1 files changed, 37 insertions, 0 deletions
diff --git a/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/UpEdgeMaintenanceTransitionConstraint.java b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/UpEdgeMaintenanceTransitionConstraint.java
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+++ b/clustercontroller-core/src/main/java/com/yahoo/vespa/clustercontroller/core/UpEdgeMaintenanceTransitionConstraint.java
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+// 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.vdslib.state.ClusterState;
+import com.yahoo.vdslib.state.Node;
+import com.yahoo.vdslib.state.NodeState;
+
+/**
+ * Simple implementation which considers a node eligible for being set to maintenance iff
+ * it was down or in maintenance in the cluster state previously published. This avoids
+ * taking down nodes with pending global merges if these have already passed through an
+ * up-edge, but runs the risk of taking down a large set of nodes when the cluster
+ * controller is restarted (due to not knowing the previously published state).
+ *
+ * Output from this checker must always be combined with other constraints to decide whether
+ * a node should be in maintenance; used alone it would most certainly cause havoc.
+ *
+ * Considered sufficient for beta testing use cases.
+ */
+public class UpEdgeMaintenanceTransitionConstraint implements MaintenanceTransitionConstraint {
+
+    private final ClusterState previouslyPublishedDerivedState;
+
+    private UpEdgeMaintenanceTransitionConstraint(ClusterState previouslyPublishedDerivedState) {
+        this.previouslyPublishedDerivedState = previouslyPublishedDerivedState;
+    }
+
+    public static UpEdgeMaintenanceTransitionConstraint forPreviouslyPublishedState(ClusterState state) {
+        return new UpEdgeMaintenanceTransitionConstraint(state);
+    }
+
+    @Override
+    public boolean maintenanceTransitionAllowed(int contentNodeIndex) {
+        NodeState prevState = previouslyPublishedDerivedState.getNodeState(Node.ofStorage(contentNodeIndex));
+        return prevState.getState().oneOf("dm");
+    }
+}