Map<Integer, String> hostnames, int distributorIndex, StorageMergeStats storageStats) {
if (!distributors.contains(distributorIndex)) {
return;
}
addStatsFromDistributor(distributorIndex, storageStats);
if (distributorToStats.size() < distributors.size()) {
// Not all distributors have reported their merge stats through getnodestate yet.
return;
}
Map<String, NodeMergeStats> hostToStatsMap = getHostToStatsMap(hostnames);
if (hostToStatsMap == null) {
return;
}
if (hostToStatsMapHashCode == 0 || hostToStatsMapHashCode != hostToStatsMap.hashCode()) {
updater.updateMergeOpMetrics(hostToStatsMap);
hostToStatsMapHashCode = hostToStatsMap.hashCode();
}
}
private Map<String, NodeMergeStats> getHostToStatsMap(Map<Integer, String> hostnames) {
Map<String, NodeMergeStats> hostToStatsMap = new HashMap<>(aggregatedStats.size());
for (NodeMergeStats nodeStats : aggregatedStats) {
// The hosts names are kept up-to-date from Slobrok, and MAY therefore be arbitrarily
// different from the node set used by aggregatedStats (and typically tied to a cluster state).
// If so, we will not pretend the returned map is complete, and will return null.
String host = hostnames.get(nodeStats.getNodeIndex());
if (host == null) {
log.log(LogLevel.DEBUG, "Failed to find the host name of storage node " + nodeStats.getNodeIndex() +
". Skipping the report from " + ClusterStatsAggregator.class.getName());
return null;
}
hostToStatsMap.put(host, nodeStats);
}
return hostToStatsMap;
}
private void addStatsFromDistributor(int distributorIndex, StorageMergeStats storageStatsFromDistributor) {
StorageMergeStats previousStorageStats = distributorToStats.put(distributorIndex, storageStatsFromDistributor);
for (NodeMergeStats storageNode : aggregatedStats) {
Integer storageNodeIndex = storageNode.getNodeIndex();
NodeMergeStats statsToAdd = storageStatsFromDistributor.getStorageNode(storageNodeIndex);
if (statsToAdd != null) {
storageNode.add(statsToAdd);
}
if (previousStorageStats != null) {
NodeMergeStats statsToSubtract = storageStatsFromDistributor.getStorageNode(storageNodeIndex);
if (statsToSubtract != null) {
storageNode.subtract(statsToSubtract);
}
}
}
}
}
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