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use eventfd::{eventfd, EfdFlags};
use nix::sys::eventfd;
use std::fs::{self, File};
use std::io::Read;
use std::os::unix::io::{AsRawFd, FromRawFd};
use std::path::{Path, PathBuf};
use std::sync::mpsc::{self, Receiver};
use std::thread;
use crate::error::ErrorKind::*;
use crate::error::*;
pub fn notify_on_oom_v2(key: &str, dir: &PathBuf) -> Result<Receiver<String>> {
register_memory_event(key, dir, "memory.oom_control", "")
}
pub fn notify_on_oom_v1(key: &str, dir: &PathBuf) -> Result<Receiver<String>> {
register_memory_event(key, dir, "memory.oom_control", "")
}
pub fn notify_memory_pressure(key: &str, dir: &PathBuf, level: &str) -> Result<Receiver<String>> {
if level != "low" && level != "medium" && level != "critical" {
return Err(Error::from_string(format!(
"invalid pressure level {}",
level
)));
}
register_memory_event(key, dir, "memory.pressure_level", level)
}
fn register_memory_event(
key: &str,
cg_dir: &PathBuf,
event_name: &str,
arg: &str,
) -> Result<Receiver<String>> {
let path = cg_dir.join(event_name);
let event_file = File::open(path).map_err(|e| Error::with_cause(ReadFailed, e))?;
let eventfd =
eventfd(0, EfdFlags::EFD_CLOEXEC).map_err(|e| Error::with_cause(ReadFailed, e))?;
let event_control_path = cg_dir.join("cgroup.event_control");
let data;
if arg.is_empty() {
data = format!("{} {}", eventfd, event_file.as_raw_fd());
} else {
data = format!("{} {} {}", eventfd, event_file.as_raw_fd(), arg);
}
fs::write(&event_control_path, data).map_err(|e| Error::with_cause(WriteFailed, e))?;
let mut eventfd_file = unsafe { File::from_raw_fd(eventfd) };
let (sender, receiver) = mpsc::channel();
let key = key.to_string();
thread::spawn(move || {
loop {
let mut buf = [0; 8];
if eventfd_file.read(&mut buf).is_err() {
return;
}
if !Path::new(&event_control_path).exists() {
return;
}
sender.send(key.clone()).unwrap();
}
});
Ok(receiver)
}