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time: add abstraction for RwLock to remove poisoning aspect (#6807)

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With #6779 we removed unnecessary allocations from the timerwheel by
wrapping it in an `std::sync::RwLock`. Since the `Mutex` used in this
part of the project uses an abstraction in `loom::sync::Mutex` to get
rid of the poisoning aspects of `std::sync::Mutex` the same should
probably be done for the used read-write lock struct.

This commit introduces an abstraction to get rid of the poisoning
aspects of `std::sync::RwLock` by introducing a wrapper to the
`loom::sync` module similar to `loom::sync::Mutex`.

Refs: #6779
This commit is contained in:
Timo
2024-09-05 23:48:05 +09:00
committed by GitHub
parent 4ed0fa21e4
commit bd4ccae184
7 changed files with 114 additions and 44 deletions
Download Patch File Download Diff File Expand all files Collapse all files
tokio/src/loom/mocked.rs
+33 -1
View File
@@ -2,7 +2,7 @@ pub(crate) use loom::*;
pub(crate) mod sync {
pub(crate) use loom::sync::MutexGuard;
pub(crate) use loom::sync::{MutexGuard, RwLockReadGuard, RwLockWriteGuard};
#[derive(Debug)]
pub(crate) struct Mutex<T>(loom::sync::Mutex<T>);
@@ -30,6 +30,38 @@ pub(crate) mod sync {
self.0.get_mut().unwrap()
}
}
#[derive(Debug)]
pub(crate) struct RwLock<T>(loom::sync::RwLock<T>);
#[allow(dead_code)]
impl<T> RwLock<T> {
#[inline]
pub(crate) fn new(t: T) -> Self {
Self(loom::sync::RwLock::new(t))
}
#[inline]
pub(crate) fn read(&self) -> RwLockReadGuard<'_, T> {
self.0.read().unwrap()
}
#[inline]
pub(crate) fn try_read(&self) -> Option<RwLockReadGuard<'_, T>> {
self.0.try_read().ok()
}
#[inline]
pub(crate) fn write(&self) -> RwLockWriteGuard<'_, T> {
self.0.write().unwrap()
}
#[inline]
pub(crate) fn try_write(&self) -> Option<RwLockWriteGuard<'_, T>> {
self.0.try_write().ok()
}
}
pub(crate) use loom::sync::*;
pub(crate) mod atomic {
tokio/src/loom/std/mod.rs
+5 -1
View File
@@ -8,6 +8,7 @@ mod barrier;
mod mutex;
#[cfg(all(feature = "parking_lot", not(miri)))]
mod parking_lot;
mod rwlock;
mod unsafe_cell;
pub(crate) mod cell {
@@ -64,11 +65,14 @@ pub(crate) mod sync {
#[cfg(not(all(feature = "parking_lot", not(miri))))]
#[allow(unused_imports)]
pub(crate) use std::sync::{Condvar, MutexGuard, RwLock, RwLockReadGuard, WaitTimeoutResult};
pub(crate) use std::sync::{Condvar, MutexGuard, RwLockReadGuard, WaitTimeoutResult};
#[cfg(not(all(feature = "parking_lot", not(miri))))]
pub(crate) use crate::loom::std::mutex::Mutex;
#[cfg(not(all(feature = "parking_lot", not(miri))))]
pub(crate) use crate::loom::std::rwlock::RwLock;
pub(crate) mod atomic {
pub(crate) use crate::loom::std::atomic_u16::AtomicU16;
pub(crate) use crate::loom::std::atomic_u32::AtomicU32;
tokio/src/loom/std/parking_lot.rs
+12 -4
View File
@@ -96,12 +96,20 @@ impl<T> RwLock<T> {
RwLock(PhantomData, parking_lot::RwLock::new(t))
}
pub(crate) fn read(&self) -> LockResult<RwLockReadGuard<'_, T>> {
Ok(RwLockReadGuard(PhantomData, self.1.read()))
pub(crate) fn read(&self) -> RwLockReadGuard<'_, T> {
RwLockReadGuard(PhantomData, self.1.read())
}
pub(crate) fn write(&self) -> LockResult<RwLockWriteGuard<'_, T>> {
Ok(RwLockWriteGuard(PhantomData, self.1.write()))
pub(crate) fn try_read(&self) -> Option<RwLockReadGuard<'_, T>> {
Some(RwLockReadGuard(PhantomData, self.1.read()))
}
pub(crate) fn write(&self) -> RwLockWriteGuard<'_, T> {
RwLockWriteGuard(PhantomData, self.1.write())
}
pub(crate) fn try_write(&self) -> Option<RwLockWriteGuard<'_, T>> {
Some(RwLockWriteGuard(PhantomData, self.1.write()))
}
}
tokio/src/loom/std/rwlock.rs
+48
View File
@@ -0,0 +1,48 @@
use std::sync::{self, RwLockReadGuard, RwLockWriteGuard, TryLockError};
/// Adapter for `std::sync::RwLock` that removes the poisoning aspects
/// from its api.
#[derive(Debug)]
pub(crate) struct RwLock<T: ?Sized>(sync::RwLock<T>);
#[allow(dead_code)]
impl<T> RwLock<T> {
#[inline]
pub(crate) fn new(t: T) -> Self {
Self(sync::RwLock::new(t))
}
#[inline]
pub(crate) fn read(&self) -> RwLockReadGuard<'_, T> {
match self.0.read() {
Ok(guard) => guard,
Err(p_err) => p_err.into_inner(),
}
}
#[inline]
pub(crate) fn try_read(&self) -> Option<RwLockReadGuard<'_, T>> {
match self.0.try_read() {
Ok(guard) => Some(guard),
Err(TryLockError::Poisoned(p_err)) => Some(p_err.into_inner()),
Err(TryLockError::WouldBlock) => None,
}
}
#[inline]
pub(crate) fn write(&self) -> RwLockWriteGuard<'_, T> {
match self.0.write() {
Ok(guard) => guard,
Err(p_err) => p_err.into_inner(),
}
}
#[inline]
pub(crate) fn try_write(&self) -> Option<RwLockWriteGuard<'_, T>> {
match self.0.try_write() {
Ok(guard) => Some(guard),
Err(TryLockError::Poisoned(p_err)) => Some(p_err.into_inner()),
Err(TryLockError::WouldBlock) => None,
}
}
}
tokio/src/runtime/time/mod.rs
+6 -28
View File
@@ -20,7 +20,7 @@ pub(crate) use source::TimeSource;
mod wheel;
use crate::loom::sync::atomic::{AtomicBool, Ordering};
use crate::loom::sync::Mutex;
use crate::loom::sync::{Mutex, RwLock};
use crate::runtime::driver::{self, IoHandle, IoStack};
use crate::time::error::Error;
use crate::time::{Clock, Duration};
@@ -28,7 +28,6 @@ use crate::util::WakeList;
use crate::loom::sync::atomic::AtomicU64;
use std::fmt;
use std::sync::RwLock;
use std::{num::NonZeroU64, ptr::NonNull};
struct AtomicOptionNonZeroU64(AtomicU64);
@@ -199,12 +198,7 @@ impl Driver {
// Finds out the min expiration time to park.
let expiration_time = {
let mut wheels_lock = rt_handle
.time()
.inner
.wheels
.write()
.expect("Timer wheel shards poisoned");
let mut wheels_lock = rt_handle.time().inner.wheels.write();
let expiration_time = wheels_lock
.0
.iter_mut()
@@ -324,11 +318,7 @@ impl Handle {
// Returns the next wakeup time of this shard.
pub(self) fn process_at_sharded_time(&self, id: u32, mut now: u64) -> Option<u64> {
let mut waker_list = WakeList::new();
let mut wheels_lock = self
.inner
.wheels
.read()
.expect("Timer wheel shards poisoned");
let mut wheels_lock = self.inner.wheels.read();
let mut lock = wheels_lock.lock_sharded_wheel(id);
if now < lock.elapsed() {
@@ -355,11 +345,7 @@ impl Handle {
waker_list.wake_all();
wheels_lock = self
.inner
.wheels
.read()
.expect("Timer wheel shards poisoned");
wheels_lock = self.inner.wheels.read();
lock = wheels_lock.lock_sharded_wheel(id);
}
}
@@ -384,11 +370,7 @@ impl Handle {
/// `add_entry` must not be called concurrently.
pub(self) unsafe fn clear_entry(&self, entry: NonNull<TimerShared>) {
unsafe {
let wheels_lock = self
.inner
.wheels
.read()
.expect("Timer wheel shards poisoned");
let wheels_lock = self.inner.wheels.read();
let mut lock = wheels_lock.lock_sharded_wheel(entry.as_ref().shard_id());
if entry.as_ref().might_be_registered() {
@@ -412,11 +394,7 @@ impl Handle {
entry: NonNull<TimerShared>,
) {
let waker = unsafe {
let wheels_lock = self
.inner
.wheels
.read()
.expect("Timer wheel shards poisoned");
let wheels_lock = self.inner.wheels.read();
let mut lock = wheels_lock.lock_sharded_wheel(entry.as_ref().shard_id());
tokio/src/sync/broadcast.rs
+5 -5
View File
@@ -599,7 +599,7 @@ impl<T> Sender<T> {
tail.pos = tail.pos.wrapping_add(1);
// Get the slot
let mut slot = self.shared.buffer[idx].write().unwrap();
let mut slot = self.shared.buffer[idx].write();
// Track the position
slot.pos = pos;
@@ -695,7 +695,7 @@ impl<T> Sender<T> {
while low < high {
let mid = low + (high - low) / 2;
let idx = base_idx.wrapping_add(mid) & self.shared.mask;
if self.shared.buffer[idx].read().unwrap().rem.load(SeqCst) == 0 {
if self.shared.buffer[idx].read().rem.load(SeqCst) == 0 {
low = mid + 1;
} else {
high = mid;
@@ -737,7 +737,7 @@ impl<T> Sender<T> {
let tail = self.shared.tail.lock();
let idx = (tail.pos.wrapping_sub(1) & self.shared.mask as u64) as usize;
self.shared.buffer[idx].read().unwrap().rem.load(SeqCst) == 0
self.shared.buffer[idx].read().rem.load(SeqCst) == 0
}
/// Returns the number of active receivers.
@@ -1057,7 +1057,7 @@ impl<T> Receiver<T> {
let idx = (self.next & self.shared.mask as u64) as usize;
// The slot holding the next value to read
let mut slot = self.shared.buffer[idx].read().unwrap();
let mut slot = self.shared.buffer[idx].read();
if slot.pos != self.next {
// Release the `slot` lock before attempting to acquire the `tail`
@@ -1074,7 +1074,7 @@ impl<T> Receiver<T> {
let mut tail = self.shared.tail.lock();
// Acquire slot lock again
slot = self.shared.buffer[idx].read().unwrap();
slot = self.shared.buffer[idx].read();
// Make sure the position did not change. This could happen in the
// unlikely event that the buffer is wrapped between dropping the
tokio/src/sync/watch.rs
+5 -5
View File
@@ -575,7 +575,7 @@ impl<T> Receiver<T> {
/// assert_eq!(*rx.borrow(), "hello");
/// ```
pub fn borrow(&self) -> Ref<'_, T> {
let inner = self.shared.value.read().unwrap();
let inner = self.shared.value.read();
// After obtaining a read-lock no concurrent writes could occur
// and the loaded version matches that of the borrowed reference.
@@ -622,7 +622,7 @@ impl<T> Receiver<T> {
/// [`changed`]: Receiver::changed
/// [`borrow`]: Receiver::borrow
pub fn borrow_and_update(&mut self) -> Ref<'_, T> {
let inner = self.shared.value.read().unwrap();
let inner = self.shared.value.read();
// After obtaining a read-lock no concurrent writes could occur
// and the loaded version matches that of the borrowed reference.
@@ -813,7 +813,7 @@ impl<T> Receiver<T> {
let mut closed = false;
loop {
{
let inner = self.shared.value.read().unwrap();
let inner = self.shared.value.read();
let new_version = self.shared.state.load().version();
let has_changed = self.version != new_version;
@@ -1087,7 +1087,7 @@ impl<T> Sender<T> {
{
{
// Acquire the write lock and update the value.
let mut lock = self.shared.value.write().unwrap();
let mut lock = self.shared.value.write();
// Update the value and catch possible panic inside func.
let result = panic::catch_unwind(panic::AssertUnwindSafe(|| modify(&mut lock)));
@@ -1164,7 +1164,7 @@ impl<T> Sender<T> {
/// assert_eq!(*tx.borrow(), "hello");
/// ```
pub fn borrow(&self) -> Ref<'_, T> {
let inner = self.shared.value.read().unwrap();
let inner = self.shared.value.read();
// The sender/producer always sees the current version
let has_changed = false;