single-instance

single-instance provides a single API to check if there are any other running instance.

Detail

On windows, init SingleInstance will create a mutex named by given &str then check error code by calling GetLastError. On linux init will bind abstract unix domain socket with given name . On macos, init will create or open a file which path is given &str, then call flock to apply an advisory lock on the open file.

[dependencies]
single-instance = "0.3"

Examples

extern crate single_instance;

use single_instance::SingleInstance;

fn main() {
    {
        let instance_a = SingleInstance::new("whatever").unwrap();
        assert!(instance_a.is_single());
        let instance_b = SingleInstance::new("whatever").unwrap();
        assert!(!instance_b.is_single());
    }
    let instance_c = SingleInstance::new("whatever").unwrap();
    assert!(instance_c.is_single());
}

Ensuring the SingleInstance stays during lifetime of the process

Users should ensure that instance of SingleInstace should lives in lifetime of the calling process. This could be achieved in multiple ways. Few ways are:

• Using std::sync::Once

static mut SINGLE_INSTANCE_VAL : Option<SingleInstance> = None;
static SINGLE_INSTANCE_VAL_LOCK: Once = Once::new();

pub fn ensure_single_instance(uniq_id: &str) -> bool {
    let instance =  SingleInstance::new(&uniq_id);
    match  instance{
        Ok(inst) => {
            let single = inst.is_single();
            if single {
                unsafe {
                    SINGLE_INSTANCE_VAL_LOCK.call_once(|| {
                        SINGLE_INSTANCE_VAL = Some(inst);
                    })
                }
            }
            single
        },
        Err(e) => {
            false
        }
    }
}

• Using Box::leak. This example is in examples/multi_instance_server.rs

pub fn ensure_single_instance(uniq_id: &str) -> bool {
   let instance = Box::new(SingleInstance::new(uniq_id).unwrap());
   if instance.is_single() {
       Box::leak(instance);
       true
   }else {
       false
   }
}