interruptable

Interruptable Read and Write wrappers in Rust

Usage

This package is to be used for interrupting IO in conjunction with signal handling crates like ctrlc. These crates do handle received signals and allow to set some flag, but if application code is performing IO, it will not able to check the flag until it completes. The Unix-like OSes do interrupt IO operations on signals, returning EINT errno (aka ErrorKind::Interrupted), but std::io utility methods sliently restart such operations.

The Interruptable wrapper for std::io::Read and std::io::Write checks the flag (std::sync::atomic::AtomicBool) on each read or write operation, and when it sees that flag is set, it returns std::io::Error (standard error for the IO operations) with std::io::ErrorKind::Other and nested error of ErrorKind::Interrupted, thus hiding it from the retrying logic.

Life without interruptabe:

use std::io;
use std::sync::atomic;
use ctrlc;

let interrupt_flag = atomic::Arc::new(atomic::AtomicBool::new(false));
let interrput_flag2 = interrupt_flag.clone();

ctrlc::set_handler(move || {
    interrput_flag2.store(true, std::sync::atomic::Ordering::SeqCst);
}).unwrap();

let file = io::BufReader::new(
   std::fs::File::open("/path/to/slow/media/data.data")?
);

let my_precious_resource = MyResource::new();

for line in file.lines() {
    // It will be checked only after whole line is read, that may
    // take arbitrary long time.
    if interrput_flag2.load(std::sync::atomic::Ordering::SeqCst) {
        std::mem::drop(my_precious_resource);
        std::process::exit(42);
    }
    let line = line?;
    ...
}

Life with interruptabe:

use std::io;
use std::sync::atomic;
use ctrlc;

let interrupt_flag = atomic::Arc::new(atomic::AtomicBool::new(false));
let interrput_flag2 = interrupt_flag.clone();

ctrlc::set_handler(move || {
    interrput_flag2.store(true, std::sync::atomic::Ordering::SeqCst);
}).unwrap();

let file = io::BufReader::new(
    // Work both for Read and Write.
    interruptable::Interruptable::new(
        std::fs::File::open("/path/to/slow/media/data.data")?,
        interrupt_flag,
    )
);

let my_precious_resource = MyResource::new();

for line in file.lines() {
    // When the signal will arrive and flag is set, line will be Err(...)
    // immediately, thus you will be able to handle it and gracefully
    // shutdown your application: my_precious_resource is destroyed
    // in the standard way, by Drop::drop.
    let line = line?;
    ...
}