Initial QSfera import

Server/vendor/github.com/dgraph-io/ristretto/z/simd/baseline.go

@@ -0,0 +1,130 @@
+package simd
+
+import (
+	"fmt"
+	"runtime"
+	"sort"
+	"sync"
+)
+
+// Search finds the key using the naive way
+func Naive(xs []uint64, k uint64) int16 {
+	var i int
+	for i = 0; i < len(xs); i += 2 {
+		x := xs[i]
+		if x >= k {
+			return int16(i / 2)
+		}
+	}
+	return int16(i / 2)
+}
+
+func Clever(xs []uint64, k uint64) int16 {
+	if len(xs) < 8 {
+		return Naive(xs, k)
+	}
+	var twos, pk [4]uint64
+	pk[0] = k
+	pk[1] = k
+	pk[2] = k
+	pk[3] = k
+	for i := 0; i < len(xs); i += 8 {
+		twos[0] = xs[i]
+		twos[1] = xs[i+2]
+		twos[2] = xs[i+4]
+		twos[3] = xs[i+6]
+		if twos[0] >= pk[0] {
+			return int16(i / 2)
+		}
+		if twos[1] >= pk[1] {
+			return int16((i + 2) / 2)
+		}
+		if twos[2] >= pk[2] {
+			return int16((i + 4) / 2)
+		}
+		if twos[3] >= pk[3] {
+			return int16((i + 6) / 2)
+		}
+
+	}
+	return int16(len(xs) / 2)
+}
+
+func Parallel(xs []uint64, k uint64) int16 {
+	cpus := runtime.NumCPU()
+	if cpus%2 != 0 {
+		panic(fmt.Sprintf("odd number of CPUs %v", cpus))
+	}
+	sz := len(xs)/cpus + 1
+	var wg sync.WaitGroup
+	retChan := make(chan int16, cpus)
+	for i := 0; i < len(xs); i += sz {
+		end := i + sz
+		if end >= len(xs) {
+			end = len(xs)
+		}
+		chunk := xs[i:end]
+		wg.Add(1)
+		go func(hd int16, xs []uint64, k uint64, wg *sync.WaitGroup, ch chan int16) {
+			for i := 0; i < len(xs); i += 2 {
+				if xs[i] >= k {
+					ch <- (int16(i) + hd) / 2
+					break
+				}
+			}
+			wg.Done()
+		}(int16(i), chunk, k, &wg, retChan)
+	}
+	wg.Wait()
+	close(retChan)
+	var min int16 = (1 << 15) - 1
+	for i := range retChan {
+		if i < min {
+			min = i
+		}
+	}
+	if min == (1<<15)-1 {
+		return int16(len(xs) / 2)
+	}
+	return min
+}
+
+func Binary(keys []uint64, key uint64) int16 {
+	return int16(sort.Search(len(keys), func(i int) bool {
+		if i*2 >= len(keys) {
+			return true
+		}
+		return keys[i*2] >= key
+	}))
+}
+
+//nolint:unused
+func cmp2_native(twos, pk [2]uint64) int16 {
+	if twos[0] == pk[0] {
+		return 0
+	}
+	if twos[1] == pk[1] {
+		return 1
+	}
+	return 2
+}
+
+//nolint:unused
+func cmp4_native(fours, pk [4]uint64) int16 {
+	for i := range fours {
+		if fours[i] >= pk[i] {
+			return int16(i)
+		}
+	}
+	return 4
+}
+
+//nolint:unused
+func cmp8_native(a [8]uint64, pk [4]uint64) int16 {
+	for i := range a {
+		if a[i] >= pk[0] {
+			return int16(i)
+		}
+	}
+	return 8
+}