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//! Interact with the `/sys` pseudo-file system
use std::fs::File;
use std::io::{self, Read};
fn read_file(path: &str) -> Result<String, io::Error> {
let mut fh = try!(File::open(path));
let mut contents = String::new();
try!(fh.read_to_string(&mut contents));
Ok(contents)
}
pub mod fs {
//! Interact with the /sys/fs file system
pub mod cgroup {
//! Interact with the cgroup unified hierarchy
//!
//! Note that this set of paths was added in linux 3.16, earlier
//! versions of linux will return `io::Errors` for everything.
pub mod cpu {
//! The CPU Controller CGroup hierarchy
//!
//! https://kernel.googlesource.com/pub/scm/linux/kernel/git/glommer/memcg/+/cpu_stat/Documentation/cgroups/cpu.txt
use std::io;
use sys::read_file;
/// The number of CPU shares this cgroup has got
pub fn shares() -> Result<u32, io::Error> {
let contents = try!(read_file("/sys/fs/cgroup/cpu/cpu.shares"));
Ok(contents.trim().parse().unwrap())
}
}
pub mod cpuacct {
//! The cpuacct directory for describing cgroups
//!
//! The most interesting file in here is cpuacct.stat which shows
//! the total cpu usage for all processes in this cgroup
//!
//! https://www.kernel.org/doc/Documentation/cgroups/cpuacct.txt
use std::io;
use linux::UserHz;
use sys::read_file;
/// Similar to /proc/stat, but shows toatal CPU usage by the cgroup
#[derive(Debug)]
pub struct Stat {
pub user: UserHz,
pub system: UserHz,
}
impl Stat {
/// Create a new `Stat` with values for the cgroup fs
pub fn load() -> Result<Stat, io::Error> {
let contents = try!(read_file("/sys/fs/cgroup/cpuacct/cpuacct.stat"));
let mut lines = contents.lines();
let user = lines.next().unwrap().split(' ').nth(1).unwrap();
let sys = lines.next().unwrap().split(' ').nth(1).unwrap();
Ok(Stat {
user: UserHz::new(user.parse().unwrap()),
system: UserHz::new(sys.parse().unwrap()),
})
}
pub fn total(&self) -> UserHz {
self.user + self.system
}
}
}
pub mod memory {
//! The memory directory for describing cgroups
//!
//! See the
//! [memory.txt](https://www.kernel.org/doc/Documentation/cgroups/memory.txt)
//! file.
use std::collections::{HashMap, HashSet};
use std::io;
use sys::read_file;
/// The memory limit for this cgroup
///
/// If it's not set, it seems to be u64::max
pub fn limit_in_bytes() -> Result<usize, io::Error> {
let contents = try!(read_file("/sys/fs/cgroup/memory/memory.limit_in_bytes"));
let bytes = contents.trim().parse().unwrap();
Ok(bytes)
}
/// Some fields from the memory.stat file
///
/// All values are in bytes, contrary to the same file from procfs
/// which reports everything in pages
#[derive(Debug)]
pub struct Stat {
/// Memory used, including the filesystem page cache. This
/// number will never decrease unless memory presure gets
/// applied from outside the cgroup.
pub cache: usize,
/// Actual memory being used by the cgroup
pub rss: usize,
/// Only hugetables. This is included in rss
pub rss_huge: usize,
/// Number of bytes that have been swapped out to disk
pub swap: usize,
}
impl Stat {
/// Read information from the filesystem and create a new `Stat`
pub fn load() -> Result<Stat, io::Error> {
let contents = try!(read_file("/sys/fs/cgroup/memory/memory.stat"));
let mut fields: HashMap<String, usize> = HashMap::new();
let needed: HashSet<_> = ["cache", "rss", "rss_huge", "swap"]
.iter()
.cloned()
.collect();
let mut found = 0;
for line in contents.lines() {
let mut parts = line.split(' ');
let field = parts.next().unwrap();
let val = parts.next().unwrap();
if needed.contains(&field) {
fields.insert(field.to_owned(), val.parse().unwrap());
found += 1;
if found >= 4 {
break;
}
}
}
Ok(Stat {
cache: *fields.get("cache").unwrap(),
rss: *fields.get("rss").unwrap(),
rss_huge: *fields.get("rss_huge").unwrap(),
swap: *fields.get("swap").unwrap(),
})
}
}
}
}
}