[ML] Add copy constructor for AssignmentStats (elastic#127230)

Author: davidkyle

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/assignment/AssignmentStats.java

@@ -432,6 +432,22 @@ public int hashCode() {
     private final Instant startTime;
     private final List<AssignmentStats.NodeStats> nodeStats;
 
+    public AssignmentStats(AssignmentStats other) {
+        this.deploymentId = other.deploymentId;
+        this.modelId = other.modelId;
+        this.threadsPerAllocation = other.threadsPerAllocation;
+        this.numberOfAllocations = other.numberOfAllocations;
+        this.adaptiveAllocationsSettings = other.adaptiveAllocationsSettings;
+        this.queueCapacity = other.queueCapacity;
+        this.startTime = other.startTime;
+        this.nodeStats = other.nodeStats;
+        this.state = other.state;
+        this.reason = other.reason;
+        this.allocationStatus = other.allocationStatus;
+        this.cacheSize = other.cacheSize;
+        this.priority = other.priority;
+    }
+
     public AssignmentStats(
         String deploymentId,
         String modelId,
@@ -535,6 +551,12 @@ public AssignmentState getState() {
         return state;
     }
 
+    public AssignmentStats setNodeStats(List<AssignmentStats.NodeStats> nodeStats) {
+        this.nodeStats.clear();
+        this.nodeStats.addAll(nodeStats);
+        return this;
+    }
+
     public AssignmentStats setState(AssignmentState state) {
         this.state = state;
         return this;

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/inference/assignment/AssignmentStatsTests.java

@@ -214,6 +214,12 @@ public void testGetOverallInferenceStatsWithOnlyStoppedNodes() {
         assertThat(stats.getFailureCount(), equalTo(0L));
     }
 
+    public void testCopyConstructor() {
+        AssignmentStats original = randomDeploymentStats();
+        AssignmentStats copy = new AssignmentStats(original);
+        assertThat(copy, equalTo(original));
+    }
+
     @Override
     protected Writeable.Reader<AssignmentStats> instanceReader() {
         return AssignmentStats::new;