Use DateTimeOffset and TimeProvider

src/NexusMods.MnemonicDB.Abstractions/Attributes/TimestampAttribute.cs

@@ -7,11 +7,11 @@ namespace NexusMods.MnemonicDB.Abstractions.Attributes;
 /// <summary>
 /// An attribute that holds a timestamp
 /// </summary>
-public class TimestampAttribute(string ns, string name) : ScalarAttribute<DateTime, long>(ValueTag.Int64, ns, name)
+public class TimestampAttribute(string ns, string name) : ScalarAttribute<DateTimeOffset, long>(ValueTag.Int64, ns, name)
 {
     /// <inheritdoc />
-    protected override long ToLowLevel(DateTime value) => value.ToFileTimeUtc();
+    protected override long ToLowLevel(DateTimeOffset value) => value.ToUnixTimeMilliseconds();
 
     /// <inheritdoc />
-    protected override DateTime FromLowLevel(long value, AttributeResolver resolver) => DateTime.FromFileTimeUtc(value);
+    protected override DateTimeOffset FromLowLevel(long value, AttributeResolver resolver) => DateTimeOffset.FromUnixTimeMilliseconds(value);
 }

src/NexusMods.MnemonicDB/Caching/IndexSegmentCache.cs

@@ -63,18 +63,25 @@ public struct CacheValue : IEquatable<CacheValue>
     public long LastAccessed;
     public readonly IndexSegment Segment;
 
-    public CacheValue(long lastAccessed, IndexSegment segment)
+    public CacheValue(IndexSegment segment)
     {
-        LastAccessed = lastAccessed;
+        LastAccessed = CreateLastAccessed();
         Segment = segment;
     }
 
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    private static long CreateLastAccessed(TimeProvider? timeProvider = null)
+    {
+        timeProvider ??= TimeProvider.System;
+        return timeProvider.GetTimestamp();
+    }
+
     /// <summary>
     /// Update the last accessed time to now.
     /// </summary>
     public void Hit()
     {
-        LastAccessed = DateTime.UtcNow.Ticks;
+        LastAccessed = CreateLastAccessed();
     }
 
     /// <inheritdoc />
@@ -133,7 +140,7 @@ public bool TryGetValue(CacheKey key, out IndexSegment segment)
     /// </summary>
     public CacheRoot With(CacheKey key, IndexSegment segment, IndexSegmentCache cache)
     {
-        var newEntries = _entries.SetItem(key, new CacheValue(DateTime.UtcNow.Ticks, segment));
+        var newEntries = _entries.SetItem(key, new CacheValue(segment));
         if (newEntries.Count > cache._entryCapacity)
         {
             newEntries = PurgeEntries(newEntries, newEntries.Count / 10);

src/NexusMods.MnemonicDB/Storage/DatomStore.cs

@@ -3,6 +3,7 @@
 using System.Collections.Frozen;
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Runtime.InteropServices;
 using System.Threading;
@@ -72,20 +73,28 @@ public sealed partial class DatomStore : IDatomStore
     /// </summary>
     private Thread? _loggerThread;
 
-    private CancellationTokenSource _shutdownToken = new();
+    private readonly CancellationTokenSource _shutdownToken = new();
     private TxId _thisTx;
 
     /// <summary>
     /// Scratch spaced to create new datoms while processing transactions
     /// </summary>
     private readonly Memory<byte> _txScratchSpace;
 
+    private readonly TimeProvider _timeProvider;
+
     /// <summary>
     /// DI constructor
     /// </summary>
-    public DatomStore(ILogger<DatomStore> logger, DatomStoreSettings settings, IStoreBackend backend, bool bootstrap = true)
+    public DatomStore(
+        ILogger<DatomStore> logger,
+        DatomStoreSettings settings,
+        IStoreBackend backend,
+        TimeProvider? timeProvider = null,
+        bool bootstrap = true)
     {
         CurrentSnapshot = default!;
+        _timeProvider = timeProvider ?? TimeProvider.System;
         _txScratchSpace = new Memory<byte>(new byte[1024]);
         _remapFunc = Remap;
         _dbStream = new DbStream();
@@ -97,10 +106,9 @@ public DatomStore(ILogger<DatomStore> logger, DatomStoreSettings settings, IStor
         _retractWriter = new PooledMemoryBufferWriter();
         _prevWriter = new PooledMemoryBufferWriter();
 
-
         Logger = logger;
         _settings = settings;
-        
+
         Backend.DeclareEAVT(IndexType.EAVTCurrent);
         Backend.DeclareEAVT(IndexType.EAVTHistory);
         Backend.DeclareAEVT(IndexType.AEVTCurrent);
@@ -123,8 +131,7 @@ public DatomStore(ILogger<DatomStore> logger, DatomStoreSettings settings, IStor
         AVETCurrent = Backend.GetIndex(IndexType.AVETCurrent);
         AVETHistory = Backend.GetIndex(IndexType.AVETHistory);
 
-        if (bootstrap) 
-            Bootstrap();
+        if (bootstrap) Bootstrap();
     }
 
     /// <inheritdoc />
@@ -411,7 +418,7 @@ internal void LogDatoms<TSource>(IWriteBatch batch, TSource datoms,  bool advanc
     /// <exception cref="NotImplementedException"></exception>
     private void LogTx(IWriteBatch batch)
     {
-        MemoryMarshal.Write(_txScratchSpace.Span, DateTime.UtcNow.ToFileTimeUtc());
+        MemoryMarshal.Write(_txScratchSpace.Span, _timeProvider.GetTimestamp());
         var id = EntityId.From(_thisTx.Value);
         var keyPrefix = new KeyPrefix(id, AttributeCache.GetAttributeId(MnemonicDB.Abstractions.BuiltInEntities.Transaction.Timestamp.Id), _thisTx, false, ValueTag.Int64);
         var datom = new Datom(keyPrefix, _txScratchSpace[..sizeof(long)]);

tests/NexusMods.MnemonicDB.Tests/AMnemonicDBTest.cs

@@ -128,7 +128,7 @@ string TruncateOrPad(string val, int length)
                     var hash = code.ToString("X16");
                     sb.Append($"Blob 0x{hash} {byteArray.Length} bytes".PadRight(48));
                     break;
-                case DateTime dateTime:
+                case DateTimeOffset:
                     sb.Append($"DateTime : {dateTimeCount++}".PadRight(48));
                     break;
                 default: