hs-test: separate infra from tests

- most functions and vars now start with a capital letter:
  needed to access them outside the package that declares
  them
- updated README.md
- very minor changes in MAKEFILE

Type: test

Change-Id: I4b5a194f08f09d59e372e57da6451fbb5a1de4da
Signed-off-by: Adrian Villin <avillin@cisco.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/extras/hs-test/infra/cpu.go b/extras/hs-test/infra/cpu.go
new file mode 100644
index 00000000000..b5555d85b98
--- /dev/null
+++ b/extras/hs-test/infra/cpu.go
@@ -0,0 +1,100 @@
+package hst
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	. "github.com/onsi/ginkgo/v2"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+var CgroupPath = "/sys/fs/cgroup/"
+
+type CpuContext struct {
+	cpuAllocator *CpuAllocatorT
+	cpus         []int
+}
+
+type CpuAllocatorT struct {
+	cpus []int
+}
+
+var cpuAllocator *CpuAllocatorT = nil
+
+func (c *CpuAllocatorT) Allocate(containerCount int, nCpus int) (*CpuContext, error) {
+	var cpuCtx CpuContext
+
+	// splitting cpus into equal parts; this will over-allocate cores but it's good enough for now
+	maxContainerCount := 4
+	// skip CPU 0
+	minCpu := ((GinkgoParallelProcess() - 1) * maxContainerCount * nCpus) + 1
+	maxCpu := (GinkgoParallelProcess() * maxContainerCount * nCpus)
+
+	if len(c.cpus)-1 < maxCpu {
+		err := fmt.Errorf("could not allocate %d CPUs; available: %d; attempted to allocate cores %d-%d",
+			nCpus*containerCount, len(c.cpus)-1, minCpu, maxCpu)
+		return nil, err
+	}
+	if containerCount == 1 {
+		cpuCtx.cpus = c.cpus[minCpu : minCpu+nCpus]
+	} else if containerCount > 1 && containerCount <= maxContainerCount {
+		cpuCtx.cpus = c.cpus[minCpu+(nCpus*(containerCount-1)) : minCpu+(nCpus*containerCount)]
+	} else {
+		return nil, fmt.Errorf("too many containers; CPU allocation for >%d containers is not implemented", maxContainerCount)
+	}
+
+	cpuCtx.cpuAllocator = c
+	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
+}