Merge pull request aeron-io#89 from qed-/master

[C#] Allow DirectBuffer to be initialised from unmanaged buffer

Author: Olivier Deheurles

main/csharp/DirectBuffer.cs

@@ -8,10 +8,10 @@ namespace Adaptive.SimpleBinaryEncoding
  /// </summary>
  public sealed unsafe class DirectBuffer : IDisposable
  {
- private readonly byte[] _buffer;
  private readonly byte* _pBuffer;
  private bool _disposed;
  private GCHandle _pinnedGCHandle;
+ private readonly bool _needToFreeGCHandle;
  private readonly int _capacity;
 
  /// <summary>
@@ -24,10 +24,25 @@ public DirectBuffer(byte[] byteArray)
 
  // pin the buffer so it does not get moved around by GC, this is required since we use pointers
  _pinnedGCHandle = GCHandle.Alloc(byteArray, GCHandleType.Pinned);
+ _needToFreeGCHandle = true;
 
- _buffer = byteArray;
- _pBuffer = (byte*) _pinnedGCHandle.AddrOfPinnedObject().ToPointer();
- _capacity = _buffer.Length;
+ _pBuffer = (byte*)_pinnedGCHandle.AddrOfPinnedObject().ToPointer();
+ _capacity = byteArray.Length;
+ }
+
+ /// <summary>
+ /// Constructs a <see cref="DirectBuffer"/> from an unmanaged byte buffer owned by external code
+ /// </summary>
+ /// <param name="pBuffer">Unmanaged byte buffer</param>
+ /// <param name="bufferLength">Length of the buffer</param>
+ public DirectBuffer(byte* pBuffer, int bufferLength)
+ {
+ if (pBuffer == null) throw new ArgumentNullException("pBuffer");
+ if (bufferLength < 0) throw new ArgumentException("Buffer size must be > 0", "bufferLength");
+
+ _pBuffer = pBuffer;
+ _capacity = bufferLength;
+ _needToFreeGCHandle = false;
  }
 
  /// <summary>
@@ -38,7 +53,7 @@ public void CheckLimit(int limit)
  {
  if (limit > _capacity)
  {
-  throw new IndexOutOfRangeException(string.Format("limit={0} is beyond capacity={1}", limit, _buffer.Length));
+ throw new IndexOutOfRangeException(string.Format("limit={0} is beyond capacity={1}", limit, _capacity));
  }
  }
 
@@ -480,7 +495,8 @@ public void DoublePutLittleEndian(int index, double value)
  public int GetBytes(int index, byte[] destination, int offsetDestination, int length)
  {
  int count = Math.Min(length, _capacity - index);
- Buffer.BlockCopy(_buffer, index, destination, offsetDestination, count);
+ Marshal.Copy((IntPtr)(_pBuffer + index), destination, offsetDestination, count);
+
  return count;
  }
 
@@ -495,12 +511,11 @@ public int GetBytes(int index, byte[] destination, int offsetDestination, int le
  public int SetBytes(int index, byte[] src, int offset, int length)
  {
  int count = Math.Min(length, _capacity - index);
- Buffer.BlockCopy(src, offset, _buffer, index, count);
+ Marshal.Copy(src, offset, (IntPtr)(_pBuffer + index), count);
 
  return count;
  }
 
-
  /// <summary>
  /// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
  /// </summary>
@@ -521,7 +536,9 @@ private void Dispose(bool disposing)
  if (_disposed)
  return;
 
- _pinnedGCHandle.Free();
+ if (_needToFreeGCHandle)
+ _pinnedGCHandle.Free();
+
  _disposed = true;
  }
  }

test/csharp/DirectBufferTests.cs

@@ -34,7 +34,23 @@ public void CheckPositionShouldThrowWhenPositionIsNotInRange()
  _directBuffer.CheckLimit(_buffer.Length + 1);
  }
 
+ [Test]
+ public void ConstructFromNativeBuffer()
+ {
+ var managedBuffer = new Byte[16];
+ var handle = GCHandle.Alloc(managedBuffer, GCHandleType.Pinned);
+ var unmanagedBuffer = (byte*) handle.AddrOfPinnedObject().ToPointer();
 
+ const int value = 5;
+ const int index = 0;
+ 
+ using (var directBufferFromUnmanagedbuffer = new DirectBuffer(unmanagedBuffer, managedBuffer.Length))
+ {
+ directBufferFromUnmanagedbuffer.Int64PutLittleEndian(index, value);
+ Assert.AreEqual(value, *(long*) (unmanagedBuffer + index));
+ }
+ }
+ 
  #region Byte
 
  [TestCase(5, 0)]