func()

in freelist.go [125:170]

• 36 lines of code
• 9 McCabe index (conditional complexity)

func (f *freelist) AllocContinuousRegion(order *allocOrder, n uint) region {
	if f.avail < n || (f.avail == n && len(f.regions) > 1) {
		return region{}
	}

	if n > math.MaxUint32 { // continuous regions max out at 4GB
		return region{}
	}

	bestFit := -1
	bestSz := uint(math.MaxUint32)
	for i, end, next := order.iter(len(f.regions)); i != end; i = next(i) {
		count := uint(f.regions[i].count)
		if n <= count && count < bestSz {
			bestFit = i
			bestSz = count
			if bestSz == n {
				break
			}
		}
	}

	if bestFit < 0 {
		// no continuous region found
		return region{}
	}

	// allocate best fitting region from list
	i := bestFit
	selected := f.regions[i]
	allocated, rest := order.allocFromRegion(selected, uint32(n))

	invariant.Check(allocated.count == uint32(n), "allocation mismatch")
	invariant.Check(allocated.count+rest.count == selected.count, "region split page count mismatch")

	if rest.count == 0 {
		// remove entry
		copy(f.regions[i:], f.regions[i+1:])
		f.regions = f.regions[:len(f.regions)-1]
	} else {
		f.regions[i] = rest
	}

	f.avail -= uint(allocated.count)
	return allocated
}