Speed up Constraint Scan.

Author: Bobris

BTDB/BTreeLib/BTreeImpl12.cs

@@ -941,7 +941,7 @@ internal static bool MoveToLast(IntPtr root, ref StructList<CursorItem> stack)
     internal IntPtr CloneNode(IntPtr nodePtr)
     {
         var size = NodeUtils12.NodeSize(nodePtr);
-        var newNode = _allocator.Allocate((IntPtr)size);
+        var newNode = _allocator.Allocate(size);
         TreeNodeUtils.CopyMemory(nodePtr, newNode, size);
         ref var header = ref NodeUtils12.Ptr2NodeHeader(newNode);
         header._referenceCount = 1;
@@ -970,9 +970,9 @@ void ReferenceAllChildren(IntPtr node)
     {
         if (NodeUtils12.Ptr2NodeHeader(node).IsNodeLeaf) return;
         var ptrs = NodeUtils12.GetBranchValuePtrs(node);
-        for (var i = 0; i < ptrs.Length; i++)
+        foreach (var t in ptrs)
         {
-            NodeUtils12.Reference(ptrs[i]);
+            NodeUtils12.Reference(t);
         }
     }
 
@@ -991,18 +991,18 @@ internal void Dereference(IntPtr node)
         if (nodeHeader.HasLongKeys)
         {
             var ptrs = NodeUtils12.GetLongKeyPtrs(node);
-            for (var i = 0; i < ptrs.Length; i++)
+            foreach (var t in ptrs)
             {
-                FreeLongKey(ptrs[i]);
+                FreeLongKey(t);
             }
         }
 
         if (!nodeHeader.IsNodeLeaf)
         {
             var ptrs = NodeUtils12.GetBranchValuePtrs(node);
-            for (var i = 0; i < ptrs.Length; i++)
+            foreach (var t in ptrs)
             {
-                Dereference(ptrs[i]);
+                Dereference(t);
             }
         }
 
@@ -1057,7 +1057,7 @@ void WritePtrInNode(in CursorItem stackItem, IntPtr newNode)
         ptr = newNode;
     }
 
-    internal unsafe bool FindExact(RootNode12 rootNode, ref StructList<CursorItem> stack, ReadOnlySpan<byte> key)
+    internal static unsafe bool FindExact(RootNode12 rootNode, ref StructList<CursorItem> stack, ReadOnlySpan<byte> key)
     {
         stack.Clear();
         var top = rootNode.Root;
@@ -1083,15 +1083,15 @@ internal unsafe bool FindExact(RootNode12 rootNode, ref StructList<CursorItem> s
                         return false;
                     }
 
-                    var comp = key.Slice(0, header._keyPrefixLength).SequenceCompareTo(prefix);
+                    var comp = key[..header._keyPrefixLength].SequenceCompareTo(prefix);
                     if (comp != 0)
                     {
                         stack.Clear();
                         return false;
                     }
                 }
 
-                var keyRest = key.Slice(header._keyPrefixLength);
+                var keyRest = key[header._keyPrefixLength..];
                 if (header.HasLongKeys)
                 {
                     var keys = NodeUtils12.GetLongKeyPtrs(top);
@@ -1439,14 +1439,14 @@ internal static bool IsKeyPrefix(IntPtr nodePtr, int idx, ReadOnlySpan<byte> pre
         if (header.HasLongKeys)
         {
             var keys = NodeUtils12.GetLongKeyPtrs(nodePtr);
-            return TreeNodeUtils.IsPrefix(NodeUtils12.LongKeyPtrToSpan(keys[idx]), prefix);
+            return ((ReadOnlySpan<byte>)NodeUtils12.LongKeyPtrToSpan(keys[idx])).StartsWith(prefix);
         }
         else
         {
             var keyOffsets = NodeUtils12.GetKeySpans(nodePtr, out var keySuffixes);
             var ofs = keyOffsets[idx];
             var lenSuffix = keyOffsets[idx + 1] - ofs;
-            return TreeNodeUtils.IsPrefix(keySuffixes.Slice(ofs, lenSuffix), prefix);
+            return ((ReadOnlySpan<byte>)keySuffixes.Slice(ofs, lenSuffix)).StartsWith(prefix);
         }
     }
 

BTDB/BTreeLib/Cursor12.cs

@@ -91,7 +91,7 @@ public long EraseTo(ICursor to)
 
     public bool FindExact(in ReadOnlySpan<byte> key)
     {
-        return _rootNode.Impl.FindExact(_rootNode, ref _stack, key);
+        return BTreeImpl12.FindExact(_rootNode, ref _stack, key);
     }
 
     public FindResult Find(in ReadOnlySpan<byte> key)
@@ -328,6 +328,8 @@ public bool KeyHasPrefix(in ReadOnlySpan<byte> prefix)
     {
         if (_stack.Count == 0)
             return false;
+        if (prefix.Length == 0)
+            return true;
         ref var stackItem = ref _stack[_stack.Count - 1];
         return BTreeImpl12.IsKeyPrefix(stackItem._node, stackItem._posInNode, prefix);
     }

BTDB/Buffer/TreeNodeUtils.cs

@@ -77,13 +77,6 @@ internal static unsafe void CopyMemory(IntPtr src, IntPtr dst, int size)
         Unsafe.CopyBlockUnaligned(dst.ToPointer(), src.ToPointer(), (uint)size);
     }
 
-    internal static bool IsPrefix(in ReadOnlySpan<byte> data, in ReadOnlySpan<byte> prefix)
-    {
-        if (data.Length < prefix.Length)
-            return false;
-        return data[..prefix.Length].SequenceEqual(prefix);
-    }
-
     internal static int FindFirstDifference(in ReadOnlySpan<byte> buf1, in ReadOnlySpan<byte> buf2)
     {
         return buf1.CommonPrefixLength(buf2);

BTDB/KVDBLayer/ReadOnly/ReadOnlyKeyValueDBTransaction.cs

@@ -244,7 +244,7 @@ bool KeyMatchesPrefix(ReadOnlySpan<byte> prefix)
             prefix = prefix[nodePrefix.Length..];
         }
 
-        return TreeNodeUtils.IsPrefix(GetKeySuffixSpan(ownerBegin, top, top._pos), prefix);
+        return GetKeySuffixSpan(ownerBegin, top, top._pos).StartsWith(prefix);
     }
 
     static ReadOnlySpan<byte> GetKeySuffixSpan(nuint ownerBegin, in StackItem top, uint topPos)

BTDB/ODBLayer/RelationEnumerator.cs

@@ -105,7 +105,7 @@ public bool MoveNext()
     [SkipLocalsInit]
     unsafe bool FindNextKey(bool first = false)
     {
-        Span<byte> buf = stackalloc byte[512];
+        Span<byte> buf = stackalloc byte[1024];
         ref var writer = ref _key;
         var i = 0;
         if (first)
@@ -165,6 +165,8 @@ unsafe bool FindNextKey(bool first = false)
             writer.UpdateBuffer(key);
             return true;
         }
+
+        var dataDidntChangedForConstraint = i;
         for (var j = i; j < _constraints.Length; j++) _constraints[j].Offset = -1;
         var offsetPrefix = i > 0 ? _constraints[i - 1].Offset : _keyBytesCount;
         fixed (void* _ = key)
@@ -206,6 +208,11 @@ unsafe bool FindNextKey(bool first = false)
             }
         }
 
+        if (dataDidntChangedForConstraint < i && _skipNextOn == -1)
+        {
+            goto goNextKey;
+        }
+
         switch (_constraints[i].MatchType)
         {
             case IConstraint.MatchType.NoPrefix:

SimpleTester/GatherSpeedTest.cs

@@ -76,10 +76,10 @@ public void Run()
         for (int i = 0; i < 2; i++)
         {
             var sw = System.Diagnostics.Stopwatch.StartNew();
-            t.GatherById(coll, 0, 100, Constraint<ulong>.Any, Constraint<ulong>.Any, Constraint<ulong>.Any,
-                Constraint.String.Exact("nonexistent"));
+            var count = t.GatherById(coll, 0, 100, Constraint<ulong>.Any, Constraint<ulong>.Any, Constraint<ulong>.Any,
+                Constraint.String.Contains("@"));
             sw.Stop();
-            Console.WriteLine("GatherById took " + sw.ElapsedMilliseconds + "ms");
+            Console.WriteLine("GatherById took " + sw.ElapsedMilliseconds + "ms Found " + count);
         }
     }
 }