/// <summary>
/// Forms a slice out of the given <see cref="ReadableBuffer"/>, beginning at 'start', and is at most length bytes
/// </summary>
/// <param name="start">The index at which to begin this slice.</param>
/// <param name="length">The length of the slice</param>
public ReadableBuffer Slice(long start, long length)
{
var begin = ReadCursorOperations.Seek(BufferStart, BufferEnd, start, false);
var end = ReadCursorOperations.Seek(begin, BufferEnd, length, false);
return(new ReadableBuffer(begin, end));
}
/// <summary>
/// Forms a slice out of the given <see cref="ReadableBuffer"/>, beginning at 'start', ending at 'end' (inclusive).
/// </summary>
/// <param name="start">The starting (inclusive) <see cref="ReadCursor"/> at which to begin this slice.</param>
/// <param name="end">The ending (inclusive) <see cref="ReadCursor"/> of the slice</param>
public ReadableBuffer Slice(ReadCursor start, ReadCursor end)
{
ReadCursorOperations.BoundsCheck(BufferEnd, end);
ReadCursorOperations.BoundsCheck(end, start);
return(new ReadableBuffer(start, end));
}
/// <summary>
/// Forms a slice out of the given <see cref="ReadableBuffer"/>, beginning at 'start', ending at 'end' (inclusive).
/// </summary>
/// <param name="start">The index at which to begin this slice.</param>
/// <param name="end">The end (inclusive) of the slice</param>
public ReadableBuffer Slice(long start, ReadCursor end)
{
ReadCursorOperations.BoundsCheck(BufferEnd, end);
var begin = ReadCursorOperations.Seek(BufferStart, end, start);
return(new ReadableBuffer(begin, end));
}
public ReadCursor Move(ReadCursor cursor, long count)
{
if (count < 0)
{
throw new ArgumentOutOfRangeException(nameof(count));
}
return(ReadCursorOperations.Seek(cursor, BufferEnd, count, false));
}
/// <summary>
/// Forms a slice out of the given <see cref="ReadableBuffer"/>, beginning at 'start', and is at most length bytes
/// </summary>
/// <param name="start">The starting (inclusive) <see cref="ReadCursor"/> at which to begin this slice.</param>
/// <param name="length">The length of the slice</param>
public ReadableBuffer Slice(ReadCursor start, long length)
{
ReadCursorOperations.BoundsCheck(BufferEnd, start);
var end = ReadCursorOperations.Seek(start, BufferEnd, length, false);
return(new ReadableBuffer(start, end));
}
/// <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 start index at which to begin this slice.</param>
public ReadableBuffer Slice(long start)
{
if (start == 0)
{
return(this);
}
var begin = ReadCursorOperations.Seek(BufferStart, BufferEnd, start, false);
return(new ReadableBuffer(begin, BufferEnd));
}
public bool TryGet(ref Position position, out ReadOnlyMemory <byte> item, bool advance = true)
{
if (position == default)
{
item = default;
return(false);
}
var(segment, index) = position.Get <object>();
var result = ReadCursorOperations.TryGetBuffer(new ReadCursor(segment, index), _buffer.End, out item, out var next);
if (advance)
{
position = Position.Create(next.Segment, next.Index);
}
return(result);
}
// 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)
{
bool examinedEverything = false;
if (examined.Segment == _commitHead)
{
examinedEverything = _commitHead != null ? examined.Index == _commitHeadIndex - _commitHead.Start : examined.Index == 0;
}
if (!consumed.IsDefault)
{
if (_readHead == null)
{
PipelinesThrowHelper.ThrowInvalidOperationException(ExceptionResource.AdvanceToInvalidCursor);
return;
}
var consumedSegment = consumed.Get <BufferSegment>();
returnStart = _readHead;
returnEnd = consumedSegment;
// Check if we crossed _maximumSizeLow and complete backpressure
var consumedBytes = ReadCursorOperations.GetLength(returnStart, _readHeadIndex, consumedSegment, 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.Length &&
!(_commitHead == returnEnd && _writingState.IsActive))
{
var nextBlock = returnEnd.NextSegment;
if (_commitHead == returnEnd)
{
_commitHead = nextBlock;
_commitHeadIndex = 0;
}
_readHead = nextBlock;
_readHeadIndex = 0;
returnEnd = nextBlock;
}
else
{
_readHead = consumedSegment;
_readHeadIndex = 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.ResetMemory();
ReturnSegmentUnsynchronized(returnStart);
returnStart = returnStart.NextSegment;
}
}
TrySchedule(_writerScheduler, continuation);
}
