contract id introduced (#482)

Author: Scooletz

src/Paprika.Tests/Store/BasePageTests.cs

@@ -65,7 +65,7 @@ public override void RegisterForFutureReuse(Page page, bool possibleImmediateReu
                 .BeTrue($"Page at {addr} should not be registered as reusable before");
         }
 
-        public override Dictionary<Keccak, uint> IdCache { get; } = new();
+        public override Dictionary<Keccak, ContractId> IdCache { get; } = new();
 
         public override string ToString() => $"Batch context used {_pageCount} pages to write the data";
 

src/Paprika/Store/BatchContextBase.cs

@@ -43,7 +43,7 @@ public Page GetWritableCopy(Page page)
 
     public virtual void NoticeAbandonedPageReused(Page page) { }
 
-    public abstract IDictionary<Keccak, uint> IdCache { get; }
+    public abstract IDictionary<Keccak, ContractId> IdCache { get; }
 
     /// <summary>
     /// Assigns the batch identifier to a given page, marking it writable by this batch.

src/Paprika/Store/ContractId.cs

@@ -0,0 +1,17 @@
+namespace Paprika.Store;
+
+/// <summary>
+/// Represents a contract id.
+/// </summary>
+/// <remarks>
+/// A contract id is an uint uniquely assigned to a contract. It's done by persisting a mapping between  
+/// between its address' Keccak and an auto-incremented uint.
+/// </remarks>
+/// <param name="Value">The underlying value.</param>
+public readonly record struct ContractId(uint Value)
+{
+    private const uint NullValue = 0;
+    public bool IsNull => Value == NullValue;
+
+    public static readonly ContractId Null = new(NullValue);
+}

src/Paprika/Store/IBatchContext.cs

@@ -122,7 +122,7 @@ public interface IReadOnlyBatchContext : IPageResolver
     /// </summary>
     uint BatchId { get; }
 
-    IDictionary<Keccak, uint> IdCache { get; }
+    IDictionary<Keccak, ContractId> IdCache { get; }
 }
 
 /// <summary>

src/Paprika/Store/PagedDb.cs

@@ -471,9 +471,9 @@ private DbAddress SetNewRoot(RootPage root)
     private sealed class ReadOnlyBatch(PagedDb db, RootPage root, string name)
         : IVisitableReadOnlyBatch, IReadOnlyBatchContext
     {
-        [ThreadStatic] private static ConcurrentDictionary<Keccak, uint>? s_cache;
+        [ThreadStatic] private static ConcurrentDictionary<Keccak, ContractId>? s_cache;
 
-        private ConcurrentDictionary<Keccak, uint> _idCache = Interlocked.Exchange(ref s_cache, null) ?? new(
+        private ConcurrentDictionary<Keccak, ContractId> _idCache = Interlocked.Exchange(ref s_cache, null) ?? new(
             Environment.ProcessorCount,
             RootPage.IdCacheLimit);
 
@@ -522,7 +522,7 @@ public bool TryGet(scoped in Key key, out ReadOnlySpan<byte> result)
 
         public uint BatchId => root.Header.BatchId;
 
-        public IDictionary<Keccak, uint> IdCache
+        public IDictionary<Keccak, ContractId> IdCache
         {
             get
             {
@@ -835,7 +835,7 @@ public override void NoticeAbandonedPageReused(Page page)
 #endif
         }
 
-        public override Dictionary<Keccak, uint> IdCache { get; }
+        public override Dictionary<Keccak, ContractId> IdCache { get; }
 
         public void Dispose()
         {
@@ -865,11 +865,11 @@ public unsafe Context()
             Page = new((byte*)NativeMemory.AlignedAlloc(Page.PageSize, (UIntPtr)UIntPtr.Size));
             Abandoned = new List<DbAddress>();
             Written = new HashSet<DbAddress>();
-            IdCache = new Dictionary<Keccak, uint>();
+            IdCache = new Dictionary<Keccak, ContractId>();
             ReusedImmediately = new Stack<DbAddress>();
         }
 
-        public Dictionary<Keccak, uint> IdCache { get; }
+        public Dictionary<Keccak, ContractId> IdCache { get; }
 
         public Page Page { get; }
 

src/Paprika/Store/RootPage.cs

@@ -123,7 +123,7 @@ public bool TryGet(scoped in Key key, IReadOnlyBatchContext batch, out ReadOnlyS
 
         if (cache.TryGetValue(keccak, out var id))
         {
-            if (id == 0)
+            if (id.IsNull)
             {
                 result = default;
                 return false;
@@ -168,7 +168,7 @@ public void SetRaw(in Key key, IBatchContext batch, ReadOnlySpan<byte> rawData)
                     Data.AccountCounter++;
 
                     // memoize in cache
-                    batch.IdCache[keccak] = id = Data.AccountCounter;
+                    batch.IdCache[keccak] = id = new ContractId(Data.AccountCounter);
 
                     // update root
                     Data.Storage.SetId(keccak, id, batch);
@@ -192,7 +192,7 @@ public void Destroy(IBatchContext batch, in NibblePath account)
         var keccak = account.UnsafeAsKeccak;
 
         // Destroy the Id entry about it
-        Data.Storage.SetId(keccak, 0, batch);
+        Data.Storage.SetId(keccak, ContractId.Null, batch);
 
         // Destroy the account entry
         SetAtRoot(batch, account, ReadOnlySpan<byte>.Empty, ref Data.StateRoot);

src/Paprika/Store/StorageFanOut.cs

@@ -120,26 +120,27 @@ public void Accept(IPageVisitor visitor, IPageResolver resolver)
             }
         }
 
-        public bool TryGetId(in Keccak keccak, out uint id, IPageResolver batch)
+        public bool TryGetId(in Keccak keccak, out ContractId id, IPageResolver batch)
         {
+            Unsafe.SkipInit(out id);
+
             var at = BuildIdIndex(NibblePath.FromKey(keccak), out var sliced);
 
             if (TryGet(batch, at, sliced, Type.Id, out var result))
             {
-                id = BinaryPrimitives.ReadUInt32LittleEndian(result);
+                id = new ContractId(BinaryPrimitives.ReadUInt32LittleEndian(result));
                 return true;
             }
 
-            id = default;
             return false;
         }
 
-        public void SetId(Keccak keccak, uint id, IBatchContext batch)
+        public void SetId(Keccak keccak, ContractId id, IBatchContext batch)
         {
             var at = BuildIdIndex(NibblePath.FromKey(keccak), out var sliced);
 
             Span<byte> span = stackalloc byte[4];
-            BinaryPrimitives.WriteUInt32LittleEndian(span, id);
+            BinaryPrimitives.WriteUInt32LittleEndian(span, id.Value);
 
             Set(batch, at, sliced, Type.Id, span);
         }
@@ -170,18 +171,18 @@ private static uint BuildIdIndex(in NibblePath path, out NibblePath sliced)
         /// </summary>
         public static int NormalizeAtForId(uint at) => (int)(at >> IdShift);
 
-        public bool TryGetStorage(uint id, scoped in NibblePath path, out ReadOnlySpan<byte> result,
+        public bool TryGetStorage(ContractId id, scoped in NibblePath path, out ReadOnlySpan<byte> result,
             IReadOnlyBatchContext batch) =>
-            TryGet(batch, id, path, Type.Storage, out result);
+            TryGet(batch, id.Value, path, Type.Storage, out result);
 
-        public void SetStorage(uint id, scoped in NibblePath path, ReadOnlySpan<byte> data, IBatchContext batch)
+        public void SetStorage(ContractId id, scoped in NibblePath path, ReadOnlySpan<byte> data, IBatchContext batch)
         {
-            Set(batch, id, path, Type.Storage, data);
+            Set(batch, id.Value, path, Type.Storage, data);
         }
 
-        public void DeleteStorageByPrefix(uint id, scoped in NibblePath prefix, IBatchContext batch)
+        public void DeleteStorageByPrefix(ContractId id, scoped in NibblePath prefix, IBatchContext batch)
         {
-            var (next, index) = GetIndex(id, Level);
+            var (next, index) = GetIndex(id.Value, Level);
             var addr = _addresses[index];
 
             if (addr.IsNull)
@@ -453,7 +454,6 @@ public Page Set(uint at, in NibblePath key, in ReadOnlySpan<byte> data, IBatchCo
             var addr = Data.Addresses[index];
 
             var child = addr.IsNull
-
                 ? batch.GetNewCleanPage<BottomPage>(out addr, StartLevel).AsPage()
                 : batch.EnsureWritableCopy(ref addr);