Add objectType to GitPackCache's key

src/NerdBank.GitVersioning/ManagedGit/GitPack.cs

@@ -178,7 +178,7 @@ public Stream GetObject(long offset, string objectType)
         }
 #endif
 
-        if (this.cache.TryOpen(offset, out Stream? stream))
+        if (this.cache.TryOpen(offset, objectType, out Stream? stream))
         {
             return stream!;
         }
@@ -216,7 +216,7 @@ public Stream GetObject(long offset, string objectType)
             throw;
         }
 
-        return this.cache.Add(offset, objectStream);
+        return this.cache.Add(offset, objectType, objectStream);
     }
 
     /// <summary>

src/NerdBank.GitVersioning/ManagedGit/GitPackCache.cs

@@ -22,14 +22,15 @@ public abstract class GitPackCache : IDisposable
     /// <param name="offset">
     /// The offset of the Git object in the Git pack.
     /// </param>
+    /// <param name="objectType">The object type of the object to retrieve.</param>
     /// <param name="stream">
     /// A <see cref="Stream"/> which will be set to the cached Git object.
     /// </param>
     /// <returns>
     /// <see langword="true"/> if the object was found in cache; otherwise,
     /// <see langword="false"/>.
     /// </returns>
-    public abstract bool TryOpen(long offset, [NotNullWhen(true)] out Stream? stream);
+    public abstract bool TryOpen(long offset, string objectType, [NotNullWhen(true)] out Stream? stream);
 
     /// <summary>
     /// Gets statistics about the cache usage.
@@ -45,14 +46,15 @@ public abstract class GitPackCache : IDisposable
     /// <param name="offset">
     /// The offset of the Git object in the Git pack.
     /// </param>
+    /// <param name="objectType">The object type of the object to add to the cache.</param>
     /// <param name="stream">
     /// A <see cref="Stream"/> which represents the object to add. This stream
     /// will be copied to the cache.
     /// </param>
     /// <returns>
     /// A <see cref="Stream"/> which represents the cached entry.
     /// </returns>
-    public abstract Stream Add(long offset, Stream stream);
+    public abstract Stream Add(long offset, string objectType, Stream stream);
 
     /// <inheritdoc/>
     public void Dispose()

src/NerdBank.GitVersioning/ManagedGit/GitPackMemoryCache.cs

@@ -21,27 +21,27 @@ namespace Nerdbank.GitVersioning.ManagedGit;
 ///   twice, it is read from the <see cref="MemoryStream"/>, rather than the underlying <see cref="Stream"/>.
 /// </para>
 /// <para>
-///   <see cref="Add(long, Stream)"/> and <see cref="TryOpen(long, out Stream?)"/> return <see cref="Stream"/>
+///   <see cref="Add(long, string, Stream)"/> and <see cref="TryOpen(long, string, out Stream?)"/> return <see cref="Stream"/>
 ///   objects which may operate on the same underlying <see cref="Stream"/>, but independently maintain
 ///   their state.
 /// </para>
 /// </summary>
 public class GitPackMemoryCache : GitPackCache
 {
-    private readonly Dictionary<long, GitPackMemoryCacheStream> cache = new Dictionary<long, GitPackMemoryCacheStream>();
+    private readonly Dictionary<(long, string), GitPackMemoryCacheStream> cache = new Dictionary<(long, string), GitPackMemoryCacheStream>();
 
     /// <inheritdoc/>
-    public override Stream Add(long offset, Stream stream)
+    public override Stream Add(long offset, string objectType, Stream stream)
     {
         var cacheStream = new GitPackMemoryCacheStream(stream);
-        this.cache.Add(offset, cacheStream);
+        this.cache.Add((offset, objectType), cacheStream);
         return new GitPackMemoryCacheViewStream(cacheStream);
     }
 
     /// <inheritdoc/>
-    public override bool TryOpen(long offset, [NotNullWhen(true)] out Stream? stream)
+    public override bool TryOpen(long offset, string objectType, [NotNullWhen(true)] out Stream? stream)
     {
-        if (this.cache.TryGetValue(offset, out GitPackMemoryCacheStream? cacheStream))
+        if (this.cache.TryGetValue((offset, objectType), out GitPackMemoryCacheStream? cacheStream))
         {
             stream = new GitPackMemoryCacheViewStream(cacheStream!);
             return true;
@@ -64,7 +64,7 @@ protected override void Dispose(bool disposing)
         {
             while (this.cache.Count > 0)
             {
-                long key = this.cache.Keys.First();
+                var key = this.cache.Keys.First();
                 GitPackMemoryCacheStream? stream = this.cache[key];
                 stream.Dispose();
                 this.cache.Remove(key);

src/NerdBank.GitVersioning/ManagedGit/GitPackNullCache.cs

@@ -19,13 +19,13 @@ public class GitPackNullCache : GitPackCache
     public static GitPackNullCache Instance { get; } = new GitPackNullCache();
 
     /// <inheritdoc/>
-    public override Stream Add(long offset, Stream stream)
+    public override Stream Add(long offset, string objectType, Stream stream)
     {
         return stream;
     }
 
     /// <inheritdoc/>
-    public override bool TryOpen(long offset, [NotNullWhen(true)] out Stream? stream)
+    public override bool TryOpen(long offset, string objectType, [NotNullWhen(true)] out Stream? stream)
     {
         stream = null;
         return false;

test/Nerdbank.GitVersioning.Tests/ManagedGit/GitPackMemoryCacheTests.cs

@@ -20,8 +20,8 @@ public void StreamsAreIndependent()
         {
             var cache = new GitPackMemoryCache();
 
-            Stream stream1 = cache.Add(0, stream);
-            Assert.True(cache.TryOpen(0, out Stream stream2));
+            Stream stream1 = cache.Add(0, "anObjectType", stream);
+            Assert.True(cache.TryOpen(0, "anObjectType", out Stream stream2));
 
             using (stream1)
             using (stream2)