o3 0.14.1

shared-nothing primitives
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154

use std::mem;

use crate::collections::slab::{self, core};

pub(in crate::collections::slab) struct Busy<'a, T, G: slab::GenerationState, M: core::Mode> {
    core: &'a core::Core<T, G, M>,
    index: core::SlotIndex,
    generation: G,
    live: bool,
}

impl<'a, T, G: slab::GenerationState, M: core::Mode> Busy<'a, T, G, M> {
    pub(in crate::collections::slab) fn take_committed(
        core: &'a core::Core<T, G, M>,
        ticket: core::Ticket<G>,
    ) -> Self {
        let slot = unsafe { core.slots.get_unchecked(ticket.index.get() as usize) };
        debug_assert!(
            slot.state.get() == core::State::Occupied && slot.generation.get() == ticket.generation
        );
        if M::REENTRANT {
            slot.state.set(core::State::Busy);
        }
        Self {
            core,
            index: ticket.index,
            generation: ticket.generation,
            live: true,
        }
    }

    pub(in crate::collections::slab) fn take(
        core: &'a core::Core<T, G, M>,
        index: u32,
    ) -> Option<Self> {
        let slot = core.slots.get(index as usize)?;
        let index = core::SlotIndex::new(index, core.slots.len())?;
        let state = if M::REENTRANT {
            slot.state.replace(core::State::Busy)
        } else {
            slot.state.get()
        };
        if state == core::State::Occupied {
            Some(Self {
                core,
                index,
                generation: slot.generation.get(),
                live: true,
            })
        } else {
            if M::REENTRANT {
                slot.state.set(state);
            }
            None
        }
    }

    pub(in crate::collections::slab) fn take_key(
        core: &'a core::Core<T, G, M>,
        index: u32,
        generation: G,
    ) -> Option<Self> {
        let busy = Self::take(core, index)?;
        (busy.generation == generation).then_some(busy)
    }

    pub(in crate::collections::slab) fn index(&self) -> u32 {
        self.index.get()
    }

    pub(in crate::collections::slab) fn generation(&self) -> G {
        self.generation
    }

    pub(in crate::collections::slab) fn value(&self) -> &T {
        unsafe { self.slot().value() }
    }

    pub(in crate::collections::slab) fn value_mut(&mut self) -> &mut T {
        unsafe {
            &mut *self
                .core
                .slots
                .get_unchecked(self.index.get() as usize)
                .value_ptr()
        }
    }

    fn slot(&self) -> &core::Slot<T, G> {
        unsafe { self.core.slots.get_unchecked(self.index.get() as usize) }
    }

    pub(in crate::collections::slab) fn commit_removal(mut self) -> (T, core::SlotIndex) {
        let next = self.generation.next();
        let value = unsafe { self.slot().take_value() };
        self.live = false;
        self.core.entries().remove_occupied(self.index);
        match next {
            Some(generation) => self.core.reservations().release(self.index, generation),
            None if self.core.recycle_generations() => {
                self.core.reservations().release(self.index, G::MIN)
            }
            None => self.slot().state.set(core::State::Retired),
        }
        (value, self.index)
    }
}

pub(super) struct Inserted<'a, T, G: slab::GenerationState, M: core::Mode> {
    busy: mem::ManuallyDrop<Busy<'a, T, G, M>>,
    rollback: bool,
}

impl<'a, T, G: slab::GenerationState, M: core::Mode> Inserted<'a, T, G, M> {
    pub(super) fn new(core: &'a core::Core<T, G, M>, ticket: core::Ticket<G>) -> Self {
        Self {
            busy: mem::ManuallyDrop::new(Busy::take_committed(core, ticket)),
            rollback: true,
        }
    }

    pub(super) fn value_mut(&mut self) -> &mut T {
        self.busy.value_mut()
    }

    pub(super) fn commit(mut self) {
        self.rollback = false;
        unsafe { mem::ManuallyDrop::drop(&mut self.busy) };
    }

    pub(super) fn rollback(mut self) -> T {
        self.rollback = false;
        unsafe { mem::ManuallyDrop::take(&mut self.busy) }
            .commit_removal()
            .0
    }
}

impl<T, G: slab::GenerationState, M: core::Mode> Drop for Inserted<'_, T, G, M> {
    fn drop(&mut self) {
        if self.rollback {
            let busy = unsafe { mem::ManuallyDrop::take(&mut self.busy) };
            drop(busy.commit_removal().0);
        }
    }
}

impl<T, G: slab::GenerationState, M: core::Mode> Drop for Busy<'_, T, G, M> {
    fn drop(&mut self) {
        if self.live && M::REENTRANT {
            self.slot().state.set(core::State::Occupied);
        }
    }
}