Auto merge of #123550 - GnomedDev:remove-initial-arc, r=Noratrieb · qinheping/verify-rust-std@a92f55c (original) (raw)

`@@ -158,9 +158,12 @@

158

`#[cfg(all(test, not(any(target_os = "emscripten", target_os = "wasi"))))]

159

`mod tests;

160

161

use core::cell::SyncUnsafeCell;

162

use core::ffi::CStr;

163

use core::mem::MaybeUninit;

164

+

161

165

`use crate::any::Any;

162

166

`use crate::cell::UnsafeCell;

163

use crate::ffi::CStr;

164

167

`use crate:📑:PhantomData;

165

168

`use crate::mem::{self, ManuallyDrop, forget};

166

169

`use crate::num::NonZero;

`@@ -1125,7 +1128,7 @@ pub fn park_timeout(dur: Duration) {

1125

1128

`let guard = PanicGuard;

1126

1129

`// SAFETY: park_timeout is called on the parker owned by this thread.

1127

1130

`unsafe {

1128

current().inner.as_ref().parker().park_timeout(dur);

1131

current().0.parker().park_timeout(dur);

1129

1132

1130

1133

`// No panic occurred, do not abort.

1131

1134

`forget(guard);

`@@ -1232,65 +1235,114 @@ impl ThreadId {

1232

1235

`// Thread

1233

1236

`////////////////////////////////////////////////////////////////////////////////

1234

1237

1235

`` -

/// The internal representation of a Thread's name.

1236

enum ThreadName {

1237

Main,

1238

Other(ThreadNameString),

1239

Unnamed,

1240

}

1241

-

1242

1238

`// This module ensures private fields are kept private, which is necessary to enforce the safety requirements.

1243

1239

`mod thread_name_string {

1244

1240

`use core::str;

1245

1241

1246

use super::ThreadName;

1247

1242

`use crate::ffi::{CStr, CString};

1248

1243

1249

1244

`` /// Like a String it's guaranteed UTF-8 and like a CString it's null terminated.

1250

1245

`pub(crate) struct ThreadNameString {

1251

1246

`inner: CString,

1252

1247

1248

+

1249

impl ThreadNameString {

1250

pub fn as_str(&self) -> &str {

1251

`` +

// SAFETY: self.inner is only initialised via String, which upholds the validity invariant of str.

1252

unsafe { str::from_utf8_unchecked(self.inner.to_bytes()) }

1253

}

1254

}

1255

+

1253

1256

`impl core::ops::Deref for ThreadNameString {

1254

1257

`type Target = CStr;

1255

1258

`fn deref(&self) -> &CStr {

1256

1259

`&self.inner

1257

1260

1258

1261

1262

+

1259

1263

`impl From for ThreadNameString {

1260

1264

`fn from(s: String) -> Self {

1261

1265

`Self {

1262

1266

`inner: CString::new(s).expect("thread name may not contain interior null bytes"),

1263

1267

1264

1268

1265

1269

1266

impl ThreadName {

1267

pub fn as_cstr(&self) -> Option<&CStr> {

1268

match self {

1269

ThreadName::Main => Some(c"main"),

1270

ThreadName::Other(other) => Some(other),

1271

ThreadName::Unnamed => None,

1272

}

1273

}

1274

-

1275

pub fn as_str(&self) -> Option<&str> {

1276

`` -

// SAFETY: as_cstr can only return Some for a fixed CStr or a ThreadNameString,

1277

// which is guaranteed to be UTF-8.

1278

self.as_cstr().map(|s| unsafe { str::from_utf8_unchecked(s.to_bytes()) })

1279

}

1280

}

1281

1270

1282

1271

`pub(crate) use thread_name_string::ThreadNameString;

1283

1272

1284

`` -

/// The internal representation of a Thread handle

1285

struct Inner {

1286

name: ThreadName, // Guaranteed to be UTF-8

1273

static MAIN_THREAD_INFO: SyncUnsafeCell<(MaybeUninit, MaybeUninit)> =

1274

SyncUnsafeCell::new((MaybeUninit::uninit(), MaybeUninit::uninit()));

1275

+

1276

`` +

/// The internal representation of a Thread that is not the main thread.

1277

struct OtherInner {

1278

name: Option,

1287

1279

`id: ThreadId,

1288

1280

`parker: Parker,

1289

1281

1290

1282

1283

`` +

/// The internal representation of a Thread handle.

1284

#[derive(Clone)]

1285

enum Inner {

1286

/// Represents the main thread. May only be constructed by Thread::new_main.

1287

Main(&'static (ThreadId, Parker)),

1288

/// Represents any other thread.

1289

Other(Pin<Arc>),

1290

}

1291

+

1291

1292

`impl Inner {

1292

fn parker(self: Pin<&Self>) -> Pin<&Parker> {

1293

unsafe { Pin::map_unchecked(self, |inner| &inner.parker) }

1293

fn id(&self) -> ThreadId {

1294

match self {

1295

Self::Main((thread_id, _)) => *thread_id,

1296

Self::Other(other) => other.id,

1297

}

1298

}

1299

+

1300

fn cname(&self) -> Option<&CStr> {

1301

match self {

1302

Self::Main(_) => Some(c"main"),

1303

Self::Other(other) => other.name.as_deref(),

1304

}

1305

}

1306

+

1307

fn name(&self) -> Option<&str> {

1308

match self {

1309

Self::Main(_) => Some("main"),

1310

Self::Other(other) => other.name.as_ref().map(ThreadNameString::as_str),

1311

}

1312

}

1313

+

1314

fn into_raw(self) -> *const () {

1315

match self {

1316

`` +

// Just return the pointer to MAIN_THREAD_INFO.

1317

Self::Main(ptr) => crate::ptr::from_ref(ptr).cast(),

1318

Self::Other(arc) => {

1319

`` +

// Safety: We only expose an opaque pointer, which maintains the Pin invariant.

1320

let inner = unsafe { Pin::into_inner_unchecked(arc) };

1321

Arc::into_raw(inner) as *const ()

1322

}

1323

}

1324

}

1325

+

1326

/// # Safety

1327

///

1328

`` +

/// See [Thread::from_raw].

1329

unsafe fn from_raw(ptr: *const ()) -> Self {

1330

`` +

// If the pointer is to MAIN_THREAD_INFO, we know it is the Main variant.

1331

if crate::ptr::eq(ptr.cast(), &MAIN_THREAD_INFO) {

1332

Self::Main(unsafe { &*ptr.cast() })

1333

} else {

1334

// Safety: Upheld by caller

1335

Self::Other(unsafe { Pin::new_unchecked(Arc::from_raw(ptr as *const OtherInner)) })

1336

}

1337

}

1338

+

1339

fn parker(&self) -> Pin<&Parker> {

1340

match self {

1341

Self::Main((_, parker_ref)) => Pin::static_ref(parker_ref),

1342

Self::Other(inner) => unsafe {

1343

Pin::map_unchecked(inner.as_ref(), |inner| &inner.parker)

1344

1345

}

1294

1346

1295

1347

1296

1348

`@@ -1314,41 +1366,55 @@ impl Inner {

1314

1366

`` /// docs of [Builder] and [spawn] for more details.

1315

1367

`///

1316

1368

`` /// [thread::current]: current::current

1317

pub struct Thread {

1318

inner: Pin<Arc>,

1319

}

1369

pub struct Thread(Inner);

1320

1370

1321

1371

`impl Thread {

1322

1372

`/// Used only internally to construct a thread object without spawning.

1323

1373

`pub(crate) fn new(id: ThreadId, name: String) -> Thread {

1324

Self::new_inner(id, ThreadName::Other(name.into()))

1374

Self::new_inner(id, Some(ThreadNameString::from(name)))

1325

1375

1326

1376

1327

1377

`pub(crate) fn new_unnamed(id: ThreadId) -> Thread {

1328

Self::new_inner(id, ThreadName::Unnamed)

1378

Self::new_inner(id, None)

1329

1379

1330

1380

1331

/// Constructs the thread handle for the main thread.

1332

pub(crate) fn new_main(id: ThreadId) -> Thread {

1333

Self::new_inner(id, ThreadName::Main)

1381

/// Used in runtime to construct main thread

1382

///

1383

/// # Safety

1384

///

1385

/// This must only ever be called once, and must be called on the main thread.

1386

pub(crate) unsafe fn new_main(thread_id: ThreadId) -> Thread {

1387

// Safety: As this is only called once and on the main thread, nothing else is accessing MAIN_THREAD_INFO

1388

`` +

// as the only other read occurs in main_thread_info after the main thread has been constructed,

1389

// and this function is the only one that constructs the main thread.

1390

1391

// Pre-main thread spawning cannot hit this either, as the caller promises that this is only called on the main thread.

1392

let main_thread_info = unsafe { &mut *MAIN_THREAD_INFO.get() };

1393

+

1394

unsafe { Parker::new_in_place((&raw mut main_thread_info.1).cast()) };

1395

main_thread_info.0.write(thread_id);

1396

+

1397

`` +

// Store a 'static ref to the initialised ThreadId and Parker,

1398

// to avoid having to repeatedly prove initialisation.

1399

Self(Inner::Main(unsafe { &*MAIN_THREAD_INFO.get().cast() }))

1334

1400

1335

1401

1336

fn new_inner(id: ThreadId, name: ThreadName) -> Thread {

1402

fn new_inner(id: ThreadId, name: Option) -> Thread {

1337

1403

`` // We have to use unsafe here to construct the Parker in-place,

1338

1404

`// which is required for the UNIX implementation.

1339

1405

`//

1340

1406

`// SAFETY: We pin the Arc immediately after creation, so its address never

1341

1407

`// changes.

1342

1408

`let inner = unsafe {

1343

let mut arc = Arc::::new_uninit();

1409

let mut arc = Arc::::new_uninit();

1344

1410

`let ptr = Arc::get_mut_unchecked(&mut arc).as_mut_ptr();

1345

1411

`(&raw mut (*ptr).name).write(name);

1346

1412

`(&raw mut (*ptr).id).write(id);

1347

1413

`Parker::new_in_place(&raw mut (*ptr).parker);

1348

1414

`Pin::new_unchecked(arc.assume_init())

1349

1415

`};

1350

1416

1351

Thread { inner }

1417

Self(Inner::Other(inner))

1352

1418

1353

1419

1354

1420

`` /// Like the public [park], but callable on any handle. This is used to

`@@ -1357,7 +1423,7 @@ impl Thread {

1357

1423

`/// # Safety

1358

1424

`/// May only be called from the thread to which this handle belongs.

1359

1425

`pub(crate) unsafe fn park(&self) {

1360

unsafe { self.inner.as_ref().parker().park() }

1426

unsafe { self.0.parker().park() }

1361

1427

1362

1428

1363

1429

`/// Atomically makes the handle's token available if it is not already.

`@@ -1393,7 +1459,7 @@ impl Thread {

1393

1459

`#[stable(feature = "rust1", since = "1.0.0")]

1394

1460

`#[inline]

1395

1461

`pub fn unpark(&self) {

1396

self.inner.as_ref().parker().unpark();

1462

self.0.parker().unpark();

1397

1463

1398

1464

1399

1465

`/// Gets the thread's unique identifier.

`@@ -1413,7 +1479,7 @@ impl Thread {

1413

1479

`#[stable(feature = "thread_id", since = "1.19.0")]

1414

1480

`#[must_use]

1415

1481

`pub fn id(&self) -> ThreadId {

1416

self.inner.id

1482

self.0.id()

1417

1483

1418

1484

1419

1485

`/// Gets the thread's name.

`@@ -1456,7 +1522,11 @@ impl Thread {

1456

1522

`#[stable(feature = "rust1", since = "1.0.0")]

1457

1523

`#[must_use]

1458

1524

`pub fn name(&self) -> Option<&str> {

1459

self.inner.name.as_str()

1525

self.0.name()

1526

}

1527

+

1528

fn cname(&self) -> Option<&CStr> {

1529

self.0.cname()

1460

1530

1461

1531

1462

1532

`` /// Consumes the Thread, returning a raw pointer.

`@@ -1480,9 +1550,7 @@ impl Thread {

1480

1550

```` /// ```

````

1481

1551

`#[unstable(feature = "thread_raw", issue = "97523")]

1482

1552

`pub fn into_raw(self) -> *const () {

1483

`` -

// Safety: We only expose an opaque pointer, which maintains the Pin invariant.

1484

let inner = unsafe { Pin::into_inner_unchecked(self.inner) };

1485

Arc::into_raw(inner) as *const ()

1553

self.0.into_raw()

1486

1554

1487

1555

1488

1556

`` /// Constructs a Thread from a raw pointer.

`@@ -1504,11 +1572,7 @@ impl Thread {

1504

1572

`#[unstable(feature = "thread_raw", issue = "97523")]

1505

1573

`pub unsafe fn from_raw(ptr: *const ()) -> Thread {

1506

1574

`// Safety: Upheld by caller.

1507

unsafe { Thread { inner: Pin::new_unchecked(Arc::from_raw(ptr as *const Inner)) } }

1508

}

1509

-

1510

fn cname(&self) -> Option<&CStr> {

1511

self.inner.name.as_cstr()

1575

unsafe { Thread(Inner::from_raw(ptr)) }

1512

1576

1513

1577

1514

1578