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Use a CallbackCollection for action dispatch observations

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This commit is contained in:
Max Brunsfeld 2023-01-06 09:15:53 -08:00
parent 82e9f736bd
commit 3da69117ae
2 changed files with 41 additions and 76 deletions
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51
crates/gpui/src/app/callback_collection.rs
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@ -1,44 +1,13 @@
use crate::MutableAppContext;
use collections::{BTreeMap, HashMap, HashSet};
use parking_lot::Mutex;
use std::sync::Arc;
use std::{hash::Hash, sync::Weak};
use parking_lot::Mutex;
pub struct CallbackCollection<K: Clone + Hash + Eq, F> {
internal: Arc<Mutex<Mapping<K, F>>>,
}
use collections::{BTreeMap, HashMap, HashSet};
use crate::MutableAppContext;
// Problem 5: Current bug callbacks currently called many times after being dropped
// update
// notify
// observe (push effect)
// subscription {id : 5}
// pending: [Effect::Notify, Effect::observe { id: 5 }]
// drop observation subscription (write None into subscriptions)
// flush effects
// notify
// observe
// Problem 6: Key-value pair is leaked if you drop a callback while calling it, and then never call that set of callbacks again
// -----------------
// Problem 1: Many very similar subscription enum variants
// Problem 2: Subscriptions and CallbackCollections use a shared mutex to update the callback status
// Problem 3: Current implementation is error prone with regard to uninitialized callbacks or dropping during callback
// Problem 4: Calling callbacks requires removing all of them from the list and adding them back
// Solution 1 CallbackState:
// Add more state to the CallbackCollection map to communicate dropped and initialized status
// Solves: P5
// Solution 2 DroppedSubscriptionList:
// Store a parallel set of dropped subscriptions in the Mapping which stores the key and subscription id for all dropped subscriptions
// which can be
// Solution 3 GarbageCollection:
// Use some type of traditional garbage collection to handle dropping of callbacks
// atomic flag per callback which is looped over in remove dropped entities
// TODO:
// - Move subscription id counter to CallbackCollection
// - Consider adding a reverse map in Mapping from subscription id to key so that the dropped subscriptions
// can be a hashset of usize and the Subscription doesn't need the key
// - Investigate why the remaining two types of callback lists can't use the same callback collection and subscriptions
pub struct Subscription<K: Clone + Hash + Eq, F> {
key: K,
id: usize,
@ -59,10 +28,6 @@ impl<K, F> Default for Mapping<K, F> {
}
}
pub(crate) struct CallbackCollection<K: Clone + Hash + Eq, F> {
internal: Arc<Mutex<Mapping<K, F>>>,
}
impl<K: Clone + Hash + Eq, F> Clone for CallbackCollection<K, F> {
fn clone(&self) -> Self {
Self {
@ -150,6 +115,10 @@ impl<K: Clone + Hash + Eq + Copy, F> CallbackCollection<K, F> {
}
impl<K: Clone + Hash + Eq, F> Subscription<K, F> {
pub fn id(&self) -> usize {
self.id
}
pub fn detach(&mut self) {
self.mapping.take();
}