private int ClaimCapacity(IAtomicBuffer buffer, int requiredCapacity)
{
var capacity = _capacity;
var tailPositionIndex = _tailPositionIndex;
var headCachePositionIndex = _headCachePositionIndex;
var mask = capacity - 1;
var head = buffer.GetLongVolatile(headCachePositionIndex);
long tail;
int tailIndex;
int padding;
do
{
tail = buffer.GetLongVolatile(tailPositionIndex);
var availableCapacity = capacity - (int)(tail - head);
if (requiredCapacity > availableCapacity)
{
head = buffer.GetLongVolatile(_headPositionIndex);
if (requiredCapacity > (capacity - (int)(tail - head)))
{
return(InsufficientCapacity);
}
buffer.PutLongOrdered(headCachePositionIndex, head);
}
padding = 0;
tailIndex = (int)tail & mask;
var toBufferEndLength = capacity - tailIndex;
if (requiredCapacity > toBufferEndLength)
{
var headIndex = (int)head & mask;
if (requiredCapacity > headIndex)
{
head = buffer.GetLongVolatile(_headPositionIndex);
headIndex = (int)head & mask;
if (requiredCapacity > headIndex)
{
return(InsufficientCapacity);
}
buffer.PutLongOrdered(headCachePositionIndex, head);
}
padding = toBufferEndLength;
}
} while (!buffer.CompareAndSetLong(tailPositionIndex, tail, tail + requiredCapacity + padding));
if (0 != padding)
{
buffer.PutLongOrdered(tailIndex, RecordDescriptor.MakeHeader(padding, PaddingMsgTypeId));
tailIndex = 0;
}
return(tailIndex);
}
private int ClaimCapacity(IAtomicBuffer buffer, int requiredCapacity)
{
var capacity = _capacity;
var tailPositionIndex = _tailPositionIndex;
var headCachePositionIndex = _headCachePositionIndex;
var mask = capacity - 1;
var head = buffer.GetLongVolatile(headCachePositionIndex);
long tail;
int tailIndex;
int padding;
do
{
tail = buffer.GetLongVolatile(tailPositionIndex);
var availableCapacity = capacity - (int) (tail - head);
if (requiredCapacity > availableCapacity)
{
head = buffer.GetLongVolatile(_headPositionIndex);
if (requiredCapacity > (capacity - (int) (tail - head)))
{
return InsufficientCapacity;
}
buffer.PutLongOrdered(headCachePositionIndex, head);
}
padding = 0;
tailIndex = (int) tail & mask;
var toBufferEndLength = capacity - tailIndex;
if (requiredCapacity > toBufferEndLength)
{
var headIndex = (int) head & mask;
if (requiredCapacity > headIndex)
{
head = buffer.GetLongVolatile(_headPositionIndex);
headIndex = (int) head & mask;
if (requiredCapacity > headIndex)
{
return InsufficientCapacity;
}
buffer.PutLongOrdered(headCachePositionIndex, head);
}
padding = toBufferEndLength;
}
} while (!buffer.CompareAndSetLong(tailPositionIndex, tail, tail + requiredCapacity + padding));
if (0 != padding)
{
buffer.PutLongOrdered(tailIndex, RecordDescriptor.MakeHeader(padding, PaddingMsgTypeId));
tailIndex = 0;
}
return tailIndex;
}
/// <summary>
/// Compare the current value to expected and if true then set to the update value atomically.
/// </summary>
/// <param name="expectedValue"> for the counter. </param>
/// <param name="updateValue"> for the counter. </param>
/// <returns> true if successful otherwise false. </returns>
public bool CompareAndSet(long expectedValue, long updateValue)
{
return(_buffer.CompareAndSetLong(_offset, expectedValue, updateValue));
}
