single-instance provides a single API to check if there are any other running instance.
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"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());
}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
}
}
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