No std ThreadId

clippy.toml

@@ -0,0 +1,3 @@
+[[disallowed-types]]
+path = "std::thread::ThreadId"
+reason = "Use crate::platform::ThreadId for `no_std` compatibility"

newsfragments/6056.added.md

@@ -0,0 +1 @@
+Add `PyThread_get_thread_ident` to the ffi crate

pyo3-ffi/src/lib.rs

@@ -486,6 +486,7 @@ pub use self::pyport::*;
 pub use self::pystate::*;
 pub use self::pystrtod::*;
 pub use self::pythonrun::*;
+pub use self::pythread::*;
 pub use self::pytypedefs::*;
 pub use self::rangeobject::*;
 pub use self::refcount::*;
@@ -578,7 +579,7 @@ mod pythonrun;
 // skipped pystrhex.h
 // skipped pystrcmp.h
 mod pystrtod;
-// skipped pythread.h
+mod pythread;
 // skipped pytime.h
 mod pytypedefs;
 mod rangeobject;

pyo3-ffi/src/pythread.rs

@@ -0,0 +1,6 @@
+use core::ffi::c_ulong;
+
+extern_libpython! {
+    #[cfg_attr(PyPy, link_name = "PyPyThread_get_thread_ident")]
+    pub fn PyThread_get_thread_ident() -> c_ulong;
+}

src/err/err_state.rs

@@ -3,11 +3,9 @@
 
 use crate::platform::prelude::*;
 use core::cell::UnsafeCell;
-use std::{
-    sync::{Mutex, Once},
-    thread::ThreadId,
-};
+use std::sync::{Mutex, Once};
 
+use crate::platform::thread::{self, ThreadId};
 #[cfg(not(Py_3_12))]
 use crate::sync::MutexExt;
 use crate::{
@@ -98,7 +96,7 @@ impl PyErrState {
         // re-entrancy guarantees.
         if let Some(thread) = self.normalizing_thread.lock().unwrap().as_ref() {
             assert!(
-                !(*thread == std::thread::current().id()),
+                !(*thread == thread::current().id()),
                 "Re-entrant normalization of PyErrState detected"
             );
         }
@@ -109,7 +107,7 @@ impl PyErrState {
                 self.normalizing_thread
                     .lock()
                     .unwrap()
-                    .replace(std::thread::current().id());
+                    .replace(thread::current().id());
 
                 // Safety: no other thread can access the inner value while we are normalizing it.
                 let state = unsafe {

src/impl_/pyclass.rs

@@ -3,6 +3,7 @@
 
 #[allow(unused_imports, reason = "conditionally used")]
 use crate::platform::prelude::*;
+use crate::platform::thread;
 use crate::{
     exceptions::{PyAttributeError, PyNotImplementedError, PyRuntimeError},
     ffi,
@@ -24,7 +25,7 @@ use core::{
     marker::PhantomData,
     ptr::{self, NonNull},
 };
-use std::{sync::Mutex, thread};
+use std::sync::Mutex;
 
 mod assertions;
 pub mod doc;

src/impl_/pyclass/lazy_type_object.rs

@@ -2,8 +2,8 @@
 #![allow(clippy::undocumented_unsafe_blocks)]
 
 use crate::platform::prelude::*;
+use crate::platform::thread::{self, ThreadId};
 use core::{ffi::CStr, marker::PhantomData};
-use std::thread::{self, ThreadId};
 
 #[cfg(Py_3_14)]
 use crate::err::error_on_minusone;

src/platform.rs

@@ -20,3 +20,5 @@ pub use hashbrown::{HashMap, HashSet};
 // TODO conditionally import these based on "std" feature
 #[cfg(not(feature = "hashbrown"))]
 pub use std::collections::{HashMap, HashSet};
+
+pub mod thread;

src/platform/thread.rs

@@ -0,0 +1,26 @@
+use core::ffi::c_ulong;
+use core::num::NonZero;
+
+use pyo3_ffi::PyThread_get_thread_ident;
+
+#[must_use]
+pub fn current() -> Thread {
+    Thread {
+        // SAFETY: PyThread_get_thread_ident never returns zero
+        // https://docs.python.org/3/c-api/threads.html#c.PyThread_get_thread_ident
+        id: ThreadId(unsafe { NonZero::new_unchecked(PyThread_get_thread_ident()) }),
+    }
+}
+
+pub struct Thread {
+    id: ThreadId,
+}
+
+impl Thread {
+    pub fn id(&self) -> ThreadId {
+        self.id
+    }
+}
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
+pub struct ThreadId(NonZero<c_ulong>);