Vendor things

third-party/vendor/cc/src/parallel/async_executor.rs

@@ -0,0 +1,118 @@
+use std::{
+    cell::Cell,
+    future::Future,
+    pin::Pin,
+    ptr,
+    task::{Context, Poll, RawWaker, RawWakerVTable, Waker},
+    thread,
+    time::Duration,
+};
+
+use crate::Error;
+
+const NOOP_WAKER_VTABLE: RawWakerVTable = RawWakerVTable::new(
+    // Cloning just returns a new no-op raw waker
+    |_| NOOP_RAW_WAKER,
+    // `wake` does nothing
+    |_| {},
+    // `wake_by_ref` does nothing
+    |_| {},
+    // Dropping does nothing as we don't allocate anything
+    |_| {},
+);
+const NOOP_RAW_WAKER: RawWaker = RawWaker::new(ptr::null(), &NOOP_WAKER_VTABLE);
+
+#[derive(Default)]
+pub(crate) struct YieldOnce(bool);
+
+impl Future for YieldOnce {
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<()> {
+        let flag = &mut std::pin::Pin::into_inner(self).0;
+        if !*flag {
+            *flag = true;
+            Poll::Pending
+        } else {
+            Poll::Ready(())
+        }
+    }
+}
+
+/// Execute the futures and return when they are all done.
+///
+/// Here we use our own homebrew async executor since cc is used in the build
+/// script of many popular projects, pulling in additional dependencies would
+/// significantly slow down its compilation.
+pub(crate) fn block_on<Fut1, Fut2>(
+    mut fut1: Fut1,
+    mut fut2: Fut2,
+    has_made_progress: &Cell<bool>,
+) -> Result<(), Error>
+where
+    Fut1: Future<Output = Result<(), Error>>,
+    Fut2: Future<Output = Result<(), Error>>,
+{
+    // Shadows the future so that it can never be moved and is guaranteed
+    // to be pinned.
+    //
+    // The same trick used in `pin!` macro.
+    //
+    // TODO: Once MSRV is bumped to 1.68, replace this with `std::pin::pin!`
+    let mut fut1 = Some(unsafe { Pin::new_unchecked(&mut fut1) });
+    let mut fut2 = Some(unsafe { Pin::new_unchecked(&mut fut2) });
+
+    // TODO: Once `Waker::noop` stablised and our MSRV is bumped to the version
+    // which it is stablised, replace this with `Waker::noop`.
+    let waker = unsafe { Waker::from_raw(NOOP_RAW_WAKER) };
+    let mut context = Context::from_waker(&waker);
+
+    let mut backoff_cnt = 0;
+
+    loop {
+        has_made_progress.set(false);
+
+        if let Some(fut) = fut2.as_mut() {
+            if let Poll::Ready(res) = fut.as_mut().poll(&mut context) {
+                fut2 = None;
+                res?;
+            }
+        }
+
+        if let Some(fut) = fut1.as_mut() {
+            if let Poll::Ready(res) = fut.as_mut().poll(&mut context) {
+                fut1 = None;
+                res?;
+            }
+        }
+
+        if fut1.is_none() && fut2.is_none() {
+            return Ok(());
+        }
+
+        if !has_made_progress.get() {
+            if backoff_cnt > 3 {
+                // We have yielded at least three times without making'
+                // any progress, so we will sleep for a while.
+                let duration = Duration::from_millis(100 * (backoff_cnt - 3).min(10));
+                thread::sleep(duration);
+            } else {
+                // Given that we spawned a lot of compilation tasks, it is unlikely
+                // that OS cannot find other ready task to execute.
+                //
+                // If all of them are done, then we will yield them and spawn more,
+                // or simply return.
+                //
+                // Thus this will not be turned into a busy-wait loop and it will not
+                // waste CPU resource.
+                thread::yield_now();
+            }
+        }
+
+        backoff_cnt = if has_made_progress.get() {
+            0
+        } else {
+            backoff_cnt + 1
+        };
+    }
+}

third-party/vendor/cc/src/parallel/job_token.rs

@@ -0,0 +1,255 @@
+use std::{marker::PhantomData, mem::MaybeUninit, sync::Once};
+
+use crate::Error;
+
+pub(crate) struct JobToken(PhantomData<()>);
+
+impl JobToken {
+    fn new() -> Self {
+        Self(PhantomData)
+    }
+}
+
+impl Drop for JobToken {
+    fn drop(&mut self) {
+        match JobTokenServer::new() {
+            JobTokenServer::Inherited(jobserver) => jobserver.release_token_raw(),
+            JobTokenServer::InProcess(jobserver) => jobserver.release_token_raw(),
+        }
+    }
+}
+
+enum JobTokenServer {
+    Inherited(inherited_jobserver::JobServer),
+    InProcess(inprocess_jobserver::JobServer),
+}
+
+impl JobTokenServer {
+    /// This function returns a static reference to the jobserver because
+    ///  - creating a jobserver from env is a bit fd-unsafe (e.g. the fd might
+    ///    be closed by other jobserver users in the process) and better do it
+    ///    at the start of the program.
+    ///  - in case a jobserver cannot be created from env (e.g. it's not
+    ///    present), we will create a global in-process only jobserver
+    ///    that has to be static so that it will be shared by all cc
+    ///    compilation.
+    fn new() -> &'static Self {
+        static INIT: Once = Once::new();
+        static mut JOBSERVER: MaybeUninit<JobTokenServer> = MaybeUninit::uninit();
+
+        unsafe {
+            INIT.call_once(|| {
+                let server = inherited_jobserver::JobServer::from_env()
+                    .map(Self::Inherited)
+                    .unwrap_or_else(|| Self::InProcess(inprocess_jobserver::JobServer::new()));
+                JOBSERVER = MaybeUninit::new(server);
+            });
+            // TODO: Poor man's assume_init_ref, as that'd require a MSRV of 1.55.
+            &*JOBSERVER.as_ptr()
+        }
+    }
+}
+
+pub(crate) enum ActiveJobTokenServer {
+    Inherited(inherited_jobserver::ActiveJobServer<'static>),
+    InProcess(&'static inprocess_jobserver::JobServer),
+}
+
+impl ActiveJobTokenServer {
+    pub(crate) fn new() -> Result<Self, Error> {
+        match JobTokenServer::new() {
+            JobTokenServer::Inherited(inherited_jobserver) => {
+                inherited_jobserver.enter_active().map(Self::Inherited)
+            }
+            JobTokenServer::InProcess(inprocess_jobserver) => {
+                Ok(Self::InProcess(inprocess_jobserver))
+            }
+        }
+    }
+
+    pub(crate) async fn acquire(&self) -> Result<JobToken, Error> {
+        match &self {
+            Self::Inherited(jobserver) => jobserver.acquire().await,
+            Self::InProcess(jobserver) => Ok(jobserver.acquire().await),
+        }
+    }
+}
+
+mod inherited_jobserver {
+    use super::JobToken;
+
+    use crate::{parallel::async_executor::YieldOnce, Error, ErrorKind};
+
+    use std::{
+        io, mem,
+        sync::{mpsc, Mutex, MutexGuard, PoisonError},
+    };
+
+    pub(super) struct JobServer {
+        /// Implicit token for this process which is obtained and will be
+        /// released in parent. Since JobTokens only give back what they got,
+        /// there should be at most one global implicit token in the wild.
+        ///
+        /// Since Rust does not execute any `Drop` for global variables,
+        /// we can't just put it back to jobserver and then re-acquire it at
+        /// the end of the process.
+        ///
+        /// Use `Mutex` to avoid race between acquire and release.
+        /// If an `AtomicBool` is used, then it's possible for:
+        ///  - `release_token_raw`: Tries to set `global_implicit_token` to true, but it is already
+        ///    set  to `true`, continue to release it to jobserver
+        ///  - `acquire` takes the global implicit token, set `global_implicit_token` to false
+        ///  - `release_token_raw` now writes the token back into the jobserver, while
+        ///    `global_implicit_token` is `false`
+        ///
+        /// If the program exits here, then cc effectively increases parallelism by one, which is
+        /// incorrect, hence we use a `Mutex` here.
+        global_implicit_token: Mutex<bool>,
+        inner: jobserver::Client,
+    }
+
+    impl JobServer {
+        pub(super) unsafe fn from_env() -> Option<Self> {
+            jobserver::Client::from_env().map(|inner| Self {
+                inner,
+                global_implicit_token: Mutex::new(true),
+            })
+        }
+
+        fn get_global_implicit_token(&self) -> MutexGuard<'_, bool> {
+            self.global_implicit_token
+                .lock()
+                .unwrap_or_else(PoisonError::into_inner)
+        }
+
+        /// All tokens except for the global implicit token will be put back into the jobserver
+        /// immediately and they cannot be cached, since Rust does not call `Drop::drop` on
+        /// global variables.
+        pub(super) fn release_token_raw(&self) {
+            let mut global_implicit_token = self.get_global_implicit_token();
+
+            if *global_implicit_token {
+                // There's already a global implicit token, so this token must
+                // be released back into jobserver.
+                //
+                // `release_raw` should not block
+                let _ = self.inner.release_raw();
+            } else {
+                *global_implicit_token = true;
+            }
+        }
+
+        pub(super) fn enter_active(&self) -> Result<ActiveJobServer<'_>, Error> {
+            ActiveJobServer::new(self)
+        }
+    }
+
+    pub(crate) struct ActiveJobServer<'a> {
+        jobserver: &'a JobServer,
+        helper_thread: jobserver::HelperThread,
+        /// When rx is dropped, all the token stored within it will be dropped.
+        rx: mpsc::Receiver<io::Result<jobserver::Acquired>>,
+    }
+
+    impl<'a> ActiveJobServer<'a> {
+        fn new(jobserver: &'a JobServer) -> Result<Self, Error> {
+            let (tx, rx) = mpsc::channel();
+
+            Ok(Self {
+                rx,
+                helper_thread: jobserver.inner.clone().into_helper_thread(move |res| {
+                    let _ = tx.send(res);
+                })?,
+                jobserver,
+            })
+        }
+
+        pub(super) async fn acquire(&self) -> Result<JobToken, Error> {
+            let mut has_requested_token = false;
+
+            loop {
+                // Fast path
+                if mem::replace(&mut *self.jobserver.get_global_implicit_token(), false) {
+                    break Ok(JobToken::new());
+                }
+
+                // Cold path, no global implicit token, obtain one
+                match self.rx.try_recv() {
+                    Ok(res) => {
+                        let acquired = res?;
+                        acquired.drop_without_releasing();
+                        break Ok(JobToken::new());
+                    }
+                    Err(mpsc::TryRecvError::Disconnected) => {
+                        break Err(Error::new(
+                            ErrorKind::JobserverHelpThreadError,
+                            "jobserver help thread has returned before ActiveJobServer is dropped",
+                        ))
+                    }
+                    Err(mpsc::TryRecvError::Empty) => {
+                        if !has_requested_token {
+                            self.helper_thread.request_token();
+                            has_requested_token = true;
+                        }
+                        YieldOnce::default().await
+                    }
+                }
+            }
+        }
+    }
+}
+
+mod inprocess_jobserver {
+    use super::JobToken;
+
+    use crate::parallel::async_executor::YieldOnce;
+
+    use std::{
+        env::var,
+        sync::atomic::{
+            AtomicU32,
+            Ordering::{AcqRel, Acquire},
+        },
+    };
+
+    pub(crate) struct JobServer(AtomicU32);
+
+    impl JobServer {
+        pub(super) fn new() -> Self {
+            // Use `NUM_JOBS` if set (it's configured by Cargo) and otherwise
+            // just fall back to a semi-reasonable number.
+            //
+            // Note that we could use `num_cpus` here but it's an extra
+            // dependency that will almost never be used, so
+            // it's generally not too worth it.
+            let mut parallelism = 4;
+            // TODO: Use std::thread::available_parallelism as an upper bound
+            // when MSRV is bumped.
+            if let Ok(amt) = var("NUM_JOBS") {
+                if let Ok(amt) = amt.parse() {
+                    parallelism = amt;
+                }
+            }
+
+            Self(AtomicU32::new(parallelism))
+        }
+
+        pub(super) async fn acquire(&self) -> JobToken {
+            loop {
+                let res = self
+                    .0
+                    .fetch_update(AcqRel, Acquire, |tokens| tokens.checked_sub(1));
+
+                if res.is_ok() {
+                    break JobToken::new();
+                }
+
+                YieldOnce::default().await
+            }
+        }
+
+        pub(super) fn release_token_raw(&self) {
+            self.0.fetch_add(1, AcqRel);
+        }
+    }
+}

third-party/vendor/cc/src/parallel/mod.rs

@@ -0,0 +1,20 @@
+pub(crate) mod async_executor;
+pub(crate) mod job_token;
+pub(crate) mod stderr;
+
+/// Remove all element in `vec` which `f(element)` returns `false`.
+///
+/// TODO: Remove this once the MSRV is bumped to v1.61
+pub(crate) fn retain_unordered_mut<T, F>(vec: &mut Vec<T>, mut f: F)
+where
+    F: FnMut(&mut T) -> bool,
+{
+    let mut i = 0;
+    while i < vec.len() {
+        if f(&mut vec[i]) {
+            i += 1;
+        } else {
+            vec.swap_remove(i);
+        }
+    }
+}

third-party/vendor/cc/src/parallel/stderr.rs

@@ -0,0 +1,90 @@
+/// Helpers functions for [ChildStderr].
+use std::{convert::TryInto, process::ChildStderr};
+
+use crate::{Error, ErrorKind};
+
+#[cfg(all(not(unix), not(windows)))]
+compile_error!("Only unix and windows support non-blocking pipes! For other OSes, disable the parallel feature.");
+
+#[cfg(unix)]
+fn get_flags(fd: std::os::unix::io::RawFd) -> Result<i32, Error> {
+    let flags = unsafe { libc::fcntl(fd, libc::F_GETFL, 0) };
+    if flags == -1 {
+        Err(Error::new(
+            ErrorKind::IOError,
+            format!(
+                "Failed to get flags for pipe {}: {}",
+                fd,
+                std::io::Error::last_os_error()
+            ),
+        ))
+    } else {
+        Ok(flags)
+    }
+}
+
+#[cfg(unix)]
+fn set_flags(fd: std::os::unix::io::RawFd, flags: std::os::raw::c_int) -> Result<(), Error> {
+    if unsafe { libc::fcntl(fd, libc::F_SETFL, flags) } == -1 {
+        Err(Error::new(
+            ErrorKind::IOError,
+            format!(
+                "Failed to set flags for pipe {}: {}",
+                fd,
+                std::io::Error::last_os_error()
+            ),
+        ))
+    } else {
+        Ok(())
+    }
+}
+
+#[cfg(unix)]
+pub fn set_non_blocking(pipe: &impl std::os::unix::io::AsRawFd) -> Result<(), Error> {
+    // On Unix, switch the pipe to non-blocking mode.
+    // On Windows, we have a different way to be non-blocking.
+    let fd = pipe.as_raw_fd();
+
+    let flags = get_flags(fd)?;
+    set_flags(fd, flags | libc::O_NONBLOCK)
+}
+
+pub fn bytes_available(stderr: &mut ChildStderr) -> Result<usize, Error> {
+    let mut bytes_available = 0;
+    #[cfg(windows)]
+    {
+        use crate::windows::windows_sys::PeekNamedPipe;
+        use std::os::windows::io::AsRawHandle;
+        use std::ptr::null_mut;
+        if unsafe {
+            PeekNamedPipe(
+                stderr.as_raw_handle(),
+                null_mut(),
+                0,
+                null_mut(),
+                &mut bytes_available,
+                null_mut(),
+            )
+        } == 0
+        {
+            return Err(Error::new(
+                ErrorKind::IOError,
+                format!(
+                    "PeekNamedPipe failed with {}",
+                    std::io::Error::last_os_error()
+                ),
+            ));
+        }
+    }
+    #[cfg(unix)]
+    {
+        use std::os::unix::io::AsRawFd;
+        if unsafe { libc::ioctl(stderr.as_raw_fd(), libc::FIONREAD, &mut bytes_available) } != 0 {
+            return Err(Error::new(
+                ErrorKind::IOError,
+                format!("ioctl failed with {}", std::io::Error::last_os_error()),
+            ));
+        }
+    }
+    Ok(bytes_available.try_into().unwrap())
+}