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));
}
public static BufferSegment Clone(ReadCursor beginBuffer, ReadCursor endBuffer, out BufferSegment lastSegment)
{
var beginOrig = beginBuffer.Segment;
var endOrig = endBuffer.Segment;
if (beginOrig == endOrig)
{
lastSegment = new BufferSegment();
lastSegment.SetMemory(beginOrig._owned, beginBuffer.Index, endBuffer.Index);
return(lastSegment);
}
var beginClone = new BufferSegment();
beginClone.SetMemory(beginOrig._owned, beginBuffer.Index, beginOrig.End);
var endClone = beginClone;
beginOrig = beginOrig.Next;
while (beginOrig != endOrig)
{
var next = new BufferSegment();
next.SetMemory(beginOrig._owned, beginOrig.Start, beginOrig.End);
endClone.SetNext(next);
endClone = endClone.Next;
beginOrig = beginOrig.Next;
}
lastSegment = new BufferSegment();
lastSegment.SetMemory(endOrig._owned, endOrig.Start, endBuffer.Index);
endClone.SetNext(lastSegment);
return(beginClone);
}
public static BufferSegment Clone(BufferSegment start, int startIndex, BufferSegment end, int endIndex, out BufferSegment lastSegment)
{
var beginOrig = start;
var endOrig = end;
if (beginOrig == endOrig)
{
lastSegment = new BufferSegment();
lastSegment.SetMemory(beginOrig._ownedMemory, startIndex, endIndex);
return(lastSegment);
}
var beginClone = new BufferSegment();
beginClone.SetMemory(beginOrig._ownedMemory, startIndex, beginOrig.End);
var endClone = beginClone;
beginOrig = beginOrig.Next;
while (beginOrig != endOrig)
{
var next = new BufferSegment();
next.SetMemory(beginOrig._ownedMemory, beginOrig.Start, beginOrig.End);
endClone.SetNext(next);
endClone = endClone.Next;
beginOrig = beginOrig.Next;
}
lastSegment = new BufferSegment();
lastSegment.SetMemory(endOrig._ownedMemory, endOrig.Start, endIndex);
endClone.SetNext(lastSegment);
return(beginClone);
}
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 AdvanceTo(BufferSegment consumedSegment, int consumedIndex, BufferSegment examinedSegment, int examinedIndex)
{
if (consumedSegment == null)
{
return;
}
var returnStart = _readHead;
var returnEnd = consumedSegment;
var consumedBytes = new ReadOnlySequence <byte>(returnStart, _readIndex, consumedSegment, consumedIndex).Length;
_bufferedBytes -= consumedBytes;
Debug.Assert(_bufferedBytes >= 0);
_examinedEverything = false;
if (examinedSegment == _readTail)
{
// If we examined everything, we force ReadAsync to actually read from the underlying stream
// instead of returning a ReadResult from TryRead.
_examinedEverything = examinedIndex == _readTail.End;
}
// Three cases here:
// 1. All data is consumed. If so, we reset _readHead and _readTail to _readTail's original memory owner
// SetMemory on a IMemoryOwner will reset the internal Memory<byte> to be an empty segment
// 2. A segment is entirely consumed but there is still more data in nextSegments
// We are allowed to remove an extra segment. by setting returnEnd to be the next block.
// 3. We are in the middle of a segment.
// Move _readHead and _readIndex to consumedSegment and index
if (_bufferedBytes == 0)
{
_readTail.SetMemory(_readTail.MemoryOwner);
_readHead = _readTail;
returnEnd = _readTail;
_readIndex = 0;
}
else if (consumedIndex == returnEnd.Length)
{
var nextBlock = returnEnd.NextSegment;
_readHead = nextBlock;
_readIndex = 0;
returnEnd = nextBlock;
}
else
{
_readHead = consumedSegment;
_readIndex = consumedIndex;
}
// Remove all blocks that are freed (except the last one)
while (returnStart != returnEnd)
{
returnStart.ResetMemory();
returnStart = returnStart.NextSegment;
}
}
private static ReadableBuffer CreateInternal(OwnedMemory <byte> data, int offset, int length)
{
var segment = new BufferSegment();
segment.SetMemory(data, offset, offset + length);
return(new ReadableBuffer(new ReadCursor(segment, offset), new ReadCursor(segment, offset + length)));
}
private BufferSegment AllocateSegment(int sizeHint)
{
BufferSegment newSegment = CreateSegmentUnsynchronized();
if (_pool is null)
{
// Use the array pool
newSegment.SetMemory(ArrayPool <byte> .Shared.Rent(GetSegmentSize(sizeHint)));
}
else if (sizeHint <= _pool.MaxBufferSize)
{
// Use the specified pool if it fits
newSegment.SetMemory(_pool.Rent(GetSegmentSize(sizeHint, _pool.MaxBufferSize)));
}
else
{
// We can't use the pool so allocate an array
newSegment.SetUnownedMemory(new byte[sizeHint]);
}
return(newSegment);
}
private void AllocateReadTail()
{
if (_readHead == null)
{
Debug.Assert(_readTail == null);
_readHead = CreateBufferSegment();
_readHead.SetMemory(_pool.Rent(GetSegmentSize()));
_readTail = _readHead;
}
else if (_readTail.WritableBytes < _minimumReadThreshold)
{
CreateNewTailSegment();
}
}
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 && remaining > 0)
{
// 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(Math.Max(_minimumSegmentSize, 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 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);
}
