span based reader

2026-10-16 17:23:04 +08:00 · 2019-04-15 14:00:00 +02:00
parent 732ea84caa
commit fbca8a6dc1
11 changed files with 194 additions and 48 deletions
@@ -0,0 +1,104 @@
+using MQTTnet.Formatter;
+using System;
+using System.Buffers.Binary;
+using System.Text;
+
+namespace MQTTnet.AspNetCore
+{
+    public class SpanBasedMqttPacketBodyReader : IMqttPacketBodyReader
+    {
+        private ReadOnlyMemory<byte> _buffer;
+        private int _offset;
+        
+        public void SetBuffer(ReadOnlyMemory<byte> buffer)
+        {
+            _buffer = buffer;
+            _offset = 0;
+        }
+
+        public ulong Length => (ulong)_buffer.Length;
+
+        public bool EndOfStream => _buffer.Length.Equals(_offset);
+        
+        public ulong Offset => (ulong)_offset;
+
+        public byte ReadByte()
+        {
+            ValidateReceiveBuffer(1);
+            return _buffer.Span[_offset++];
+        }
+
+        public byte[] ReadRemainingData()
+        {
+            return _buffer.ToArray();
+        }
+
+        public ushort ReadUInt16()
+        {
+            ValidateReceiveBuffer(2);
+
+            var result = BinaryPrimitives.ReadUInt16BigEndian(_buffer.Span);
+            _offset += 2;
+            return result;
+        }
+
+        public byte[] ReadWithLengthPrefix()
+        {
+            return ReadSegmentWithLengthPrefix().ToArray();
+        }
+
+        private ReadOnlyMemory<byte> ReadSegmentWithLengthPrefix()
+        {
+            var length = ReadUInt16();
+
+            ValidateReceiveBuffer(length);
+
+            var result = _buffer.Slice(_offset, length);
+            _offset += length;
+            return result;
+        }
+
+        private void ValidateReceiveBuffer(ushort length)
+        {
+            if (_buffer.Length < _offset + length)
+            {
+                throw new ArgumentOutOfRangeException(nameof(_buffer), $"expected at least {_offset + length} bytes but there are only {_buffer.Length} bytes");
+            }
+        }
+
+        public unsafe string ReadStringWithLengthPrefix()
+        {
+            var buffer = ReadSegmentWithLengthPrefix();
+            fixed (byte* bytes = &buffer.Span.GetPinnableReference())
+            {
+                var result = Encoding.UTF8.GetString(bytes, buffer.Length);
+                return result;
+            }
+        }
+
+        public ushort ReadTwoByteInteger()
+        {
+            throw new NotImplementedException();
+        }
+
+        public uint ReadFourByteInteger()
+        {
+            throw new NotImplementedException();
+        }
+
+        public uint ReadVariableLengthInteger()
+        {
+            throw new NotImplementedException();
+        }
+
+        public bool ReadBoolean()
+        {
+            throw new NotImplementedException();
+        }
+
+        public void Seek(ulong position)
+        {
+            throw new NotImplementedException();
+        }
+    }
+}