Merge pull request #195 from maxmind/greg/net-9

Update targets

.github/workflows/codeql-analysis.yml

@@ -33,9 +33,8 @@ jobs:
       uses: actions/setup-dotnet@v4
       with:
         dotnet-version: |
-          6.0.x
-          7.0.x
           8.0.x
+          9.0.x
 
     # Initializes the CodeQL tools for scanning.
     - name: Initialize CodeQL

.github/workflows/test.yml

@@ -21,9 +21,8 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: |
-            6.0.x
-            7.0.x
             8.0.x
+            9.0.x
 
       - name: Build
         run: |

MaxMind.Db.Benchmark/MaxMind.Db.Benchmark.csproj

@@ -3,8 +3,8 @@
   <PropertyGroup>
     <Description>Benchmark project to validate .NET reader for the MaxMind DB file format</Description>
     <VersionPrefix>4.0.0</VersionPrefix>
-    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">net8.0;net7.0;net6.0;net472</TargetFrameworks>
-    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">net8.0;net7.0;net6.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">net9.0;net8.0;net481</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">net9.0;net8.0</TargetFrameworks>
     <AssemblyName>MaxMind.Db.Benchmark</AssemblyName>
     <OutputType>Exe</OutputType>
     <PackageId>MaxMind.Db.Benchmark</PackageId>
@@ -18,7 +18,7 @@
     <GenerateAssemblyCopyrightAttribute>false</GenerateAssemblyCopyrightAttribute>
     <GenerateAssemblyVersionAttribute>false</GenerateAssemblyVersionAttribute>
     <GenerateAssemblyFileVersionAttribute>false</GenerateAssemblyFileVersionAttribute>
-    <LangVersion>12.0</LangVersion>
+    <LangVersion>13.0</LangVersion>
     <Nullable>enable</Nullable>
     <AnalysisLevel>latest</AnalysisLevel>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>

MaxMind.Db.Test/MaxMind.Db.Test.csproj

@@ -3,8 +3,8 @@
   <PropertyGroup>
     <Description>Test project to validate .NET reader for the MaxMind DB file format</Description>
     <VersionPrefix>4.0.0</VersionPrefix>
-    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">net8.0;net7.0;net6.0;net472</TargetFrameworks>
-    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">net8.0;net7.0;net6.0</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' == 'Windows_NT' ">net9.0;net8.0;net481</TargetFrameworks>
+    <TargetFrameworks Condition=" '$(OS)' != 'Windows_NT' ">net9.0;net8.0</TargetFrameworks>
     <AssemblyName>MaxMind.Db.Test</AssemblyName>
     <AssemblyOriginatorKeyFile>../MaxMind.snk</AssemblyOriginatorKeyFile>
     <SignAssembly>true</SignAssembly>
@@ -21,7 +21,7 @@
     <GenerateAssemblyCopyrightAttribute>false</GenerateAssemblyCopyrightAttribute>
     <GenerateAssemblyVersionAttribute>false</GenerateAssemblyVersionAttribute>
     <GenerateAssemblyFileVersionAttribute>false</GenerateAssemblyFileVersionAttribute>
-    <LangVersion>12.0</LangVersion>
+    <LangVersion>13.0</LangVersion>
     <Nullable>enable</Nullable>
     <AnalysisLevel>latest</AnalysisLevel>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
@@ -34,7 +34,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="FluentAssertions" Version="6.12.2" />
     <PackageReference Include="xunit" Version="2.9.2" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.8.2">

MaxMind.Db.Test/ReaderTest.cs

@@ -480,7 +480,7 @@ private static void TestIPV6(Reader reader, string file)
         {
             TestAddresses(reader,
                 file,
-                new[] { "::1:ffff:ffff", "::2:0:0", "::2:0:40", "::2:0:50", "::2:0:58" },
+                ["::1:ffff:ffff", "::2:0:0", "::2:0:40", "::2:0:50", "::2:0:58"],
                 new Dictionary<string, string>
                 {
                     {"::2:0:1", "::2:0:0"},
@@ -492,7 +492,7 @@ private static void TestIPV6(Reader reader, string file)
                     {"::2:0:57", "::2:0:50"},
                     {"::2:0:59", "::2:0:58"}
                 },
-                new[] { "1.1.1.33", "255.254.253.123", "89fa::" },
+                ["1.1.1.33", "255.254.253.123", "89fa::"],
                 new Dictionary<string, int>
                 {
                     {"::2:0:1", 122}
@@ -514,7 +514,7 @@ private static void TestIPV4(Reader reader, string file)
                     {"1.1.1.17", "1.1.1.16"},
                     {"1.1.1.31", "1.1.1.16"}
                 },
-                new[] { "1.1.1.33", "255.254.253.123" },
+                ["1.1.1.33", "255.254.253.123"],
                 new Dictionary<string, int>
                 {
                     {"1.1.1.3", 31},

MaxMind.Db/CachedDictionary.cs

@@ -21,16 +21,6 @@ limitations under the License.
 
 namespace MaxMind.Db
 {
-    /// <summary>
-    /// Delegate that can be used to be notified when an item is removed from a CachedDictionary because the size was too big
-    /// </summary>
-    /// <typeparam name="TKey">Type of key</typeparam>
-    /// <typeparam name="TValue">Type of value</typeparam>
-    /// <param name="dictionary">Dictionary</param>
-    /// <param name="key">Key</param>
-    /// <param name="value">Value</param>
-    internal delegate void CachedItemRemovedDelegate<TKey, TValue>(CachedDictionary<TKey, TValue> dictionary, TKey key, TValue value);
-
     /// <summary>
     /// A dictionary that caches up to N values in memory. Once the dictionary reaches N count, the last item in the internal list is removed.
     /// New items are always added to the start of the internal list.
@@ -95,10 +85,10 @@ protected virtual bool OnGetExternalKeyValue(ref TKey key, out TValue value)
         /// Sets a new comparer. Clears the cache.
         /// </summary>
         /// <param name="comparer">New comparer</param>
-        protected void SetComparer(IEqualityComparer<TKey> comparer)
+        private void SetComparer(IEqualityComparer<TKey> comparer)
         {
             dictionary = new Dictionary<TKey, LinkedListNode<KeyValuePair<TKey, TValue>>>(comparer);
-            priorityList = new LinkedList<KeyValuePair<TKey, TValue>>();
+            priorityList = [];
         }
 
         /// <summary>
@@ -126,10 +116,7 @@ public CachedDictionary(int maxCount, IEqualityComparer<TKey> comparer)
             {
                 throw new ArgumentOutOfRangeException("Maxcount is " + maxCount + ", it must be greater than 0");
             }
-            if (comparer == null)
-            {
-                comparer = EqualityComparer<TKey>.Default;
-            }
+            comparer ??= EqualityComparer<TKey>.Default;
             this.maxCount = maxCount;
             SetComparer(comparer);
         }
@@ -210,7 +197,7 @@ public bool TryGetValue(TKey key, out TValue value)
         /// <param name="key">Key to find (receives the found key)</param>
         /// <param name="value">Found value (default of TValue if not found)</param>
         /// <returns>True if found, false if not</returns>
-        public bool TryGetValueRef(ref TKey key, out TValue value)
+        private bool TryGetValueRef(ref TKey key, out TValue value)
         {
             if (dictionary.TryGetValue(key, out var node))
             {

MaxMind.Db/Decoder.cs

@@ -513,7 +513,7 @@ private object DecodeArray(Type expectedType, int size, long offset, out long ou
             for (var i = 0; i < size; i++)
             {
                 var r = Decode(argType, offset, out offset, injectables, network);
-                addMethod.Invoke(array, new[] { r });
+                addMethod.Invoke(array, [r]);
             }
 
             outOffset = offset;

MaxMind.Db/DictionaryActivatorCreator.cs

@@ -32,7 +32,7 @@ private static ObjectActivator DictionaryActivator(Type expectedType)
             {
                 var dictType = typeof(Dictionary<,>).MakeGenericType(genericArgs);
                 ReflectionUtil.CheckType(expectedType, dictType);
-                constructor = dictType.GetConstructor(new[] { typeof(int) });
+                constructor = dictType.GetConstructor([typeof(int)]);
             }
             else
             {

MaxMind.Db/ListActivatorCreator.cs

@@ -32,7 +32,7 @@ private static ObjectActivator ListActivator(Type expectedType)
             var listType = typeof(List<>).MakeGenericType(argType);
             if (expectedType.IsAssignableFrom(listType))
             {
-                constructor = listType.GetConstructor(new[] { typeof(int) });
+                constructor = listType.GetConstructor([typeof(int)]);
             }
             else
             {

MaxMind.Db/MaxMind.Db.csproj

@@ -3,7 +3,7 @@
   <PropertyGroup>
     <Description>.NET reader for the MaxMind DB file format</Description>
     <VersionPrefix>4.1.0</VersionPrefix>
-    <TargetFrameworks>net8.0;net7.0;net6.0;netstandard2.1;netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>net9.0;net8.0;netstandard2.1;netstandard2.0</TargetFrameworks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyName>MaxMind.Db</AssemblyName>
     <AssemblyOriginatorKeyFile>../MaxMind.snk</AssemblyOriginatorKeyFile>
@@ -26,7 +26,7 @@
     <GenerateAssemblyCopyrightAttribute>false</GenerateAssemblyCopyrightAttribute>
     <GenerateAssemblyVersionAttribute>false</GenerateAssemblyVersionAttribute>
     <GenerateAssemblyFileVersionAttribute>false</GenerateAssemblyFileVersionAttribute>
-    <LangVersion>12.0</LangVersion>
+    <LangVersion>13.0</LangVersion>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <Nullable>enable</Nullable>
     <AnalysisLevel>latest</AnalysisLevel>

MaxMind.Db/MemoryMapBuffer.cs

@@ -3,15 +3,16 @@
 using System;
 using System.IO;
 using System.IO.MemoryMappedFiles;
+using System.Security.Cryptography;
 using System.Text;
+using System.Threading;
 
 #endregion
 
 namespace MaxMind.Db
 {
     internal sealed class MemoryMapBuffer : Buffer
     {
-        private static readonly object FileLocker = new();
         private readonly MemoryMappedFile _memoryMappedFile;
         private readonly MemoryMappedViewAccessor _view;
         private bool _disposed;
@@ -29,14 +30,30 @@ private MemoryMapBuffer(string file, bool useGlobalNamespace, FileInfo fileInfo)
             // easily available from C#.
             var objectNamespace = useGlobalNamespace ? "Global" : "Local";
 
-            string? mapName = $"{objectNamespace}\\{fileInfo.FullName.Replace("\\", "-")}-{Length}";
-            lock (FileLocker)
+            // We create a sha256 here as there are limitations on mutex names.
+            using var sha256 = SHA256.Create();
+            var suffixTxt = $"{fileInfo.FullName.Replace("\\", "-")}-{Length}";
+            var hashBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(suffixTxt));
+            var suffix = BitConverter.ToString(hashBytes).Replace("-", "");
+
+            var mapName = $"{objectNamespace}\\{suffix}";
+            var mutexName = $"{mapName}-Mutex";
+
+            using (var mutex = new Mutex(false, mutexName))
             {
+                var hasHandle = false;
+
                 try
                 {
+                    hasHandle = mutex.WaitOne(TimeSpan.FromSeconds(10), false);
+                    if (!hasHandle)
+                    {
+                        throw new TimeoutException("Timeout waiting for mutex.");
+                    }
+
                     _memoryMappedFile = MemoryMappedFile.OpenExisting(mapName, MemoryMappedFileRights.Read);
                 }
-                catch (Exception ex) when (ex is IOException || ex is NotImplementedException || ex is PlatformNotSupportedException)
+                catch (Exception ex) when (ex is IOException or NotImplementedException or PlatformNotSupportedException)
                 {
                     // In .NET Core, named maps are not supported for Unices yet: https://github.com/dotnet/corefx/issues/1329
                     // When executed on unsupported platform, we get the PNSE. In which case, we consruct the memory map by
@@ -47,6 +64,13 @@ private MemoryMapBuffer(string file, bool useGlobalNamespace, FileInfo fileInfo)
                     _memoryMappedFile = MemoryMappedFile.CreateFromFile(stream, mapName, Length,
                             MemoryMappedFileAccess.Read, HandleInheritability.None, false);
                 }
+                finally
+                {
+                    if (hasHandle)
+                    {
+                        mutex.ReleaseMutex();
+                    }
+                }
             }
 
             _view = _memoryMappedFile.CreateViewAccessor(0, Length, MemoryMappedFileAccess.Read);
@@ -77,7 +101,7 @@ public override string ReadString(long offset, int count)
             }
             unsafe
             {
-                byte* ptr = (byte*)0;
+                var ptr = (byte*)0;
                 try
                 {
                     _view.SafeMemoryMappedViewHandle.AcquirePointer(ref ptr);

MaxMind.Db/Reader.cs

@@ -89,18 +89,17 @@ private struct NetNode
         private readonly long _nodeByteSize;
         private readonly long _nodeCount;
         private readonly int _recordSize;
-        private readonly long _searchTreeSize;
 
         // The property getter was a hotspot during profiling.
 
         private readonly byte[] _metadataStartMarker =
-        {
+        [
             0xAB, 0xCD, 0xEF, 77, 97, 120, 77, 105, 110, 100, 46, 99, 111,
             109
-        };
+        ];
 
         private bool _disposed;
-        private int _ipV4Start;
+        private readonly int _ipV4Start;
 
         /// <summary>
         ///     Initializes a new instance of the <see cref="Reader" /> class.
@@ -144,10 +143,9 @@ private Reader(Buffer buffer, string? file)
             _nodeByteSize = Metadata.NodeByteSize;
             _nodeCount = Metadata.NodeCount;
             _recordSize = Metadata.RecordSize;
-            _searchTreeSize = Metadata.SearchTreeSize;
             Decoder = new Decoder(_database, Metadata.SearchTreeSize + DataSectionSeparatorSize);
 
-            if (_dbIPVersion ==6)
+            if (_dbIPVersion == 6)
             {
                 var node = 0;
                 for (var i = 0; i < 96 && node < _nodeCount; i++)
@@ -379,7 +377,7 @@ private long FindMetadataStart()
 
             for (var i = dbLength - markerLength; i > 0; i--)
             {
-                int j = 0;
+                var j = 0;
                 for (; j < markerLength; j++)
                 {
                     if (_metadataStartMarker[j] != _database.ReadOne(i + j))

MaxMind.Db/TypeAcivatorCreator.cs

@@ -11,15 +11,14 @@
 
 namespace MaxMind.Db
 {
-    internal struct TypeActivator
+    internal readonly struct TypeActivator
     {
         internal readonly ObjectActivator Activator;
         internal readonly List<ParameterInfo> AlwaysCreatedParameters;
-        internal readonly object?[] _defaultParameters;
+        private readonly object?[] _defaultParameters;
         internal readonly Dictionary<Key, ParameterInfo> DeserializationParameters;
         internal readonly Dictionary<string, ParameterInfo> InjectableParameters;
         internal readonly List<ParameterInfo> NetworkParameters;
-        internal readonly Type[] ParameterTypes;
 
         internal TypeActivator(
             ObjectActivator activator,
@@ -35,9 +34,8 @@ List<ParameterInfo> alwaysCreatedParameters
             InjectableParameters = injectables;
 
             NetworkParameters = networkParameters;
-            ParameterTypes =
-                deserializationParameters.Values.OrderBy(x => x.Position).Select(x => x.ParameterType).ToArray();
-            _defaultParameters = ParameterTypes.Select(DefaultValue).ToArray();
+            Type[] parameterTypes = deserializationParameters.Values.OrderBy(x => x.Position).Select(x => x.ParameterType).ToArray();
+            _defaultParameters = parameterTypes.Select(DefaultValue).ToArray();
         }
 
         internal object[] DefaultParameters() => (object[])_defaultParameters.Clone();

releasenotes.md

@@ -1,5 +1,16 @@
 # Release Notes #
 
+## 4.2.0
+
+* .NET 6.0 and .NET 7.0 have been removed as targets as they have both
+  reach their end of support from Microsoft. If you are using these versions,
+  the .NET Standard 2.1 target should continue working for you.
+* .NET 9.0 has been added as a target.
+* We now use a mutex rather than a lock statement when opening the
+  database. This is done to reduce the likelihood of a race condition
+  when process are opening a single database when using
+  `FileAccessMode.MemoryMappedGlobal`.
+
 ## 4.1.0 (2023-12-05) ##
 
 * .NET 5.0 has been removed as a target as it has reach its end of life.