/*
* Copyright (c) 2023 Vaughn Nugent
*
* Library: VNLib
* Package: VNLib.Plugins.Extensions.VNCache
* File: AddOrUpdateBuffer.cs
*
* AddOrUpdateBuffer.cs is part of VNLib.Plugins.Extensions.VNCache
* which is part of the larger VNLib collection of libraries and utilities.
*
* VNLib.Plugins.Extensions.VNCache is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* VNLib.Plugins.Extensions.VNCache is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see https://www.gnu.org/licenses/.
*/
using System;
using System.Buffers;
using VNLib.Utils;
using VNLib.Utils.Memory;
using VNLib.Utils.Extensions;
using VNLib.Data.Caching;
namespace VNLib.Plugins.Extensions.VNCache
{
///
/// Implements a buffer writer that serves to serialize object data and
/// store the object data for use by the memory cache store, and the
/// remote cache store
///
class AddOrUpdateBuffer : VnDisposeable, IBufferWriter, IObjectData
{
private int _count;
private readonly IUnmangedHeap _heap;
private MemoryHandle? _buffer;
public AddOrUpdateBuffer(IUnmangedHeap heap)
{
_heap = heap;
}
public void Advance(int count)
{
//Update count
_count += count;
}
public Memory GetMemory(int sizeHint = 0)
{
throw new NotImplementedException();
}
public Span GetSpan(int sizeHint = 0)
{
//Round to nearest page for new size
nint newSize = MemoryUtil.NearestPage(sizeHint + _count);
//Alloc buffer it not yet allocated
if (_buffer == null)
{
_buffer = _heap.Alloc(newSize);
}
else
{
//check for resize if allocated
_buffer.ResizeIfSmaller(newSize);
}
return _buffer.AsSpan(_count);
}
public void SetData(ReadOnlySpan data)
{
throw new NotSupportedException();
}
public ReadOnlySpan GetData()
{
//Get stored data from within handle
return _buffer!.AsSpan(0, _count);
}
protected override void Free()
{
_buffer?.Dispose();
}
}
}