Merge pull request #5069 from vespa-engine/geirst/initial-handling-of-bucket-spaces-stats-in-clustercontroller

Geirst/initial handling of bucket spaces stats in clustercontroller

16 files changed, 424 insertions, 567 deletions

diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateView.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateView.java
index a0e93c2a9ad..ea638010ab7 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateView.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateView.java
@@ -29,31 +29,25 @@ public class ClusterStateView {
     private static Logger log = Logger.getLogger(ClusterStateView.class.getName());
     private final ClusterState clusterState;
     private final ClusterStatsAggregator statsAggregator;
-    private final MetricUpdater metricUpdater;
 
-    /**
-     * @param metricUpdater may be null, in which case no stats will be reported.
-     */
-    public static ClusterStateView create(String serializedClusterState, MetricUpdater metricUpdater)
-            throws ParseException {
+    public static ClusterStateView create(String serializedClusterState) throws ParseException {
         ClusterState clusterState = new ClusterState(serializedClusterState);
-        return new ClusterStateView(clusterState, createNewAggregator(clusterState, metricUpdater), metricUpdater);
+        return new ClusterStateView(clusterState, createNewAggregator(clusterState));
     }
 
-    public static ClusterStateView create(final ClusterState clusterState, final MetricUpdater metricUpdater) {
-        return new ClusterStateView(clusterState, createNewAggregator(clusterState, metricUpdater), metricUpdater);
+    public static ClusterStateView create(final ClusterState clusterState) {
+        return new ClusterStateView(clusterState, createNewAggregator(clusterState));
     }
 
-    private static ClusterStatsAggregator createNewAggregator(ClusterState clusterState, MetricUpdater metricUpdater) {
+    private static ClusterStatsAggregator createNewAggregator(ClusterState clusterState) {
         Set<Integer> upDistributors = getIndicesOfUpNodes(clusterState, NodeType.DISTRIBUTOR);
         Set<Integer> upStorageNodes = getIndicesOfUpNodes(clusterState, NodeType.STORAGE);
-        return new ClusterStatsAggregator(upDistributors, upStorageNodes, metricUpdater);
+        return new ClusterStatsAggregator(upDistributors, upStorageNodes);
     }
 
-    ClusterStateView(ClusterState clusterState, ClusterStatsAggregator statsAggregator, MetricUpdater metricUpdater) {
+    ClusterStateView(ClusterState clusterState, ClusterStatsAggregator statsAggregator) {
         this.clusterState = clusterState;
         this.statsAggregator = statsAggregator;
-        this.metricUpdater = metricUpdater;
     }
 
     /**
@@ -85,8 +79,7 @@ public class ClusterStateView {
         ClusterState clonedClusterState = clusterState.clone();
         return new ClusterStateView(
                 clonedClusterState,
-                createNewAggregator(clonedClusterState, metricUpdater),
-                metricUpdater);
+                createNewAggregator(clonedClusterState));
     }
 
     public ClusterState getClusterState() { return clusterState; }
@@ -115,8 +108,8 @@ public class ClusterStateView {
             return;
         }
 
-        statsAggregator.updateForDistributor(
-                hostnames, node.getNodeIndex(), StorageNodeStatsBridge.generate(hostInfo.getDistributor()));
+        statsAggregator.updateForDistributor(node.getNodeIndex(),
+                StorageNodeStatsBridge.generate(hostInfo.getDistributor()));
     }
 
     public String toString() {
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregator.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregator.java
index 849a2aa23c2..3f7cd129fc1 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregator.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregator.java
@@ -4,16 +4,13 @@ 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.
+ * Class that stores content cluster stats (with bucket space stats per node) for
+ * the current cluster state version.
  *
- * Each distributor reports outstanding merge operations for the different
- * storage nodes. These reports arrive with getnodestate RPC calls,
+ * Each distributor reports bucket space stats for the different content 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
@@ -25,97 +22,55 @@ import com.yahoo.log.LogLevel;
  *   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
  */
 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<>();
+    // Maps the distributor node index to a map of content node index to the
+    // content node's stats.
+    private final Map<Integer, ContentClusterStats> 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 is only needed as an optimization. Is just the sum of distributorToStats' ContentClusterStats.
+    // Maps the content node index to the content node stats for that node.
     // This MUST be kept up-to-date with distributorToStats;
-    private final StorageMergeStats aggregatedStats;
+    private final ContentClusterStats aggregatedStats;
 
-    private int hostToStatsMapHashCode = 0;
-
-    ClusterStatsAggregator(Set<Integer> distributors, Set<Integer> storageNodes, MetricUpdater updater) {
+    ClusterStatsAggregator(Set<Integer> distributors, Set<Integer> storageNodes) {
         this.distributors = distributors;
-        aggregatedStats = new StorageMergeStats(storageNodes);
-        this.updater = updater;
+        aggregatedStats = new ContentClusterStats(storageNodes);
+    }
+
+    ContentClusterStats getAggregatedStats() {
+        return aggregatedStats;
     }
 
     /**
      * 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) {
+    void updateForDistributor(int distributorIndex, ContentClusterStats clusterStats) {
         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;
+        addStatsFromDistributor(distributorIndex, clusterStats);
     }
 
-    private void addStatsFromDistributor(int distributorIndex, StorageMergeStats storageStatsFromDistributor) {
-        StorageMergeStats previousStorageStats = distributorToStats.put(distributorIndex, storageStatsFromDistributor);
+    private void addStatsFromDistributor(int distributorIndex, ContentClusterStats clusterStats) {
+        ContentClusterStats prevClusterStats = distributorToStats.put(distributorIndex, clusterStats);
 
-        for (NodeMergeStats storageNode : aggregatedStats) {
-            Integer storageNodeIndex = storageNode.getNodeIndex();
+        for (ContentNodeStats contentNode : aggregatedStats) {
+            Integer nodeIndex = contentNode.getNodeIndex();
 
-            NodeMergeStats statsToAdd = storageStatsFromDistributor.getStorageNode(storageNodeIndex);
+            ContentNodeStats statsToAdd = clusterStats.getContentNode(nodeIndex);
             if (statsToAdd != null) {
-                storageNode.add(statsToAdd);
+                contentNode.add(statsToAdd);
             }
 
-            if (previousStorageStats != null) {
-                NodeMergeStats statsToSubtract = storageStatsFromDistributor.getStorageNode(storageNodeIndex);
+            if (prevClusterStats != null) {
+                ContentNodeStats statsToSubtract = prevClusterStats.getContentNode(nodeIndex);
                 if (statsToSubtract != null) {
-                    storageNode.subtract(statsToSubtract);
+                    contentNode.subtract(statsToSubtract);
                 }
             }
         }
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentClusterStats.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentClusterStats.java
new file mode 100644
index 00000000000..2698b079073
--- /dev/null
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentClusterStats.java
@@ -0,0 +1,58 @@
+// Copyright 2018 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.*;
+
+/**
+ * Class for storing pending content node stats for all content nodes in the cluster.
+ *
+ * @author hakonhall
+ */
+public class ContentClusterStats implements Iterable<ContentNodeStats> {
+
+    // Maps a content node index to the content node's stats.
+    private final Map<Integer, ContentNodeStats> mapToNodeStats;
+
+    public ContentClusterStats(Set<Integer> storageNodes) {
+        mapToNodeStats = new HashMap<>(storageNodes.size());
+        for (Integer index : storageNodes) {
+            mapToNodeStats.put(index, new ContentNodeStats(index));
+        }
+    }
+
+    public ContentClusterStats(Map<Integer, ContentNodeStats> mapToNodeStats) {
+        this.mapToNodeStats = mapToNodeStats;
+    }
+
+    @Override
+    public Iterator<ContentNodeStats> iterator() {
+        return mapToNodeStats.values().iterator();
+    }
+
+    ContentNodeStats getContentNode(Integer index) {
+        return mapToNodeStats.get(index);
+    }
+
+    int size() {
+        return mapToNodeStats.size();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ContentClusterStats that = (ContentClusterStats) o;
+        return Objects.equals(mapToNodeStats, that.mapToNodeStats);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(mapToNodeStats);
+    }
+
+    @Override
+    public String toString() {
+        return String.format("{mapToNodeStats=[%s]}",
+                Arrays.toString(mapToNodeStats.entrySet().toArray()));
+    }
+}
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentNodeStats.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentNodeStats.java
new file mode 100644
index 00000000000..cefb3c3c31f
--- /dev/null
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ContentNodeStats.java
@@ -0,0 +1,139 @@
+// Copyright 2018 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 com.yahoo.vespa.clustercontroller.core.hostinfo.StorageNode;
+
+import java.util.*;
+
+/**
+ * @author hakonhall
+ */
+public class ContentNodeStats {
+
+    private int nodeIndex;
+    private Map<String, BucketSpaceStats> bucketSpaces = new HashMap<>();
+
+    public static class BucketSpaceStats {
+        private long bucketsTotal;
+        private long bucketsPending;
+
+        private BucketSpaceStats() {
+            this.bucketsTotal = 0;
+            this.bucketsPending = 0;
+        }
+
+        private BucketSpaceStats(long bucketsTotal, long bucketsPending) {
+            this.bucketsTotal = bucketsTotal;
+            this.bucketsPending = bucketsPending;
+        }
+
+        public static BucketSpaceStats empty() {
+            return new BucketSpaceStats();
+        }
+
+        public static BucketSpaceStats of(long bucketsTotal, long bucketsPending) {
+            return new BucketSpaceStats(bucketsTotal, bucketsPending);
+        }
+
+        public long getBucketsTotal() {
+            return bucketsTotal;
+        }
+
+        public long getBucketsPending() {
+            return bucketsPending;
+        }
+
+        public void merge(BucketSpaceStats rhs, int factor) {
+            this.bucketsTotal += (factor * rhs.bucketsTotal);
+            this.bucketsPending += (factor * rhs.bucketsPending);
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+            BucketSpaceStats that = (BucketSpaceStats) o;
+            return bucketsTotal == that.bucketsTotal &&
+                    bucketsPending == that.bucketsPending;
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(bucketsTotal, bucketsPending);
+        }
+
+        @Override
+        public String toString() {
+            return "{bucketsTotal=" + bucketsTotal + ", bucketsPending=" + bucketsPending + "}";
+        }
+    }
+
+    public ContentNodeStats(StorageNode storageNode) {
+        this.nodeIndex = storageNode.getIndex();
+        for (StorageNode.BucketSpaceStats stats : storageNode.getBucketSpacesStats()) {
+            if (stats.valid()) {
+                this.bucketSpaces.put(stats.getName(),
+                        BucketSpaceStats.of(stats.getBucketStats().getTotal(),
+                                stats.getBucketStats().getPending()));
+            } else {
+                this.bucketSpaces.put(stats.getName(), BucketSpaceStats.empty());
+            }
+        }
+    }
+
+    public ContentNodeStats(int index) {
+        this(index, new HashMap<>());
+    }
+
+    public ContentNodeStats(int index, Map<String, BucketSpaceStats> bucketSpaces) {
+        this.nodeIndex = index;
+        this.bucketSpaces = bucketSpaces;
+    }
+
+    public int getNodeIndex() { return nodeIndex; }
+
+    public void add(ContentNodeStats stats) {
+        merge(stats, 1);
+    }
+
+    public void subtract(ContentNodeStats stats) {
+        merge(stats, -1);
+    }
+
+    private void merge(ContentNodeStats stats, int factor) {
+        for (Map.Entry<String, BucketSpaceStats> entry : stats.bucketSpaces.entrySet()) {
+            BucketSpaceStats statsToUpdate = bucketSpaces.get(entry.getKey());
+            if (statsToUpdate == null && factor == 1) {
+                statsToUpdate = new BucketSpaceStats();
+                bucketSpaces.put(entry.getKey(), statsToUpdate);
+            }
+            if (statsToUpdate != null) {
+                statsToUpdate.merge(entry.getValue(), factor);
+            }
+        }
+    }
+
+    public Map<String, BucketSpaceStats> getBucketSpaces() {
+        return bucketSpaces;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        ContentNodeStats that = (ContentNodeStats) o;
+        return nodeIndex == that.nodeIndex &&
+                Objects.equals(bucketSpaces, that.bucketSpaces);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(nodeIndex, bucketSpaces);
+    }
+
+    @Override
+    public String toString() {
+        return String.format("{index=%d, bucketSpaces=[%s]}",
+                nodeIndex, Arrays.toString(bucketSpaces.entrySet().toArray()));
+    }
+}
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/FleetController.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/FleetController.java
index a5419c64818..ba56d75ab4c 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/FleetController.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/FleetController.java
@@ -122,7 +122,7 @@ public class FleetController implements NodeStateOrHostInfoChangeHandler, NodeAd
         this.stateGatherer = nodeStateGatherer;
         this.stateChangeHandler = stateChangeHandler;
         this.systemStateBroadcaster = systemStateBroadcaster;
-        this.stateVersionTracker = new StateVersionTracker(metricUpdater);
+        this.stateVersionTracker = new StateVersionTracker();
         this.metricUpdater = metricUpdater;
 
         this.statusPageServer = statusPage;
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/MetricUpdater.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/MetricUpdater.java
index b3b10e1d0d8..199e9a3169b 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/MetricUpdater.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/MetricUpdater.java
@@ -85,7 +85,4 @@ public class MetricUpdater {
         metricReporter.add("node-event", 1);
     }
 
-    public void updateMergeOpMetrics(Map<String, NodeMergeStats> storageNodeStats) {
-        // TODO(hakonhall): Remove this method once we figure out how to propagate metrics to state HTTP API.
-    }
 }
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/NodeMergeStats.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/NodeMergeStats.java
deleted file mode 100644
index 97112e01aed..00000000000
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/NodeMergeStats.java
+++ /dev/null
@@ -1,151 +0,0 @@
-// 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 com.yahoo.vespa.clustercontroller.core.hostinfo.StorageNode;
-
-/**
- * @author hakonhall
- */
-public class NodeMergeStats {
-
-    /**
-     * Constructor that sets values to zero if not present.
-     */
-    public NodeMergeStats(StorageNode storageNodePojo) {
-        this.nodeIndex = storageNodePojo.getIndex();
-
-        StorageNode.OutstandingMergeOps mergeOps = storageNodePojo.getOutstandingMergeOpsOrNull();
-        if (mergeOps == null) {
-            mergeOps = new StorageNode.OutstandingMergeOps();
-        }
-        syncing = createAmount(mergeOps.getSyncingOrNull());
-        copyingIn = createAmount(mergeOps.getCopyingInOrNull());
-        movingOut = createAmount(mergeOps.getMovingOutOrNull());
-        copyingOut = createAmount(mergeOps.getCopyingOutOrNull());
-    }
-
-    private static Amount createAmount(StorageNode.Buckets bucketOrNull) {
-        if (bucketOrNull == null) {
-            return new Amount();
-        }
-        return new Amount(bucketOrNull.getBuckets());
-    }
-
-    static public class Amount {
-        private long buckets;
-
-        Amount() { this(0); }
-        Amount(long buckets) { this.buckets = buckets; }
-
-        public void set(Amount other) {
-            buckets = other.buckets;
-        }
-
-        public long getBuckets() {
-            return buckets;
-        }
-
-        /**
-         * Logically, add (factor * amount) to this object.
-         */
-        void scaledAdd(int factor, Amount amount) {
-            buckets += factor * amount.buckets;
-        }
-
-        public boolean equals(Object other) {
-            if (!(other instanceof Amount)) {
-                return false;
-            }
-            Amount otherAmount = (Amount) other;
-            return buckets == otherAmount.buckets;
-        }
-
-        public int hashCode() {
-                return (int)buckets;
-        }
-
-        public String toString() {
-            return String.format("{buckets = %d}", buckets);
-        }
-    }
-
-    private final Amount syncing;
-    private final Amount copyingIn;
-    private final Amount movingOut;
-    private final Amount copyingOut;
-    private int nodeIndex;
-
-    /**
-     * An instance with all 0 amounts.
-     */
-    public NodeMergeStats(int index) {
-        this(index, new Amount(), new Amount(), new Amount(), new Amount());
-    }
-
-    NodeMergeStats(int index, Amount syncing, Amount copyingIn, Amount movingOut, Amount copyingOut) {
-        this.nodeIndex = index;
-        this.syncing = syncing;
-        this.copyingIn = copyingIn;
-        this.movingOut = movingOut;
-        this.copyingOut = copyingOut;
-    }
-
-    public void set(NodeMergeStats stats) {
-        nodeIndex = stats.nodeIndex;
-        syncing.set(stats.syncing);
-        copyingIn.set(stats.copyingIn);
-        movingOut.set(stats.movingOut);
-        copyingOut.set(stats.copyingOut);
-    }
-
-    int getNodeIndex() { return nodeIndex; }
-    public Amount getSyncing() { return syncing; }
-    public Amount getCopyingIn() { return copyingIn; }
-    public Amount getMovingOut() { return movingOut; }
-    public Amount getCopyingOut() { return copyingOut; }
-
-    void add(NodeMergeStats stats) {
-        scaledAdd(1, stats);
-    }
-
-    void subtract(NodeMergeStats stats) {
-        scaledAdd(-1, stats);
-    }
-
-    /**
-     * Logically, adds (factor * stats) to this object. factor of 1 is normal add, -1 is subtraction.
-     */
-    private void scaledAdd(int factor, NodeMergeStats stats) {
-        syncing.scaledAdd(factor, stats.syncing);
-        copyingIn.scaledAdd(factor, stats.copyingIn);
-        movingOut.scaledAdd(factor, stats.movingOut);
-        copyingOut.scaledAdd(factor, stats.copyingOut);
-    }
-
-    @Override
-    public int hashCode() {
-        return (int) (syncing.buckets +
-                copyingIn.buckets * 31 +
-                movingOut.buckets * 17 +
-                copyingOut.buckets * 7);
-    }
-
-    @Override
-    public boolean equals(Object other) {
-        if (!(other instanceof NodeMergeStats)) {
-            return false;
-        }
-
-        NodeMergeStats otherStats = (NodeMergeStats) other;
-        return nodeIndex == otherStats.nodeIndex &&
-                syncing.equals(otherStats.syncing) &&
-                copyingIn.equals(otherStats.copyingIn) &&
-                movingOut.equals(otherStats.movingOut) &&
-                copyingOut.equals(otherStats.copyingOut);
-    }
-
-    public String toString() {
-        return String.format("{index = %d, syncing = %s, copyingIn = %s, movingOut = %s, copyingOut = %s}",
-                nodeIndex, syncing, copyingIn, movingOut, copyingOut);
-    }
-}
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StateVersionTracker.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StateVersionTracker.java
index 518361f18fc..902189fca8b 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StateVersionTracker.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StateVersionTracker.java
@@ -32,15 +32,13 @@ public class StateVersionTracker {
     private AnnotatedClusterState latestCandidateState = AnnotatedClusterState.emptyState();
     private AnnotatedClusterState currentClusterState = latestCandidateState;
 
-    private final MetricUpdater metricUpdater;
     private ClusterStateView clusterStateView;
 
     private final LinkedList<ClusterStateHistoryEntry> clusterStateHistory = new LinkedList<>();
     private int maxHistoryEntryCount = 50;
 
-    StateVersionTracker(final MetricUpdater metricUpdater) {
-        this.metricUpdater = metricUpdater;
-        clusterStateView = ClusterStateView.create(currentUnversionedState, metricUpdater);
+    StateVersionTracker() {
+        clusterStateView = ClusterStateView.create(currentUnversionedState);
     }
 
     void setVersionRetrievedFromZooKeeper(final int version) {
@@ -121,7 +119,7 @@ public class StateVersionTracker {
                 lowestObservedDistributionBits,
                 newState.getClusterState().getDistributionBitCount());
         // TODO should this take place in updateLatestCandidateState instead? I.e. does it require a consolidated state?
-        clusterStateView = ClusterStateView.create(currentClusterState.getClusterState(), metricUpdater);
+        clusterStateView = ClusterStateView.create(currentClusterState.getClusterState());
     }
 
     private void recordCurrentStateInHistoryAtTime(final long currentTimeMs) {
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StorageMergeStats.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StorageMergeStats.java
deleted file mode 100644
index 6a44bee8cce..00000000000
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/StorageMergeStats.java
+++ /dev/null
@@ -1,63 +0,0 @@
-// 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.Iterator;
-import java.util.Map;
-import java.util.Set;
-
-/**
- * Class for storing the pending merge operation stats for all the storage nodes.
- *
- * @author hakonhall
- */
-public class StorageMergeStats implements Iterable<NodeMergeStats> {
-
-    // Maps a storage node index to the storage node's pending merges stats.
-    private final Map<Integer, NodeMergeStats> mapToNodeStats;
-
-    public StorageMergeStats(Set<Integer> storageNodes) {
-        mapToNodeStats = new HashMap<>(storageNodes.size());
-        for (Integer index : storageNodes) {
-            mapToNodeStats.put(index, new NodeMergeStats(index));
-        }
-    }
-
-    public StorageMergeStats(Map<Integer, NodeMergeStats> mapToNodeStats) {
-        this.mapToNodeStats = mapToNodeStats;
-    }
-
-    @Override
-    public Iterator<NodeMergeStats> iterator() {
-        return mapToNodeStats.values().iterator();
-    }
-
-    NodeMergeStats getStorageNode(Integer index) {
-        return mapToNodeStats.get(index);
-    }
-
-    int size() {
-        return mapToNodeStats.size();
-    }
-
-    @Override
-    public boolean equals(Object o) {
-        if (this == o) return true;
-        if (!(o instanceof StorageMergeStats)) {
-            return false;
-        }
-
-        StorageMergeStats that = (StorageMergeStats) o;
-
-        if (mapToNodeStats != null ? !mapToNodeStats.equals(that.mapToNodeStats) : that.mapToNodeStats != null) {
-            return false;
-        }
-        return true;
-    }
-
-    @Override
-    public int hashCode() {
-        return mapToNodeStats != null ? mapToNodeStats.hashCode() : 0;
-    }
-
-}
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNode.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNode.java
index 9e951236c45..bf7c1fad6ca 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNode.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNode.java
@@ -4,6 +4,9 @@ package com.yahoo.vespa.clustercontroller.core.hostinfo;
 import com.fasterxml.jackson.annotation.JsonCreator;
 import com.fasterxml.jackson.annotation.JsonProperty;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * Keeping information about a storage node seen from the distributor.
  *
@@ -36,31 +39,43 @@ public class StorageNode {
         public Put getPut() { return put; }
     }
 
-    static public class Buckets {
-        private final long buckets;
+    static public class BucketStats {
+        private final long total;
+        private final long pending;
 
         @JsonCreator
-        public Buckets(@JsonProperty("buckets") Long buckets) {
-            this.buckets = buckets;
+        public BucketStats(@JsonProperty("total") Long total, @JsonProperty("pending") Long pending) {
+            this.total = total;
+            this.pending = pending;
         }
 
-        public long getBuckets() { return buckets; }
+        public long getTotal() {
+            return total;
+        }
+        public long getPending() {
+            return pending;
+        }
     }
 
-    static public class OutstandingMergeOps {
-        @JsonProperty("syncing")
-        private Buckets syncing;
-        @JsonProperty("copying-in")
-        private Buckets copyingIn;
-        @JsonProperty("moving-out")
-        private Buckets movingOut;
-        @JsonProperty("copying-out")
-        private Buckets copyingOut;
-
-        public Buckets getSyncingOrNull() { return syncing; }
-        public Buckets getCopyingInOrNull() { return copyingIn; }
-        public Buckets getMovingOutOrNull() { return movingOut; }
-        public Buckets getCopyingOutOrNull() { return copyingOut; }
+    static public class BucketSpaceStats {
+        private final String name;
+        @JsonProperty("buckets")
+        private BucketStats bucketStats = null;
+
+        @JsonCreator
+        public BucketSpaceStats(@JsonProperty("name") String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return name;
+        }
+        public boolean valid() {
+            return bucketStats != null;
+        }
+        public BucketStats getBucketStats() {
+            return bucketStats;
+        }
     }
 
     private final Integer index;
@@ -74,8 +89,8 @@ public class StorageNode {
     @JsonProperty("min-current-replication-factor")
     private Integer minCurrentReplicationFactor;
 
-    @JsonProperty("outstanding-merge-ops")
-    private OutstandingMergeOps outstandingMergeOps;
+    @JsonProperty("bucket-spaces")
+    private List<BucketSpaceStats> bucketSpacesStats = new ArrayList<>();
 
     @JsonCreator
     public StorageNode(@JsonProperty("node-index") Integer index) {
@@ -95,8 +110,7 @@ public class StorageNode {
         return minCurrentReplicationFactor;
     }
 
-    public OutstandingMergeOps getOutstandingMergeOpsOrNull() {
-        return outstandingMergeOps;
+    public List<BucketSpaceStats> getBucketSpacesStats() {
+        return bucketSpacesStats;
     }
-
 }
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridge.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridge.java
index 6d0da8a9fba..55b7e4bb8c1 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridge.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridge.java
@@ -1,11 +1,7 @@
 // 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.hostinfo;
 
-import com.yahoo.vespa.clustercontroller.core.LatencyStats;
-import com.yahoo.vespa.clustercontroller.core.NodeMergeStats;
-import com.yahoo.vespa.clustercontroller.core.StorageMergeStats;
-import com.yahoo.vespa.clustercontroller.core.StorageNodeStats;
-import com.yahoo.vespa.clustercontroller.core.StorageNodeStatsContainer;
+import com.yahoo.vespa.clustercontroller.core.*;
 
 import java.util.HashMap;
 import java.util.List;
@@ -45,12 +41,12 @@ public class StorageNodeStatsBridge {
         return container;
     }
 
-    public static StorageMergeStats generate(Distributor distributor) {
-        Map<Integer, NodeMergeStats> mapToNodeStats = new HashMap<>();
+    public static ContentClusterStats generate(Distributor distributor) {
+        Map<Integer, ContentNodeStats> mapToNodeStats = new HashMap<>();
         for (StorageNode storageNode : distributor.getStorageNodes()) {
-            mapToNodeStats.put(storageNode.getIndex(), new NodeMergeStats(storageNode));
+            mapToNodeStats.put(storageNode.getIndex(), new ContentNodeStats(storageNode));
         }
-        return new StorageMergeStats(mapToNodeStats);
+        return new ContentClusterStats(mapToNodeStats);
     }
 
 }
diff --git a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStateViewTest.java b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStateViewTest.java
index 3b04fec3e79..dc8a4a0d441 100644
--- a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStateViewTest.java
+++ b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStateViewTest.java
@@ -22,10 +22,8 @@ public class ClusterStateViewTest {
     final NodeInfo nodeInfo = mock(NodeInfo.class);
     final Node node = mock(Node.class);
     final ClusterStatsAggregator statsAggregator = mock(ClusterStatsAggregator.class);
-    final StorageMergeStats storageStats = mock(StorageMergeStats.class);
     final ClusterState clusterState = mock(ClusterState.class);
-    final MetricUpdater metricUpdater = mock(MetricUpdater.class);
-    final ClusterStateView clusterStateView = new ClusterStateView(clusterState, statsAggregator, metricUpdater);
+    final ClusterStateView clusterStateView = new ClusterStateView(clusterState, statsAggregator);
 
     HostInfo createHostInfo(String version) {
         return HostInfo.createHostInfo("{ \"cluster-state-version\": " + version + " }");
@@ -37,7 +35,7 @@ public class ClusterStateViewTest {
 
         clusterStateView.handleUpdatedHostInfo(hostnames, nodeInfo, createHostInfo("101"));
 
-        verify(statsAggregator, never()).updateForDistributor(any(), anyInt(), any());
+        verify(statsAggregator, never()).updateForDistributor(anyInt(), any());
     }
 
 
@@ -49,7 +47,7 @@ public class ClusterStateViewTest {
 
         clusterStateView.handleUpdatedHostInfo(hostnames, nodeInfo, createHostInfo("22"));
 
-        verify(statsAggregator, never()).updateForDistributor(any(), anyInt(), any());
+        verify(statsAggregator, never()).updateForDistributor(anyInt(), any());
     }
 
     @Test
@@ -59,7 +57,7 @@ public class ClusterStateViewTest {
 
         clusterStateView.handleUpdatedHostInfo(hostnames, nodeInfo, createHostInfo("22"));
 
-        verify(statsAggregator, never()).updateForDistributor(any(), anyInt(), any());
+        verify(statsAggregator, never()).updateForDistributor(anyInt(), any());
     }
 
     @Test
@@ -81,8 +79,7 @@ public class ClusterStateViewTest {
 
         clusterStateView.handleUpdatedHostInfo(hostnames, nodeInfo, hostInfo);
 
-        verify(statsAggregator).updateForDistributor(
-                hostnames, 3, StorageNodeStatsBridge.generate(hostInfo.getDistributor()));
+        verify(statsAggregator).updateForDistributor(3, StorageNodeStatsBridge.generate(hostInfo.getDistributor()));
     }
 
     @Test
diff --git a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregatorTest.java b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregatorTest.java
index eb4455b9492..c92d414aac8 100644
--- a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregatorTest.java
+++ b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/ClusterStatsAggregatorTest.java
@@ -1,217 +1,142 @@
 // 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 com.google.common.collect.Sets;
 import org.junit.Test;
-import org.junit.runner.RunWith;
-import org.mockito.runners.MockitoJUnitRunner;
 
 import java.util.*;
 
 import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
-import static org.mockito.Matchers.any;
-import static org.mockito.Mockito.*;
 
 /**
  * @author hakonhall
  * @since 5.34
  */
-@RunWith(MockitoJUnitRunner.class)
 public class ClusterStatsAggregatorTest {
 
-    final Set<Integer> distributors = new HashSet<>();
-    final Set<Integer> storageNodes = new HashSet<>();
-    final Map<Integer, String> hostnames = new HashMap<>();
-    final MetricUpdater updater = mock(MetricUpdater.class);
-    StorageMergeStats storageStats;
+    private static class StatsBuilder {
+        private final Map<Integer, Map<String, ContentNodeStats.BucketSpaceStats> > stats = new HashMap<>();
 
-    private void addDistributors(Integer... indices) {
-        for (Integer i : indices) {
-            distributors.add(i);
+        public StatsBuilder add(int nodeIndex, String bucketSpace, long bucketsTotal, long bucketsPending) {
+            return add(nodeIndex, bucketSpace, ContentNodeStats.BucketSpaceStats.of(bucketsTotal, bucketsPending));
         }
-    }
-
-    private static class StorageNodeSpec {
-        public StorageNodeSpec(Integer index, String hostname) {
-            this.index = index;
-            this.hostname = hostname;
+        public StatsBuilder add(int nodeIndex, String bucketSpace) {
+            return add(nodeIndex, bucketSpace, ContentNodeStats.BucketSpaceStats.empty());
+        }
+        public StatsBuilder add(int nodeIndex, String bucketSpace, ContentNodeStats.BucketSpaceStats bucketSpaceStats) {
+            Map<String, ContentNodeStats.BucketSpaceStats> contentNodeStats = stats.get(nodeIndex);
+            if (contentNodeStats == null) {
+                contentNodeStats = new HashMap<>();
+                stats.put(nodeIndex, contentNodeStats);
+            }
+            contentNodeStats.put(bucketSpace, bucketSpaceStats);
+            return this;
+        }
+        public StatsBuilder add(int nodeIndex) {
+            stats.put(nodeIndex, new HashMap<>());
+            return this;
+        }
+        public ContentClusterStats build() {
+            Map<Integer, ContentNodeStats> nodeToStatsMap = new HashMap<>();
+            stats.forEach((nodeIndex, bucketSpaces) ->
+                    nodeToStatsMap.put(nodeIndex, new ContentNodeStats(nodeIndex, bucketSpaces)));
+            return new ContentClusterStats(nodeToStatsMap);
         }
-        public Integer index;
-        public String hostname;
     }
 
-    private void addStorageNodes(StorageNodeSpec... specs) {
-        for (StorageNodeSpec spec : specs) {
-            storageNodes.add(spec.index);
-            hostnames.put(spec.index, spec.hostname);
+    private static class Fixture {
+        private ClusterStatsAggregator aggregator;
+        public Fixture(Set<Integer> distributorNodes,
+                Set<Integer> contentNodes) {
+            aggregator = new ClusterStatsAggregator(distributorNodes, contentNodes);
+        }
+        public void update(int distributorIndex, StatsBuilder clusterStats) {
+            aggregator.updateForDistributor(distributorIndex, clusterStats.build());
+        }
+        public void verify(StatsBuilder expectedStats) {
+            assertEquals(expectedStats.build(), aggregator.getAggregatedStats());
         }
-        storageStats = new StorageMergeStats(storageNodes);
     }
 
-    private void putStorageStats(int index, int syncing, int copyingIn, int movingOut, int copyingOut) {
-        storageStats.getStorageNode(index).set(createStats(index, syncing, copyingIn, movingOut, copyingOut));
+    private static Set<Integer> distributorNodes(Integer... indices) {
+        return Sets.newHashSet(indices);
     }
 
-    private static NodeMergeStats createStats(int index, int syncing, int copyingIn, int movingOut, int copyingOut) {
-        return new NodeMergeStats(
-                index,
-                new NodeMergeStats.Amount(syncing),
-                new NodeMergeStats.Amount(copyingIn),
-                new NodeMergeStats.Amount(movingOut),
-                new NodeMergeStats.Amount(copyingOut));
+    private static Set<Integer> contentNodes(Integer... indices) {
+        return Sets.newHashSet(indices);
     }
 
     @Test
-    public void testSimple() {
-        final int distributorIndex = 1;
-        addDistributors(distributorIndex);
-
-        final int storageNodeIndex = 11;
-        addStorageNodes(new StorageNodeSpec(storageNodeIndex, "storage-node"));
-
-        putStorageStats(storageNodeIndex, 5, 6, 7, 8);
-
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
-        aggregator.updateForDistributor(hostnames, distributorIndex, storageStats);
-
-        Map<String, NodeMergeStats> expectedStorageNodeStats = new HashMap<>();
-        expectedStorageNodeStats.put("storage-node", createStats(storageNodeIndex, 5, 6, 7, 8));
-
-        verify(updater).updateMergeOpMetrics(expectedStorageNodeStats);
+    public void aggregator_handles_updates_to_single_distributor_and_content_node() {
+        Fixture f = new Fixture(distributorNodes(1), contentNodes(3));
+        StatsBuilder stats = new StatsBuilder()
+                .add(3, "default", 10, 1)
+                .add(3, "global", 11, 2);
+        f.update(1, stats);
+        f.verify(stats);
     }
 
     @Test
-    public void testComplex() {
-        final int distributor1 = 1;
-        final int distributor2 = 2;
-        addDistributors(distributor1, distributor2);
-
-        final int storageNode1 = 11;
-        final int storageNode2 = 12;
-        addStorageNodes(
-                new StorageNodeSpec(storageNode1, "storage-node-1"),
-                new StorageNodeSpec(storageNode2, "storage-node-2"));
-
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
-
-        // Distributor 1.
-        putStorageStats(storageNode1, 0, 1, 2, 3);
-        putStorageStats(storageNode2, 20, 21, 22, 23);
-        aggregator.updateForDistributor(hostnames, distributor1, storageStats);
-
-        // Distributor 2.
-        putStorageStats(storageNode1, 10, 11, 12, 13);
-        putStorageStats(storageNode2, 30, 31, 32, 33);
-        aggregator.updateForDistributor(hostnames, distributor2, storageStats);
-
-        Map<String, NodeMergeStats> expectedStorageNodeStats = new HashMap<>();
-        expectedStorageNodeStats.put("storage-node-1", createStats(storageNode1, 0 + 10, 1 + 11, 2 + 12, 3 + 13));
-        expectedStorageNodeStats.put("storage-node-2", createStats(storageNode2, 20 + 30, 21 + 31, 22 + 32, 23 + 33));
-
-        verify(updater, times(1)).updateMergeOpMetrics(expectedStorageNodeStats);
+    public void aggregator_handles_updates_to_multiple_distributors_and_content_nodes() {
+        Fixture f = new Fixture(distributorNodes(1, 2), contentNodes(3, 4));
+
+        f.update(1, new StatsBuilder()
+                .add(3, "default", 10, 1)
+                .add(3, "global", 11, 2)
+                .add(4, "default", 12, 3)
+                .add(4, "global", 13, 4));
+        f.update(2, new StatsBuilder()
+                .add(3, "default", 14, 5)
+                .add(3, "global", 15, 6)
+                .add(4, "default", 16, 7)
+                .add(4, "global", 17, 8));
+        f.verify(new StatsBuilder()
+                .add(3, "default", 10 + 14, 1 + 5)
+                .add(3, "global", 11 + 15, 2 + 6)
+                .add(4, "default", 12 + 16, 3 + 7)
+                .add(4, "global", 13 + 17, 4 + 8));
     }
 
     @Test
-    public void testHashCodeCache() {
-        final int distributor1 = 1;
-        final int distributor2 = 2;
-        addDistributors(distributor1, distributor2);
+    public void aggregator_handles_multiple_updates_from_same_distributor() {
+        Fixture f = new Fixture(distributorNodes(1, 2), contentNodes(3));
 
-        final int storageNode1 = 11;
-        final int storageNode2 = 12;
-        addStorageNodes(
-                new StorageNodeSpec(storageNode1, "storage-node-1"),
-                new StorageNodeSpec(storageNode2, "storage-node-2"));
+        f.update(1, new StatsBuilder().add(3, "default"));
+        f.verify(new StatsBuilder().add(3, "default"));
 
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
+        f.update(2, new StatsBuilder().add(3, "default", 10, 1));
+        f.verify(new StatsBuilder().add(3, "default", 10, 1));
 
-        // Distributor 1.
-        putStorageStats(storageNode1, 0, 1, 2, 3);
-        putStorageStats(storageNode2, 20, 21, 22, 23);
-        aggregator.updateForDistributor(hostnames, distributor1, storageStats);
+        f.update(1, new StatsBuilder().add(3, "default", 11, 2));
+        f.verify(new StatsBuilder().add(3, "default", 10 + 11, 1 + 2));
 
-        // Distributor 2.
-        putStorageStats(storageNode1, 10, 11, 12, 13);
-        putStorageStats(storageNode2, 30, 31, 32, 33);
-        aggregator.updateForDistributor(hostnames, distributor2, storageStats);
+        f.update(2, new StatsBuilder().add(3, "default", 15, 6));
+        f.verify(new StatsBuilder().add(3, "default", 11 + 15, 2 + 6));
 
-        // If we add call another updateForDistributor with the same arguments, updateMergeOpMetrics() should not be called.
-        // See times(1) below.
-        aggregator.updateForDistributor(hostnames, distributor2, storageStats);
+        f.update(1, new StatsBuilder().add(3, "default", 16, 7));
+        f.verify(new StatsBuilder().add(3, "default", 15 + 16, 6 + 7));
 
-        Map<String, NodeMergeStats> expectedStorageNodeStats = new HashMap<>();
-        expectedStorageNodeStats.put("storage-node-1", createStats(storageNode1, 0 + 10, 1 + 11, 2 + 12, 3 + 13));
-        expectedStorageNodeStats.put("storage-node-2", createStats(storageNode2, 20 + 30, 21 + 31, 22 + 32, 23 + 33));
-
-
-        verify(updater, times(1)).updateMergeOpMetrics(expectedStorageNodeStats);
+        f.update(2, new StatsBuilder().add(3, "default", 12, 3));
+        f.verify(new StatsBuilder().add(3, "default", 16 + 12, 7 + 3));
     }
 
     @Test
-    public void testUnknownDistributor() {
-        final int upDistributor = 1;
-        final int DownDistributorIndex = 2;
-        addDistributors(upDistributor);
-
-        final int storageNodeIndex = 11;
-        addStorageNodes(new StorageNodeSpec(storageNodeIndex, "storage-node"));
-
-        putStorageStats(storageNodeIndex, 5, 6, 7, 8);
-
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
-        aggregator.updateForDistributor(hostnames, DownDistributorIndex, storageStats);
-
-        verify(updater, never()).updateMergeOpMetrics(any());
+    public void aggregator_handles_more_content_nodes_that_distributors() {
+        Fixture f = new Fixture(distributorNodes(1), contentNodes(3, 4));
+        StatsBuilder stats = new StatsBuilder()
+                .add(3, "default", 10, 1)
+                .add(4, "default", 11, 2);
+        f.update(1, stats);
+        f.verify(stats);
     }
 
     @Test
-    public void testMoreStorageNodesThanDistributors() {
-        final int distributor1 = 1;
-        addDistributors(distributor1);
-
-        final int storageNode1 = 11;
-        final int storageNode2 = 12;
-        addStorageNodes(
-                new StorageNodeSpec(storageNode1, "storage-node-1"),
-                new StorageNodeSpec(storageNode2, "storage-node-2"));
-
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
-
-        // Distributor 1.
-        putStorageStats(storageNode1, 0, 1, 2, 3);
-        putStorageStats(storageNode2, 20, 21, 22, 23);
-        aggregator.updateForDistributor(hostnames, distributor1, storageStats);
-
-        Map<String, NodeMergeStats> expectedStorageNodeStats = new HashMap<>();
-        expectedStorageNodeStats.put("storage-node-1", createStats(storageNode1, 0, 1, 2, 3));
-        expectedStorageNodeStats.put("storage-node-2", createStats(storageNode2, 20, 21, 22, 23));
-
-        verify(updater, times(1)).updateMergeOpMetrics(expectedStorageNodeStats);
+    public void aggregator_ignores_updates_to_unknown_distributor() {
+        Fixture f = new Fixture(distributorNodes(1), contentNodes(3));
+        final int downDistributorIndex = 2;
+        f.update(downDistributorIndex, new StatsBuilder()
+                .add(3, "default", 7, 3));
+        f.verify(new StatsBuilder().add(3));
     }
 
-    @Test
-    public void testMoreDistributorsThanStorageNodes() {
-        final int distributor1 = 1;
-        final int distributor2 = 2;
-        addDistributors(distributor1, distributor2);
-
-        final int storageNode1 = 11;
-        addStorageNodes(new StorageNodeSpec(storageNode1, "storage-node-1"));
-
-        ClusterStatsAggregator aggregator = new ClusterStatsAggregator(distributors, storageNodes, updater);
-
-        // Distributor 1.
-        putStorageStats(storageNode1, 0, 1, 2, 3);
-        aggregator.updateForDistributor(hostnames, distributor1, storageStats);
-
-        // Distributor 2.
-        putStorageStats(storageNode1, 10, 11, 12, 13);
-        aggregator.updateForDistributor(hostnames, distributor2, storageStats);
-
-        Map<String, NodeMergeStats> expectedStorageNodeStats = new HashMap<>();
-        expectedStorageNodeStats.put("storage-node-1", createStats(storageNode1, 0 + 10, 1 + 11, 2 + 12, 3 + 13));
-
-        verify(updater, times(1)).updateMergeOpMetrics(expectedStorageNodeStats);
-    }
 }
diff --git a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/StateVersionTrackerTest.java b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/StateVersionTrackerTest.java
index 0af7bcbfeaf..d27acf8bc17 100644
--- a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/StateVersionTrackerTest.java
+++ b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/StateVersionTrackerTest.java
@@ -11,14 +11,11 @@ import org.junit.Test;
 import java.util.Arrays;
 import java.util.Optional;
 
-import static org.hamcrest.CoreMatchers.hasItems;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertThat;
 import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-import static org.mockito.Mockito.mock;
 
 public class StateVersionTrackerTest {
 
@@ -28,7 +25,7 @@ public class StateVersionTrackerTest {
     }
 
     private static StateVersionTracker createWithMockedMetrics() {
-        return new StateVersionTracker(mock(MetricUpdater.class));
+        return new StateVersionTracker();
     }
 
     private static void updateAndPromote(final StateVersionTracker versionTracker,
diff --git a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridgeTest.java b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridgeTest.java
index 8a17fedee86..5319d741503 100644
--- a/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridgeTest.java
+++ b/clustercontroller-core/src/test/java/com/yahoo/vespa/clustercontroller/core/hostinfo/StorageNodeStatsBridgeTest.java
@@ -1,8 +1,8 @@
 // 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.hostinfo;
 
-import com.yahoo.vespa.clustercontroller.core.NodeMergeStats;
-import com.yahoo.vespa.clustercontroller.core.StorageMergeStats;
+import com.yahoo.vespa.clustercontroller.core.ContentNodeStats;
+import com.yahoo.vespa.clustercontroller.core.ContentClusterStats;
 import com.yahoo.vespa.clustercontroller.core.StorageNodeStats;
 import com.yahoo.vespa.clustercontroller.core.StorageNodeStatsContainer;
 import org.junit.Test;
@@ -12,11 +12,11 @@ import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.Iterator;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.core.Is.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.*;
 
 /**
  * @author hakonhall
@@ -49,19 +49,30 @@ public class StorageNodeStatsBridgeTest {
     }
 
     @Test
-    public void testStorageMergeStats() throws IOException {
+    public void testContentNodeStats() throws IOException {
         String data = getJsonString();
         HostInfo hostInfo = HostInfo.createHostInfo(data);
 
-        StorageMergeStats storageMergeStats = StorageNodeStatsBridge.generate(hostInfo.getDistributor());
-        int size = 0;
-        for (NodeMergeStats mergeStats : storageMergeStats) {
-            assertThat(mergeStats.getCopyingIn().getBuckets(), is(2L));
-            assertThat(mergeStats.getCopyingOut().getBuckets(), is(4L));
-            assertThat(mergeStats.getSyncing().getBuckets(), is(1L));
-            assertThat(mergeStats.getMovingOut().getBuckets(), is(3L));
-            size++;
+        ContentClusterStats clusterStats = StorageNodeStatsBridge.generate(hostInfo.getDistributor());
+        Iterator<ContentNodeStats> itr = clusterStats.iterator();
+        { // content node 0
+            ContentNodeStats stats = itr.next();
+            assertThat(stats.getNodeIndex(), is(0));
+            assertThat(stats.getBucketSpaces().size(), is(2));
+            assertBucketSpaceStats(11, 3, stats.getBucketSpaces().get("default"));
+            assertBucketSpaceStats(13, 5, stats.getBucketSpaces().get("global"));
         }
-        assertThat(size, is(2));
+        { // content node 1
+            ContentNodeStats stats = itr.next();
+            assertThat(stats.getNodeIndex(), is(1));
+            assertThat(stats.getBucketSpaces().size(), is(1));
+            assertBucketSpaceStats(0, 0, stats.getBucketSpaces().get("default"));
+        }
+        assertFalse(itr.hasNext());
+    }
+
+    private static void assertBucketSpaceStats(long expBucketsTotal, long expBucketsPending, ContentNodeStats.BucketSpaceStats stats) {
+        assertThat(stats.getBucketsTotal(), is(expBucketsTotal));
+        assertThat(stats.getBucketsPending(), is(expBucketsPending));
     }
 }
diff --git a/protocols/getnodestate/host_info.json b/protocols/getnodestate/host_info.json
index 5ef62d1a84f..305f279c847 100644
--- a/protocols/getnodestate/host_info.json
+++ b/protocols/getnodestate/host_info.json
@@ -48,20 +48,22 @@
                         "count": 16
                     }
                 },
-                "outstanding-merge-ops": {
-                    "syncing": {
-                        "buckets": 1
+                "bucket-spaces": [
+                    {
+                        "name": "default",
+                        "buckets": {
+                            "total": 11,
+                            "pending": 3
+                        }
                     },
-                    "copying-in": {
-                        "buckets": 2
-                    },
-                    "moving-out": {
-                        "buckets": 3
-                    },
-                    "copying-out": {
-                        "buckets": 4
+                    {
+                        "name": "global",
+                        "buckets": {
+                            "total": 13,
+                            "pending": 5
+                        }
                     }
-                }
+                ]
             },
             {
                 "node-index": 1,
@@ -71,24 +73,13 @@
                         "latency-ms-sum": 17,
                         "count": 18
                     }
-                 },
-                 "outstanding-merge-ops": {
-                    "syncing": {
-                        "buckets": 1
-                    },
-                    "copying-in": {
-                        "buckets": 2
-                    },
-                    "moving-out": {
-                        "buckets": 3
-                    },
-                    "copying-out": {
-                        "buckets": 4
+                },
+                "bucket-spaces": [
+                    {
+                        "name": "default"
                     }
-                }
-
+                ]
             }
-
         ]
     }
 }