Rollup merge of rust-lang#106372 - joboet:solid_id_parking, r=m-ou-se

Use id-based thread parking on SOLID

By using the [`slp_tsk`/`wup_tsk`](https://cs.uwaterloo.ca/~brecht/courses/702/Possible-Readings/embedded/uITRON-4.0-specification.pdf) system functions instead of an event-flag structure, `Parker` becomes cheaper to construct and SOLID can share the implementation used by NetBSD and SGX.

ping ``@kawadakk``
r? ``@m-ou-se``
``@rustbot`` label +T-libs

Author: Dylan-DPC

library/std/src/sys/itron/thread_parking.rs

@@ -0,0 +1,37 @@
+use super::abi;
+use super::error::expect_success_aborting;
+use super::time::with_tmos;
+use crate::time::Duration;
+
+pub type ThreadId = abi::ID;
+
+pub use super::task::current_task_id_aborting as current;
+
+pub fn park(_hint: usize) {
+    match unsafe { abi::slp_tsk() } {
+        abi::E_OK | abi::E_RLWAI => {}
+        err => {
+            expect_success_aborting(err, &"slp_tsk");
+        }
+    }
+}
+
+pub fn park_timeout(dur: Duration, _hint: usize) {
+    match with_tmos(dur, |tmo| unsafe { abi::tslp_tsk(tmo) }) {
+        abi::E_OK | abi::E_RLWAI | abi::E_TMOUT => {}
+        err => {
+            expect_success_aborting(err, &"tslp_tsk");
+        }
+    }
+}
+
+pub fn unpark(id: ThreadId, _hint: usize) {
+    match unsafe { abi::wup_tsk(id) } {
+        // It is allowed to try to wake up a destroyed or unrelated task, so we ignore all
+        // errors that could result from that situation.
+        abi::E_OK | abi::E_NOEXS | abi::E_OBJ | abi::E_QOVR => {}
+        err => {
+            expect_success_aborting(err, &"wup_tsk");
+        }
+    }
+}

library/std/src/sys/itron/wait_flag.rs

@@ -13,9 +13,9 @@ mod itron {
     pub(super) mod spin;
     pub(super) mod task;
     pub mod thread;
+    pub mod thread_parking;
     pub(super) mod time;
     use super::unsupported;
-    pub mod wait_flag;
 }
 
 pub mod alloc;
@@ -43,8 +43,8 @@ pub use self::itron::thread;
 pub mod memchr;
 pub mod thread_local_dtor;
 pub mod thread_local_key;
+pub use self::itron::thread_parking;
 pub mod time;
-pub use self::itron::wait_flag;
 
 mod rwlock;
 

library/std/src/sys/solid/mod.rs

@@ -14,12 +14,10 @@ cfg_if::cfg_if! {
     } else if #[cfg(any(
         target_os = "netbsd",
         all(target_vendor = "fortanix", target_env = "sgx"),
+        target_os = "solid_asp3",
     ))] {
         mod id;
         pub use id::Parker;
-    } else if #[cfg(target_os = "solid_asp3")] {
-        mod wait_flag;
-        pub use wait_flag::Parker;
     } else if #[cfg(any(windows, target_family = "unix"))] {
         pub use crate::sys::thread_parking::Parker;
     } else {