container: rm libcontainer.GetAllCgroupSubsystems

It is equivalent to GetCgroupSubsystems(nil) which is easy to use,
and there's only one user. Remove the function, patch the user.

While at it, document the includeMetrics argument of
GetCgroupSubsystems.

Signed-off-by: Kir Kolyshkin <[email protected]>

Author: kolyshkin

container/libcontainer/helpers.go

@@ -32,6 +32,10 @@ import (
 // GetCgroupSubsystems returns information about the cgroup subsystems that are
 // of interest as a map of cgroup controllers to their mount points.
 // For example, "cpu" -> "/sys/fs/cgroup/cpu".
+//
+// The incudeMetrics arguments specifies which metrics are requested,
+// and is used to filter out some cgroups and their mounts. If nil,
+// all supported cgroup subsystems are included.
 func GetCgroupSubsystems(includedMetrics container.MetricSet) (map[string]string, error) {
 	// Get all cgroup mounts.
 	allCgroups, err := cgroups.GetCgroupMounts(true)
@@ -42,17 +46,6 @@ func GetCgroupSubsystems(includedMetrics container.MetricSet) (map[string]string
 	return getCgroupSubsystemsHelper(allCgroups, includedMetrics)
 }
 
-// Get information about all the cgroup subsystems.
-func GetAllCgroupSubsystems() (map[string]string, error) {
-	// Get all cgroup mounts.
-	allCgroups, err := cgroups.GetCgroupMounts(true)
-	if err != nil {
-		return nil, err
-	}
-
-	return getCgroupSubsystemsHelper(allCgroups, nil)
-}
-
 func getCgroupSubsystemsHelper(allCgroups []cgroups.Mount, includedMetrics container.MetricSet) (map[string]string, error) {
 	if len(allCgroups) == 0 {
 		return nil, fmt.Errorf("failed to find cgroup mounts")

container/raw/watcher.go

@@ -44,7 +44,7 @@ type rawContainerWatcher struct {
 }
 
 func NewRawContainerWatcher() (watcher.ContainerWatcher, error) {
-	cgroupSubsystems, err := libcontainer.GetAllCgroupSubsystems()
+	cgroupSubsystems, err := libcontainer.GetCgroupSubsystems(nil)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get cgroup subsystems: %v", err)
 	}