func()

in alloc.go [639:682]

• 31 lines of code
• 6 McCabe index (conditional complexity)

func (a *dataAllocator) Free(st *txAllocState, id PageID) {
	traceln("free page:", id)

	if id < 2 || id >= a.data.endMarker {
		panic(fmt.Sprintf("freed page ID %v out of bounds", id))
	}

	a.onFree(st, 1)

	if !st.data.new.Has(id) {
		// fast-path, page has not been allocated in current transaction
		st.data.freed.Add(id)
		return
	}

	// page has been allocated in current transaction -> return to allocator for immediate re-use
	a.data.freelist.AddRegion(region{id: id, count: 1})

	if st.data.endMarker >= id {
		// allocation from within old data region
		return
	}

	// allocation was from past the old end-marker. Check if we can shrink the
	// end marker again
	regions := a.data.freelist.regions
	last := len(regions) - 1
	start, end := regions[last].Range()
	if end < a.data.endMarker {
		// in middle of new data region -> can not adjust end marker -> keep update to freelist
		return
	}

	if st.data.endMarker > start {
		start = st.data.endMarker
		count := uint(end - start)
		regions[last].count -= uint32(count)
		a.data.freelist.avail -= count
	} else {
		a.data.freelist.avail -= uint(regions[last].count)
		a.data.freelist.regions = regions[:last]
	}
	a.data.endMarker = start
}