Merge pull request aeron-io#106 from qed-/directbuffer

Recycleable DirectBuffer, Resolves aeron-io#101

Author: Olivier Deheurles

main/csharp/DirectBuffer.cs

@@ -8,20 +8,45 @@ namespace Adaptive.SimpleBinaryEncoding
  /// </summary>
  public sealed unsafe class DirectBuffer : IDisposable
  {
- private readonly byte* _pBuffer;
+ private byte* _pBuffer;
  private bool _disposed;
  private GCHandle _pinnedGCHandle;
- private readonly bool _needToFreeGCHandle;
- private readonly int _capacity;
+ private bool _needToFreeGCHandle;
+ private int _capacity;
 
  /// <summary>
  /// Constructs a <see cref="DirectBuffer"/>
  /// </summary>
  /// <param name="byteArray">The byte array that will act as the backing buffer.</param>
  public DirectBuffer(byte[] byteArray)
+ {
+ Reset(byteArray);
+ }
+
+ /// <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)
+ {
+ Reset(pBuffer, bufferLength);
+ }
+
+ public DirectBuffer()
+ {
+ }
+
+ /// <summary>
+ /// Recycles an existing <see cref="DirectBuffer"/>
+ /// </summary>
+ /// <param name="byteArray">The byte array that will act as the backing buffer.</param>
+ public void Reset(byte[] byteArray)
  {
  if (byteArray == null) throw new ArgumentNullException("byteArray");
 
+ FreeGCHandle();
+
  // 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;
@@ -31,15 +56,17 @@ public DirectBuffer(byte[] byteArray)
  }
 
  /// <summary>
- /// Constructs a <see cref="DirectBuffer"/> from an unmanaged byte buffer owned by external code
+ /// Recycles an existing <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)
+ public void Reset(byte* pBuffer, int bufferLength)
  {
  if (pBuffer == null) throw new ArgumentNullException("pBuffer");
  if (bufferLength < 0) throw new ArgumentException("Buffer size must be > 0", "bufferLength");
 
+ FreeGCHandle();
+
  _pBuffer = pBuffer;
  _capacity = bufferLength;
  _needToFreeGCHandle = false;
@@ -539,10 +566,18 @@ private void Dispose(bool disposing)
  if (_disposed)
  return;
 
- if (_needToFreeGCHandle)
- _pinnedGCHandle.Free();
+ FreeGCHandle();
 
  _disposed = true;
  }
+
+ private void FreeGCHandle()
+ {
+ if (_needToFreeGCHandle)
+ {
+ _pinnedGCHandle.Free();
+ _needToFreeGCHandle = false;
+ }
+ }
  }
 }

test/csharp/DirectBufferTests.cs

@@ -50,7 +50,27 @@ public void ConstructFromNativeBuffer()
  Assert.AreEqual(value, *(long*) (unmanagedBuffer + index));
  }
  }
- 
+
+ [Test]
+ public void Recycle()
+ {
+ var directBuffer = new DirectBuffer();
+ var firstBuffer = new Byte[16];
+ directBuffer.Reset(firstBuffer);
+
+ directBuffer.Int64PutLittleEndian(0, 1);
+ Assert.AreEqual(1, BitConverter.ToInt64(firstBuffer, 0));
+
+ var secondBuffer = new byte[16];
+ var secondBufferHandle = GCHandle.Alloc(secondBuffer, GCHandleType.Pinned);
+ var secondUnmanagedBuffer = (byte*)secondBufferHandle.AddrOfPinnedObject().ToPointer();
+ directBuffer.Reset(secondUnmanagedBuffer, 16);
+ directBuffer.Int64PutLittleEndian(0, 2);
+ Assert.AreEqual(2, BitConverter.ToInt64(secondBuffer, 0));
+
+ directBuffer.Dispose();
+ }
+
  #region Byte
 
  [TestCase(5, 0)]