public static int Seek(ReadCursor begin, ReadCursor end, out ReadCursor result, byte byte0)
{
var enumerator = new SegmentEnumerator(begin, end);
while (enumerator.MoveNext())
{
var segmentPart = enumerator.Current;
var segment = segmentPart.Segment;
var span = segment.Buffer.Span.Slice(segmentPart.Start, segmentPart.Length);
int index = span.IndexOf(byte0);
if (index != -1)
{
result = new ReadCursor(segment, segmentPart.Start + index);
return(span[index]);
}
}
result = end;
return(-1);
}
private void GetResult(ref ReadResult result)
{
if (_writerCompletion.IsCompletedOrThrow())
{
result.ResultFlags |= ResultFlags.Completed;
}
var isCancelled = _readerAwaitable.ObserveCancelation();
if (isCancelled)
{
result.ResultFlags |= ResultFlags.Cancelled;
}
// No need to read end if there is no head
var head = _readHead;
if (head != null)
{
// Reading commit head shared with writer
result.ResultBuffer.BufferEnd.Segment = _commitHead;
result.ResultBuffer.BufferEnd.Index = _commitHeadIndex;
result.ResultBuffer.BufferLength = ReadCursor.GetLength(head, head.Start, _commitHead, _commitHeadIndex);
result.ResultBuffer.BufferStart.Segment = head;
result.ResultBuffer.BufferStart.Index = head.Start;
}
if (isCancelled)
{
_readingState.BeginTentative(ExceptionResource.AlreadyReading);
}
else
{
_readingState.Begin(ExceptionResource.AlreadyReading);
}
}
// Reading
void IPipeReader.Advance(ReadCursor consumed, ReadCursor examined)
{
BufferSegment returnStart = null;
BufferSegment returnEnd = null;
// Reading commit head shared with writer
Action continuation = null;
lock (_sync)
{
var examinedEverything = examined.Segment == _commitHead && examined.Index == _commitHeadIndex;
if (!consumed.IsDefault)
{
if (_readHead == null)
{
PipelinesThrowHelper.ThrowInvalidOperationException(ExceptionResource.AdvanceToInvalidCursor);
return;
}
returnStart = _readHead;
returnEnd = consumed.Segment;
// Check if we crossed _maximumSizeLow and complete backpressure
var consumedBytes = ReadCursor.GetLength(returnStart, returnStart.Start, consumed.Segment, consumed.Index);
var oldLength = _length;
_length -= consumedBytes;
if (oldLength >= _maximumSizeLow &&
_length < _maximumSizeLow)
{
continuation = _writerAwaitable.Complete();
}
// Check if we consumed entire last segment
// if we are going to return commit head
// we need to check that there is no writing operation that
// might be using tailspace
if (consumed.Index == returnEnd.End &&
!(_commitHead == returnEnd && _writingState.IsActive))
{
var nextBlock = returnEnd.Next;
if (_commitHead == returnEnd)
{
_commitHead = nextBlock;
_commitHeadIndex = nextBlock?.Start ?? 0;
}
_readHead = nextBlock;
returnEnd = nextBlock;
}
else
{
_readHead = consumed.Segment;
_readHead.Start = consumed.Index;
}
}
// We reset the awaitable to not completed if we've examined everything the producer produced so far
// but only if writer is not completed yet
if (examinedEverything && !_writerCompletion.IsCompleted)
{
// Prevent deadlock where reader awaits new data and writer await backpressure
if (!_writerAwaitable.IsCompleted)
{
PipelinesThrowHelper.ThrowInvalidOperationException(ExceptionResource.BackpressureDeadlock);
}
_readerAwaitable.Reset();
}
_readingState.End(ExceptionResource.NoReadToComplete);
}
while (returnStart != null && returnStart != returnEnd)
{
returnStart.Dispose();
returnStart = returnStart.Next;
}
TrySchedule(_writerScheduler, continuation);
}
public static void Advance(this IPipeReader input, ReadCursor cursor)
{
input.Advance(cursor, cursor);
}
internal ReadableBuffer(ReadCursor start, ReadCursor end)
{
BufferStart = start;
BufferEnd = end;
BufferLength = start.GetLength(end);
}
internal void ClearCursors()
{
BufferStart = default(ReadCursor);
BufferEnd = default(ReadCursor);
}
/// <summary>
/// Forms a slice out of the given <see cref="ReadableBuffer"/>, beginning at 'start', ending at the existing <see cref="ReadableBuffer"/>'s end.
/// </summary>
/// <param name="start">The starting (inclusive) <see cref="ReadCursor"/> at which to begin this slice.</param>
public ReadableBuffer Slice(ReadCursor start)
{
BufferEnd.BoundsCheck(start);
return(new ReadableBuffer(start, BufferEnd));
}
/// <summary>
///
/// </summary>
public BufferEnumerator(ReadCursor start, ReadCursor end)
{
_segmentEnumerator = new SegmentEnumerator(start, end);
_current = default(Buffer <byte>);
}
