public MemoryMappedPage GetPage(int blockId)
{
if (blockId < 0)
{
throw new ArgumentOutOfRangeException("blockId");
}
int pageIndex = blockId / this.BlocksPerPage;
int index = 0;
lock (_pages)
{
//在页面队列中查找指定页面号的页面对象，如果找到则直接返回
for (; index < _pages.Length; index++)
{
if (_pages[index] == null)
{
break;
}
if (pageIndex == _pages[index].PageIndex)
{
return(_pages[index]);
}
}
//获取即将要彻底销毁的页面对象
var page = _pages[Math.Min(index, _pages.Length - 1)];
//如果即将要销毁的页面对象不为空则彻底销毁它
if (page != null)
{
page.Kill();
}
//以下循环移动待页面队列，以腾出位置给新页面对象
for (int i = Math.Min(index, _pages.Length - 1); i > 0; i--)
{
_pages[i] = _pages[i - 1];
}
return(_pages[0] = new MemoryMappedPage(this, pageIndex, _bufferManager.Storage.CreateViewStream(_storagePosition + (pageIndex * PageSize), PageSize)));
}
}
public MemoryMappedPage GetPage(int blockId)
{
if(blockId < 0)
throw new ArgumentOutOfRangeException("blockId");
int pageIndex = blockId / this.BlocksPerPage;
int index = 0;
lock(_pages)
{
//在页面队列中查找指定页面号的页面对象，如果找到则直接返回
for(; index < _pages.Length; index++)
{
if(_pages[index] == null)
break;
if(pageIndex == _pages[index].PageIndex)
return _pages[index];
}
//获取即将要彻底销毁的页面对象
var page = _pages[Math.Min(index, _pages.Length - 1)];
//如果即将要销毁的页面对象不为空则彻底销毁它
if(page != null)
page.Kill();
//以下循环移动待页面队列，以腾出位置给新页面对象
for(int i = Math.Min(index, _pages.Length - 1); i > 0; i--)
{
_pages[i] = _pages[i - 1];
}
return _pages[0] = new MemoryMappedPage(this, pageIndex, _bufferManager.Storage.CreateViewStream(_storagePosition + (pageIndex * PageSize), PageSize));
}
}
