Function single_instance 

pub fn single_instance(app_id: &str) -> Result<Option<InstanceGuard>>

Attempts to acquire a named process-wide single-instance guard.

Returns Ok(Some(InstanceGuard)) for the first instance and Ok(None) if another instance with the same app_id is already running.

This is a convenience wrapper around single_instance_with_scope using InstanceScope::CurrentSession.

The mutex name is derived from app_id using a Local\... namespace, so the single-instance behavior is scoped to the current Windows session.

Keep the returned guard alive for as long as the current process should continue to own the single-instance lock.

Errors

Returns Error::InvalidInput if app_id is empty, contains only whitespace, contains NUL bytes, or contains backslashes. Windows reserves backslashes in named kernel objects for namespace separators such as Local\ and Global\. Returns Error::WindowsApi if CreateMutexW fails.

Examples

let app_id = format!("demo-app-{}", std::process::id());
let guard = win_desktop_utils::single_instance(&app_id)?;
assert!(guard.is_some());

Examples found in repository

examples/single_instance.rs (line 2)

fn main() -> Result<(), Box<dyn std::error::Error>> {
    match win_desktop_utils::single_instance("demo-app")? {
        Some(_guard) => {
            println!("first instance in the current session");
            println!("press Enter to exit");
            let mut s = String::new();
            std::io::stdin().read_line(&mut s)?;
        }
        None => {
            println!("already running in this session");
        }
    }

    Ok(())
}