1 use jobserver_crate::Client;
2 use lazy_static::lazy_static;
5 // We can only call `from_env` once per process
7 // Note that this is unsafe because it may misinterpret file descriptors
8 // on Unix as jobserver file descriptors. We hopefully execute this near
9 // the beginning of the process though to ensure we don't get false
10 // positives, or in other words we try to execute this before we open
11 // any file descriptors ourselves.
13 // Pick a "reasonable maximum" if we don't otherwise have
14 // a jobserver in our environment, capping out at 32 so we
15 // don't take everything down by hogging the process run queue.
16 // The fixed number is used to have deterministic compilation
19 // Also note that we stick this in a global because there could be
20 // multiple rustc instances in this process, and the jobserver is
22 static ref GLOBAL_CLIENT: Client = unsafe {
23 Client::from_env().unwrap_or_else(|| {
24 let client = Client::new(32).expect("failed to create jobserver");
25 // Acquire a token for the main thread which we can release later
26 client.acquire_raw().ok();
32 pub fn client() -> Client {
36 pub fn acquire_thread() {
37 GLOBAL_CLIENT.acquire_raw().ok();
40 pub fn release_thread() {
41 GLOBAL_CLIENT.release_raw().ok();