From 25774078f4714b232004c303f66ca12a4e8820c6 Mon Sep 17 00:00:00 2001
From: halgari <tbaldridge@gmail.com>
Date: Mon, 10 Jun 2024 17:19:42 -0600
Subject: [PATCH] Fix off-by-one error in in-memory datom storage

---
 .../DynamicCache.cs                           | 17 ------------
 .../InMemoryBackend/Snapshot.cs               | 26 +++++++++++++------
 .../ABackendTest.cs                           | 11 ++++++++
 ...sts.CanLoadExistingAttributes.verified.txt |  3 +++
 ...sDB.CanLoadExistingAttributes.verified.txt |  3 +++
 5 files changed, 35 insertions(+), 25 deletions(-)
 delete mode 100644 src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs
 create mode 100644 tests/NexusMods.MnemonicDB.Storage.Tests/InMemoryTests.CanLoadExistingAttributes.verified.txt
 create mode 100644 tests/NexusMods.MnemonicDB.Storage.Tests/RocksDB.CanLoadExistingAttributes.verified.txt

diff --git a/src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs b/src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs
deleted file mode 100644
index 9d96af5d..00000000
--- a/src/NexusMods.MnemonicDB.Abstractions/DynamicCache.cs
+++ /dev/null
@@ -1,17 +0,0 @@
-using System;
-using System.Collections.Concurrent;
-using System.Linq;
-using System.Reactive.Linq;
-using System.Reactive.Subjects;
-using DynamicData;
-using NexusMods.MnemonicDB.Abstractions.Models;
-
-namespace NexusMods.MnemonicDB.Abstractions;
-
-public class DynamicCache : IDynamicCache
-{
-    public IObservable<IChangeSet<Attribute<THighLevel, TLowLevel>.ReadDatom, EntityId>> Query<TModel, THighLevel, TLowLevel>(Attribute<THighLevel, TLowLevel> attr, THighLevel value)
-    {
-        throw new NotImplementedException();
-    }
-}
diff --git a/src/NexusMods.MnemonicDB.Storage/InMemoryBackend/Snapshot.cs b/src/NexusMods.MnemonicDB.Storage/InMemoryBackend/Snapshot.cs
index 65ff8fd2..5797b376 100644
--- 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
index d7ccb7f3..ce03d8f7 100644
--- 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/tests/NexusMods.MnemonicDB.Storage.Tests/InMemoryTests.CanLoadExistingAttributes.verified.txt b/tests/NexusMods.MnemonicDB.Storage.Tests/InMemoryTests.CanLoadExistingAttributes.verified.txt
new file mode 100644
index 00000000..db4922fd
--- /dev/null
+++ b/tests/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
new file mode 100644
index 00000000..db4922fd
--- /dev/null
+++ 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