8366809: JFR: Use factory for aggregator functions

Reviewed-by: mgronlun

Author: egahlin

src/jdk.jfr/share/classes/jdk/jfr/internal/query/Field.java

@@ -33,6 +33,7 @@
 import jdk.jfr.internal.query.Configuration.Truncate;
 import jdk.jfr.internal.query.Query.Grouper;
 import jdk.jfr.internal.query.Query.OrderElement;
+import jdk.jfr.internal.query.Function.FunctionFactory;
 
 /**
  * Field is the core class of the package.
@@ -137,6 +138,8 @@ final class Field {
 
     public int precision = -1;
 
+    public FunctionFactory functionFactory;
+
     public Field(FilteredType type, String name) {
         this.type = type;
         this.name = name;

src/jdk.jfr/share/classes/jdk/jfr/internal/query/Function.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2023, 2024, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2023, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -35,45 +35,49 @@
 
 abstract class Function {
 
+    interface FunctionFactory {
+        Function newFunction();
+    }
+
     public abstract void add(Object value);
 
     public abstract Object result();
 
-    public static Function create(Field field) {
+    public static FunctionFactory createFactory(Field field) {
         Aggregator aggregator = field.aggregator;
 
         if (field.grouper != null || aggregator == Aggregator.MISSING) {
-            return new FirstNonNull();
+            return () -> new FirstNonNull();
         }
         if (aggregator == Aggregator.LIST) {
-            return new Container(new ArrayList<>());
+            return () -> new Container(new ArrayList<>());
         }
 
         if (aggregator == Aggregator.SET) {
-            return new Container(new LinkedHashSet<>());
+            return () -> new Container(new LinkedHashSet<>());
         }
 
         if (aggregator == Aggregator.DIFFERENCE) {
             if (field.timestamp) {
-                return new TimeDifference();
+                return () -> new TimeDifference();
             } else {
-                return new Difference();
+                return () -> new Difference();
             }
         }
 
         if (aggregator == Aggregator.STANDARD_DEVIATION) {
             if (field.timespan) {
-                return new TimespanFunction(new StandardDeviation());
+                return () -> new TimespanFunction(new StandardDeviation());
             } else {
-                return new StandardDeviation();
+                return () -> new StandardDeviation();
             }
         }
 
         if (aggregator == Aggregator.MEDIAN) {
             if (field.timespan) {
-                return new TimespanFunction(new Median());
+                return () -> new TimespanFunction(new Median());
             } else {
-                return new Median();
+                return () -> new Median();
             }
         }
 
@@ -83,7 +87,6 @@ public static Function create(Field field) {
 
         if (aggregator == Aggregator.P95) {
             return createPercentile(field, 0.95);
-
         }
         if (aggregator == Aggregator.P99) {
             return createPercentile(field, 0.99);
@@ -92,46 +95,46 @@ public static Function create(Field field) {
             return createPercentile(field, 0.999);
         }
         if (aggregator == Aggregator.MAXIMUM) {
-            return new Maximum();
+            return () -> new Maximum();
         }
         if (aggregator == Aggregator.MINIMUM) {
-            return new Minimum();
+            return () -> new Minimum();
         }
         if (aggregator == Aggregator.SUM) {
             if (field.timespan) {
-                return new SumDuration();
+                return () -> new SumDuration();
             }
             if (field.fractionalType) {
-                return new SumDouble();
+                return () -> new SumDouble();
             }
             if (field.integralType) {
-                return new SumLong();
+                return () -> new SumLong();
             }
         }
 
         if (aggregator == Aggregator.FIRST) {
-            return new First();
+            return () -> new First();
         }
         if (aggregator == Aggregator.LAST_BATCH) {
-            return new LastBatch(field);
+            return () -> new LastBatch(field);
         }
         if (aggregator == Aggregator.LAST) {
-            return new Last();
+            return () -> new Last();
         }
         if (aggregator == Aggregator.AVERAGE) {
             if (field.timespan) {
-                return new AverageDuration();
+                return () -> new AverageDuration();
             } else {
-                return new Average();
+                return () -> new Average();
             }
         }
         if (aggregator == Aggregator.COUNT) {
-            return new Count();
+            return () -> new Count();
         }
         if (aggregator == Aggregator.UNIQUE) {
-            return new Unique();
+            return () -> new Unique();
         }
-        return new Null();
+        return () -> new Null();
     }
 
     // **** AVERAGE ****
@@ -507,12 +510,11 @@ public Object result() {
     }
 
     // **** PERCENTILE ****
-    private static Function createPercentile(Field field, double percentile) {
-        Percentile p = new Percentile(percentile);
+    private static FunctionFactory createPercentile(Field field, double percentile) {
         if (field.timespan) {
-            return new TimespanFunction(p);
+            return () -> new TimespanFunction(new Percentile(percentile));
         } else {
-            return p;
+            return () -> new Percentile(percentile);
         }
     }
 

src/jdk.jfr/share/classes/jdk/jfr/internal/query/Histogram.java

@@ -122,6 +122,9 @@ public boolean equals(Object object) {
 
     public void addFields(List<Field> fields) {
         this.fields.addAll(fields);
+        for (Field field : fields) {
+            field.functionFactory = Function.createFactory(field);
+        }
     }
 
     public void add(RecordedEvent e, FilteredType type, List<Field> sourceFields) {
@@ -168,7 +171,7 @@ public List<Row> toRows() {
     private Function[] createFunctions() {
         Function[] functions = new Function[fields.size()];
         for (int i = 0; i < functions.length; i++) {
-            functions[i] = Function.create(fields.get(i));
+            functions[i] = fields.get(i).functionFactory.newFunction();
         }
         return functions;
     }