Revert "Convert double script to return array (#61504)"

This reverts commit 6d8170c. We've
decided to stick with the `value` style functions for runtime fields.

Author: nik9000

x-pack/plugin/runtime-fields/qa/rest/src/yamlRestTest/java/org/elasticsearch/xpack/runtimefields/rest/CoreTestsWithRuntimeFieldsIT.java

@@ -166,9 +166,6 @@ private static String painlessToLoadFromSource(String name, String type) {
             return null;
         }
         StringBuilder b = new StringBuilder();
-        if ("double".equals(type)) {
-            b.append("List result = new ArrayList();");
-        }
         b.append("def v = source['").append(name).append("'];\n");
         b.append("if (v instanceof Iterable) {\n");
         b.append("  for (def vv : ((Iterable) v)) {\n");
@@ -183,9 +180,6 @@ private static String painlessToLoadFromSource(String name, String type) {
         b.append("    ").append(emit).append("\n");
         b.append("  }\n");
         b.append("}\n");
-        if ("double".equals(type)) {
-            b.append("return result;");
-        }
         return b.toString();
     }
 
@@ -194,7 +188,7 @@ private static String painlessToLoadFromSource(String name, String type) {
         Map.entry(DateFieldMapper.CONTENT_TYPE, "millis(parse(value.toString()));"),
         Map.entry(
             NumberType.DOUBLE.typeName(),
-            "result.add(value instanceof Number ? ((Number) value).doubleValue() : Double.parseDouble(value.toString()));"
+            "value(value instanceof Number ? ((Number) value).doubleValue() : Double.parseDouble(value.toString()));"
         ),
         Map.entry(KeywordFieldMapper.CONTENT_TYPE, "value(value.toString());"),
         Map.entry(IpFieldMapper.CONTENT_TYPE, "stringValue(value.toString());"),

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/AbstractLongScriptFieldScript.java

@@ -23,8 +23,6 @@ public AbstractLongScriptFieldScript(Map<String, Object> params, SearchLookup se
         super(params, searchLookup, ctx);
     }
 
-    public abstract void execute();
-
     /**
      * Execute the script for the provided {@code docId}.
      */

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/AbstractScriptFieldScript.java

@@ -81,4 +81,6 @@ public final Map<String, Object> getSource() {
     public final Map<String, ScriptDocValues<?>> getDoc() {
         return leafSearchLookup.doc();
     }
+
+    public abstract void execute();
 }

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/BooleanScriptFieldScript.java

@@ -42,8 +42,6 @@ public BooleanScriptFieldScript(Map<String, Object> params, SearchLookup searchL
         super(params, searchLookup, ctx);
     }
 
-    public abstract void execute();
-
     /**
      * Execute the script for the provided {@code docId}.
      */

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/DoubleScriptFieldScript.java

@@ -7,14 +7,14 @@
 package org.elasticsearch.xpack.runtimefields;
 
 import org.apache.lucene.index.LeafReaderContext;
+import org.apache.lucene.util.ArrayUtil;
 import org.elasticsearch.painless.spi.Whitelist;
 import org.elasticsearch.painless.spi.WhitelistLoader;
 import org.elasticsearch.script.ScriptContext;
 import org.elasticsearch.script.ScriptFactory;
 import org.elasticsearch.search.lookup.SearchLookup;
 
 import java.io.IOException;
-import java.util.Collection;
 import java.util.List;
 import java.util.Map;
 
@@ -35,40 +35,55 @@ public interface LeafFactory {
         DoubleScriptFieldScript newInstance(LeafReaderContext ctx) throws IOException;
     }
 
+    private double[] values = new double[1];
+    private int count;
+
     public DoubleScriptFieldScript(Map<String, Object> params, SearchLookup searchLookup, LeafReaderContext ctx) {
         super(params, searchLookup, ctx);
     }
 
-    public abstract double[] execute();
-
     /**
      * Execute the script for the provided {@code docId}.
      */
-    public final double[] runForDoc(int docId) {
+    public final void runForDoc(int docId) {
+        count = 0;
         setDocument(docId);
-        return execute();
+        execute();
     }
 
-    public static double[] convertFromDouble(double v) {
-        return new double[] { v };
+    /**
+     * Values from the last time {@link #runForDoc(int)} was called. This array
+     * is mutable and will change with the next call of {@link #runForDoc(int)}.
+     * It is also oversized and will contain garbage at all indices at and
+     * above {@link #count()}.
+     */
+    public final double[] values() {
+        return values;
     }
 
-    public static double[] convertFromCollection(Collection<?> v) {
-        double[] result = new double[v.size()];
-        int i = 0;
-        for (Object o : v) {
-            result[i++] = ((Number) o).doubleValue();
+    /**
+     * The number of results produced the last time {@link #runForDoc(int)} was called.
+     */
+    public final int count() {
+        return count;
+    }
+
+    private void collectValue(double v) {
+        if (values.length < count + 1) {
+            values = ArrayUtil.grow(values, count + 1);
         }
-        return result;
+        values[count++] = v;
     }
 
-    public static double[] convertFromDef(Object o) {
-        if (o instanceof Number) {
-            return convertFromDouble(((Number) o).doubleValue());
-        } else if (o instanceof Collection) {
-            return convertFromCollection((Collection<?>) o);
-        } else {
-            return (double[]) o;
+    public static class Value {
+        private final DoubleScriptFieldScript script;
+
+        public Value(DoubleScriptFieldScript script) {
+            this.script = script;
+        }
+
+        public void value(double v) {
+            script.collectValue(v);
         }
     }
 }

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/IpScriptFieldScript.java

@@ -63,8 +63,6 @@ public IpScriptFieldScript(Map<String, Object> params, SearchLookup searchLookup
         super(params, searchLookup, ctx);
     }
 
-    public abstract void execute();
-
     /**
      * Execute the script for the provided {@code docId}.
      */

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/StringScriptFieldScript.java

@@ -41,8 +41,6 @@ public StringScriptFieldScript(Map<String, Object> params, SearchLookup searchLo
         super(params, searchLookup, ctx);
     }
 
-    public abstract void execute();
-
     /**
      * Execute the script for the provided {@code docId}.
      * <p>

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/fielddata/ScriptDoubleDocValues.java

@@ -14,7 +14,6 @@
 
 public final class ScriptDoubleDocValues extends SortedNumericDoubleValues {
     private final DoubleScriptFieldScript script;
-    private double[] values;
     private int cursor;
 
     ScriptDoubleDocValues(DoubleScriptFieldScript script) {
@@ -23,22 +22,22 @@ public final class ScriptDoubleDocValues extends SortedNumericDoubleValues {
 
     @Override
     public boolean advanceExact(int docId) {
-        values = script.runForDoc(docId);
-        if (values.length == 0) {
+        script.runForDoc(docId);
+        if (script.count() == 0) {
             return false;
         }
-        Arrays.sort(values);
+        Arrays.sort(script.values(), 0, script.count());
         cursor = 0;
         return true;
     }
 
     @Override
     public double nextValue() throws IOException {
-        return values[cursor++];
+        return script.values()[cursor++];
     }
 
     @Override
     public int docValueCount() {
-        return values.length;
+        return script.count();
     }
 }

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/query/AbstractDoubleScriptFieldQuery.java

@@ -36,7 +36,7 @@ abstract class AbstractDoubleScriptFieldQuery extends AbstractScriptFieldQuery {
     /**
      * Does the value match this query?
      */
-    protected abstract boolean matches(double[] values);
+    protected abstract boolean matches(double[] values, int count);
 
     @Override
     public final Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException {
@@ -53,7 +53,8 @@ public Scorer scorer(LeafReaderContext ctx) throws IOException {
                 TwoPhaseIterator twoPhase = new TwoPhaseIterator(approximation) {
                     @Override
                     public boolean matches() throws IOException {
-                        return AbstractDoubleScriptFieldQuery.this.matches(script.runForDoc(approximation().docID()));
+                        script.runForDoc(approximation().docID());
+                        return AbstractDoubleScriptFieldQuery.this.matches(script.values(), script.count());
                     }
 
                     @Override

x-pack/plugin/runtime-fields/src/main/java/org/elasticsearch/xpack/runtimefields/query/DoubleScriptFieldExistsQuery.java

@@ -15,8 +15,8 @@ public DoubleScriptFieldExistsQuery(Script script, DoubleScriptFieldScript.LeafF
     }
 
     @Override
-    protected boolean matches(double[] values) {
-        return values.length > 0;
+    protected boolean matches(double[] values, int count) {
+        return count > 0;
     }
 
     @Override