From 1287abc6a140568827beb075b3ed5fc603319645 Mon Sep 17 00:00:00 2001
From: "zed-zippy[bot]" <234243425+zed-zippy[bot]@users.noreply.github.com>
Date: Fri, 19 Dec 2025 15:33:56 +0000
Subject: [PATCH] adjusted scheduler prioritization algorithm (#45367)
 (cherry-pick to preview) (#45370)
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Cherry-pick of #45367 to preview

----
This fixes a number of issues where zed depends on the order of polling
which changed when switching scheduler. We have adjusted the algorithm
so it matches the previous order while keeping the prioritization
feature.

Release Notes:
- N/A

Co-authored-by: Yara 🏳️‍⚧️ <git@yara.blue>
---
 crates/gpui/src/queue.rs | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/crates/gpui/src/queue.rs b/crates/gpui/src/queue.rs
index 9e9da710977ee80df1853791918eebe5e7f01096..1ecec183c6c58a86e305343f7bcd1056cda7a581 100644
--- a/crates/gpui/src/queue.rs
+++ b/crates/gpui/src/queue.rs
@@ -1,4 +1,5 @@
 use std::{
+    collections::VecDeque,
     fmt,
     iter::FusedIterator,
     sync::{Arc, atomic::AtomicUsize},
@@ -9,9 +10,9 @@ use rand::{Rng, SeedableRng, rngs::SmallRng};
 use crate::Priority;
 
 struct PriorityQueues<T> {
-    high_priority: Vec<T>,
-    medium_priority: Vec<T>,
-    low_priority: Vec<T>,
+    high_priority: VecDeque<T>,
+    medium_priority: VecDeque<T>,
+    low_priority: VecDeque<T>,
 }
 
 impl<T> PriorityQueues<T> {
@@ -42,9 +43,9 @@ impl<T> PriorityQueueState<T> {
         let mut queues = self.queues.lock();
         match priority {
             Priority::Realtime(_) => unreachable!(),
-            Priority::High => queues.high_priority.push(item),
-            Priority::Medium => queues.medium_priority.push(item),
-            Priority::Low => queues.low_priority.push(item),
+            Priority::High => queues.high_priority.push_back(item),
+            Priority::Medium => queues.medium_priority.push_back(item),
+            Priority::Low => queues.low_priority.push_back(item),
         };
         self.condvar.notify_one();
         Ok(())
@@ -141,9 +142,9 @@ impl<T> PriorityQueueReceiver<T> {
     pub(crate) fn new() -> (PriorityQueueSender<T>, Self) {
         let state = PriorityQueueState {
             queues: parking_lot::Mutex::new(PriorityQueues {
-                high_priority: Vec::new(),
-                medium_priority: Vec::new(),
-                low_priority: Vec::new(),
+                high_priority: VecDeque::new(),
+                medium_priority: VecDeque::new(),
+                low_priority: VecDeque::new(),
             }),
             condvar: parking_lot::Condvar::new(),
             receiver_count: AtomicUsize::new(1),
@@ -226,7 +227,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.high_priority.is_empty() {
             let flip = self.rand.random_ratio(P::High.probability(), mass);
             if flip {
-                return Ok(queues.high_priority.pop());
+                return Ok(queues.high_priority.pop_front());
             }
             mass -= P::High.probability();
         }
@@ -234,7 +235,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.medium_priority.is_empty() {
             let flip = self.rand.random_ratio(P::Medium.probability(), mass);
             if flip {
-                return Ok(queues.medium_priority.pop());
+                return Ok(queues.medium_priority.pop_front());
             }
             mass -= P::Medium.probability();
         }
@@ -242,7 +243,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.low_priority.is_empty() {
             let flip = self.rand.random_ratio(P::Low.probability(), mass);
             if flip {
-                return Ok(queues.low_priority.pop());
+                return Ok(queues.low_priority.pop_front());
             }
         }