1 files changed, 90 insertions, 0 deletions
diff --git a/extras/hs-test/cpu.go b/extras/hs-test/cpu.go
new file mode 100644
index 00000000000..a976f47d8a5
--- /dev/null
+++ b/extras/hs-test/cpu.go
@@ -0,0 +1,90 @@
+package main
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+var CgroupPath = "/sys/fs/cgroup/"
+
+type CpuContext struct {
+	cpuAllocator *CpuAllocatorT
+	cpus         []int
+}
+
+func (c *CpuContext) Release() {
+	c.cpuAllocator.cpus = append(c.cpuAllocator.cpus, c.cpus...)
+	c.cpus = c.cpus[:0] // empty the list
+}
+
+type CpuAllocatorT struct {
+	cpus []int
+}
+
+var cpuAllocator *CpuAllocatorT = nil
+
+func (c *CpuAllocatorT) Allocate(nCpus int) (*CpuContext, error) {
+	var cpuCtx CpuContext
+
+	if len(c.cpus) < nCpus {
+		return nil, fmt.Errorf("could not allocate %d CPUs; available: %d", nCpus, len(c.cpus))
+	}
+	cpuCtx.cpus = c.cpus[0:nCpus]
+	cpuCtx.cpuAllocator = c
+	c.cpus = c.cpus[nCpus:]
+	return &cpuCtx, nil
+}
+
+func (c *CpuAllocatorT) readCpus() error {
+	var first, last int
+
+	// Path depends on cgroup version. We need to check which version is in use.
+	// For that following command can be used: 'stat -fc %T /sys/fs/cgroup/'
+	// In case the output states 'cgroup2fs' then cgroups v2 is used, 'tmpfs' in case cgroups v1.
+	cmd := exec.Command("stat", "-fc", "%T", "/sys/fs/cgroup/")
+	byteOutput, err := cmd.CombinedOutput()
+	if err != nil {
+		return err
+	}
+	CpuPath := CgroupPath
+	if strings.Contains(string(byteOutput), "tmpfs") {
+		CpuPath += "cpuset/cpuset.effective_cpus"
+	} else if strings.Contains(string(byteOutput), "cgroup2fs") {
+		CpuPath += "cpuset.cpus.effective"
+	} else {
+		return errors.New("cgroup unknown fs: " + string(byteOutput))
+	}
+
+	file, err := os.Open(CpuPath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	sc := bufio.NewScanner(file)
+	sc.Scan()
+	line := sc.Text()
+	_, err = fmt.Sscanf(line, "%d-%d", &first, &last)
+	if err != nil {
+		return err
+	}
+	for i := first; i <= last; i++ {
+		c.cpus = append(c.cpus, i)
+	}
+	return nil
+}
+
+func CpuAllocator() (*CpuAllocatorT, error) {
+	if cpuAllocator == nil {
+		cpuAllocator = new(CpuAllocatorT)
+		err := cpuAllocator.readCpus()
+		if err != nil {
+			return nil, err
+		}
+	}
+	return cpuAllocator, nil
+}