dotnet 9 and sequential id

2025-08-01 22:21:42 +04:00
parent 2b68ba982d
commit 3665abaab8
14 changed files with 428 additions and 68 deletions
--- a/Core.Tests/SeqIdTests/NextId.cs
+++ b/Core.Tests/SeqIdTests/NextId.cs
@@ -0,0 +1,140 @@
+namespace Just.Core.Tests.SeqIdTests;
+
+public class NextId
+{
+    private static readonly DateTime TestEpoch = new(2025, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+    private readonly SeqId _seqId = new(TestEpoch);
+
+    private const int TimestampShift = 22; // 63 - 41 = 22
+    private const long TimestampMask = 0x1FFFFFFFFFF; // 41 bits mask
+    private const int SeqShift = 14; // TimestampShift - 8 = 14
+    private const long SeqMask = 0xFF; // 8 bits mask
+    private const long RandMask = 0x3FFF; // 14 bits mask (since 2^14 = 16384)
+
+    [Fact]
+    public void NextId_ShouldHaveCorrectBitStructure()
+    {
+        // Arrange
+        var time = TestEpoch.AddMilliseconds(500);
+
+        // Act
+        long id = _seqId.Next(time);
+
+        // Assert
+        long timestampPart = (id >> TimestampShift) & TimestampMask;
+        long sequencePart = (id >> SeqShift) & SeqMask;
+        long randomPart = id & RandMask;
+
+        timestampPart.Should().Be(500);
+        sequencePart.Should().Be(0);
+        randomPart.Should().BeInRange(0, RandMask);
+    }
+
+    [Fact]
+    public void NextId_ShouldIncrementSequenceForSameTimestamp()
+    {
+        // Arrange
+        var time = TestEpoch.AddMilliseconds(100);
+
+        // Act
+        long id1 = _seqId.Next(time);
+        long id2 = _seqId.Next(time);
+
+        // Assert
+        long sequence1 = (id1 >> SeqShift) & SeqMask;
+        long sequence2 = (id2 >> SeqShift) & SeqMask;
+
+        sequence2.Should().Be(sequence1 + 1);
+    }
+
+    [Fact]
+    public void NextId_ShouldResetSequenceForNewTimestamp()
+    {
+        // Arrange
+        var time1 = TestEpoch.AddMilliseconds(100);
+        var time2 = time1.AddMilliseconds(1);
+
+        // Act
+        _ = _seqId.Next(time1); // Sequence increments to 0
+        _ = _seqId.Next(time1); // Sequence increments to 1
+        long id = _seqId.Next(time2); // Should reset to 0
+
+        // Assert
+        long sequence = (id >> SeqShift) & SeqMask;
+        sequence.Should().Be(0);
+    }
+
+    [Fact]
+    public void NextId_ShouldThrowWhenTimestampDecreases()
+    {
+        // Arrange
+        var time1 = TestEpoch.AddMilliseconds(200);
+        var time2 = TestEpoch.AddMilliseconds(100);
+
+        // Act & Assert
+        _seqId.Next(time1); // First call sets last timestamp
+        Action act = () => _seqId.Next(time2);
+        act.Should().Throw<InvalidOperationException>()
+            .WithMessage("Refused to create new SeqId. Last timestamp is in the future.");
+    }
+
+    [Fact]
+    public void NextId_ShouldThrowWhenSequenceExhausted()
+    {
+        // Arrange
+        var time = TestEpoch.AddMilliseconds(200);
+
+        // Act & Assert
+        for (int i = 0; i < 255; i++)
+        {
+            _seqId.Next(time); // Exhauste sequence
+        }
+        Action act = () => _seqId.Next(time);
+        act.Should().Throw<IndexOutOfRangeException>()
+            .WithMessage("Refused to create new SeqId. Sequence exhausted.");
+    }
+
+    [Fact]
+    public void NextId_WithStrongEntropy_ShouldSetLower14Bits()
+    {
+        // Arrange
+        var time = TestEpoch.AddMilliseconds(300);
+
+        // Act
+        long id = _seqId.Next(time, RngEntropy.Strong);
+
+        // Assert
+        long randomPart = id & RandMask;
+        randomPart.Should().BeInRange(0, RandMask);
+    }
+
+    [Fact]
+    public void NextId_WithWeakEntropy_ShouldSetLower14Bits()
+    {
+        // Arrange
+        var time = TestEpoch.AddMilliseconds(400);
+
+        // Act
+        long id = _seqId.Next(time, RngEntropy.Weak);
+
+        // Assert
+        long randomPart = id & RandMask;
+        randomPart.Should().BeInRange(0, RandMask);
+    }
+
+    [Fact]
+    public void DefaultInstance_NextId_ShouldUseDefaultEpoch()
+    {
+        // Arrange
+        var now = DateTime.UtcNow;
+        var defaultEpoch = new DateTime(2025, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+        long expectedTimestamp = (long)(now - defaultEpoch).TotalMilliseconds;
+
+        // Act
+        long id = SeqId.NextId();
+
+        // Assert
+        long timestampPart = (id >> TimestampShift) & TimestampMask;
+        timestampPart.Should().BeCloseTo(expectedTimestamp & TimestampMask, 1); // Mask handles overflow
+    }
+}