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kubelet/kuberuntime: use sync.OnceValue

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This was added to Go 1.21, and makes the code simpler.

(Best reviewed ignoring changes in amount of whitespace).

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
This commit is contained in:
Kir Kolyshkin 2024-11-07 13:09:09 -08:00
parent 3a1b0f2864
commit 19477b7eed
1 changed files with 23 additions and 30 deletions
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53
pkg/kubelet/kuberuntime/kuberuntime_container_linux.go
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@ -338,42 +338,35 @@ var isCgroup2UnifiedMode = func() bool {
return libcontainercgroups.IsCgroup2UnifiedMode()
}
var (
swapControllerAvailability bool
swapControllerAvailabilityOnce sync.Once
)
// Note: this function variable is being added here so it would be possible to mock
// the swap controller availability for unit tests by assigning a new function to it. Without it,
// the swap controller availability would solely depend on the environment running the test.
var swapControllerAvailable = func() bool {
var swapControllerAvailable = sync.OnceValue(func() bool {
// See https://github.com/containerd/containerd/pull/7838/
swapControllerAvailabilityOnce.Do(func() {
const warn = "Failed to detect the availability of the swap controller, assuming not available"
p := "/sys/fs/cgroup/memory/memory.memsw.limit_in_bytes"
if isCgroup2UnifiedMode() {
// memory.swap.max does not exist in the cgroup root, so we check /sys/fs/cgroup/<SELF>/memory.swap.max
cm, err := libcontainercgroups.ParseCgroupFile("/proc/self/cgroup")
if err != nil {
klog.V(5).ErrorS(fmt.Errorf("failed to parse /proc/self/cgroup: %w", err), warn)
return
}
// Fr cgroup v2 unified hierarchy, there are no per-controller
// cgroup paths, so the cm map returned by ParseCgroupFile above
// has a single element where the key is empty string ("") and
// the value is the cgroup path the <pid> is in.
p = filepath.Join("/sys/fs/cgroup", cm[""], "memory.swap.max")
const warn = "Failed to detect the availability of the swap controller, assuming not available"
p := "/sys/fs/cgroup/memory/memory.memsw.limit_in_bytes"
if isCgroup2UnifiedMode() {
// memory.swap.max does not exist in the cgroup root, so we check /sys/fs/cgroup/<SELF>/memory.swap.max
cm, err := libcontainercgroups.ParseCgroupFile("/proc/self/cgroup")
if err != nil {
klog.V(5).ErrorS(fmt.Errorf("failed to parse /proc/self/cgroup: %w", err), warn)
return false
}
if _, err := os.Stat(p); err != nil {
if !errors.Is(err, os.ErrNotExist) {
klog.V(5).ErrorS(err, warn)
}
return
// Fr cgroup v2 unified hierarchy, there are no per-controller
// cgroup paths, so the cm map returned by ParseCgroupFile above
// has a single element where the key is empty string ("") and
// the value is the cgroup path the <pid> is in.
p = filepath.Join("/sys/fs/cgroup", cm[""], "memory.swap.max")
}
if _, err := os.Stat(p); err != nil {
if !errors.Is(err, os.ErrNotExist) {
klog.V(5).ErrorS(err, warn)
}
swapControllerAvailability = true
})
return swapControllerAvailability
}
return false
}
return true
})
type swapConfigurationHelper struct {
machineInfo cadvisorv1.MachineInfo