1 files changed, 61 insertions, 11 deletions

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);
     }
 
 }