rayon 0.4.3

//! Package up unwind recovery. Note that if you are in some sensitive
//! place, you can use the `AbortIfPanic` helper to protect against
//! accidental panics in the rayon code itself.

use libc;
use std::any::Any;
use std::panic::{self, AssertUnwindSafe};
use std::io::stderr;
use std::io::prelude::*;
use std::thread;

/// Executes `f` and captures any panic, translating that panic into a
/// `Err` result. The assumption is that any panic will be propagated
/// later with `resume_unwinding`, and hence `f` can be treated as
/// exception safe.
pub fn halt_unwinding<F,R>(func: F) -> thread::Result<R>
    where F: FnOnce() -> R
{
    panic::catch_unwind(AssertUnwindSafe(func))
}

pub fn resume_unwinding(payload: Box<Any + Send>) -> ! {
    panic::resume_unwind(payload)
}

pub struct AbortIfPanic;

impl Drop for AbortIfPanic {
    fn drop(&mut self) {
        unsafe {
            let _ = writeln!(&mut stderr(), "Rayon: detected unexpected panic; aborting");
            libc::abort();
        }
    }
}

pub fn finally<A,F>(arg: A, func: F) -> FinallyGuard<A,F>
    where F: FnMut(&mut A)
{
    FinallyGuard { arg: arg, func: func }
}

pub struct FinallyGuard<A, F>
    where F: FnMut(&mut A)
{
    arg: A,
    func: F,
}

impl<A, F> Drop for FinallyGuard<A, F>
    where F: FnMut(&mut A)
{
    fn drop(&mut self) {
        (self.func)(&mut self.arg)
    }
}