//! Process-global interrupt handling//!//! This module contains facilities to globally request an interrupt, which will cause supporting computations to//! abort once it is observed.//! Such checks for interrupts are provided in custom implementations of various traits to transparently add interrupt//! support to methods who wouldn't otherwise by injecting it. see [`Read`]. mod init { use std::{ io, sync::atomic::{AtomicBool, AtomicUsize, Ordering}, }; static IS_INITIALIZED: AtomicBool = AtomicBool::new(false); #[derive(Default)] pub struct Deregister(Vec<(i32, signal_hook::SigId)>); pub struct AutoDeregister(Deregister); impl Deregister { /// Remove all previously registered handlers, and assure the default behaviour is reinstated. /// /// Note that only the instantiation of the default behaviour can fail. pub fn deregister(self) -> std::io::Result<()> { if self.0.is_empty() { return Ok(()); } static REINSTATE_DEFAULT_BEHAVIOUR: AtomicBool = AtomicBool::new(true); for (_, hook_id) in &self.0 { signal_hook::low_level::unregister(*hook_id); } IS_INITIALIZED.store(false, Ordering::SeqCst); if REINSTATE_DEFAULT_BEHAVIOUR .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| Some(false)) .expect("always returns value") { for (sig, _) in self.0 { // # SAFETY // * we only call a handler that is specifically designed to run in this environment. #[allow(unsafe_code)] unsafe { signal_hook::low_level::register(sig, move || { signal_hook::low_level::emulate_default_handler(sig).ok(); })?; } } } Ok(()) } /// Return a type that deregisters all installed signal handlers on drop. pub fn auto_deregister(self) -> AutoDeregister { AutoDeregister(self) } } impl Drop for AutoDeregister { fn drop(&mut self) { std::mem::take(&mut self.0).deregister().ok(); } } /// Initialize a signal handler to listen to SIGINT and SIGTERM and trigger our [`trigger()`][super::trigger()] that way. /// Also trigger `interrupt()` which promises to never use a Mutex, allocate or deallocate. /// /// # Note /// /// It will abort the process on second press and won't inform the user about this behaviour either as we are unable to do so without /// deadlocking even when trying to write to stderr directly. pub fn init_handler(interrupt: impl Fn() + Send + Sync + Clone + 'static) -> io::Result<Deregister> { if IS_INITIALIZED .fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| Some(true)) .expect("always returns value") { return Err(io::Error::new(io::ErrorKind::Other, "Already initialized")); } let mut hooks = Vec::with_capacity(signal_hook::consts::TERM_SIGNALS.len()); for sig in signal_hook::consts::TERM_SIGNALS { // # SAFETY // * we only set atomics or call functions that do // * there is no use of the heap let interrupt = interrupt.clone(); #[allow(unsafe_code)] unsafe { let hook_id = signal_hook::low_level::register(*sig, move || { static INTERRUPT_COUNT: AtomicUsize = AtomicUsize::new(0); if !super::is_triggered() { INTERRUPT_COUNT.store(0, Ordering::SeqCst); } let msg_idx = INTERRUPT_COUNT.fetch_add(1, Ordering::SeqCst); if msg_idx == 1 { git_tempfile::handler::cleanup_tempfiles(); signal_hook::low_level::emulate_default_handler(*sig).ok(); } interrupt(); super::trigger(); })?; hooks.push((*sig, hook_id)); } } // This means that they won't setup a handler allowing us to call them right before we actually abort. git_tempfile::setup(git_tempfile::SignalHandlerMode::None); Ok(Deregister(hooks)) }}use std::{ io, sync::atomic::{AtomicBool, Ordering},}; pub use init::init_handler; /// A wrapper for an inner iterator which will check for interruptions on each iteration.pub struct Iter<I, EFN> { /// The actual iterator to yield elements from. inner: git_features::interrupt::IterWithErr<'static, I, EFN>,} impl<I, EFN, E> Iter<I, EFN>where I: Iterator, EFN: FnOnce() -> E,{ /// Create a new iterator over `inner` which checks for interruptions on each iteration and calls `make_err()` to /// signal an interruption happened, causing no further items to be iterated from that point on. pub fn new(inner: I, make_err: EFN) -> Self { Iter { inner: git_features::interrupt::IterWithErr::new(inner, make_err, &IS_INTERRUPTED), } } /// Return the inner iterator pub fn into_inner(self) -> I { self.inner.inner } /// Return the inner iterator as reference pub fn inner(&self) -> &I { &self.inner.inner }} impl<I, EFN, E> Iterator for Iter<I, EFN>where I: Iterator, EFN: FnOnce() -> E,{ type Item = Result<I::Item, E>; fn next(&mut self) -> Option<Self::Item> { self.inner.next() }} /// A wrapper for implementors of [`std::io::Read`] or [`std::io::BufRead`] with interrupt support.////// It fails a [read][`std::io::Read::read`] while an interrupt was requested.pub struct Read<R> { /// The actual implementor of [`std::io::Read`] to which interrupt support will be added. inner: git_features::interrupt::Read<'static, R>,} impl<R> Read<R>where R: io::Read,{ /// Create a new interruptible reader from `read`. pub fn new(read: R) -> Self { Read { inner: git_features::interrupt::Read { inner: read, should_interrupt: &IS_INTERRUPTED, }, } } /// Return the inner reader pub fn into_inner(self) -> R { self.inner.inner }} impl<R> io::Read for Read<R>where R: io::Read,{ fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> { self.inner.read(buf) }} impl<R> io::BufRead for Read<R>where R: io::BufRead,{ fn fill_buf(&mut self) -> io::Result<&[u8]> { self.inner.fill_buf() } fn consume(&mut self, amt: usize) { self.inner.consume(amt) }} /// The flag behind all utility functions in this module.pub static IS_INTERRUPTED: AtomicBool = AtomicBool::new(false); /// Returns true if an interrupt is requested.pub fn is_triggered() -> bool { IS_INTERRUPTED.load(Ordering::Relaxed)} /// Trigger an interrupt, signalling to those checking for [`is_triggered()`] to stop what they are doing.pub fn trigger() { IS_INTERRUPTED.store(true, Ordering::SeqCst);} /// Sets the interrupt request to false, thus allowing those checking for [`is_triggered()`] to proceed.pub fn reset() { IS_INTERRUPTED.store(false, Ordering::SeqCst);}
//! Process-global interrupt handling
//!
//! This module contains facilities to globally request an interrupt, which will cause supporting computations to
//! abort once it is observed.
//! Such checks for interrupts are provided in custom implementations of various traits to transparently add interrupt
//! support to methods who wouldn't otherwise by injecting it. see [`Read`].
mod init {
use std::{
io,
sync::atomic::{AtomicBool, AtomicUsize, Ordering},
};
static IS_INITIALIZED: AtomicBool = AtomicBool::new(false);
#[derive(Default)]
pub struct Deregister(Vec<(i32, signal_hook::SigId)>);
pub struct AutoDeregister(Deregister);
impl Deregister {
/// Remove all previously registered handlers, and assure the default behaviour is reinstated.
///
/// Note that only the instantiation of the default behaviour can fail.
pub fn deregister(self) -> std::io::Result<()> {
if self.0.is_empty() {
return Ok(());
}
static REINSTATE_DEFAULT_BEHAVIOUR: AtomicBool = AtomicBool::new(true);
for (_, hook_id) in &self.0 {
signal_hook::low_level::unregister(*hook_id);
}
IS_INITIALIZED.store(false, Ordering::SeqCst);
if REINSTATE_DEFAULT_BEHAVIOUR
.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| Some(false))
.expect("always returns value")
{
for (sig, _) in self.0 {
// # SAFETY
// * we only call a handler that is specifically designed to run in this environment.
#[allow(unsafe_code)]
unsafe {
signal_hook::low_level::register(sig, move || {
signal_hook::low_level::emulate_default_handler(sig).ok();
})?;
}
}
}
Ok(())
}
/// Return a type that deregisters all installed signal handlers on drop.
pub fn auto_deregister(self) -> AutoDeregister {
AutoDeregister(self)
}
}
impl Drop for AutoDeregister {
fn drop(&mut self) {
std::mem::take(&mut self.0).deregister().ok();
}
}
/// Initialize a signal handler to listen to SIGINT and SIGTERM and trigger our [`trigger()`][super::trigger()] that way.
/// Also trigger `interrupt()` which promises to never use a Mutex, allocate or deallocate.
///
/// # Note
///
/// It will abort the process on second press and won't inform the user about this behaviour either as we are unable to do so without
/// deadlocking even when trying to write to stderr directly.
pub fn init_handler(interrupt: impl Fn() + Send + Sync + Clone + 'static) -> io::Result<Deregister> {
if IS_INITIALIZED
.fetch_update(Ordering::SeqCst, Ordering::SeqCst, |_| Some(true))
.expect("always returns value")
{
return Err(io::Error::new(io::ErrorKind::Other, "Already initialized"));
}
let mut hooks = Vec::with_capacity(signal_hook::consts::TERM_SIGNALS.len());
for sig in signal_hook::consts::TERM_SIGNALS {
// # SAFETY
// * we only set atomics or call functions that do
// * there is no use of the heap
let interrupt = interrupt.clone();
#[allow(unsafe_code)]
unsafe {
let hook_id = signal_hook::low_level::register(*sig, move || {
static INTERRUPT_COUNT: AtomicUsize = AtomicUsize::new(0);
if !super::is_triggered() {
INTERRUPT_COUNT.store(0, Ordering::SeqCst);
}
let msg_idx = INTERRUPT_COUNT.fetch_add(1, Ordering::SeqCst);
if msg_idx == 1 {
git_tempfile::handler::cleanup_tempfiles();
signal_hook::low_level::emulate_default_handler(*sig).ok();
}
interrupt();
super::trigger();
})?;
hooks.push((*sig, hook_id));
}
}
// This means that they won't setup a handler allowing us to call them right before we actually abort.
git_tempfile::setup(git_tempfile::SignalHandlerMode::None);
Ok(Deregister(hooks))
}
}
use std::{
io,
sync::atomic::{AtomicBool, Ordering},
};
pub use init::init_handler;
/// A wrapper for an inner iterator which will check for interruptions on each iteration.
pub struct Iter<I, EFN> {
/// The actual iterator to yield elements from.
inner: git_features::interrupt::IterWithErr<'static, I, EFN>,
}
impl<I, EFN, E> Iter<I, EFN>
where
I: Iterator,
EFN: FnOnce() -> E,
{
/// Create a new iterator over `inner` which checks for interruptions on each iteration and calls `make_err()` to
/// signal an interruption happened, causing no further items to be iterated from that point on.
pub fn new(inner: I, make_err: EFN) -> Self {
Iter {
inner: git_features::interrupt::IterWithErr::new(inner, make_err, &IS_INTERRUPTED),
}
}
/// Return the inner iterator
pub fn into_inner(self) -> I {
self.inner.inner
}
/// Return the inner iterator as reference
pub fn inner(&self) -> &I {
&self.inner.inner
}
}
impl<I, EFN, E> Iterator for Iter<I, EFN>
where
I: Iterator,
EFN: FnOnce() -> E,
{
type Item = Result<I::Item, E>;
fn next(&mut self) -> Option<Self::Item> {
self.inner.next()
}
}
/// A wrapper for implementors of [`std::io::Read`] or [`std::io::BufRead`] with interrupt support.
///
/// It fails a [read][`std::io::Read::read`] while an interrupt was requested.
pub struct Read<R> {
/// The actual implementor of [`std::io::Read`] to which interrupt support will be added.
inner: git_features::interrupt::Read<'static, R>,
}
impl<R> Read<R>
where
R: io::Read,
{
/// Create a new interruptible reader from `read`.
pub fn new(read: R) -> Self {
Read {
inner: git_features::interrupt::Read {
inner: read,
should_interrupt: &IS_INTERRUPTED,
},
}
}
/// Return the inner reader
pub fn into_inner(self) -> R {
self.inner.inner
}
}
impl<R> io::Read for Read<R>
where
R: io::Read,
{
fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
self.inner.read(buf)
}
}
impl<R> io::BufRead for Read<R>
where
R: io::BufRead,
{
fn fill_buf(&mut self) -> io::Result<&[u8]> {
self.inner.fill_buf()
}
fn consume(&mut self, amt: usize) {
self.inner.consume(amt)
}
}
/// The flag behind all utility functions in this module.
pub static IS_INTERRUPTED: AtomicBool = AtomicBool::new(false);
/// Returns true if an interrupt is requested.
pub fn is_triggered() -> bool {
IS_INTERRUPTED.load(Ordering::Relaxed)
}
/// Trigger an interrupt, signalling to those checking for [`is_triggered()`] to stop what they are doing.
pub fn trigger() {
IS_INTERRUPTED.store(true, Ordering::SeqCst);
}
/// Sets the interrupt request to false, thus allowing those checking for [`is_triggered()`] to proceed.
pub fn reset() {
IS_INTERRUPTED.store(false, Ordering::SeqCst);
}