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use std::io::Read;
use std::path::{Path, PathBuf};
use super::{FileWrapper, Io, Schedstat, Stat, Status};
use crate::{ProcError, ProcResult};
use procfs_core::FromRead;
use rustix::fd::{BorrowedFd, OwnedFd};
/// A task (aka Thread) inside of a [`Process`](crate::process::Process)
///
/// Created by [`Process::tasks`](crate::process::Process::tasks), tasks in
/// general are similar to Processes and should have mostly the same fields.
#[derive(Debug)]
pub struct Task {
fd: OwnedFd,
/// The ID of the process that this task belongs to
pub pid: i32,
/// The task ID
pub tid: i32,
/// Task root: `/proc/<pid>/task/<tid>`
pub(crate) root: PathBuf,
}
impl Task {
/// Create a new `Task` inside of the process
///
/// This API is designed to be ergonomic from inside of [`TasksIter`](super::TasksIter)
pub(crate) fn from_process_at<P: AsRef<Path>, Q: AsRef<Path>>(
base: P,
dirfd: BorrowedFd,
path: Q,
pid: i32,
tid: i32,
) -> ProcResult<Task> {
use rustix::fs::{Mode, OFlags};
let p = path.as_ref();
let root = base.as_ref().join(p);
let fd = wrap_io_error!(
root,
rustix::fs::openat(
dirfd,
p,
OFlags::PATH | OFlags::DIRECTORY | OFlags::CLOEXEC,
Mode::empty()
)
)?;
Ok(Task { fd, pid, tid, root })
}
/// Thread info from `/proc/<pid>/task/<tid>/stat`
///
/// Many of the returned fields will be the same as the parent process, but some fields like `utime` and `stime` will be per-task
pub fn stat(&self) -> ProcResult<Stat> {
self.read("stat")
}
/// Thread info from `/proc/<pid>/task/<tid>/status`
///
/// Many of the returned fields will be the same as the parent process
pub fn status(&self) -> ProcResult<Status> {
self.read("status")
}
/// Thread IO info from `/proc/<pid>/task/<tid>/io`
///
/// This data will be unique per task.
pub fn io(&self) -> ProcResult<Io> {
self.read("io")
}
/// Thread scheduler info from `/proc/<pid>/task/<tid>/schedstat`
///
/// This data will be unique per task.
pub fn schedstat(&self) -> ProcResult<Schedstat> {
self.read("schedstat")
}
/// Thread children from `/proc/<pid>/task/<tid>/children`
///
/// WARNING:
/// This interface is not reliable unless all the child processes are stoppped or frozen.
/// If a child task exits while the file is being read, non-exiting children may be omitted.
/// See the procfs(5) man page for more information.
///
/// This data will be unique per task.
pub fn children(&self) -> ProcResult<Vec<u32>> {
let mut buf = String::new();
let mut file = FileWrapper::open_at(&self.root, &self.fd, "children")?;
file.read_to_string(&mut buf)?;
buf.split_whitespace()
.map(|child| {
child
.parse()
.map_err(|_| ProcError::Other("Failed to parse task's child PIDs".to_string()))
})
.collect()
}
/// Deliberately generate an IO error
#[cfg(test)]
pub(crate) fn generate_error(&self) -> ProcResult<()> {
let _ = FileWrapper::open_at(&self.root, &self.fd, "does_not_exist")?;
Ok(())
}
/// Parse a file relative to the task proc structure.
pub fn read<T: FromRead>(&self, path: &str) -> ProcResult<T> {
FromRead::from_read(FileWrapper::open_at(&self.root, &self.fd, path)?)
}
}
#[cfg(test)]
mod tests {
use crate::process::Io;
use crate::ProcError;
use rustix;
use std::process;
use std::sync::{Arc, Barrier};
#[test]
#[cfg(not(tarpaulin))] // this test is unstable under tarpaulin, and i'm yet sure why
// When this test runs in CI, run it single-threaded
fn test_task_runsinglethread() {
use std::io::Read;
let me = crate::process::Process::myself().unwrap();
let (work_barrier, w_a, w_b) = {
let b = Arc::new(Barrier::new(3));
(b.clone(), b.clone(), b)
};
let (done_barrier, d_a, d_b) = {
let b = Arc::new(Barrier::new(3));
(b.clone(), b.clone(), b)
};
let bytes_to_read = 2_000_000;
// create a new task to do some work
let join_a = std::thread::Builder::new()
.name("one".to_owned())
.spawn(move || {
let mut vec = Vec::new();
let zero = std::fs::File::open("/dev/zero").unwrap();
zero.take(bytes_to_read).read_to_end(&mut vec).unwrap();
assert_eq!(vec.len(), bytes_to_read as usize);
// spin for about 52 ticks (utime accounting isn't perfectly accurate)
let dur = std::time::Duration::from_millis(52 * (1000 / crate::ticks_per_second()) as u64);
let start = std::time::Instant::now();
while start.elapsed() <= dur {
// spin
}
w_a.wait();
d_a.wait()
})
.unwrap();
// create a new task that does nothing
let join_b = std::thread::Builder::new()
.name("two".to_owned())
.spawn(move || {
w_b.wait();
d_b.wait();
})
.unwrap();
work_barrier.wait();
let mut found_one = false;
let mut found_two = false;
let mut summed_io = Io {
rchar: 0,
wchar: 0,
syscr: 0,
syscw: 0,
read_bytes: 0,
write_bytes: 0,
cancelled_write_bytes: 0,
};
for task in me.tasks().unwrap() {
let task = task.unwrap();
let stat = task.stat().unwrap();
let status = task.status().unwrap();
let io = task.io().unwrap();
summed_io.rchar += io.rchar;
summed_io.wchar += io.wchar;
summed_io.syscr += io.syscr;
summed_io.syscw += io.syscw;
summed_io.read_bytes += io.read_bytes;
summed_io.write_bytes += io.write_bytes;
summed_io.cancelled_write_bytes += io.cancelled_write_bytes;
if stat.comm == "one" && status.name == "one" {
found_one = true;
assert!(io.rchar >= bytes_to_read);
assert!(stat.utime >= 50, "utime({}) too small", stat.utime);
}
if stat.comm == "two" && status.name == "two" {
found_two = true;
// The process might read miscellaneous things from procfs or
// things like /sys/devices/system/cpu/online; allow some small
// reads.
assert!(io.rchar < bytes_to_read);
assert_eq!(io.wchar, 0);
assert_eq!(stat.utime, 0);
}
}
let proc_io = me.io().unwrap();
// these should be mostly the same (though creating the IO struct in the above line will cause some IO to occur)
println!("{:?}", summed_io);
println!("{:?}", proc_io);
// signal the threads to exit
done_barrier.wait();
join_a.join().unwrap();
join_b.join().unwrap();
assert!(found_one);
assert!(found_two);
}
#[test]
fn test_task_children() {
// Use tail -f /dev/null to create two infinite processes
let mut command = process::Command::new("tail");
command.arg("-f").arg("/dev/null");
let (mut child1, mut child2) = (command.spawn().unwrap(), command.spawn().unwrap());
let tid = rustix::thread::gettid();
let children = crate::process::Process::myself()
.unwrap()
.task_from_tid(tid.as_raw_nonzero().get() as i32)
.unwrap()
.children()
.unwrap();
assert!(children.contains(&child1.id()));
assert!(children.contains(&child2.id()));
child1.kill().unwrap();
child2.kill().unwrap();
}
#[test]
fn test_error_msg() {
let myself = crate::process::Process::myself().unwrap();
// let mytask = myself.task_main_thread().unwrap();
for task in myself.tasks().unwrap() {
let task = task.unwrap();
let err = task.generate_error().unwrap_err();
// make sure the contained path in the error is correct
if let ProcError::NotFound(Some(p)) = err {
assert!(
p.display()
.to_string()
.ends_with(&format!("/task/{}/does_not_exist", task.tid)),
"NotFound path({:?}) doesn't look right",
p
);
} else {
panic!("Unexpected error from task.generate_error()");
}
}
}
}