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// **********************************************************************
//
// Copyright (c) 2003-2016 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
namespace IceInternal
{
using System.Diagnostics;
//
// An instance of ByteBuffer cannot grow beyond its initial capacity.
// This class wraps a ByteBuffer and supports reallocation.
//
public class Buffer
{
public Buffer() : this(ByteBuffer.ByteOrder.LITTLE_ENDIAN)
{
}
public Buffer(ByteBuffer.ByteOrder order)
{
b = _emptyBuffer;
_size = 0;
_capacity = 0;
_order = order;
}
public Buffer(byte[] data) : this(data, ByteBuffer.ByteOrder.LITTLE_ENDIAN)
{
}
public Buffer(byte[] data, ByteBuffer.ByteOrder order)
{
b = ByteBuffer.wrap(data);
b.order(order);
_size = data.Length;
_capacity = 0;
_order = order;
}
public int size()
{
return _size;
}
public bool empty()
{
return _size == 0;
}
public void clear()
{
b = _emptyBuffer;
_size = 0;
_capacity = 0;
}
//
// Call expand(n) to add room for n additional bytes. Note that expand()
// examines the current position of the buffer first; we don't want to
// expand the buffer if the caller is writing to a location that is
// already in the buffer.
//
public void expand(int n)
{
int sz = (b == _emptyBuffer) ? n : b.position() + n;
if(sz > _size)
{
resize(sz, false);
}
}
public void resize(int n, bool reading)
{
Debug.Assert(b == _emptyBuffer || _capacity > 0);
if(n == 0)
{
clear();
}
else if(n > _capacity)
{
reserve(n);
}
_size = n;
//
// When used for reading, we want to set the buffer's limit to the new size.
//
if(reading)
{
b.limit(_size);
}
}
public void reset()
{
if(_size > 0 && _size * 2 < _capacity)
{
//
// If the current buffer size is smaller than the
// buffer capacity, we shrink the buffer memory to the
// current size. This is to avoid holding on to too much
// memory if it's not needed anymore.
//
if(++_shrinkCounter > 2)
{
reserve(_size);
_shrinkCounter = 0;
}
}
else
{
_shrinkCounter = 0;
}
_size = 0;
if(b != _emptyBuffer)
{
b.limit(b.capacity());
b.position(0);
}
}
private void reserve(int n)
{
Debug.Assert(_capacity == b.capacity());
if(n > _capacity)
{
_capacity = System.Math.Max(n, 2 * _capacity);
_capacity = System.Math.Max(240, _capacity);
}
else if(n < _capacity)
{
_capacity = n;
}
else
{
return;
}
try
{
ByteBuffer buf = ByteBuffer.allocate(_capacity);
if(b == _emptyBuffer)
{
b = buf;
}
else
{
int pos = b.position();
b.position(0);
b.limit(System.Math.Min(_capacity, b.capacity()));
buf.put(b);
b = buf;
b.limit(b.capacity());
b.position(pos);
}
b.order(_order);
}
catch(System.OutOfMemoryException)
{
_capacity = b.capacity(); // Restore the previous capacity
throw;
}
catch(System.Exception ex)
{
_capacity = b.capacity(); // Restore the previous capacity.
Ice.MarshalException e = new Ice.MarshalException(ex);
e.reason = "unexpected exception while trying to allocate a ByteBuffer:\n" + ex;
throw e;
}
finally
{
Debug.Assert(_capacity == b.capacity());
}
}
public ByteBuffer b;
// Sentinel used for null buffer.
static private ByteBuffer _emptyBuffer = new ByteBuffer();
private int _size;
private int _capacity; // Cache capacity to avoid excessive method calls.
private int _shrinkCounter;
private ByteBuffer.ByteOrder _order;
}
}
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