add basic v2 cpu/memory functions

Signed-off-by: bin liu <bin@hyper.sh>

tests/cgroup.rs

@@ -1,5 +1,7 @@
 //! Simple unit tests about the control groups system.
-use cgroups::{Cgroup, CgroupPid, Hierarchy};
+use cgroups::{Cgroup, CgroupPid, Hierarchy, Subsystem};
+use cgroups::memory::{MemController, SetMemory};
+use std::collections::HashMap;
 
 #[test]
 fn test_tasks_iterator() {
@@ -24,3 +26,24 @@ fn test_tasks_iterator() {
     }
     cg.delete();
 }
+
+
+#[test]
+fn test_cgroup_with_prefix() {
+    let h = cgroups::hierarchies::auto();
+    let h = Box::new(&*h);
+    let mut prefixes = HashMap::new();
+    prefixes.insert("memory".to_string(), "/memory/abc/def".to_string());
+    let cg = Cgroup::new_with_prefix(h, String::from("test_cgroup_with_prefix"), prefixes);
+    {
+        let subsystems = cg.subsystems();
+        println!("mem path: {:?}", &subsystems);
+        subsystems.into_iter().for_each(|sub| match sub {
+            Subsystem::Pid(c) => {println!("path {:?}", c);},
+            // base: "/sys/fs/cgroup", path: "/sys/fs/cgroup/memory/abc/def/test_cgroup_with_prefix"
+            Subsystem::Mem(c) => {println!("path {:?}", c);},
+            _ => {}, 
+        });
+    }
+    cg.delete();
+}