Don't store full bundle objects in cluster state history

Bundles have a lot of sub-objects per state, so in systems with a
high amount of node entries, this adds unnecessary pressure on the
heap. Instead, store the string representations of the bundle and
the string representation of the diff to the previous state version
(if any). This is also inherently faster than computing the diffs
on-demand on every status page render.

Also remove mutable `official` field from `ClusterState`. Not worth
violating immutability of an object just to get some prettier (but
with high likelihood actually more confusing) status page rendering.

8 files changed, 175 insertions, 115 deletions

diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistory.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistory.java
new file mode 100644
index 00000000000..0d7a689a981
--- /dev/null
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistory.java
@@ -0,0 +1,44 @@
+package com.yahoo.vespa.clustercontroller.core;
+
+import java.util.Collections;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Tracks a configurable max number of cluster state history entries, pruning old entries
+ * as newer entries are added. To save memory, state diffs are computed once and cached as
+ * a string upon adding a new state bundle. Only the most recent bundle is retained in its
+ * entirety.
+ */
+public class ClusterStateHistory {
+
+    private final LinkedList<ClusterStateHistoryEntry> stateHistory = new LinkedList<>();
+    private int maxHistoryEntryCount = 50;
+    private ClusterStateBundle prevStateBundle = null;
+
+    /**
+     * Sets limit on how many cluster states can be kept in the in-memory queue. Once
+     * the list exceeds this limit, the oldest state is repeatedly removed until the limit
+     * is no longer exceeded.
+     */
+    void setMaxHistoryEntryCount(final int maxHistoryEntryCount) {
+        this.maxHistoryEntryCount = maxHistoryEntryCount;
+    }
+
+    List<ClusterStateHistoryEntry> getHistory() {
+        return Collections.unmodifiableList(stateHistory);
+    }
+
+    public void add(ClusterStateBundle currentClusterState, long currentTimeMs) {
+        if (prevStateBundle != null) {
+            stateHistory.addFirst(ClusterStateHistoryEntry.makeSuccessor(currentClusterState, prevStateBundle, currentTimeMs));
+        } else {
+            stateHistory.addFirst(ClusterStateHistoryEntry.makeFirstEntry(currentClusterState, currentTimeMs));
+        }
+        prevStateBundle = currentClusterState;
+        while (stateHistory.size() > maxHistoryEntryCount) {
+            stateHistory.removeLast();
+        }
+    }
+
+}
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistoryEntry.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistoryEntry.java
index 65c0f210fd5..17c6d6b721f 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistoryEntry.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/ClusterStateHistoryEntry.java
@@ -5,25 +5,74 @@ import com.yahoo.vdslib.state.ClusterState;
 
 import java.util.Map;
 import java.util.Objects;
+import java.util.TreeMap;
 import java.util.stream.Collectors;
 
+/**
+ * Represents the absolute cluster states (baseline + derived) for a given version
+ * as well as the relative diffs (baseline + derived) since the previous version.
+ */
 public class ClusterStateHistoryEntry {
 
-    private final ClusterStateBundle state;
+    public final static String BASELINE = "-";
+
     private final long time;
+    private final Map<String, String> states = new TreeMap<>();
+    private final Map<String, String> diffs = new TreeMap<>();
+
+    ClusterStateHistoryEntry(ClusterStateBundle state, long time) {
+        this.time = time;
+        populateStateStrings(state);
+        // No diffs for the first entry in the history.
+    }
 
-    ClusterStateHistoryEntry(final ClusterStateBundle state, final long time) {
-        this.state = state;
+    ClusterStateHistoryEntry(ClusterStateBundle state, ClusterStateBundle prevState, long time) {
         this.time = time;
+        populateStateStrings(state);
+        populateDiffStrings(state, prevState);
+    }
+
+    private void populateStateStrings(ClusterStateBundle state) {
+        states.put(BASELINE, state.getBaselineClusterState().toString());
+        var derivedStates = state.getDerivedBucketSpaceStates().entrySet().stream()
+                .collect(Collectors.toMap(
+                        entry -> entry.getKey(),
+                        entry -> entry.getValue().getClusterState().toString()));
+        states.putAll(derivedStates);
+    }
+
+    private void populateDiffStrings(ClusterStateBundle state, ClusterStateBundle prevState) {
+        // Yes, it's correct to get the diff by doing old.getHtmlDifference(new) rather than the other way around.
+        diffs.put(BASELINE, prevState.getBaselineClusterState().getHtmlDifference(state.getBaselineClusterState()));
+        var spaceDiffs = state.getDerivedBucketSpaceStates().entrySet().stream()
+                .collect(Collectors.toMap(
+                        entry -> entry.getKey(),
+                        entry -> derivedStateOf(prevState, entry.getKey()).getHtmlDifference(entry.getValue().getClusterState())));
+        diffs.putAll(spaceDiffs);
+    }
+
+    public static ClusterStateHistoryEntry makeFirstEntry(ClusterStateBundle state, long time) {
+        return new ClusterStateHistoryEntry(state, time);
+    }
+
+    public static ClusterStateHistoryEntry makeSuccessor(ClusterStateBundle state, ClusterStateBundle prevState, long time) {
+        return new ClusterStateHistoryEntry(state, prevState, time);
+    }
+
+    private static ClusterState derivedStateOf(ClusterStateBundle state, String space) {
+        return state.getDerivedBucketSpaceStates().getOrDefault(space, AnnotatedClusterState.emptyState()).getClusterState();
+    }
+
+    public Map<String, String> getRawStates() {
+        return states;
     }
 
-    public ClusterState getBaselineState() {
-        return state.getBaselineClusterState();
+    public String getStateString(String space) {
+        return states.getOrDefault(space, "");
     }
 
-    public Map<String, ClusterState> getDerivedBucketSpaceStates() {
-        return state.getDerivedBucketSpaceStates().entrySet().stream()
-                .collect(Collectors.toMap(entry -> entry.getKey(), entry -> entry.getValue().getClusterState()));
+    public String getDiffString(String space) {
+        return diffs.getOrDefault(space, "");
     }
 
     public long time() {
@@ -36,18 +85,19 @@ public class ClusterStateHistoryEntry {
         if (o == null || getClass() != o.getClass()) return false;
         ClusterStateHistoryEntry that = (ClusterStateHistoryEntry) o;
         return time == that.time &&
-                Objects.equals(state, that.state);
+                Objects.equals(states, that.states) &&
+                Objects.equals(diffs, that.diffs);
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(state, time);
+        return Objects.hash(time, states, diffs);
     }
 
     // String representation only used for test expectation failures and debugging output.
     // Actual status page history entry rendering emits formatted date/time.
     public String toString() {
-        return String.format("state '%s' at time %d", state, time);
+        return String.format("state '%s' at time %d", getStateString(BASELINE), time);
     }
 
 }
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 3c9b457e477..aa6e2973014 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
@@ -4,8 +4,6 @@ package com.yahoo.vespa.clustercontroller.core;
 import com.yahoo.vdslib.state.ClusterState;
 import com.yahoo.vespa.clustercontroller.core.hostinfo.HostInfo;
 
-import java.util.Collections;
-import java.util.LinkedList;
 import java.util.List;
 
 /**
@@ -34,8 +32,7 @@ public class StateVersionTracker {
     private ClusterStateView clusterStateView;
     private final ClusterStatsChangeTracker clusterStatsChangeTracker;
 
-    private final LinkedList<ClusterStateHistoryEntry> clusterStateHistory = new LinkedList<>();
-    private int maxHistoryEntryCount = 50;
+    private final ClusterStateHistory clusterStateHistory = new ClusterStateHistory();
     private double minMergeCompletionRatio;
 
     StateVersionTracker(double minMergeCompletionRatio) {
@@ -72,8 +69,8 @@ public class StateVersionTracker {
      *
      * Takes effect upon the next invocation of promoteCandidateToVersionedState().
      */
-    void setMaxHistoryEntryCount(final int maxHistoryEntryCount) {
-        this.maxHistoryEntryCount = maxHistoryEntryCount;
+    void setMaxHistoryEntryCount(int maxHistoryEntryCount) {
+        this.clusterStateHistory.setMaxHistoryEntryCount(maxHistoryEntryCount);
     }
 
     void setMinMergeCompletionRatio(double minMergeCompletionRatio) {
@@ -129,7 +126,7 @@ public class StateVersionTracker {
     }
 
     public List<ClusterStateHistoryEntry> getClusterStateHistory() {
-        return Collections.unmodifiableList(clusterStateHistory);
+        return clusterStateHistory.getHistory();
     }
 
     boolean candidateChangedEnoughFromCurrentToWarrantPublish() {
@@ -159,10 +156,7 @@ public class StateVersionTracker {
     }
 
     private void recordCurrentStateInHistoryAtTime(final long currentTimeMs) {
-        clusterStateHistory.addFirst(new ClusterStateHistoryEntry(currentClusterState, currentTimeMs));
-        while (clusterStateHistory.size() > maxHistoryEntryCount) {
-            clusterStateHistory.removeLast();
-        }
+        clusterStateHistory.add(currentClusterState, currentTimeMs);
     }
 
     void handleUpdatedHostInfo(final NodeInfo node, final HostInfo hostInfo) {
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/SystemStateBroadcaster.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/SystemStateBroadcaster.java
index 5a1399c8f29..0364d46f582 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/SystemStateBroadcaster.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/SystemStateBroadcaster.java
@@ -26,6 +26,7 @@ public class SystemStateBroadcaster {
     private final static long minTimeBetweenNodeErrorLogging = 10 * 60 * 1000;
     private final Map<Node, Long> lastErrorReported = new TreeMap<>();
 
+    private int lastOfficialStateVersion = 0;
     private int lastStateVersionBundleAcked = 0;
     private int lastClusterStateVersionConverged = 0;
     private ClusterStateBundle lastClusterStateBundleConverged;
@@ -255,6 +256,14 @@ public class SystemStateBroadcaster {
         return lastClusterStateVersionConverged == clusterStateBundle.getVersion();
     }
 
+    private boolean currentBundleVersionIsTaggedOfficial() {
+        return clusterStateBundle.getVersion() == lastOfficialStateVersion;
+    }
+
+    private void tagCurrentBundleVersionAsOfficial() {
+        lastOfficialStateVersion = clusterStateBundle.getVersion();
+    }
+
     public boolean broadcastNewStateBundleIfRequired(DatabaseHandler.Context dbContext, Communicator communicator,
                                                      int lastClusterStateVersionWrittenToZooKeeper) {
         if (clusterStateBundle == null) {
@@ -266,9 +275,9 @@ public class SystemStateBroadcaster {
 
         ClusterState baselineState = clusterStateBundle.getBaselineClusterState();
 
-        if (!baselineState.isOfficial()) {
+        if (!currentBundleVersionIsTaggedOfficial()) {
             log.log(Level.INFO, String.format("Publishing cluster state version %d", baselineState.getVersion()));
-            baselineState.setOfficial(true); // FIXME this violates state bundle immutability
+            tagCurrentBundleVersionAsOfficial();
         }
 
         List<NodeInfo> recipients = resolveStateVersionSendSet(dbContext);
@@ -291,7 +300,7 @@ public class SystemStateBroadcaster {
     }
 
     public boolean broadcastStateActivationsIfRequired(DatabaseHandler.Context dbContext, Communicator communicator) {
-        if (clusterStateBundle == null || !clusterStateBundle.getBaselineClusterState().isOfficial()) {
+        if (clusterStateBundle == null || !currentBundleVersionIsTaggedOfficial()) {
             return false;
         }
 
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/status/LegacyIndexPageRequestHandler.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/status/LegacyIndexPageRequestHandler.java
index 9d5e5e46f08..2813280add2 100644
--- a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/status/LegacyIndexPageRequestHandler.java
+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/status/LegacyIndexPageRequestHandler.java
@@ -101,25 +101,15 @@ public class LegacyIndexPageRequestHandler implements StatusPageServer.RequestHa
         if ( ! stateVersionTracker.getClusterStateHistory().isEmpty()) {
             TimeZone tz = TimeZone.getTimeZone("UTC");
             sb.append("<h3 id=\"clusterstatehistory\">Cluster state history</h3>\n");
-            if (showLocal) {
-                sb.append("<p>Cluster states shown in gray are just transition states on the fleet controller and has never been sent to any nodes.</p>");
-            }
             sb.append("<table border=\"1\" cellspacing=\"0\"><tr>\n")
               .append("  <th>Creation date (").append(tz.getDisplayName(false, TimeZone.SHORT)).append(")</th>\n")
               .append("  <th>Bucket space</th>\n")
               .append("  <th>Cluster state</th>\n")
               .append("</tr>\n");
-            // Write cluster state history in reverse order (newest on top)
-            Iterator<ClusterStateHistoryEntry> stateIterator = stateVersionTracker.getClusterStateHistory().iterator();
-            ClusterStateHistoryEntry current = null;
-            while (stateIterator.hasNext()) {
-                ClusterStateHistoryEntry nextEntry = stateIterator.next();
-                if (nextEntry.getBaselineState().isOfficial() || showLocal) {
-                    if (current != null) writeClusterStateEntry(current, nextEntry, sb, tz);
-                    current = nextEntry;
-                }
+            // Write cluster state history in descending time point order (newest on top)
+            for (var historyEntry : stateVersionTracker.getClusterStateHistory()) {
+                writeClusterStateEntry(historyEntry, sb, tz);
             }
-            if (current != null) writeClusterStateEntry(current, null, sb, tz);
             sb.append("</table>\n");
         }
     }
@@ -131,59 +121,36 @@ public class LegacyIndexPageRequestHandler implements StatusPageServer.RequestHa
         });
     }
 
-    private void writeClusterStateEntry(ClusterStateHistoryEntry entry, ClusterStateHistoryEntry last, StringBuilder sb, TimeZone tz) {
-        List<ClusterStateTransition> derivedTransitions = calculateDerivedClusterStateTransitions(entry, last);
-        sb.append("<tr><td rowspan=\"" + (derivedTransitions.size() + 1) + "\">").append(RealTimer.printDate(entry.time(), tz)).append("</td>");
-        writeClusterStateTransition(ClusterStateTransition.forBaseline(entry.getBaselineState(),
-                (last != null ? last.getBaselineState() : null)), entry.getBaselineState().isOfficial(), sb);
-        derivedTransitions.forEach(transition -> {
-            sb.append("<tr>");
-            writeClusterStateTransition(transition, entry.getBaselineState().isOfficial(), sb);
-        });
-    }
+    private void writeClusterStateEntry(ClusterStateHistoryEntry entry, StringBuilder sb, TimeZone tz) {
+        sb.append("<tr><td rowspan=\"").append(entry.getRawStates().size()).append("\">")
+          .append(RealTimer.printDate(entry.time(), tz)).append("</td>");
 
-    private void writeClusterStateTransition(ClusterStateTransition transition, boolean isOfficial, StringBuilder sb) {
-        sb.append("<td align=\"center\">").append(transition.bucketSpace).append("</td>");
-        sb.append("<td>").append(isOfficial ? "" : "<font color=\"grey\">");
-        sb.append(transition.current);
-        if (transition.last != null) {
-            sb.append("<br><b>Diff</b>: ").append(transition.last.getHtmlDifference(transition.current));
+        for (var space : entry.getRawStates().keySet()) {
+            if (!space.equals(ClusterStateHistoryEntry.BASELINE)) { // Always ordered first
+                sb.append("<tr>");
+            }
+            writeClusterStateTransition(space, entry.getStateString(space), entry.getDiffString(space),
+                                        entry.getStateString(ClusterStateHistoryEntry.BASELINE),
+                                        entry.getDiffString(ClusterStateHistoryEntry.BASELINE), sb);
         }
-        sb.append(isOfficial ? "" : "</font>").append("</td></tr>\n");
     }
 
-    private List<ClusterStateTransition> calculateDerivedClusterStateTransitions(ClusterStateHistoryEntry currentEntry,
-                                                                                 ClusterStateHistoryEntry lastEntry) {
-        List<ClusterStateTransition> result = new ArrayList<>();
-        currentEntry.getDerivedBucketSpaceStates().forEach((bucketSpace, currentState) -> {
-            ClusterState lastState = (lastEntry != null ? lastEntry.getDerivedBucketSpaceStates().get(bucketSpace) : null);
-            if ((!currentState.equals(currentEntry.getBaselineState())) ||
-                    ((lastState != null) && (!lastState.equals(lastEntry.getBaselineState())))) {
-                result.add(ClusterStateTransition.forBucketSpace(currentState, lastState, bucketSpace));
+    private void writeClusterStateTransition(String bucketSpace, String state, String diff,
+                                             String baselineState, String baselineDiff, StringBuilder sb) {
+        sb.append("<td align=\"center\">").append(bucketSpace).append("</td><td>");
+        if (!bucketSpace.equals(ClusterStateHistoryEntry.BASELINE) &&
+            state.equals(baselineState) && diff.equals(baselineDiff))
+        {
+            // Don't bother duplicating output for non-baseline states if they exactly match
+            // what's being output for the baseline state.
+            sb.append("<span style=\"color: gray\">(identical to baseline state)</span>");
+        } else {
+            sb.append(state);
+            if (!diff.isEmpty()) {
+                sb.append("<br><b>Diff</b>: ").append(diff);
             }
-        });
-        return result;
-    }
-
-    private static class ClusterStateTransition {
-        public final ClusterState current;
-        public final ClusterState last;
-        public final String bucketSpace;
-
-        private ClusterStateTransition(ClusterState current, ClusterState last, String bucketSpace) {
-            this.current = current;
-            this.last = last;
-            this.bucketSpace = bucketSpace;
-        }
-
-        public static ClusterStateTransition forBaseline(ClusterState current, ClusterState last) {
-            return new ClusterStateTransition(current, last, "-");
         }
-
-        public static ClusterStateTransition forBucketSpace(ClusterState current, ClusterState last, String bucketSpace) {
-            return new ClusterStateTransition(current, last, bucketSpace);
-        }
-
+        sb.append("</td></tr>\n");
     }
 
 }
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 83bdbfa0213..496d2a3b29a 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
@@ -180,8 +180,13 @@ public class StateVersionTrackerTest {
         assertTrue(versionTracker.getClusterStateHistory().isEmpty());
     }
 
-    private static ClusterStateHistoryEntry historyEntry(final String state, final long time) {
-        return new ClusterStateHistoryEntry(stateBundleWithoutAnnotations(state), time);
+    private static ClusterStateHistoryEntry historyEntry(String state, long time) {
+        return ClusterStateHistoryEntry.makeFirstEntry(stateBundleWithoutAnnotations(state), time);
+    }
+
+    private static ClusterStateHistoryEntry historyEntry(String state, String prevState, long time) {
+        return ClusterStateHistoryEntry.makeSuccessor(stateBundleWithoutAnnotations(state),
+                                                      stateBundleWithoutAnnotations(prevState), time);
     }
 
     @Test
@@ -191,12 +196,16 @@ public class StateVersionTrackerTest {
         updateAndPromote(versionTracker, stateWithoutAnnotations("distributor:3 storage:3"), 200);
         updateAndPromote(versionTracker, stateWithoutAnnotations("distributor:4 storage:4"), 300);
 
+        String s4 = "version:4 distributor:4 storage:4";
+        String s3 = "version:3 distributor:3 storage:3";
+        String s2 = "version:2 distributor:2 storage:2";
+
         // Note: newest entry first
         assertThat(versionTracker.getClusterStateHistory(),
                 equalTo(Arrays.asList(
-                         historyEntry("version:4 distributor:4 storage:4", 300),
-                         historyEntry("version:3 distributor:3 storage:3", 200),
-                         historyEntry("version:2 distributor:2 storage:2", 100))));
+                         historyEntry(s4, s3, 300),
+                         historyEntry(s3, s2, 200),
+                         historyEntry(s2, 100))));
     }
 
     @Test
@@ -208,17 +217,22 @@ public class StateVersionTrackerTest {
         updateAndPromote(versionTracker, stateWithoutAnnotations("distributor:3 storage:3"), 200);
         updateAndPromote(versionTracker, stateWithoutAnnotations("distributor:4 storage:4"), 300);
 
+        String s5 = "version:5 distributor:5 storage:5";
+        String s4 = "version:4 distributor:4 storage:4";
+        String s3 = "version:3 distributor:3 storage:3";
+        String s2 = "version:2 distributor:2 storage:2";
+
         assertThat(versionTracker.getClusterStateHistory(),
                 equalTo(Arrays.asList(
-                        historyEntry("version:4 distributor:4 storage:4", 300),
-                        historyEntry("version:3 distributor:3 storage:3", 200))));
+                        historyEntry(s4, s3, 300),
+                        historyEntry(s3, s2, 200))));
 
         updateAndPromote(versionTracker, stateWithoutAnnotations("distributor:5 storage:5"), 400);
 
         assertThat(versionTracker.getClusterStateHistory(),
                 equalTo(Arrays.asList(
-                        historyEntry("version:5 distributor:5 storage:5", 400),
-                        historyEntry("version:4 distributor:4 storage:4", 300))));
+                        historyEntry(s5, s4, 400),
+                        historyEntry(s4, s3, 300))));
     }
 
     @Test
diff --git a/vdslib/src/main/java/com/yahoo/vdslib/state/ClusterState.java b/vdslib/src/main/java/com/yahoo/vdslib/state/ClusterState.java
index b13b6230d3e..c536fc0f4cd 100644
--- a/vdslib/src/main/java/com/yahoo/vdslib/state/ClusterState.java
+++ b/vdslib/src/main/java/com/yahoo/vdslib/state/ClusterState.java
@@ -30,7 +30,6 @@ public class ClusterState implements Cloneable {
 
     private String description = "";
     private int distributionBits = 16;
-    private boolean official = false;
 
     public ClusterState(String serialized) throws ParseException {
         nodeCount.add(0);
@@ -169,16 +168,6 @@ public class ClusterState implements Cloneable {
                 : DEFAULT_DISTRIBUTOR_UP_NODE_STATE;
     }
 
-    /**
-     * Fleet controller marks states that are actually sent out to nodes as official states. Only fleetcontroller
-     * should set this to official, and only just before sending it out. This state is currently not serialized with
-     * the system state, but only used internally in the fleetcontroller. Might be useful client side though, where
-     * clients modify states to mark nodes down that they cannot speak with.
-     */
-    public void setOfficial(boolean official) { this.official = official; }
-    /** Whether this system state is an unmodified version of an official system state. */
-    public boolean isOfficial() { return official; }
-
     /** Used during deserialization */
     private class NodeData {
 
@@ -202,7 +191,6 @@ public class ClusterState implements Cloneable {
     }
 
     private void deserialize(String serialized) throws ParseException {
-        official = false;
         StringTokenizer st = new StringTokenizer(serialized, " \t\n\f\r", false);
         NodeData nodeData = new NodeData();
         String lastAbsolutePath = "";
@@ -323,9 +311,6 @@ public class ClusterState implements Cloneable {
         if (distributionBits != other.distributionBits) {
             diff.add(new Diff.Entry("bits", distributionBits, other.distributionBits));
         }
-        if (official != other.official) {
-            diff.add(new Diff.Entry("official", official, other.official));
-        }
         for (NodeType type : NodeType.getTypes()) {
             Diff typeDiff = new Diff();
             int maxCount = Math.max(getNodeCount(type), other.getNodeCount(type));
@@ -348,7 +333,6 @@ public class ClusterState implements Cloneable {
     }
 
     public void setVersion(int version) {
-        official = false;
         this.version = version;
     }
 
diff --git a/vdslib/src/test/java/com/yahoo/vdslib/state/ClusterStateTestCase.java b/vdslib/src/test/java/com/yahoo/vdslib/state/ClusterStateTestCase.java
index 258a79f5362..dbc8888cfda 100644
--- a/vdslib/src/test/java/com/yahoo/vdslib/state/ClusterStateTestCase.java
+++ b/vdslib/src/test/java/com/yahoo/vdslib/state/ClusterStateTestCase.java
@@ -188,9 +188,8 @@ public class ClusterStateTestCase{
         state2.setDistributionBits(21);
         state1.setVersion(123);
         state1.setNodeState(new Node(NodeType.STORAGE, 2), new NodeState(NodeType.STORAGE, State.INITIALIZING).setInitProgress(0.2f).setDescription("Booting"));
-        state2.setOfficial(true);
 
-        assertEquals("version: 123 => 0, bits: 16 => 21, official: false => true, storage: [2: [Initializing => Up, description: Booting => ], 4: Down => Up, 5: Down => Up], distributor: [7: Up => Down, 8: Up => Down]", state1.getTextualDifference(state2));
+        assertEquals("version: 123 => 0, bits: 16 => 21, storage: [2: [Initializing => Up, description: Booting => ], 4: Down => Up, 5: Down => Up], distributor: [7: Up => Down, 8: Up => Down]", state1.getTextualDifference(state2));
     }
 
     @Test
@@ -221,9 +220,8 @@ public class ClusterStateTestCase{
         state1.setVersion(123);
         state1.setNodeState(new Node(NodeType.STORAGE, 2), new NodeState(NodeType.STORAGE, State.INITIALIZING).setInitProgress(0.2f).setDescription("Booting"));
         state2.setDistributionBits(21);
-        state2.setOfficial(true);
-        assertEquals("version: 123 => 0, bits: 16 => 21, official: false => true, storage: [2: [Initializing => Up, description: Booting => ], 4: Down => Up, 5: Down => Up], distributor: [7: Up => Down, 8: Up => Down]", state1.getTextualDifference(state2));
-        assertEquals("version: 123 =&gt; 0, bits: 16 =&gt; 21, official: false =&gt; true, storage: [<br>\n" +
+        assertEquals("version: 123 => 0, bits: 16 => 21, storage: [2: [Initializing => Up, description: Booting => ], 4: Down => Up, 5: Down => Up], distributor: [7: Up => Down, 8: Up => Down]", state1.getTextualDifference(state2));
+        assertEquals("version: 123 =&gt; 0, bits: 16 =&gt; 21, storage: [<br>\n" +
                 "&nbsp;2: [<b>Initializing</b> =&gt; <b>Up</b>, description: Booting =&gt; ], <br>\n" +
                 "&nbsp;4: <b>Down</b> =&gt; <b>Up</b>, <br>\n" +
                 "&nbsp;5: <b>Down</b> =&gt; <b>Up</b><br>\n" +