Function panicking 

pub fn panicking() -> bool

Determines whether the current thread is panicking.

This returns true both when the thread is unwinding due to a panic, or executing a panic hook. Note that the latter case will still happen when panic=abort is set.

A common use of this feature is to poison shared resources when writing unsafe code, by checking panicking when the drop is called.

This is usually not needed when writing safe code, as Mutexes already poison themselves when a thread panics while holding the lock.

This can also be used in multithreaded applications, in order to send a message to other threads warning that a thread has panicked (e.g., for monitoring purposes).

Examples

use std::thread;

struct SomeStruct;

impl Drop for SomeStruct {
    fn drop(&mut self) {
        if thread::panicking() {
            println!("dropped while unwinding");
        } else {
            println!("dropped while not unwinding");
        }
    }
}

{
    print!("a: ");
    let a = SomeStruct;
}

{
    print!("b: ");
    let b = SomeStruct;
    panic!()
}