Fix off-by-one error in in-memory datom storage

Nexus-Mods · Jun 10, 2024 · 2577407 · 2577407
1 parent a0fae78
commit 2577407
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Showing 5 changed files with 35 additions and 25 deletions.
diff --git a/src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs b/src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs
diff --git a/src/NexusMods.MnemonicDB.Storage/InMemoryBackend/Snapshot.cs b/src/NexusMods.MnemonicDB.Storage/InMemoryBackend/Snapshot.cs
@@ -30,42 +30,52 @@ public IndexSegment Datoms(SliceDescriptor descriptor)
 
         var idxLower = thisIndex.IndexOf(descriptor.From.RawSpan.ToArray());
         var idxUpper = thisIndex.IndexOf(descriptor.To.RawSpan.ToArray());
+        bool upperExact = true;
+        bool lowerExact = true;
 
         if (idxLower < 0)
+        {
             idxLower = ~idxLower;
+            lowerExact = false;
+        }
 
         if (idxUpper < 0)
+        {
             idxUpper = ~idxUpper;
+            upperExact = false;
+        }
 
         var lower = idxLower;
         var upper = idxUpper;
-        var reverse = false;
 
-        if (idxLower > idxUpper)
+        if (descriptor.IsReverse)
         {
             lower = idxUpper;
             upper = idxLower;
-            reverse = true;
+            (lowerExact, upperExact) = (upperExact, lowerExact);
         }
 
         using var segmentBuilder = new IndexSegmentBuilder(_registry);
 
-        if (!reverse)
+        if (descriptor.IsReverse)
         {
-            for (var i = lower; i <= upper; i++)
+            if (!lowerExact)
+                lower++;
+            for (var i = upper; i >= lower; i--)
             {
-                if (i >= thisIndex.Count)
-                    break;
                 segmentBuilder.Add(thisIndex.ElementAt(i));
             }
         }
         else
         {
-            for (var i = upper; i >= lower; i--)
+            if (!upperExact)
+                upper--;
+            for (var i = lower; i <= upper; i++)
             {
                 segmentBuilder.Add(thisIndex.ElementAt(i));
             }
         }
+
         return segmentBuilder.Build();
     }
 

diff --git a/tests/NexusMods.MnemonicDB.Storage.Tests/ABackendTest.cs b/tests/NexusMods.MnemonicDB.Storage.Tests/ABackendTest.cs
@@ -252,4 +252,15 @@ await Verify(datoms.ToTable(Registry))
             .UseDirectory("BackendTestVerifyData")
             .UseParameters(type);
     }
+
+
+    [Fact]
+    public async Task CanLoadExistingAttributes()
+    {
+        var attrs = DatomStore.GetSnapshot().Datoms(SliceDescriptor.Create(BuiltInAttributes.UniqueId, Registry))
+            .Select(d => d.Resolved)
+            .ToArray();
+
+        await Verify(attrs.ToTable(Registry));
+    }
 }
diff --git a/...s/NexusMods.MnemonicDB.Storage.Tests/InMemoryTests.CanLoadExistingAttributes.verified.txt b/...s/NexusMods.MnemonicDB.Storage.Tests/InMemoryTests.CanLoadExistingAttributes.verified.txt
@@ -0,0 +1,3 @@
++ | 0000000000000001 | (0001) UniqueId                 | NexusMods.MnemonicDB.DatomStore/UniqueId         | 0100000000000001
++ | 0000000000000002 | (0001) UniqueId                 | NexusMods.MnemonicDB.DatomStore/ValueType        | 0100000000000001
++ | 0000000000000003 | (0001) UniqueId                 | NexusMods.MnemonicDB.Transaction/Timestamp       | 0100000000000001
diff --git a/tests/NexusMods.MnemonicDB.Storage.Tests/RocksDB.CanLoadExistingAttributes.verified.txt b/tests/NexusMods.MnemonicDB.Storage.Tests/RocksDB.CanLoadExistingAttributes.verified.txt
@@ -0,0 +1,3 @@
++ | 0000000000000001 | (0001) UniqueId                 | NexusMods.MnemonicDB.DatomStore/UniqueId         | 0100000000000001
++ | 0000000000000002 | (0001) UniqueId                 | NexusMods.MnemonicDB.DatomStore/ValueType        | 0100000000000001
++ | 0000000000000003 | (0001) UniqueId                 | NexusMods.MnemonicDB.Transaction/Timestamp       | 0100000000000001