[ES|QL] Register AggregateMetricDoubleLiteral (elastic#135054)

This literal was not previously being registered because it was
primarily being used in testing code, but when aggregate_metric_double
is folded it is used as the java object representation, so it requires
registering.

Author: limotova

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/data/AggregateMetricDoubleBlockBuilder.java

@@ -206,6 +206,10 @@ public String getLabel() {
         }
     }
 
+    /**
+     * Literal to represent AggregateMetricDouble and primarily used for testing and during folding.
+     * For all other purposes it is preferred to use the individual builders over the literal for generating blocks when possible.
+     */
     public record AggregateMetricDoubleLiteral(Double min, Double max, Double sum, Integer count) implements GenericNamedWriteable {
         public AggregateMetricDoubleLiteral {
             min = (min == null || min.isNaN()) ? null : min;
@@ -247,4 +251,28 @@ public TransportVersion getMinimalSupportedVersion() {
             throw new UnsupportedOperationException("must not be called when overriding supportsVersion");
         }
     }
+
+    public AggregateMetricDoubleBlockBuilder appendLiteral(AggregateMetricDoubleLiteral literal) {
+        if (literal.min != null) {
+            minBuilder.appendDouble(literal.min);
+        } else {
+            minBuilder.appendNull();
+        }
+        if (literal.max != null) {
+            maxBuilder.appendDouble(literal.max);
+        } else {
+            maxBuilder.appendNull();
+        }
+        if (literal.sum != null) {
+            sumBuilder.appendDouble(literal.sum);
+        } else {
+            sumBuilder.appendNull();
+        }
+        if (literal.count != null) {
+            countBuilder.appendInt(literal.count);
+        } else {
+            countBuilder.appendNull();
+        }
+        return this;
+    }
 }

x-pack/plugin/esql/compute/src/main/java/org/elasticsearch/compute/data/BlockUtils.java

@@ -217,6 +217,7 @@ public static void appendValue(Block.Builder builder, Object val, ElementType ty
             case FLOAT -> ((FloatBlock.Builder) builder).appendFloat((Float) val);
             case DOUBLE -> ((DoubleBlock.Builder) builder).appendDouble((Double) val);
             case BOOLEAN -> ((BooleanBlock.Builder) builder).appendBoolean((Boolean) val);
+            case AGGREGATE_METRIC_DOUBLE -> ((AggregateMetricDoubleBlockBuilder) builder).appendLiteral((AggregateMetricDoubleLiteral) val);
             default -> throw new UnsupportedOperationException("unsupported element type [" + type + "]");
         }
     }

x-pack/plugin/esql/qa/testFixtures/src/main/java/org/elasticsearch/xpack/esql/CsvTestUtils.java

@@ -143,7 +143,7 @@ void append(String stringValue) {
                         return;
                     }
                     stringValue = mvStrings[0].replace(ESCAPED_COMMA_SEQUENCE, ",");
-                } else if (stringValue.contains(",")) {// multi-value field
+                } else if (stringValue.contains(",") && type != Type.AGGREGATE_METRIC_DOUBLE) {// multi-value field
                     builderWrapper().builder().beginPositionEntry();
 
                     String[] arrayOfValues = delimitedListToStringArray(stringValue, ",");

x-pack/plugin/esql/qa/testFixtures/src/main/resources/inlinestats.csv-spec

@@ -3913,3 +3913,26 @@ from employees
 10003          |0              |null           
 ;
 
+inlineStatsOnAggregateMetricDouble
+required_capability: inline_stats
+required_capability: aggregate_metric_double_literal_registered
+required_capability: aggregate_metric_double_convert_to
+FROM k8s-downsampled
+| EVAL a = TO_AGGREGATE_METRIC_DOUBLE(1)     // Temporary workaround to enable aggregate_metric_double
+| INLINE STATS tx_max = MAX(network.eth0.tx) BY pod
+| SORT @timestamp, cluster, pod
+| KEEP @timestamp, cluster, pod, network.eth0.tx, tx_max
+| LIMIT 9
+;
+
+@timestamp:datetime      | cluster:keyword | pod:keyword | network.eth0.tx:aggregate_metric_double                  | tx_max:double
+2024-05-09T23:30:00.000Z | prod            | one         | {"min":565.0,"max":829.0,"sum":7290.0,"value_count":10}  | 1060.0
+2024-05-09T23:30:00.000Z | prod            | three       | {"min":201.0,"max":582.0,"sum":1794.0,"value_count":6}   | 824.0
+2024-05-09T23:30:00.000Z | prod            | two         | {"min":20.0,"max":190.0,"sum":370.0,"value_count":10}    | 1419.0
+2024-05-09T23:30:00.000Z | qa              | one         | {"min":346.0,"max":356.0,"sum":1765.0,"value_count":5}   | 1060.0
+2024-05-09T23:30:00.000Z | qa              | three       | {"min":605.0,"max":605.0,"sum":605.0,"value_count":1}    | 824.0
+2024-05-09T23:30:00.000Z | qa              | two         | {"min":304.0,"max":1148.0,"sum":8590.0,"value_count":10} | 1419.0
+2024-05-09T23:30:00.000Z | staging         | one         | {"min":263.0,"max":740.0,"sum":5390.0,"value_count":10}  | 1060.0
+2024-05-09T23:30:00.000Z | staging         | three       | {"min":341.0,"max":592.0,"sum":1956.0,"value_count":5}   | 824.0
+2024-05-09T23:30:00.000Z | staging         | two         | {"min":442.0,"max":1011.0,"sum":3850.0,"value_count":7}  | 1419.0
+;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/action/EsqlCapabilities.java

@@ -976,6 +976,11 @@ public enum Cap {
          */
         AGGREGATE_METRIC_DOUBLE_MV_EXPAND(AGGREGATE_METRIC_DOUBLE_FEATURE_FLAG),
 
+        /**
+         * Registering AggregateMetricDoubleLiteral as a NamedWritable.
+         */
+        AGGREGATE_METRIC_DOUBLE_LITERAL_REGISTERED(AGGREGATE_METRIC_DOUBLE_FEATURE_FLAG),
+
         /**
          * Support change point detection "CHANGE_POINT".
          */

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/ExpressionWritables.java

@@ -8,6 +8,8 @@
 package org.elasticsearch.xpack.esql.expression;
 
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
+import org.elasticsearch.compute.data.AggregateMetricDoubleBlockBuilder;
+import org.elasticsearch.plugins.SearchPlugin;
 import org.elasticsearch.xpack.esql.action.EsqlCapabilities;
 import org.elasticsearch.xpack.esql.core.expression.ExpressionCoreWritables;
 import org.elasticsearch.xpack.esql.expression.function.UnsupportedAttribute;
@@ -124,6 +126,12 @@ public static List<NamedWriteableRegistry.Entry> getNamedWriteables() {
         return entries;
     }
 
+    public static List<SearchPlugin.GenericNamedWriteableSpec> getGenericNamedWriteables() {
+        List<SearchPlugin.GenericNamedWriteableSpec> entries = new ArrayList<>();
+        entries.addAll(literals());
+        return entries;
+    }
+
     public static List<NamedWriteableRegistry.Entry> attributes() {
         List<NamedWriteableRegistry.Entry> entries = new ArrayList<>();
         entries.addAll(ExpressionCoreWritables.attributes());
@@ -267,4 +275,13 @@ private static List<NamedWriteableRegistry.Entry> fullText() {
     private static List<NamedWriteableRegistry.Entry> vector() {
         return VectorWritables.getNamedWritables();
     }
+
+    public static List<SearchPlugin.GenericNamedWriteableSpec> literals() {
+        return List.of(
+            new SearchPlugin.GenericNamedWriteableSpec(
+                "AggregateMetricDoubleLiteral",
+                AggregateMetricDoubleBlockBuilder.AggregateMetricDoubleLiteral::new
+            )
+        );
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plugin/EsqlPlugin.java

@@ -42,6 +42,7 @@
 import org.elasticsearch.plugins.ActionPlugin;
 import org.elasticsearch.plugins.ExtensiblePlugin;
 import org.elasticsearch.plugins.Plugin;
+import org.elasticsearch.plugins.SearchPlugin;
 import org.elasticsearch.rest.RestController;
 import org.elasticsearch.rest.RestHandler;
 import org.elasticsearch.threadpool.ExecutorBuilder;
@@ -90,7 +91,7 @@
 import java.util.function.Predicate;
 import java.util.function.Supplier;
 
-public class EsqlPlugin extends Plugin implements ActionPlugin, ExtensiblePlugin {
+public class EsqlPlugin extends Plugin implements ActionPlugin, ExtensiblePlugin, SearchPlugin {
 
     public static final String ESQL_WORKER_THREAD_POOL_NAME = "esql_worker";
 
@@ -374,4 +375,9 @@ public List<ExecutorBuilder<?>> getExecutorBuilders(Settings settings) {
     public void loadExtensions(ExtensionLoader loader) {
         extraCheckerProviders.addAll(loader.loadExtensions(PlanCheckerProvider.class));
     }
+
+    @Override
+    public List<SearchPlugin.GenericNamedWriteableSpec> getGenericNamedWriteables() {
+        return ExpressionWritables.getGenericNamedWriteables();
+    }
 }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/type/EsqlDataTypeConverter.java

@@ -813,22 +813,24 @@ public static AggregateMetricDoubleBlockBuilder.AggregateMetricDoubleLiteral str
         Double max = null;
         Double sum = null;
         Integer count = null;
+
+        s = s.replace("\\,", ",");
         String[] values = s.substring(1, s.length() - 1).split(",");
         for (String v : values) {
             var pair = v.split(":");
             String type = pair[0];
             String number = pair[1];
             switch (type) {
-                case "min":
+                case "min", "\"min\"":
                     min = Double.parseDouble(number);
                     break;
-                case "max":
+                case "max", "\"max\"":
                     max = Double.parseDouble(number);
                     break;
-                case "sum":
+                case "sum", "\"sum\"":
                     sum = Double.parseDouble(number);
                     break;
-                case "value_count":
+                case "value_count", "\"value_count\"":
                     count = Integer.parseInt(number);
                     break;
                 default: