Make Cgroup can be stored in struct

- Change type of hier to remove lifetimes
- impl Clone, Default, Debug for Cgroup

Signed-off-by: Tim Zhang <tim@hyper.sh>

src/cgroup.rs

@@ -28,16 +28,37 @@ use std::path::{Path, PathBuf};
 /// > specialized behaviour.
 ///
 /// This crate is an attempt at providing a Rust-native way of managing these cgroups.
-pub struct Cgroup<'b> {
+#[derive(Debug)]
+pub struct Cgroup {
     /// The list of subsystems that control this cgroup
     subsystems: Vec<Subsystem>,
 
     /// The hierarchy.
-    hier: &'b dyn Hierarchy,
+    hier: Box<dyn Hierarchy>,
     path: String,
 }
 
-impl<'b> Cgroup<'b> {
+impl Clone for Cgroup {
+    fn clone(&self) -> Self {
+        Cgroup {
+            subsystems: self.subsystems.clone(),
+            path: self.path.clone(),
+            hier: crate::hierarchies::auto(),
+        }
+    }
+}
+
+impl Default for Cgroup {
+    fn default() -> Self {
+        Cgroup {
+            subsystems: Vec::new(),
+            hier: crate::hierarchies::auto(),
+            path: "".to_string(),
+        }
+    }
+}
+
+impl Cgroup {
     /// Create this control group.
     fn create(&self) {
         if self.hier.v2() {
@@ -56,10 +77,7 @@ impl<'b> Cgroup<'b> {
     /// Create a new control group in the hierarchy `hier`, with name `path`.
     ///
     /// Returns a handle to the control group that can be used to manipulate it.
-    ///
-    /// Note that if the handle goes out of scope and is dropped, the control group is _not_
-    /// destroyed.
-    pub fn new<P: AsRef<Path>>(hier: &dyn Hierarchy, path: P) -> Cgroup {
+    pub fn new<P: AsRef<Path>>(hier: Box<dyn Hierarchy>, path: P) -> Cgroup {
         let cg = Cgroup::load(hier, path);
         cg.create();
         cg
@@ -68,11 +86,8 @@ impl<'b> Cgroup<'b> {
     /// Create a new control group in the hierarchy `hier`, with name `path` and `relative_paths`
     ///
     /// Returns a handle to the control group that can be used to manipulate it.
-    ///
-    /// Note that if the handle goes out of scope and is dropped, the control group is _not_
-    /// destroyed.
     pub fn new_with_relative_paths<P: AsRef<Path>>(
-        hier: &dyn Hierarchy,
+        hier: Box<dyn Hierarchy>,
         path: P,
         relative_paths: HashMap<String, String>,
     ) -> Cgroup {
@@ -85,10 +100,7 @@ impl<'b> Cgroup<'b> {
     ///
     /// Returns a handle to the control group (that possibly does not exist until `create()` has
     /// been called on the cgroup.
-    ///
-    /// Note that if the handle goes out of scope and is dropped, the control group is _not_
-    /// destroyed.
-    pub fn load<P: AsRef<Path>>(hier: &dyn Hierarchy, path: P) -> Cgroup {
+    pub fn load<P: AsRef<Path>>(hier: Box<dyn Hierarchy>, path: P) -> Cgroup {
         let path = path.as_ref();
         let mut subsystems = hier.subsystems();
         if path.as_os_str() != "" {
@@ -101,7 +113,7 @@ impl<'b> Cgroup<'b> {
         let cg = Cgroup {
             path: path.to_str().unwrap().to_string(),
             subsystems: subsystems,
-            hier: hier,
+            hier,
         };
 
         cg
@@ -111,11 +123,8 @@ impl<'b> Cgroup<'b> {
     ///
     /// Returns a handle to the control group (that possibly does not exist until `create()` has
     /// been called on the cgroup.
-    ///
-    /// Note that if the handle goes out of scope and is dropped, the control group is _not_
-    /// destroyed.
     pub fn load_with_relative_paths<P: AsRef<Path>>(
-        hier: &dyn Hierarchy,
+        hier: Box<dyn Hierarchy>,
         path: P,
         relative_paths: HashMap<String, String>,
     ) -> Cgroup {
@@ -141,7 +150,7 @@ impl<'b> Cgroup<'b> {
 
         let cg = Cgroup {
             subsystems: subsystems,
-            hier: hier,
+            hier,
             path: path.to_str().unwrap().to_string(),
         };
 

src/cgroup_builder.rs

@@ -77,59 +77,57 @@ macro_rules! gen_setter {
 }
 
 /// A control group builder instance
-pub struct CgroupBuilder<'a> {
+pub struct CgroupBuilder {
     name: String,
-    hierarchy: Box<&'a dyn Hierarchy>,
     /// Internal, unsupported field: use the associated builders instead.
     resources: Resources,
 }
 
-impl<'a> CgroupBuilder<'a> {
+impl CgroupBuilder {
     /// Start building a control group with the supplied hierarchy and name pair.
     ///
     /// Note that this does not actually create the control group until `build()` is called.
-    pub fn new(name: &'a str, hierarchy: Box<&'a dyn Hierarchy>) -> CgroupBuilder<'a> {
+    pub fn new(name: &str) -> CgroupBuilder {
         CgroupBuilder {
             name: name.to_owned(),
-            hierarchy: hierarchy,
             resources: Resources::default(),
         }
     }
 
     /// Builds the memory resources of the control group.
-    pub fn memory(self) -> MemoryResourceBuilder<'a> {
+    pub fn memory(self) -> MemoryResourceBuilder {
         MemoryResourceBuilder { cgroup: self }
     }
 
     /// Builds the pid resources of the control group.
-    pub fn pid(self) -> PidResourceBuilder<'a> {
+    pub fn pid(self) -> PidResourceBuilder {
         PidResourceBuilder { cgroup: self }
     }
 
     /// Builds the cpu resources of the control group.
-    pub fn cpu(self) -> CpuResourceBuilder<'a> {
+    pub fn cpu(self) -> CpuResourceBuilder {
         CpuResourceBuilder { cgroup: self }
     }
 
     /// Builds the devices resources of the control group, disallowing or
     /// allowing access to certain devices in the system.
-    pub fn devices(self) -> DeviceResourceBuilder<'a> {
+    pub fn devices(self) -> DeviceResourceBuilder {
         DeviceResourceBuilder { cgroup: self }
     }
 
     /// Builds the network resources of the control group, setting class id, or
     /// various priorities on networking interfaces.
-    pub fn network(self) -> NetworkResourceBuilder<'a> {
+    pub fn network(self) -> NetworkResourceBuilder {
         NetworkResourceBuilder { cgroup: self }
     }
 
     /// Builds the hugepage/hugetlb resources available to the control group.
-    pub fn hugepages(self) -> HugepagesResourceBuilder<'a> {
+    pub fn hugepages(self) -> HugepagesResourceBuilder {
         HugepagesResourceBuilder { cgroup: self }
     }
 
     /// Builds the block I/O resources available for the control group.
-    pub fn blkio(self) -> BlkIoResourcesBuilder<'a> {
+    pub fn blkio(self) -> BlkIoResourcesBuilder {
         BlkIoResourcesBuilder {
             cgroup: self,
             throttling_iops: false,
@@ -137,19 +135,19 @@ impl<'a> CgroupBuilder<'a> {
     }
 
     /// Finalize the control group, consuming the builder and creating the control group.
-    pub fn build(self) -> Cgroup<'a> {
-        let cg = Cgroup::new(*self.hierarchy, self.name);
+    pub fn build(self, hier: Box<dyn Hierarchy>) -> Cgroup {
+        let cg = Cgroup::new(hier, self.name);
         let _ret = cg.apply(&self.resources);
         cg
     }
 }
 
 /// A builder that configures the memory controller of a control group.
-pub struct MemoryResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct MemoryResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> MemoryResourceBuilder<'a> {
+impl MemoryResourceBuilder {
     gen_setter!(
         memory,
         MemController,
@@ -182,17 +180,17 @@ impl<'a> MemoryResourceBuilder<'a> {
     gen_setter!(memory, MemController, set_swappiness, swappiness, u64);
 
     /// Finish the construction of the memory resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the pid controller of a control group.
-pub struct PidResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct PidResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> PidResourceBuilder<'a> {
+impl PidResourceBuilder {
     gen_setter!(
         pid,
         PidController,
@@ -202,17 +200,17 @@ impl<'a> PidResourceBuilder<'a> {
     );
 
     /// Finish the construction of the pid resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the cpuset & cpu controllers of a control group.
-pub struct CpuResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct CpuResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> CpuResourceBuilder<'a> {
+impl CpuResourceBuilder {
     gen_setter!(cpu, CpuSetController, set_cpus, cpus, String);
     gen_setter!(cpu, CpuSetController, set_mems, mems, String);
     gen_setter!(cpu, CpuController, set_shares, shares, u64);
@@ -222,17 +220,17 @@ impl<'a> CpuResourceBuilder<'a> {
     gen_setter!(cpu, CpuController, set_rt_period, realtime_period, u64);
 
     /// Finish the construction of the cpu resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the devices controller of a control group.
-pub struct DeviceResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct DeviceResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> DeviceResourceBuilder<'a> {
+impl DeviceResourceBuilder {
     /// Restrict (or allow) a device to the tasks inside the control group.
     pub fn device(
         mut self,
@@ -241,7 +239,7 @@ impl<'a> DeviceResourceBuilder<'a> {
         devtype: crate::devices::DeviceType,
         allow: bool,
         access: Vec<crate::devices::DevicePermissions>,
-    ) -> DeviceResourceBuilder<'a> {
+    ) -> DeviceResourceBuilder {
         self.cgroup.resources.devices.devices.push(DeviceResource {
             major,
             minor,
@@ -253,22 +251,22 @@ impl<'a> DeviceResourceBuilder<'a> {
     }
 
     /// Finish the construction of the devices resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the net_cls & net_prio controllers of a control group.
-pub struct NetworkResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct NetworkResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> NetworkResourceBuilder<'a> {
+impl NetworkResourceBuilder {
     gen_setter!(network, NetclsController, set_class, class_id, u64);
 
     /// Set the priority of the tasks when operating on a networking device defined by `name` to be
     /// `priority`.
-    pub fn priority(mut self, name: String, priority: u64) -> NetworkResourceBuilder<'a> {
+    pub fn priority(mut self, name: String, priority: u64) -> NetworkResourceBuilder {
         self.cgroup
             .resources
             .network
@@ -278,19 +276,19 @@ impl<'a> NetworkResourceBuilder<'a> {
     }
 
     /// Finish the construction of the network resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the hugepages controller of a control group.
-pub struct HugepagesResourceBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct HugepagesResourceBuilder {
+    cgroup: CgroupBuilder,
 }
 
-impl<'a> HugepagesResourceBuilder<'a> {
+impl HugepagesResourceBuilder {
     /// Limit the usage of certain hugepages (determined by `size`) to be at most `limit` bytes.
-    pub fn limit(mut self, size: String, limit: u64) -> HugepagesResourceBuilder<'a> {
+    pub fn limit(mut self, size: String, limit: u64) -> HugepagesResourceBuilder {
         self.cgroup
             .resources
             .hugepages
@@ -300,18 +298,18 @@ impl<'a> HugepagesResourceBuilder<'a> {
     }
 
     /// Finish the construction of the network resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }
 
 /// A builder that configures the blkio controller of a control group.
-pub struct BlkIoResourcesBuilder<'a> {
-    cgroup: CgroupBuilder<'a>,
+pub struct BlkIoResourcesBuilder {
+    cgroup: CgroupBuilder,
     throttling_iops: bool,
 }
 
-impl<'a> BlkIoResourcesBuilder<'a> {
+impl BlkIoResourcesBuilder {
     gen_setter!(blkio, BlkIoController, set_weight, weight, u16);
     gen_setter!(blkio, BlkIoController, set_leaf_weight, leaf_weight, u16);
 
@@ -322,7 +320,7 @@ impl<'a> BlkIoResourcesBuilder<'a> {
         minor: u64,
         weight: Option<u16>,
         leaf_weight: Option<u16>,
-    ) -> BlkIoResourcesBuilder<'a> {
+    ) -> BlkIoResourcesBuilder {
         self.cgroup
             .resources
             .blkio
@@ -337,19 +335,19 @@ impl<'a> BlkIoResourcesBuilder<'a> {
     }
 
     /// Start configuring the I/O operations per second metric.
-    pub fn throttle_iops(mut self) -> BlkIoResourcesBuilder<'a> {
+    pub fn throttle_iops(mut self) -> BlkIoResourcesBuilder {
         self.throttling_iops = true;
         self
     }
 
     /// Start configuring the bytes per second metric.
-    pub fn throttle_bps(mut self) -> BlkIoResourcesBuilder<'a> {
+    pub fn throttle_bps(mut self) -> BlkIoResourcesBuilder {
         self.throttling_iops = false;
         self
     }
 
     /// Limit the read rate of the current metric for a certain device.
-    pub fn read(mut self, major: u64, minor: u64, rate: u64) -> BlkIoResourcesBuilder<'a> {
+    pub fn read(mut self, major: u64, minor: u64, rate: u64) -> BlkIoResourcesBuilder {
         let throttle = BlkIoDeviceThrottleResource { major, minor, rate };
         if self.throttling_iops {
             self.cgroup
@@ -368,7 +366,7 @@ impl<'a> BlkIoResourcesBuilder<'a> {
     }
 
     /// Limit the write rate of the current metric for a certain device.
-    pub fn write(mut self, major: u64, minor: u64, rate: u64) -> BlkIoResourcesBuilder<'a> {
+    pub fn write(mut self, major: u64, minor: u64, rate: u64) -> BlkIoResourcesBuilder {
         let throttle = BlkIoDeviceThrottleResource { major, minor, rate };
         if self.throttling_iops {
             self.cgroup
@@ -387,7 +385,7 @@ impl<'a> BlkIoResourcesBuilder<'a> {
     }
 
     /// Finish the construction of the blkio resources of a control group.
-    pub fn done(self) -> CgroupBuilder<'a> {
+    pub fn done(self) -> CgroupBuilder {
         self.cgroup
     }
 }

src/hierarchies.rs

@@ -32,10 +32,12 @@ use crate::{Controllers, Hierarchy, Subsystem};
 use crate::cgroup::Cgroup;
 
 /// The standard, original cgroup implementation. Often referred to as "cgroupv1".
+#[derive(Debug)]
 pub struct V1 {
     mountinfo: Vec<Mountinfo>,
 }
 
+#[derive(Debug)]
 pub struct V2 {
     root: String,
 }
@@ -98,8 +100,7 @@ impl Hierarchy for V1 {
     }
 
     fn root_control_group(&self) -> Cgroup {
-        let b: &dyn Hierarchy = self as &dyn Hierarchy;
-        Cgroup::load(&*b, "".to_string())
+        Cgroup::load(auto(), "".to_string())
     }
 
     fn root(&self) -> PathBuf {
@@ -170,8 +171,7 @@ impl Hierarchy for V2 {
     }
 
     fn root_control_group(&self) -> Cgroup {
-        let b: &dyn Hierarchy = self as &dyn Hierarchy;
-        Cgroup::load(&*b, "".to_string())
+        Cgroup::load(auto(), "".to_string())
     }
 
     fn root(&self) -> PathBuf {

src/lib.rs

@@ -71,7 +71,7 @@ use crate::systemd::SystemdController;
 pub use crate::cgroup::Cgroup;
 
 /// Contains all the subsystems that are available in this crate.
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub enum Subsystem {
     /// Controller for the `Pid` subsystem, see `PidController` for more information.
     Pid(PidController),
@@ -104,7 +104,7 @@ pub enum Subsystem {
 }
 
 #[doc(hidden)]
-#[derive(Eq, PartialEq, Debug)]
+#[derive(Eq, PartialEq, Debug, Clone)]
 pub enum Controllers {
     Pids,
     Mem,
@@ -357,7 +357,7 @@ pub trait ControllIdentifier {
 
 /// Control group hierarchy (right now, only V1 is supported, but in the future Unified will be
 /// implemented as well).
-pub trait Hierarchy {
+pub trait Hierarchy: std::fmt::Debug + Send {
     /// Returns what subsystems are supported by the hierarchy.
     fn subsystems(&self) -> Vec<Subsystem>;