First commit, experimental run of v0.3.0
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/target
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Cargo.lock
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[package]
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name = "eventbus"
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version = "0.3.0"
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authors = ["SoniEx2 <endermoneymod@gmail.com>"]
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description = "Safe, fast and concurrent event system, inspired by the MinecraftForge event bus."
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keywords = ["event", "safe", "fast", "concurrent", "bus"]
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license = "AGPL-3.0+"
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repository = "https://bitbucket.org/TeamSoni/eventbus.rs"
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[dependencies]
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lazy_static = "1.1.0"
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anymap = "0.12.1"
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/*
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* Event Bus
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* Copyright (C) 2018 Soni L.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <https://www.gnu.org/licenses/>.
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*/
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/// Registers an event hook.
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///
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/// Usage: `register_hook!(bus, priority, type, handler)`
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#[macro_export]
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macro_rules! register_hook {
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($b:expr, $p:expr, $t:ty, $h:expr) => {
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{
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static EVENT_ID: ::std::sync::atomic::AtomicUsize = std::sync::atomic::ATOMIC_USIZE_INIT;
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static EVENT_ID_INIT: ::std::sync::Once = std::sync::ONCE_INIT;
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// no generics allowed.
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static DUMMY: ::std::marker::PhantomData<$t> = ::std::marker::PhantomData;
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EVENT_ID_INIT.call_once(|| {
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EVENT_ID.store($crate::get_event_id::<$t>(), std::sync::atomic::Ordering::Relaxed);
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});
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let id = EVENT_ID.load(std::sync::atomic::Ordering::Relaxed);
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$crate::register::<$t, _>($b, $p, $h, id)
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}
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}
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}
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/// Posts an event.
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///
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/// Usage: `post!(bus, type, event)`
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#[macro_export]
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macro_rules! post_event {
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($b:expr, $t:ty, $e:expr) => {
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{
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static EVENT_ID: ::std::sync::atomic::AtomicUsize = std::sync::atomic::ATOMIC_USIZE_INIT;
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static EVENT_ID_INIT: ::std::sync::Once = std::sync::ONCE_INIT;
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// no generics allowed.
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static DUMMY: ::std::marker::PhantomData<$t> = ::std::marker::PhantomData;
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EVENT_ID_INIT.call_once(|| {
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EVENT_ID.store($crate::get_event_id::<$t>(), std::sync::atomic::Ordering::Relaxed);
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});
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let id = EVENT_ID.load(std::sync::atomic::Ordering::Relaxed);
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let event: &mut $t = $e;
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let handlers = $crate::get_post_targets::<$t>($b, event, id);
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for (_pri, fun) in handlers.iter() {
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fun(event);
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if <$t>::cancellable() && event.cancelled() {
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break;
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}
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}
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<$t>::cancellable() && event.cancelled()
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}
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}
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}
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/// Basic trait for defining an event.
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pub trait Event: 'static {
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/// Returns whether this event is cancellable.
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///
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/// When this is true, `cancelled` and `cancel` should also be implemented.
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fn cancellable() -> bool {
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false
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}
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/// Returns whether this event has been cancelled.
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fn cancelled(&self) -> bool {
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false
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}
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/// Sets whether this event is cancelled.
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///
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/// # Panics
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///
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/// Panics if this event is not cancellable.
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fn set_cancelled(&mut self, cancel: bool) {
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panic!("not cancellable");
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}
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}
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/// An event bus.
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pub struct EventBus {
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id: usize,
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dropper: Mutex<LinkedList<Box<dyn Fn(usize) + Send + Sync>>>,
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}
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#[macro_use]
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extern crate lazy_static;
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extern crate anymap;
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//use std::marker::PhantomData;
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use std::sync::atomic::AtomicUsize;
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use std::sync::atomic::ATOMIC_USIZE_INIT;
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use std::sync::atomic::Ordering as AtomicOrdering;
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use std::sync::Mutex;
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use std::collections::LinkedList;
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use std::any::Any;
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use std::sync::Arc;
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use std::sync::RwLock;
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use std::mem;
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/* only exists as a module to keep us from accidentally misusing these */
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mod id_map {
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use std::marker::PhantomData;
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use std::sync::atomic::AtomicUsize;
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use std::sync::atomic::ATOMIC_USIZE_INIT;
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use std::sync::atomic::Ordering as AtomicOrdering;
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use std::sync::Mutex;
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use std::sync::Arc;
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use super::Event;
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use super::Handlers;
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lazy_static! {
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static ref EVENT_ID_MAP: Mutex<::anymap::Map<::anymap::any::Any + Send + Sync>> = Mutex::new(::anymap::Map::new());
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}
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struct EventId<T: Event> {
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id: usize,
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_t: PhantomData<dyn Fn(&mut T) + Send + Sync>
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}
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pub fn get_event_id<T: Event>() -> usize {
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static EVENT_ID_COUNT: AtomicUsize = ATOMIC_USIZE_INIT;
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let id = EVENT_ID_MAP.lock().expect("failed to allocate event id").entry::<EventId<T>>().or_insert_with(|| EventId { id: EVENT_ID_COUNT.fetch_add(1, AtomicOrdering::SeqCst), _t: PhantomData }).id;
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let handlers: Arc<Handlers<T>> = Default::default();
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Arc::make_mut(&mut super::HANDLERS.write().expect("???")).push(handlers);
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id
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}
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}
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/// Low-level event handling function, returns the event ID for use with get_post_targets.
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///
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/// This function is (extremely) slow!
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pub fn get_event_id<T: Event>() -> usize {
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id_map::get_event_id::<T>()
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}
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type RwArcVec<T> = RwLock<Arc<Vec<T>>>;
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struct Handlers<T: Event>(RwArcVec<RwArcVec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>>);
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impl<T: Event> Default for Handlers<T> {
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fn default() -> Self {
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Handlers(Default::default())
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}
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}
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lazy_static! {
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static ref HANDLERS: RwArcVec<Arc<dyn Any + Send + Sync>> = Default::default();
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}
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/// Low-level event handling function, returns the handlers that should be called to post the
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/// event.
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///
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/// This is useful if you want to simulate inheritance.
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///
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/// # Panics
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///
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/// Panics if `id` doesn't match the given `T` (but not if the given `id` doesn't exist).
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pub fn get_post_targets<T: Event>(bus: &EventBus, event: &mut T, id: usize) -> Arc<Vec<(i32, Arc<dyn Fn(&mut T) + Send + Sync>)>> {
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let target: Option<Arc<Vec<_>>> = HANDLERS.read().expect("failed to lock for reading").get(id).map(|arc| Arc::clone(arc))
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.map(|any| Arc::downcast::<Handlers<T>>(any).expect("Wrong id"))
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.and_then(|handlers| handlers.0.read().expect("failed to lock for reading").get(bus.id).map(|hooks| Arc::clone(&*hooks.read().expect("failed to lock for reading"))));
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target.unwrap_or_else(|| Arc::new(Vec::new()))
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}
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/// Low-level event handling function, registers an event.
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///
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/// This function is kinda slow. It doesn't block currently executing hooks (and, in fact, may be
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/// safely called from a running hook), but does block threads from starting hook execution.
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///
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/// # Panics
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///
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/// Panics if `id` doesn't match the given `T`, or if `id` doesn't exist.
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pub fn register<T: Event, F: for<'a> Fn(&'a mut T) + Send + Sync + 'static>(bus: &EventBus, priority: i32, handler: F, id: usize) {
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HANDLERS.read().expect("failed to lock for reading").get(id).map(|arc| Arc::clone(arc))
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.map(|any| Arc::downcast::<Handlers<T>>(any).expect("Wrong id"))
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.map(|handlers| {
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let mut lock = handlers.0.read().expect("failed to lock for reading");
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if lock.len() <= id {
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mem::drop(lock);
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let mut wlock = handlers.0.write().expect("failed to lock for writing");
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if wlock.len() <= id { // another thread may have touched this
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let vec = Arc::get_mut(&mut wlock).expect("failed to mutate busses");
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let count = id - vec.len() + 1;
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vec.reserve_exact(count);
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for _ in 0..count {
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vec.push(Default::default());
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}
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}
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// there's no way to downgrade a write lock, but as long as we never shrink the
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// vecs it should be fine.
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mem::drop(wlock);
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lock = handlers.0.read().expect("failed to lock for reading");
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}
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let option = lock.get(bus.id);
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// last RwLock
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let hooks = option.expect("failed to make vecs");
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let hook: (i32, Arc<dyn Fn(&mut T) + Send + Sync + 'static>) = (priority, Arc::new(handler));
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let mut wlock = hooks.write().expect("failed to lock for writing");
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let vec = Arc::make_mut(&mut wlock);
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// would be nice if Result had a .coalesce()
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let pos = match vec.binary_search_by(|probe| probe.0.cmp(&priority)) { Ok(p) => p, Err(p) => p };
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vec.insert(pos, hook);
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}).expect("No such id");
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}
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static BUS_ID: AtomicUsize = ATOMIC_USIZE_INIT;
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lazy_static! {
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// this is the closest to high-performance we can get with std
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// would be nicer if this didn't lock the whole list
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static ref FREED_BUS_IDS: Mutex<LinkedList<usize>> = Mutex::new(LinkedList::new());
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}
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impl EventBus {
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/// Makes a new EventBus.
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pub fn new() -> EventBus {
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EventBus {
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id: FREED_BUS_IDS.lock().unwrap().pop_front().unwrap_or_else(|| BUS_ID.fetch_add(1, AtomicOrdering::SeqCst)),
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dropper: Default::default(),
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}
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}
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}
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impl Drop for EventBus {
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fn drop(&mut self) {
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// TODO
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}
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}
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@ -0,0 +1,38 @@
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#[macro_use]
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extern crate eventbus;
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use eventbus::{Event, EventBus};
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struct MyEvent {
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i: i32
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}
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impl Event for MyEvent {
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}
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fn add_handler(e: &mut MyEvent) {
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/* adds 1 */
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e.i += 1;
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}
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fn no_handler(e: &mut MyEvent) {
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/* does nothing */
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e.i += 0;
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}
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#[test]
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fn test_basic_usage() {
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let event_bus = EventBus::new();
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//let handler_id = event_bus.register(add_handler, 0);
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register_hook!(&event_bus, 0, MyEvent, add_handler);
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let mut event = MyEvent { i: 3 };
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assert_eq!(event.i, 3);
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post_event!(&event_bus, MyEvent, &mut event);
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assert_eq!(event.i, 4);
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register_hook!(&event_bus, 1, MyEvent, no_handler);
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post_event!(&event_bus, MyEvent, &mut event);
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assert_eq!(event.i, 5);
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//event_bus.unregister(handler_id);
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post_event!(&event_bus, MyEvent, &mut event);
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//assert_eq!(event.i, 5);
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}
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