Function NewCircularBuffer

internal/profiling/buffer/buffer.go:144–167

NewCircularBuffer allocates a circular buffer of size size and returns a reference to the struct. Only circular buffers of size 2^k are allowed (saves us from having to do expensive modulo operations).

(size uint32)

// reference to the struct. Only circular buffers of size 2^k are allowed
// (saves us from having to do expensive modulo operations).
func NewCircularBuffer(size uint32) (*CircularBuffer, error) {
	if size&(size-1) != 0 {
		return nil, errInvalidCircularBufferSize
	}

	n := numCircularBufferPairs
	if size/numCircularBufferPairs < 8 {
		// If each circular buffer is going to hold less than a very small number
		// of items (let's say 8), using multiple circular buffers is very likely
		// wasteful. Instead, fallback to one circular buffer holding everything.
		n = 1
	}

	cb := &CircularBuffer{
		qp:     make([]*queuePair, n),
		qpMask: n - 1,
	}

	for i := uint32(0); i < n; i++ {
		cb.qp[i] = newQueuePair(size / n)
	}

	return cb, nil
}

// Push pushes an element in to the circular buffer. Guaranteed to complete in
// a finite number of steps (also lock-free). Does not guarantee that push