From 1ce94d237a8ae5b61e18882edba846316e36fdb0 Mon Sep 17 00:00:00 2001
From: Xiaoyang Liu <siujoeng.lau@gmail.com>
Date: Sat, 11 Nov 2023 23:02:11 -0800
Subject: [PATCH] docs(libcgroup): add docs for several items in
 'libcgroup::v2'

Signed-off-by: Xiaoyang Liu <siujoeng.lau@gmail.com>
---
 crates/libcgroups/src/v2/manager.rs | 7 ++++++-
 crates/libcgroups/src/v2/util.rs    | 3 +++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/crates/libcgroups/src/v2/manager.rs b/crates/libcgroups/src/v2/manager.rs
index 9aa5b8d5..d6e354a9 100644
--- a/crates/libcgroups/src/v2/manager.rs
+++ b/crates/libcgroups/src/v2/manager.rs
@@ -75,6 +75,9 @@ pub enum V2ManagerError {
     IoStats(#[from] V2IoStatsError),
 }
 
+/// Represents a management interface for a cgroup located at `{root_path}/{cgroup_path}`
+///
+/// This struct does not have ownership of the cgroup
 pub struct Manager {
     root_path: PathBuf,
     cgroup_path: PathBuf,
@@ -94,10 +97,11 @@ impl Manager {
         })
     }
 
+    /// Creates a unified cgroup at `self.full_path` and attaches a process to it
     fn create_unified_cgroup(&self, pid: Pid) -> Result<(), V2ManagerError> {
         let controllers: Vec<String> = util::get_available_controllers(&self.root_path)?
             .iter()
-            .map(|c| format!("{}{}", "+", c))
+            .map(|c| format!("+{c}"))
             .collect();
 
         Self::write_controllers(&self.root_path, &controllers)?;
@@ -129,6 +133,7 @@ impl Manager {
         Ok(())
     }
 
+    /// Writes a list of controllers to the `{path}/cgroup.subtree_control` file
     fn write_controllers(path: &Path, controllers: &[String]) -> Result<(), WrappedIoError> {
         for controller in controllers {
             common::write_cgroup_file_str(path.join(CGROUP_SUBTREE_CONTROL), controller)?;
diff --git a/crates/libcgroups/src/v2/util.rs b/crates/libcgroups/src/v2/util.rs
index 57746bc3..8971fe98 100644
--- a/crates/libcgroups/src/v2/util.rs
+++ b/crates/libcgroups/src/v2/util.rs
@@ -21,6 +21,7 @@ pub enum V2UtilError {
     DoesNotExist(PathBuf),
 }
 
+// Reads the `/proc/self/mountinfo` to get the mount point of this cgroup
 pub fn get_unified_mount_point() -> Result<PathBuf, V2UtilError> {
     Process::myself()?
         .mountinfo()?
@@ -30,6 +31,8 @@ pub fn get_unified_mount_point() -> Result<PathBuf, V2UtilError> {
         .ok_or(V2UtilError::CouldNotFind)
 }
 
+/// Reads the `{root_path}/cgroup.controllers` file to get the list of the controllers that are
+/// available in this cgroup
 pub fn get_available_controllers<P: AsRef<Path>>(
     root_path: P,
 ) -> Result<Vec<ControllerType>, V2UtilError> {