func()

in cpc/cpc_sketch.go [273:331]

• 55 lines of code
• 14 McCabe index (conditional complexity)

func (c *CpcSketch) updateWindowed(rowCol int) error {
	if c.windowOffset < 0 || c.windowOffset > 56 {
		return fmt.Errorf("windowOffset < 0 || windowOffset > 56")
	}
	k := uint64(1) << c.lgK
	c32pre := c.numCoupons << 5
	if c32pre < (3 * k) {
		return fmt.Errorf("C < 3K/32")
	}
	c8pre := c.numCoupons << 3
	w8pre := uint64(c.windowOffset << 3)
	if c8pre >= ((uint64(27) + w8pre) * k) {
		return fmt.Errorf("C >= (K * 27/8) + (K * windowOffset)")
	}

	isNovel := false //novel if new coupon
	err := error(nil)
	col := rowCol & 63

	if col < c.windowOffset { // track the surprising 0's "before" the window
		isNovel, err = c.pairTable.maybeDelete(rowCol)
		if err != nil {
			return err
		}
	} else if col < (c.windowOffset + 8) { // track the 8 bits inside the window
		row := rowCol >> 6
		oldBits := c.slidingWindow[row]
		newBits := oldBits | (1 << (col - c.windowOffset))
		if newBits != oldBits {
			c.slidingWindow[row] = newBits
			isNovel = true
		}
	} else { // track the surprising 1's "after" the window
		isNovel, err = c.pairTable.maybeInsert(rowCol)
		if err != nil {
			return err
		}
	}

	if isNovel {
		c.numCoupons++
		c.updateHIP(rowCol)
		c8post := c.numCoupons << 3
		if c8post >= ((27 + w8pre) * k) {
			if err := c.modifyOffset(c.windowOffset + 1); err != nil {
				return err
			}
			if c.windowOffset < 1 || c.windowOffset > 56 {
				return fmt.Errorf("windowOffset < 1 || windowOffset > 56")
			}
			w8post := uint64(c.windowOffset << 3)
			if c8post >= ((uint64(27) + w8post) * k) {
				return fmt.Errorf("C < (K * 27/8) + (K * windowOffset)")
			}
		}

	}
	return nil
}