private async Task <ForkedStreamBuffer> GetNextPageAsync()
{
if (this.IsLastPage)
{
return(null);
}
if (_nextPage == null)
{
await _navGuard.WaitAsync();
try
{
if (_nextPage == null)
{
if (_pageAvailable != null)
{
await _pageAvailable.WaitAsync();
}
_nextPage = new ForkedStreamBuffer(this);
}
}
finally
{
_navGuard.Release();
}
}
return(_nextPage);
}
public async override Task <int> ReadAsync(byte[] buffer, int offset, int count, CancellationToken cancellationToken = default(CancellationToken))
{
if (_buffer == null)
{
return(0);
}
var startPos = _position;
_buffer = await _buffer.ReadAsync(this, buffer, offset, count);
return(Convert.ToInt32(_position - startPos));
}
public static Stream[] Fork(this Stream stream, int count, long bufferSize = 0)
{
Stream[] streams = new Stream[count];
var buff = ForkedStreamBuffer.FromStream(stream, count, bufferSize);
for (int i = 0; i < count; i++)
{
streams[i] = new ForkStream(buff);
}
return(streams);
}
private ForkedStreamBuffer(Stream source, int feedCount, int pageSize, long basePos, SemaphoreSlim pagesAvailable)
{
_source = source;
_pageData = new byte[pageSize];
_basePos = basePos;
_bytesRead = 0;
_feedCount = feedCount;
_readCount = 0;
_initialized = false;
_navGuard = new SemaphoreSlim(1, 1);
_initGuard = new SemaphoreSlim(1, 1);
_pageAvailable = pagesAvailable;
_nextPage = null;
}
public ForkStream(ForkedStreamBuffer buffer)
{
_buffer = buffer;
_position = 0;
}
private ForkedStreamBuffer(ForkedStreamBuffer prevPage) :
this(prevPage._source, prevPage._feedCount, prevPage.PageSize, prevPage._basePos + prevPage.PageSize, prevPage._pageAvailable)
{
}