waitpidx

waitpidx provides Linux process waiting by PID (not limited to child processes).

It uses pidfd_open(2) + poll(2) under the hood and supports both:

• synchronous waiting
• asynchronous waiting with Tokio

Requirements

• Linux only
• Kernel >= 5.3 (pidfd_open)
• Rust stable (Edition 2024)

Install

[dependencies]
waitpidx = "0.0.1"

Disable default async feature when you only need sync API:

[dependencies]
waitpidx = { version = "0.0.1", default-features = false }

Quick start

Sync API

use std::{process::Command, time::Duration};

fn main() -> std::io::Result<()> {
    let mut child = Command::new("sleep").arg("0.1").spawn()?;
    waitpidx::waitpid(child.id(), Some(Duration::from_secs(5)))?;
    child.wait()?;
    Ok(())
}

Async API (Tokio)

use std::process::Command;

#[tokio::main(flavor = "current_thread")]
async fn main() -> std::io::Result<()> {
    let mut child = Command::new("sleep").arg("0.1").spawn()?;
    waitpidx::waitpid_async(child.id()).await?;
    child.wait()?;
    Ok(())
}

Public API

• waitpid(pid, timeout)
  • Wait for process exit with optional timeout.
  • Returns TimedOut when timeout expires.
• waitpid_async(pid)
  • Async wait for process exit.
• pidfd::PidFd / pidfd::AsyncPidFd
  • Low-level wrappers if you need reusable wait handles.
• process_exists(pid)
  • Cheap existence check based on signal 0 semantics.

Error behavior

Common std::io::ErrorKind values:

• InvalidInput: invalid PID (for example 0), or invalid timeout conversion
• TimedOut: timeout reached in sync wait
• NotFound / PermissionDenied / others: forwarded from OS (pidfd_open, poll, etc.)

Features

• async (default): enables Tokio-based async API

Examples

Run included examples:

cargo run --example waitpid -- <pid>
cargo run --example waitpid_async --features async -- <pid>
cargo run --example waitpid_many_async --features async -- <pid1> <pid2>

License

Apache-2.0