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use std::collections::BinaryHeap;
use std::sync::Mutex;
use std::usize;
struct ThreadIdManager {
limit: usize,
free_list: BinaryHeap<usize>,
}
impl ThreadIdManager {
fn new() -> ThreadIdManager {
ThreadIdManager {
limit: usize::MAX,
free_list: BinaryHeap::new(),
}
}
fn alloc(&mut self) -> usize {
if let Some(id) = self.free_list.pop() {
id
} else {
let id = self.limit;
self.limit = self.limit.checked_sub(1).expect("Ran out of thread IDs");
id
}
}
fn free(&mut self, id: usize) {
self.free_list.push(id);
}
}
lazy_static! {
static ref THREAD_ID_MANAGER: Mutex<ThreadIdManager> = Mutex::new(ThreadIdManager::new());
}
struct ThreadId(usize);
impl ThreadId {
fn new() -> ThreadId {
ThreadId(THREAD_ID_MANAGER.lock().unwrap().alloc())
}
}
impl Drop for ThreadId {
fn drop(&mut self) {
THREAD_ID_MANAGER.lock().unwrap().free(self.0);
}
}
thread_local!(static THREAD_ID: ThreadId = ThreadId::new());
pub fn get() -> usize {
THREAD_ID.with(|x| x.0)
}