private void AllocateMemory(int sizeHint)
{
if (_head == null)
{
// We need to allocate memory to write since nobody has written before
BufferSegment newSegment = AllocateSegment(sizeHint);
// Set all the pointers
_head = _tail = newSegment;
_tailBytesBuffered = 0;
}
else
{
int bytesLeftInBuffer = _tailMemory.Length;
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < sizeHint)
{
if (_tailBytesBuffered > 0)
{
// Flush buffered data to the segment
_tail.End += _tailBytesBuffered;
_tailBytesBuffered = 0;
}
BufferSegment newSegment = AllocateSegment(sizeHint);
_tail.SetNext(newSegment);
_tail = newSegment;
}
}
}
private void AllocateWriteHeadUnsynchronized(int sizeHint)
{
_operationState.BeginWrite();
if (_writingHead == null)
{
// We need to allocate memory to write since nobody has written before
BufferSegment newSegment = CreateSegmentUnsynchronized();
newSegment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint)));
// Set all the pointers
_writingHead = _readHead = _readTail = newSegment;
}
else
{
int bytesLeftInBuffer = _writingHead.WritableBytes;
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < sizeHint)
{
BufferSegment newSegment = CreateSegmentUnsynchronized();
newSegment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint)));
_writingHead.SetNext(newSegment);
_writingHead = newSegment;
}
}
}
internal Memory <byte> GetMemory(int minimumSize)
{
if (_writerCompletion.IsCompleted)
{
ThrowHelper.ThrowInvalidOperationException_NoWritingAllowed();
}
if (minimumSize < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.minimumSize);
}
lock (_sync)
{
BufferSegment segment = _writingHead ?? AllocateWriteHeadUnsynchronized(minimumSize);
int bytesLeftInBuffer = segment.WritableBytes;
// If inadequate bytes left or if the segment is readonly
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < minimumSize || segment.ReadOnly)
{
BufferSegment nextSegment = CreateSegmentUnsynchronized();
nextSegment.SetMemory(_pool.Rent(Math.Max(_minimumSegmentSize, minimumSize)));
segment.SetNext(nextSegment);
_writingHead = nextSegment;
}
}
return(_writingHead.AvailableMemory.Slice(_writingHead.End, _writingHead.WritableBytes));
}
private void AllocateWriteHeadSynchronized(int sizeHint)
{
lock (_sync)
{
_operationState.BeginWrite();
if (_writingHead == null)
{
// We need to allocate memory to write since nobody has written before
BufferSegment newSegment = AllocateSegment(sizeHint);
// Set all the pointers
_writingHead = _readHead = _readTail = _lastExamined = newSegment;
}
else
{
int bytesLeftInBuffer = _writingMemory.Length;
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < sizeHint)
{
if (_buffered > 0)
{
// Flush buffered data to the segment
_writingHead.End += _buffered;
_buffered = 0;
}
BufferSegment newSegment = AllocateSegment(sizeHint);
_writingHead.SetNext(newSegment);
_writingHead = newSegment;
}
}
}
}
private void AllocateWriteHeadUnsynchronized(int sizeHint)
{
BufferSegment segment = null;
if (_writingHead != null)
{
segment = _writingHead;
int bytesLeftInBuffer = segment.WritableBytes;
// If inadequate bytes left or if the segment is readonly
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < sizeHint || segment.ReadOnly)
{
BufferSegment nextSegment = CreateSegmentUnsynchronized();
nextSegment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint)));
segment.SetNext(nextSegment);
_writingHead = nextSegment;
}
}
else
{
if (_commitHead != null && !_commitHead.ReadOnly)
{
// Try to return the tail so the calling code can append to it
int remaining = _commitHead.WritableBytes;
if (sizeHint <= remaining && remaining > 0)
{
// Free tail space of the right amount, use that
segment = _commitHead;
// Set write head to assigned segment
_writingHead = segment;
return;
}
}
// No free tail space, allocate a new segment
segment = CreateSegmentUnsynchronized();
segment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint)));
if (_commitHead == null)
{
// No previous writes have occurred
_commitHead = segment;
}
else if (segment != _commitHead && _commitHead.Next == null)
{
// Append the segment to the commit head if writes have been committed
// and it isn't the same segment (unused tail space)
_commitHead.SetNext(segment);
}
// Set write head to assigned segment
_writingHead = segment;
}
}
private void CreateNewTailSegment()
{
var nextSegment = CreateBufferSegment();
nextSegment.SetMemory(_pool.Rent(GetSegmentSize()));
_readTail.SetNext(nextSegment);
_readTail = nextSegment;
}
private BufferSegment AllocateWriteHeadUnsynchronized(int count)
{
BufferSegment segment = null;
if (_commitHead != null && !_commitHead.ReadOnly)
{
// Try to return the tail so the calling code can append to it
int remaining = _commitHead.WritableBytes;
if (count <= remaining)
{
// Free tail space of the right amount, use that
segment = _commitHead;
}
}
if (segment == null)
{
// No free tail space, allocate a new segment
segment = CreateSegmentUnsynchronized();
segment.SetMemory(_pool.Rent(count));
}
if (_commitHead == null)
{
// No previous writes have occurred
_commitHead = segment;
}
else if (segment != _commitHead && _commitHead.Next == null)
{
// Append the segment to the commit head if writes have been committed
// and it isn't the same segment (unused tail space)
_commitHead.SetNext(segment);
}
// Set write head to assigned segment
_writingHead = segment;
return(segment);
}
internal void Append(ReadableBuffer buffer)
{
if (buffer.IsEmpty)
{
return; // nothing to do
}
EnsureAlloc();
BufferSegment clonedEnd;
var clonedBegin = BufferSegment.Clone(buffer.Start, buffer.End, out clonedEnd);
if (_writingHead == null)
{
// No active write
lock (_sync)
{
if (_commitHead == null)
{
// No allocated buffers yet, not locking as _readHead will be null
_commitHead = clonedBegin;
}
else
{
Debug.Assert(_commitHead.Next == null);
// Allocated buffer, append as next segment
_commitHead.SetNext(clonedBegin);
}
}
}
else
{
Debug.Assert(_writingHead.Next == null);
// Active write, append as next segment
_writingHead.SetNext(clonedBegin);
}
// Move write head to end of buffer
_writingHead = clonedEnd;
_currentWriteLength += buffer.Length;
}
internal Memory <byte> GetMemory(int sizeHint)
{
if (_writerCompletion.IsCompleted)
{
ThrowHelper.ThrowInvalidOperationException_NoWritingAllowed();
}
if (sizeHint < 0)
{
ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.minimumSize);
}
lock (_sync)
{
BufferSegment segment = _writingHead ?? AllocateWriteHeadUnsynchronized(sizeHint);
int bytesLeftInBuffer = segment.WritableBytes;
// If inadequate bytes left or if the segment is readonly
if (bytesLeftInBuffer == 0 || bytesLeftInBuffer < sizeHint || segment.ReadOnly)
{
BufferSegment nextSegment = CreateSegmentUnsynchronized();
nextSegment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint)));
segment.SetNext(nextSegment);
_writingHead = nextSegment;
}
}
// Slice the AvailableMemory to the WritableBytes size
int end = _writingHead.End;
Memory <byte> availableMemory = _writingHead.AvailableMemory;
availableMemory = availableMemory.Slice(end, availableMemory.Length - end);
return(availableMemory);
}
