zrx_stream/stream/barrier/set/
drain.rs

1// Copyright (c) 2025-2026 Zensical and contributors
2
3// SPDX-License-Identifier: MIT
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23
24// ----------------------------------------------------------------------------
25
26//! Drain iterator implementation for [`Barriers`].
27
28use zrx_scheduler::{Id, Key};
29use zrx_store::stash::{items, Items};
30use zrx_store::Stash;
31
32use crate::stream::barrier::Barrier;
33
34use super::{Advance, Barriers};
35
36// ----------------------------------------------------------------------------
37// Structs
38// ----------------------------------------------------------------------------
39
40/// Drain iterator for [`Barriers`].
41pub struct Drain<'a, I> {
42    /// Inner set of barriers.
43    inner: &'a Stash<Key<I>, Barrier<I>>,
44    /// All known scopes.
45    scopes: &'a Stash<Key<I>, Items>,
46    /// Drain iterator over fulfilled barriers.
47    items: items::Drain<'a>,
48}
49
50// ----------------------------------------------------------------------------
51// Implementations
52// ----------------------------------------------------------------------------
53
54impl<I> Barriers<I>
55where
56    I: Id,
57{
58    /// Creates a drain iterator over the barrier set.
59    ///
60    /// Returns all pending advances, consuming only those that are still
61    /// fulfilled at the time of collection. Barriers that were fulfilled but
62    /// subsequently invalidated by a new scope insertion are excluded and
63    /// removed from the pending set.
64    #[must_use]
65    pub fn drain(&mut self) -> Drain<'_, I> {
66        Drain {
67            inner: &self.inner,
68            scopes: &self.scopes,
69            items: self.fulfilled.drain(),
70        }
71    }
72}
73
74// ----------------------------------------------------------------------------
75// Trait implementations
76// ----------------------------------------------------------------------------
77
78impl<'a, I> Iterator for Drain<'a, I>
79where
80    I: Id,
81{
82    type Item = Advance<'a, I>;
83
84    /// Returns the next barrier advancement.
85    fn next(&mut self) -> Option<Self::Item> {
86        let index = self.items.next()?;
87        let barrier = &self.inner[index];
88        Some(Advance::new(
89            self.inner.key(index).expect("invariant"),
90            barrier.items(),
91            self.scopes,
92        ))
93    }
94}
zrx_stream/stream/barrier/set/drain.rs

zrx_stream/stream/barrier/set/
drain.rs
