Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 331 insertions, 0 deletions

diff --git a/vendor/parking_lot-0.11.2/src/raw_mutex.rs b/vendor/parking_lot-0.11.2/src/raw_mutex.rs
new file mode 100644
index 000000000..06667d32d
--- /dev/null
+++ b/vendor/parking_lot-0.11.2/src/raw_mutex.rs
@@ -0,0 +1,331 @@
+// Copyright 2016 Amanieu d'Antras
+//
+// Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
+// http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
+// http://opensource.org/licenses/MIT>, at your option. This file may not be
+// copied, modified, or distributed except according to those terms.
+
+use crate::{deadlock, util};
+use core::{
+    sync::atomic::{AtomicU8, Ordering},
+    time::Duration,
+};
+use instant::Instant;
+use lock_api::RawMutex as RawMutex_;
+use parking_lot_core::{self, ParkResult, SpinWait, UnparkResult, UnparkToken, DEFAULT_PARK_TOKEN};
+
+// UnparkToken used to indicate that that the target thread should attempt to
+// lock the mutex again as soon as it is unparked.
+pub(crate) const TOKEN_NORMAL: UnparkToken = UnparkToken(0);
+
+// UnparkToken used to indicate that the mutex is being handed off to the target
+// thread directly without unlocking it.
+pub(crate) const TOKEN_HANDOFF: UnparkToken = UnparkToken(1);
+
+/// This bit is set in the `state` of a `RawMutex` when that mutex is locked by some thread.
+const LOCKED_BIT: u8 = 0b01;
+/// This bit is set in the `state` of a `RawMutex` just before parking a thread. A thread is being
+/// parked if it wants to lock the mutex, but it is currently being held by some other thread.
+const PARKED_BIT: u8 = 0b10;
+
+/// Raw mutex type backed by the parking lot.
+pub struct RawMutex {
+    /// This atomic integer holds the current state of the mutex instance. Only the two lowest bits
+    /// are used. See `LOCKED_BIT` and `PARKED_BIT` for the bitmask for these bits.
+    ///
+    /// # State table:
+    ///
+    /// PARKED_BIT | LOCKED_BIT | Description
+    ///     0      |     0      | The mutex is not locked, nor is anyone waiting for it.
+    /// -----------+------------+------------------------------------------------------------------
+    ///     0      |     1      | The mutex is locked by exactly one thread. No other thread is
+    ///            |            | waiting for it.
+    /// -----------+------------+------------------------------------------------------------------
+    ///     1      |     0      | The mutex is not locked. One or more thread is parked or about to
+    ///            |            | park. At least one of the parked threads are just about to be
+    ///            |            | unparked, or a thread heading for parking might abort the park.
+    /// -----------+------------+------------------------------------------------------------------
+    ///     1      |     1      | The mutex is locked by exactly one thread. One or more thread is
+    ///            |            | parked or about to park, waiting for the lock to become available.
+    ///            |            | In this state, PARKED_BIT is only ever cleared when a bucket lock
+    ///            |            | is held (i.e. in a parking_lot_core callback). This ensures that
+    ///            |            | we never end up in a situation where there are parked threads but
+    ///            |            | PARKED_BIT is not set (which would result in those threads
+    ///            |            | potentially never getting woken up).
+    state: AtomicU8,
+}
+
+unsafe impl lock_api::RawMutex for RawMutex {
+    const INIT: RawMutex = RawMutex {
+        state: AtomicU8::new(0),
+    };
+
+    type GuardMarker = crate::GuardMarker;
+
+    #[inline]
+    fn lock(&self) {
+        if self
+            .state
+            .compare_exchange_weak(0, LOCKED_BIT, Ordering::Acquire, Ordering::Relaxed)
+            .is_err()
+        {
+            self.lock_slow(None);
+        }
+        unsafe { deadlock::acquire_resource(self as *const _ as usize) };
+    }
+
+    #[inline]
+    fn try_lock(&self) -> bool {
+        let mut state = self.state.load(Ordering::Relaxed);
+        loop {
+            if state & LOCKED_BIT != 0 {
+                return false;
+            }
+            match self.state.compare_exchange_weak(
+                state,
+                state | LOCKED_BIT,
+                Ordering::Acquire,
+                Ordering::Relaxed,
+            ) {
+                Ok(_) => {
+                    unsafe { deadlock::acquire_resource(self as *const _ as usize) };
+                    return true;
+                }
+                Err(x) => state = x,
+            }
+        }
+    }
+
+    #[inline]
+    unsafe fn unlock(&self) {
+        deadlock::release_resource(self as *const _ as usize);
+        if self
+            .state
+            .compare_exchange(LOCKED_BIT, 0, Ordering::Release, Ordering::Relaxed)
+            .is_ok()
+        {
+            return;
+        }
+        self.unlock_slow(false);
+    }
+
+    #[inline]
+    fn is_locked(&self) -> bool {
+        let state = self.state.load(Ordering::Relaxed);
+        state & LOCKED_BIT != 0
+    }
+}
+
+unsafe impl lock_api::RawMutexFair for RawMutex {
+    #[inline]
+    unsafe fn unlock_fair(&self) {
+        deadlock::release_resource(self as *const _ as usize);
+        if self
+            .state
+            .compare_exchange(LOCKED_BIT, 0, Ordering::Release, Ordering::Relaxed)
+            .is_ok()
+        {
+            return;
+        }
+        self.unlock_slow(true);
+    }
+
+    #[inline]
+    unsafe fn bump(&self) {
+        if self.state.load(Ordering::Relaxed) & PARKED_BIT != 0 {
+            self.bump_slow();
+        }
+    }
+}
+
+unsafe impl lock_api::RawMutexTimed for RawMutex {
+    type Duration = Duration;
+    type Instant = Instant;
+
+    #[inline]
+    fn try_lock_until(&self, timeout: Instant) -> bool {
+        let result = if self
+            .state
+            .compare_exchange_weak(0, LOCKED_BIT, Ordering::Acquire, Ordering::Relaxed)
+            .is_ok()
+        {
+            true
+        } else {
+            self.lock_slow(Some(timeout))
+        };
+        if result {
+            unsafe { deadlock::acquire_resource(self as *const _ as usize) };
+        }
+        result
+    }
+
+    #[inline]
+    fn try_lock_for(&self, timeout: Duration) -> bool {
+        let result = if self
+            .state
+            .compare_exchange_weak(0, LOCKED_BIT, Ordering::Acquire, Ordering::Relaxed)
+            .is_ok()
+        {
+            true
+        } else {
+            self.lock_slow(util::to_deadline(timeout))
+        };
+        if result {
+            unsafe { deadlock::acquire_resource(self as *const _ as usize) };
+        }
+        result
+    }
+}
+
+impl RawMutex {
+    // Used by Condvar when requeuing threads to us, must be called while
+    // holding the queue lock.
+    #[inline]
+    pub(crate) fn mark_parked_if_locked(&self) -> bool {
+        let mut state = self.state.load(Ordering::Relaxed);
+        loop {
+            if state & LOCKED_BIT == 0 {
+                return false;
+            }
+            match self.state.compare_exchange_weak(
+                state,
+                state | PARKED_BIT,
+                Ordering::Relaxed,
+                Ordering::Relaxed,
+            ) {
+                Ok(_) => return true,
+                Err(x) => state = x,
+            }
+        }
+    }
+
+    // Used by Condvar when requeuing threads to us, must be called while
+    // holding the queue lock.
+    #[inline]
+    pub(crate) fn mark_parked(&self) {
+        self.state.fetch_or(PARKED_BIT, Ordering::Relaxed);
+    }
+
+    #[cold]
+    fn lock_slow(&self, timeout: Option<Instant>) -> bool {
+        let mut spinwait = SpinWait::new();
+        let mut state = self.state.load(Ordering::Relaxed);
+        loop {
+            // Grab the lock if it isn't locked, even if there is a queue on it
+            if state & LOCKED_BIT == 0 {
+                match self.state.compare_exchange_weak(
+                    state,
+                    state | LOCKED_BIT,
+                    Ordering::Acquire,
+                    Ordering::Relaxed,
+                ) {
+                    Ok(_) => return true,
+                    Err(x) => state = x,
+                }
+                continue;
+            }
+
+            // If there is no queue, try spinning a few times
+            if state & PARKED_BIT == 0 && spinwait.spin() {
+                state = self.state.load(Ordering::Relaxed);
+                continue;
+            }
+
+            // Set the parked bit
+            if state & PARKED_BIT == 0 {
+                if let Err(x) = self.state.compare_exchange_weak(
+                    state,
+                    state | PARKED_BIT,
+                    Ordering::Relaxed,
+                    Ordering::Relaxed,
+                ) {
+                    state = x;
+                    continue;
+                }
+            }
+
+            // Park our thread until we are woken up by an unlock
+            let addr = self as *const _ as usize;
+            let validate = || self.state.load(Ordering::Relaxed) == LOCKED_BIT | PARKED_BIT;
+            let before_sleep = || {};
+            let timed_out = |_, was_last_thread| {
+                // Clear the parked bit if we were the last parked thread
+                if was_last_thread {
+                    self.state.fetch_and(!PARKED_BIT, Ordering::Relaxed);
+                }
+            };
+            // SAFETY:
+            //   * `addr` is an address we control.
+            //   * `validate`/`timed_out` does not panic or call into any function of `parking_lot`.
+            //   * `before_sleep` does not call `park`, nor does it panic.
+            match unsafe {
+                parking_lot_core::park(
+                    addr,
+                    validate,
+                    before_sleep,
+                    timed_out,
+                    DEFAULT_PARK_TOKEN,
+                    timeout,
+                )
+            } {
+                // The thread that unparked us passed the lock on to us
+                // directly without unlocking it.
+                ParkResult::Unparked(TOKEN_HANDOFF) => return true,
+
+                // We were unparked normally, try acquiring the lock again
+                ParkResult::Unparked(_) => (),
+
+                // The validation function failed, try locking again
+                ParkResult::Invalid => (),
+
+                // Timeout expired
+                ParkResult::TimedOut => return false,
+            }
+
+            // Loop back and try locking again
+            spinwait.reset();
+            state = self.state.load(Ordering::Relaxed);
+        }
+    }
+
+    #[cold]
+    fn unlock_slow(&self, force_fair: bool) {
+        // Unpark one thread and leave the parked bit set if there might
+        // still be parked threads on this address.
+        let addr = self as *const _ as usize;
+        let callback = |result: UnparkResult| {
+            // If we are using a fair unlock then we should keep the
+            // mutex locked and hand it off to the unparked thread.
+            if result.unparked_threads != 0 && (force_fair || result.be_fair) {
+                // Clear the parked bit if there are no more parked
+                // threads.
+                if !result.have_more_threads {
+                    self.state.store(LOCKED_BIT, Ordering::Relaxed);
+                }
+                return TOKEN_HANDOFF;
+            }
+
+            // Clear the locked bit, and the parked bit as well if there
+            // are no more parked threads.
+            if result.have_more_threads {
+                self.state.store(PARKED_BIT, Ordering::Release);
+            } else {
+                self.state.store(0, Ordering::Release);
+            }
+            TOKEN_NORMAL
+        };
+        // SAFETY:
+        //   * `addr` is an address we control.
+        //   * `callback` does not panic or call into any function of `parking_lot`.
+        unsafe {
+            parking_lot_core::unpark_one(addr, callback);
+        }
+    }
+
+    #[cold]
+    fn bump_slow(&self) {
+        unsafe { deadlock::release_resource(self as *const _ as usize) };
+        self.unlock_slow(true);
+        self.lock();
+    }
+}