New SpanByteLruCache and BonBuilder speedup.

Author: Bobris

BTDB/Bon/Bon.cs

@@ -358,8 +358,9 @@ enum State
     StructList<ulong> _objKeys = new();
     MemWriter _topData;
     uint _items = 0;
-    readonly LruCache<string, ulong> _strCache = new(512);
-    readonly LruCache<(bool IsClass, StructList<ulong> ObjKeys), ulong> _objKeysCache = new(64);
+    LruCache<string, ulong>? _strCache = null;
+    SpanByteLruCache<ulong>? _u8Cache = null;
+    LruCache<(bool IsClass, StructList<ulong> ObjKeys), ulong>? _objKeysCache = null;
     HashSet<string>? _objKeysSet;
 
     public BonBuilder(in MemWriter memWriter)
@@ -640,16 +641,16 @@ public void FinishObject()
                 rootData = ref _stack[0].Item2;
             }
 
-            if (!_objKeysCache.TryGetValue((false, objKeys), out var posKeys))
+            _objKeysCache ??= new();
+            ref var posKeys = ref _objKeysCache.GetOrAddValueRef((false, objKeys), out var added);
+            if (added)
             {
                 posKeys = (ulong)rootData.GetCurrentPosition();
                 rootData.WriteVUInt32(items);
                 foreach (var keyOfs in objKeys)
                 {
                     rootData.WriteVUInt64(keyOfs);
                 }
-
-                _objKeysCache[(false, objKeys)] = posKeys;
             }
 
             var pos = rootData.GetCurrentPosition();
@@ -695,16 +696,16 @@ public void FinishClass()
             rootData = ref _stack[0].Item2;
         }
 
-        if (!_objKeysCache.TryGetValue((true, objKeys), out var posKeys))
+        _objKeysCache ??= new();
+        ref var posKeys = ref _objKeysCache.GetOrAddValueRef((true, objKeys), out var added);
+        if (added)
         {
             posKeys = (ulong)rootData.GetCurrentPosition();
             rootData.WriteVUInt32(items);
             foreach (var keyOfs in objKeys)
             {
                 rootData.WriteVUInt64(keyOfs);
             }
-
-            _objKeysCache[(true, objKeys)] = posKeys;
         }
 
         var pos = rootData.GetCurrentPosition();
@@ -846,7 +847,9 @@ void ThrowWrongState()
 
     ulong WriteDedupString(string value)
     {
-        if (_strCache.TryGetValue(value, out var pos))
+        _strCache ??= new(512);
+        ref var pos = ref _strCache.GetOrAddValueRef(value, out var added);
+        if (!added)
         {
             return pos;
         }
@@ -859,21 +862,28 @@ ulong WriteDedupString(string value)
 
         pos = (ulong)writer.GetCurrentPosition();
         writer.WriteStringInUtf8(value);
-        _strCache[value] = pos;
         return pos;
     }
 
     ulong WriteDedupString(ReadOnlySpan<byte> value)
     {
+        _u8Cache ??= new(512);
+        ref var pos = ref _u8Cache.GetOrAddValueRef(value, out var added);
+        if (!added)
+        {
+            return pos;
+        }
+
         ref var writer = ref _topData;
         if (_stack.Count > 0)
         {
             writer = ref _stack[0].Data;
         }
 
-        var pos = (ulong)writer.GetCurrentPosition();
+        pos = (ulong)writer.GetCurrentPosition();
         writer.WriteVUInt32((uint)value.Length);
         writer.WriteBlock(value);
+        _u8Cache[value] = pos;
         return pos;
     }
 

BTDB/Collections/LruCache.cs

@@ -181,10 +181,20 @@ public bool Remove(TKey key)
         return false;
     }
 
-    public ref TValue this[TKey key] => ref GetOrAddValueRef(key);
+    public void Clear()
+    {
+        Array.Clear(_buckets);
+        Array.Clear(_entries, 0, _count);
+        _count = 0;
+        _freeList = -1;
+        UsageHead = -1;
+        UsageTail = -1;
+    }
+
+    public ref TValue this[TKey key] => ref GetOrAddValueRef(key, out _);
 
     // Not safe for concurrent _reads_ (at least, if either of them add)
-    public ref TValue GetOrAddValueRef(TKey key)
+    public ref TValue GetOrAddValueRef(TKey key, out bool added)
     {
         if (key == null) HashHelpers.ThrowKeyArgumentNullException();
         var entries = _entries;
@@ -216,6 +226,7 @@ public ref TValue GetOrAddValueRef(TKey key)
                     UsageHead = i;
                 }
 
+                added = false;
                 return ref entries[i].Value;
             }
 
@@ -229,6 +240,7 @@ public ref TValue GetOrAddValueRef(TKey key)
             collisionCount++;
         }
 
+        added = true;
         return ref AddKey(key, bucketIndex, hash);
     }