/// <summary>
/// 分配Page
/// </summary>
/// <param name="buf"></param>
/// <param name="elemSize">Page页的元素尺寸</param>
/// <param name="size">实际申请的字节数</param>
/// <returns></returns>
public PoolPage AllocPage(IByteBuf buf, int elemSize, int size)
{
if (!this.CanAlloc)
{
return(null);
}
//如果可用的字节数不足则返回null
if (this.Availables < size)
{
return(null);
}
PoolPage page = AllocPage(elemSize, size);
if (page == null)
{
return(null);
}
//分配一个句柄
long handle = page.Alloc(elemSize);
//计算偏移
int offset = HandleToOffset(handle, elemSize);
//初始化ByteBuf
BytebufInit(this.memory, buf, handle, offset, size);
return(page);
}
/// <summary>
/// 申请一个Page
/// </summary>
/// <param name="elemSize">page元素的尺寸</param>
/// <param name="size">实际申请的内存尺寸</param>
/// <returns></returns>
public PoolPage AllocPage(int elemSize, int size)
{
//如果可用的字节数不足则返回null
if (this.Availables < size)
{
return(null);
}
//计算申请内存尺寸在memoryMap中的深度
AllocInfo alloc = CalcAllocDepth(size);
//通过深度获得节点编号
int id = AllocHandle(alloc.Depth);
int tableId = PageIdx(id);
PoolPage page = subpages[tableId];
if (page == null)
{
page = new PoolPage(this, id, alloc.PageCapacity, elemSize);
subpages[tableId] = page;
}
else if (!page.Allocated)
{
//找到一个被重置过的Page则重新进行分配
page.ReAlloc(alloc.PageCapacity, elemSize);
}
usedables += pageSize;
return(page);
}
public bool TryAllocPage(IByteBuf buf, int newSize, int size, out PoolPage page)
{
page = null;
if (Head == Tail && Head == null)
{
return(false);
}
PoolChunk chunk = Head;
page = chunk.AllocPage(buf, newSize, size);
while (page == null)
{
chunk = chunk.Next;
if (chunk == null)
{
return(false);
}
page = chunk.AllocPage(buf, newSize, size);
}
//转移chunk
TryTransfer(chunk);
return(true);
}
private void ValidHandle(int handle)
{
try
{
PoolPage page = subpages[PageIdx(handle)];
if (page == null)
{
throw new IndexOutOfRangeException();
}
}
catch (IndexOutOfRangeException)
{
throw new IndexOutOfRangeException("handle的值不合法");
}
}
/// <summary>
/// 释放handle，当length=PageSize则表示释放整个Page的长度
/// 否则只释放length长度
///
/// 异常：
/// IndexOutOfRangeException：如果handle不合法抛出异常
/// IndexOutOfRangeException
///
/// </summary>
/// <param name="handle">需要释放的句柄</param>
/// <param name="length">需要释放的长度</param>
public void Return(int handle)
{
ValidHandle(handle);
//将当前节点的值还原
SetValue(handle, ValueDefaut(handle));
//更新父节点
UpdateParentNodeAllocation(handle);
PoolPage page = subpages[PageIdx(handle)];
page.Clear();
usedables -= pageSize;
//如果chunk空了。
if (usedables == 0)
{
Return();
arena.Return(this);
}
}