Fix unbounded memory growth in DoubleArrayConverter (#6412)

* Fix unbounded memory growth in DoubleArrayConverter * Whitespace
NethermindEth · Dec 22, 2023 · aa6800c · aa6800c
1 parent bb1840f
commit aa6800c
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Showing 2 changed files with 34 additions and 7 deletions.
diff --git a/src/Nethermind/Nethermind.Core.Test/Json/DoubleArrayConverterTests.cs b/src/Nethermind/Nethermind.Core.Test/Json/DoubleArrayConverterTests.cs
@@ -0,0 +1,25 @@
+// SPDX-FileCopyrightText: 2023 Demerzel Solutions Limited
+// SPDX-License-Identifier: LGPL-3.0-only
+
+using System;
+using System.Text.Json;
+using Nethermind.Serialization.Json;
+
+using NUnit.Framework;
+
+namespace Nethermind.Core.Test.Json;
+
+[TestFixture]
+public class DoubleArrayConverterTests : ConverterTestBase<double[]>
+{
+    static readonly DoubleArrayConverter converter = new();
+
+    [Test]
+    public void Test_roundtrip()
+    {
+        TestConverter(new double[] { -0.5, 0.5, 1.0, 1.5, 2.0, 2.5 }, (a, b) => a.AsSpan().SequenceEqual(b), converter);
+        TestConverter(new double[] { 1, 1, 1, 1 }, (a, b) => a.AsSpan().SequenceEqual(b), converter);
+        TestConverter(new double[] { 0, 0, 0, 0 }, (a, b) => a.AsSpan().SequenceEqual(b), converter);
+        TestConverter(Array.Empty<double>(), (a, b) => a.AsSpan().SequenceEqual(b), converter);
+    }
+}
diff --git a/src/Nethermind/Nethermind.Serialization.Json/DoubleConverter.cs b/src/Nethermind/Nethermind.Serialization.Json/DoubleConverter.cs
@@ -5,7 +5,7 @@
 
 namespace Nethermind.Serialization.Json
 {
-    using System.Collections.Generic;
+    using Nethermind.Core.Collections;
     using System.Runtime.CompilerServices;
     using System.Text.Json;
     using System.Text.Json.Serialization;
@@ -47,19 +47,21 @@ public class DoubleArrayConverter : JsonConverter<double[]>
             {
                 throw new JsonException();
             }
-            List<double> values = null;
-            reader.Read();
-            while (reader.TokenType == JsonTokenType.Number)
+            using ArrayPoolList<double> values = new ArrayPoolList<double>(16);
+            while (reader.Read() && reader.TokenType == JsonTokenType.Number)
             {
-                values ??= new List<double>();
                 values.Add(reader.GetDouble());
             }
             if (reader.TokenType != JsonTokenType.EndArray)
             {
                 throw new JsonException();
             }
-            reader.Read();
-            return values?.ToArray() ?? Array.Empty<double>();
+
+            if (values.Count == 0) return Array.Empty<double>();
+
+            double[] result = new double[values.Count];
+            values.CopyTo(result, 0);
+            return result;
         }
 
         [SkipLocalsInit]