Samuka007/asterinas
1
0
Fork 0
mirror of https://github.com/asterinas/asterinas.git synced 2025-06-24 18:03:25 +00:00
Code Issues Packages Projects Releases Wiki Activity

Rewrite the Poller&Pollee with Observer&Subject

Browse Source
This commit is contained in:
LI Qing
2023-04-24 16:47:40 +08:00
committed by Tate, Hongliang Tian
parent 2b1ecdcfa6
commit aec46295c4
11 changed files with 155 additions and 116 deletions
Download Patch File Download Diff File Expand all files Collapse all files

32
services/libs/jinux-std/src/events/events.rs
View File

@ -1,2 +1,34 @@
/// A trait to represent any events.
pub trait Events: Copy + Clone + Send + Sync + 'static {}
/// A trait to filter events.
///
/// # The no-op event filter
///
/// The unit type `()` can serve as a no-op event filter.
/// It implements `EventsFilter<E>` for any events type `E`,
/// with a `filter` method that always returns `true`.
/// If the `F` type of `Subject<E, F>` is not specified explicitly,
/// then the unit type `()` is chosen as the event filter.
///
/// # Per-object event filter
///
/// Any `Option<F: EventsFilter>` is also an event filter thanks to
/// the blanket implementations the `EventsFilter` trait.
/// By using `Option<F: EventsFilter>`, we can decide, on a per-observer basis,
/// if an observer needs an event filter.
pub trait EventsFilter<E: Events>: Send + Sync + 'static {
fn filter(&self, event: &E) -> bool;
}
impl<E: Events> EventsFilter<E> for () {
fn filter(&self, _events: &E) -> bool {
true
}
}
impl<E: Events, F: EventsFilter<E>> EventsFilter<E> for Option<F> {
fn filter(&self, events: &E) -> bool {
self.as_ref().map_or(true, |f| f.filter(events))
}
}

2
services/libs/jinux-std/src/events/mod.rs
View File

@ -2,6 +2,6 @@ mod events;
mod observer;
mod subject;
pub use self::events::Events;
pub use self::events::{Events, EventsFilter};
pub use self::observer::Observer;
pub use self::subject::Subject;

75
services/libs/jinux-std/src/events/subject.rs
View File

@ -1,43 +1,86 @@
use crate::prelude::*;
use super::{Events, Observer};
use core::sync::atomic::{AtomicUsize, Ordering};
use keyable_arc::KeyableWeak;
/// A Subject notify interesting events to registered observers.
pub struct Subject<E: Events> {
observers: Mutex<Vec<Weak<dyn Observer<E>>>>,
use super::{Events, EventsFilter, Observer};
/// A Subject notifies interesting events to registered observers.
pub struct Subject<E: Events, F: EventsFilter<E> = ()> {
// A table that maintains all interesting observers.
observers: Mutex<BTreeMap<KeyableWeak<dyn Observer<E>>, F>>,
// To reduce lock contentions, we maintain a counter for the size of the table
num_observers: AtomicUsize,
}
impl<E: Events> Subject<E> {
impl<E: Events, F: EventsFilter<E>> Subject<E, F> {
pub fn new() -> Self {
Self {
observers: Mutex::new(Vec::new()),
observers: Mutex::new(BTreeMap::new()),
num_observers: AtomicUsize::new(0),
}
}
/// Register an observer.
pub fn register_observer(&self, observer: Weak<dyn Observer<E>>) {
///
/// A registered observer will get notified through its `on_events` method.
/// If events `filter` is provided, only filtered events will notify the observer.
///
/// If the given observer has already been registered, then its registered events
/// filter will be updated.
pub fn register_observer(&self, observer: Weak<dyn Observer<E>>, filter: F) {
let mut observers = self.observers.lock();
observers.push(observer);
let is_new = {
let observer: KeyableWeak<dyn Observer<E>> = observer.into();
observers.insert(observer, filter).is_none()
};
if is_new {
self.num_observers.fetch_add(1, Ordering::Release);
}
}
/// Unregister an observer.
pub fn unregister_observer(&self, observer: &Weak<dyn Observer<E>>) {
///
/// If such an observer is found, then the registered observer will be
/// removed from the subject and returned as the return value. Otherwise,
/// a `None` will be returned.
pub fn unregister_observer(
&self,
observer: &Weak<dyn Observer<E>>,
) -> Option<Weak<dyn Observer<E>>> {
let observer: KeyableWeak<dyn Observer<E>> = observer.clone().into();
let mut observers = self.observers.lock();
observers.retain(|e| !Weak::ptr_eq(&e, observer));
let observer = observers
.remove_entry(&observer)
.map(|(observer, _)| observer.into());
if observer.is_some() {
self.num_observers.fetch_sub(1, Ordering::Relaxed);
}
observer
}
/// Notify events to all registered observers.
///
/// It will remove the observers which have been freed.
pub fn notify_observers(&self, events: &E) {
// Fast path.
if self.num_observers.load(Ordering::Relaxed) == 0 {
return;
}
// Slow path: broadcast the new events to all observers.
let mut observers = self.observers.lock();
let mut idx = 0;
while idx < observers.len() {
if let Some(observer) = observers[idx].upgrade() {
observers.retain(|observer, filter| {
if let Some(observer) = observer.upgrade() {
if !filter.filter(events) {
return true;
}
observer.on_events(events);
idx += 1;
true
} else {
observers.remove(idx);
}
self.num_observers.fetch_sub(1, Ordering::Relaxed);
false
}
});
}
}

17
services/libs/jinux-std/src/fs/epoll/epoll_file.rs
View File

@ -76,7 +76,7 @@ impl EpollFile {
if interest.contains_key(&fd) {
return_errno_with_message!(Errno::EEXIST, "the fd has been added");
}
file.register_observer(entry.clone(), IoEvents::all())?;
file.register_observer(entry.self_weak() as _, IoEvents::all())?;
interest.insert(fd, entry.clone());
// Register self to the file table entry
file_table_entry.register_observer(self.weak_self.clone() as _);
@ -113,7 +113,7 @@ impl EpollFile {
None => return Ok(()),
};
file.unregister_observer(&(entry as _)).unwrap();
file.unregister_observer(&(entry.self_weak() as _)).unwrap();
Ok(())
}
@ -294,7 +294,7 @@ impl Drop for EpollFile {
.map(|(fd, entry)| {
entry.set_deleted();
if let Some(file) = entry.file() {
let _ = file.unregister_observer(&(entry as _));
let _ = file.unregister_observer(&(entry.self_weak() as _));
}
fd
})
@ -326,7 +326,7 @@ impl FileLike for EpollFile {
fn register_observer(
&self,
observer: Arc<dyn Observer<IoEvents>>,
observer: Weak<dyn Observer<IoEvents>>,
mask: IoEvents,
) -> Result<()> {
self.pollee.register_observer(observer, mask);
@ -335,8 +335,8 @@ impl FileLike for EpollFile {
fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Result<Arc<dyn Observer<IoEvents>>> {
observer: &Weak<dyn Observer<IoEvents>>,
) -> Result<Weak<dyn Observer<IoEvents>>> {
self.pollee
.unregister_observer(observer)
.ok_or_else(|| Error::with_message(Errno::ENOENT, "observer is not registered"))
@ -398,6 +398,11 @@ impl EpollEntry {
self.weak_self.upgrade().unwrap()
}
/// Get an instance of `Weak` that refers to this epoll entry.
pub fn self_weak(&self) -> Weak<Self> {
self.weak_self.clone()
}
/// Get the file associated with this epoll entry.
///
/// Since an epoll entry only holds a weak reference to the file,

6
services/libs/jinux-std/src/fs/file_handle.rs
View File

@ -51,7 +51,7 @@ pub trait FileLike: Send + Sync + Any {
fn register_observer(
&self,
observer: Arc<dyn Observer<IoEvents>>,
observer: Weak<dyn Observer<IoEvents>>,
mask: IoEvents,
) -> Result<()> {
return_errno_with_message!(Errno::EINVAL, "register_observer is not supported")
@ -59,8 +59,8 @@ pub trait FileLike: Send + Sync + Any {
fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Result<Arc<dyn Observer<IoEvents>>> {
observer: &Weak<dyn Observer<IoEvents>>,
) -> Result<Weak<dyn Observer<IoEvents>>> {
return_errno_with_message!(Errno::EINVAL, "unregister_observer is not supported")
}

4
services/libs/jinux-std/src/fs/file_table.rs
View File

@ -114,7 +114,7 @@ impl FileTable {
}
pub fn register_observer(&self, observer: Weak<dyn Observer<FdEvents>>) {
self.subject.register_observer(observer);
self.subject.register_observer(observer, ());
}
pub fn unregister_observer(&self, observer: &Weak<dyn Observer<FdEvents>>) {
@ -170,7 +170,7 @@ impl FileTableEntry {
}
pub fn register_observer(&self, epoll: Weak<dyn Observer<FdEvents>>) {
self.subject.register_observer(epoll);
self.subject.register_observer(epoll, ());
}
pub fn unregister_observer(&self, epoll: &Weak<dyn Observer<FdEvents>>) {

12
services/libs/jinux-std/src/fs/pipe.rs
View File

@ -45,7 +45,7 @@ impl FileLike for PipeReader {
fn register_observer(
&self,
observer: Arc<dyn Observer<IoEvents>>,
observer: Weak<dyn Observer<IoEvents>>,
mask: IoEvents,
) -> Result<()> {
self.consumer.register_observer(observer, mask)
@ -53,8 +53,8 @@ impl FileLike for PipeReader {
fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Result<Arc<dyn Observer<IoEvents>>> {
observer: &Weak<dyn Observer<IoEvents>>,
) -> Result<Weak<dyn Observer<IoEvents>>> {
self.consumer.unregister_observer(observer)
}
@ -104,7 +104,7 @@ impl FileLike for PipeWriter {
fn register_observer(
&self,
observer: Arc<dyn Observer<IoEvents>>,
observer: Weak<dyn Observer<IoEvents>>,
mask: IoEvents,
) -> Result<()> {
self.producer.register_observer(observer, mask)
@ -112,8 +112,8 @@ impl FileLike for PipeWriter {
fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Result<Arc<dyn Observer<IoEvents>>> {
observer: &Weak<dyn Observer<IoEvents>>,
) -> Result<Weak<dyn Observer<IoEvents>>> {
self.producer.unregister_observer(observer)
}

6
services/libs/jinux-std/src/fs/utils/channel.rs
View File

@ -83,7 +83,7 @@ macro_rules! impl_common_methods_for_channel {
pub fn register_observer(
&self,
observer: Arc<dyn Observer<IoEvents>>,
observer: Weak<dyn Observer<IoEvents>>,
mask: IoEvents,
) -> Result<()> {
self.this_end().pollee.register_observer(observer, mask);
@ -92,8 +92,8 @@ macro_rules! impl_common_methods_for_channel {
pub fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Result<Arc<dyn Observer<IoEvents>>> {
observer: &Weak<dyn Observer<IoEvents>>,
) -> Result<Weak<dyn Observer<IoEvents>>> {
self.this_end()
.pollee
.unregister_observer(observer)

8
services/libs/jinux-std/src/fs/utils/io_events.rs
View File

@ -1,4 +1,4 @@
use crate::events::Events;
use crate::events::{Events, EventsFilter};
crate::bitflags! {
pub struct IoEvents: u32 {
@ -15,3 +15,9 @@ crate::bitflags! {
}
impl Events for IoEvents {}
impl EventsFilter<IoEvents> for IoEvents {
fn filter(&self, events: &IoEvents) -> bool {
self.intersects(*events)
}
}

97
services/libs/jinux-std/src/fs/utils/poll.rs
View File

@ -1,10 +1,10 @@
use super::IoEvents;
use crate::events::Observer;
use crate::events::{Observer, Subject};
use crate::prelude::*;
use core::sync::atomic::{AtomicU32, AtomicUsize, Ordering};
use jinux_frame::sync::WaitQueue;
use keyable_arc::KeyableArc;
use keyable_arc::KeyableWeak;
/// A pollee maintains a set of active events, which can be polled with
/// pollers or be monitored with observers.
@ -13,21 +13,18 @@ pub struct Pollee {
}
struct PolleeInner {
// A table that maintains all interesting pollers
pollers: Mutex<BTreeMap<KeyableArc<dyn Observer<IoEvents>>, IoEvents>>,
// For efficient manipulation, we use AtomicU32 instead of RwLock<IoEvents>
// A subject which is monitored with pollers.
subject: Subject<IoEvents, IoEvents>,
// For efficient manipulation, we use AtomicU32 instead of RwLock<IoEvents>.
events: AtomicU32,
// To reduce lock contentions, we maintain a counter for the size of the table
num_pollers: AtomicUsize,
}
impl Pollee {
/// Creates a new instance of pollee.
pub fn new(init_events: IoEvents) -> Self {
let inner = PolleeInner {
pollers: Mutex::new(BTreeMap::new()),
subject: Subject::new(),
events: AtomicU32::new(init_events.bits()),
num_pollers: AtomicUsize::new(0),
};
Self {
inner: Arc::new(inner),
@ -51,7 +48,7 @@ impl Pollee {
return revents;
}
// Slow path: register the provided poller
// Register the provided poller.
self.register_poller(poller.unwrap(), mask);
// It is important to check events again to handle race conditions
@ -60,17 +57,11 @@ impl Pollee {
}
fn register_poller(&self, poller: &Poller, mask: IoEvents) {
let mut pollers = self.inner.pollers.lock();
let is_new = {
let observer = poller.observer();
pollers.insert(observer, mask).is_none()
};
if is_new {
self.inner
.subject
.register_observer(poller.observer(), mask);
let mut pollees = poller.inner.pollees.lock();
pollees.push(Arc::downgrade(&self.inner));
self.inner.num_pollers.fetch_add(1, Ordering::Release);
}
pollees.insert(Arc::downgrade(&self.inner).into(), ());
}
/// Register an IoEvents observer.
@ -84,23 +75,9 @@ impl Pollee {
///
/// Note that the observer will always get notified of the events in
/// `IoEvents::ALWAYS_POLL` regardless of the value of `mask`.
///
/// # Memory leakage
///
/// Since an `Arc` for each observer is kept internally by a pollee,
/// it is important for the user to call the `unregister_observer` method
/// when the observer is no longer interested in the pollee. Otherwise,
/// the observer will not be dropped.
pub fn register_observer(&self, observer: Arc<dyn Observer<IoEvents>>, mask: IoEvents) {
let mut pollers = self.inner.pollers.lock();
let is_new = {
let observer: KeyableArc<dyn Observer<IoEvents>> = observer.into();
pub fn register_observer(&self, observer: Weak<dyn Observer<IoEvents>>, mask: IoEvents) {
let mask = mask | IoEvents::ALWAYS_POLL;
pollers.insert(observer, mask).is_none()
};
if is_new {
self.inner.num_pollers.fetch_add(1, Ordering::Release);
}
self.inner.subject.register_observer(observer, mask);
}
/// Unregister an IoEvents observer.
@ -110,17 +87,9 @@ impl Pollee {
/// a `None` will be returned.
pub fn unregister_observer(
&self,
observer: &Arc<dyn Observer<IoEvents>>,
) -> Option<Arc<dyn Observer<IoEvents>>> {
let observer: KeyableArc<dyn Observer<IoEvents>> = observer.clone().into();
let mut pollers = self.inner.pollers.lock();
let observer = pollers
.remove_entry(&observer)
.map(|(observer, _)| observer.into());
if observer.is_some() {
self.inner.num_pollers.fetch_sub(1, Ordering::Relaxed);
}
observer
observer: &Weak<dyn Observer<IoEvents>>,
) -> Option<Weak<dyn Observer<IoEvents>>> {
self.inner.subject.unregister_observer(observer)
}
/// Add some events to the pollee's state.
@ -129,18 +98,7 @@ impl Pollee {
/// the added events.
pub fn add_events(&self, events: IoEvents) {
self.inner.events.fetch_or(events.bits(), Ordering::Release);
// Fast path
if self.inner.num_pollers.load(Ordering::Relaxed) == 0 {
return;
}
// Slow path: broadcast the new events to all pollers
let pollers = self.inner.pollers.lock();
pollers
.iter()
.filter(|(_, mask)| mask.intersects(events))
.for_each(|(poller, mask)| poller.on_events(&(events & *mask)));
self.inner.subject.notify_observers(&events);
}
/// Remove some events from the pollee's state.
@ -170,14 +128,14 @@ impl Pollee {
/// A poller gets notified when its associated pollees have interesting events.
pub struct Poller {
inner: KeyableArc<PollerInner>,
inner: Arc<PollerInner>,
}
struct PollerInner {
// Use event counter to wait or wake up a poller
event_counter: EventCounter,
// All pollees that are interesting to this poller
pollees: Mutex<Vec<Weak<PolleeInner>>>,
pollees: Mutex<BTreeMap<KeyableWeak<PolleeInner>, ()>>,
}
impl Poller {
@ -185,10 +143,10 @@ impl Poller {
pub fn new() -> Self {
let inner = PollerInner {
event_counter: EventCounter::new(),
pollees: Mutex::new(Vec::with_capacity(1)),
pollees: Mutex::new(BTreeMap::new()),
};
Self {
inner: KeyableArc::new(inner),
inner: Arc::new(inner),
}
}
@ -197,8 +155,8 @@ impl Poller {
self.inner.event_counter.read();
}
fn observer(&self) -> KeyableArc<dyn Observer<IoEvents>> {
self.inner.clone() as KeyableArc<dyn Observer<IoEvents>>
fn observer(&self) -> Weak<dyn Observer<IoEvents>> {
Arc::downgrade(&self.inner) as _
}
}
@ -216,14 +174,9 @@ impl Drop for Poller {
}
let self_observer = self.observer();
for weak_pollee in pollees.drain(..) {
for (weak_pollee, _) in pollees.drain_filter(|_, _| true) {
if let Some(pollee) = weak_pollee.upgrade() {
let mut pollers = pollee.pollers.lock();
let res = pollers.remove(&self_observer);
assert!(res.is_some());
drop(pollers);
pollee.num_pollers.fetch_sub(1, Ordering::Relaxed);
pollee.subject.unregister_observer(&self_observer);
}
}
}

2
services/libs/jinux-std/src/process/process_table.rs
View File

@ -65,7 +65,7 @@ pub fn pgid_to_process_group(pgid: Pgid) -> Option<Arc<ProcessGroup>> {
}
pub fn register_observer(observer: Weak<dyn Observer<PidEvent>>) {
PROCESS_TABLE_SUBJECT.register_observer(observer);
PROCESS_TABLE_SUBJECT.register_observer(observer, ());
}
pub fn unregister_observer(observer: &Weak<dyn Observer<PidEvent>>) {