wire tests

Author: mhl-b

server/src/main/java/org/elasticsearch/TransportVersions.java

@@ -365,6 +365,7 @@ static TransportVersion def(int id) {
     public static final TransportVersion ESQL_LOOKUP_JOIN_ON_MANY_FIELDS = def(9_139_0_00);
     public static final TransportVersion SIMULATE_INGEST_EFFECTIVE_MAPPING = def(9_140_0_00);
     public static final TransportVersion RESOLVE_INDEX_MODE_ADDED = def(9_141_0_00);
+    public static final TransportVersion ALLOCATION_DECISION_YES_NOT_PREFERRED = def(9_142_0_00);
 
     /*
      * STOP! READ THIS FIRST! No, really,

server/src/main/java/org/elasticsearch/cluster/routing/allocation/decider/AllocationDeciders.java

@@ -216,7 +216,7 @@ private Decision withDeciders(
                     return decision;
                 } else if (finalDecision.type() == Decision.Type.YES && decision.type() == Decision.Type.THROTTLE) {
                     finalDecision = decision;
-                } else if (finalDecision.preferred() == Decision.Preferred.NO) {
+                } else if (decision.preferred() == Decision.Preferred.NO) {
                     preferred = Decision.Preferred.NO;
                 }
             }

server/src/main/java/org/elasticsearch/cluster/routing/allocation/decider/Decision.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.cluster.routing.allocation.decider;
 
+import org.elasticsearch.TransportVersions;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
@@ -90,16 +91,20 @@ static Decision readFrom(StreamInput in) throws IOException {
 
     private static Single readSingleFrom(StreamInput in) throws IOException {
         final Type type = Type.readFrom(in);
+        Preferred preferred = Preferred.YES;
+        if (in.getTransportVersion().onOrAfter(TransportVersions.ALLOCATION_DECISION_YES_NOT_PREFERRED)) {
+            preferred = in.readEnum(Preferred.class);
+        }
         final String label = in.readOptionalString();
         final String explanation = in.readOptionalString();
         if (label == null && explanation == null) {
             return switch (type) {
-                case YES -> YES;
+                case YES -> preferred == Preferred.YES ? YES : YES_NOT_PREFERRED;
                 case THROTTLE -> THROTTLE;
                 case NO -> NO;
             };
         }
-        return new Single(type, label, explanation);
+        return new Single(type, preferred, label, explanation);
     }
 
     /**
@@ -253,7 +258,7 @@ public String getExplanation() {
 
         @Override
         public String toString() {
-            var preference = type == Type.YES && preferred == Preferred.NO ? "_NOT_PREFERRED": "";
+            var preference = type == Type.YES && preferred == Preferred.NO ? "_NOT_PREFERRED" : "";
             if (explanationString != null) {
                 return type + preference + "(" + explanationString + ")";
             }
@@ -274,6 +279,9 @@ public XContentBuilder toXContent(XContentBuilder builder, Params params) throws
         public void writeTo(StreamOutput out) throws IOException {
             out.writeBoolean(false); // flag specifying its a single decision
             type.writeTo(out);
+            if (out.getTransportVersion().onOrAfter(TransportVersions.ALLOCATION_DECISION_YES_NOT_PREFERRED)) {
+                out.writeEnum(preferred);
+            }
             out.writeOptionalString(label);
             // Flatten explanation on serialization, so that explanationParams
             // do not need to be serialized
@@ -317,16 +325,12 @@ public Type type() {
 
         @Override
         public Preferred preferred() {
-            var preferred = Preferred.YES;
             for (var decision : decisions) {
-                if (decision.type() != Type.YES) {
+                if (decision.type() != Type.YES || decision.preferred() == Preferred.NO) {
                     return Preferred.NO;
                 }
-                if (decision.preferred() == Preferred.NO) {
-                    preferred = Preferred.NO;
-                }
             }
-            return preferred;
+            return Preferred.YES;
         }
 
         @Override

server/src/test/java/org/elasticsearch/cluster/routing/allocation/decider/DecisionTests.java

@@ -9,8 +9,13 @@
 
 package org.elasticsearch.cluster.routing.allocation.decider;
 
+import org.elasticsearch.TransportVersions;
 import org.elasticsearch.cluster.routing.allocation.decider.Decision.Type;
-import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.common.io.stream.Writeable;
+import org.elasticsearch.test.AbstractWireSerializingTestCase;
+import org.elasticsearch.test.TransportVersionUtils;
+
+import java.io.IOException;
 
 import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.NO;
 import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.THROTTLE;
@@ -19,7 +24,7 @@
 /**
  * A class for unit testing the {@link Decision} class.
  */
-public class DecisionTests extends ESTestCase {
+public class DecisionTests extends AbstractWireSerializingTestCase<Decision> {
 
     /**
      * Tests {@link Type#higherThan(Type)}
@@ -40,4 +45,34 @@ public void testHigherThan() {
         assertFalse(NO.higherThan(THROTTLE));
         assertFalse(NO.higherThan(YES));
     }
+
+    public void testNotPreferredSerializationBeforeVersion() throws IOException {
+        var inDecision = Decision.YES_NOT_PREFERRED;
+        var outDecision = copyInstance(
+            inDecision,
+            TransportVersionUtils.getPreviousVersion(TransportVersions.ALLOCATION_DECISION_YES_NOT_PREFERRED)
+        );
+        assertEquals("should fallback to always-preferred in prior versions", Decision.YES, outDecision);
+    }
+
+    public void testNotPreferredSerialization() throws IOException {
+        var inDecision = Decision.YES_NOT_PREFERRED;
+        var outDecision = copyInstance(inDecision, TransportVersions.ALLOCATION_DECISION_YES_NOT_PREFERRED);
+        assertEquals(inDecision, outDecision);
+    }
+
+    @Override
+    protected Writeable.Reader<Decision> instanceReader() {
+        return Decision::readFrom;
+    }
+
+    @Override
+    protected Decision createTestInstance() {
+        return Decision.single(YES, null, null, (Object[]) null);
+    }
+
+    @Override
+    protected Decision mutateInstance(Decision instance) throws IOException {
+        return instance.type() == YES ? Decision.NO : Decision.YES;
+    }
 }

x-pack/plugin/autoscaling/src/test/java/org/elasticsearch/xpack/autoscaling/storage/NodeDecisionTestUtils.java

@@ -11,6 +11,7 @@
 import org.elasticsearch.cluster.routing.allocation.decider.Decision;
 import org.elasticsearch.cluster.routing.allocation.decider.DiskThresholdDecider;
 import org.elasticsearch.cluster.routing.allocation.decider.FilterAllocationDecider;
+import org.elasticsearch.cluster.routing.allocation.decider.WriteLoadConstraintDecider;
 
 import static java.util.Collections.emptySet;
 import static org.elasticsearch.test.ESTestCase.randomAlphaOfLength;
@@ -30,6 +31,7 @@ static Decision randomDecision() {
         return randomFrom(
             new Decision.Single(Decision.Type.NO, DiskThresholdDecider.NAME, "Unable to allocate on disk"),
             new Decision.Single(Decision.Type.YES, FilterAllocationDecider.NAME, "Filter allows allocation"),
+            new Decision.Single(Decision.Type.YES, Decision.Preferred.NO, WriteLoadConstraintDecider.NAME, "Write-Load is above threshold"),
             new Decision.Single(Decision.Type.THROTTLE, "throttle label", "Throttling the consumer"),
             new Decision.Multi().add(randomFrom(Decision.NO, Decision.YES, Decision.THROTTLE))
                 .add(new Decision.Single(Decision.Type.NO, "multi_no", "No multi decision"))