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

//! Caching implementation.
//!
//! Fetches changes from the ring buffer only when there is no more slots to perform requested operation.

use super::{direct::Obs, frozen::Frozen, traits::Wrap};
use crate::{
    rb::RbRef,
    traits::{
        consumer::{impl_consumer_traits, Consumer},
        producer::{impl_producer_traits, Producer},
        Observer,
    },
};
use core::{mem::MaybeUninit, num::NonZeroUsize};

/// Caching wrapper of a ring buffer.
pub struct Caching<R: RbRef, const P: bool, const C: bool> {
    frozen: Frozen<R, P, C>,
}

/// Caching producer implementation.
pub type CachingProd<R> = Caching<R, true, false>;
/// Caching consumer implementation.
pub type CachingCons<R> = Caching<R, false, true>;

impl<R: RbRef, const P: bool, const C: bool> Caching<R, P, C> {
    /// Create a new ring buffer cached wrapper.
    ///
    /// Panics if wrapper with matching rights already exists.
    pub fn new(rb: R) -> Self {
        Self { frozen: Frozen::new(rb) }
    }

    /// Get ring buffer observer.
    pub fn observe(&self) -> Obs<R> {
        self.frozen.observe()
    }

    /// Freeze current state.
    pub fn freeze(self) -> Frozen<R, P, C> {
        self.frozen
    }
}

impl<R: RbRef, const P: bool, const C: bool> Wrap for Caching<R, P, C> {
    type RbRef = R;

    fn rb_ref(&self) -> &R {
        self.frozen.rb_ref()
    }
    fn into_rb_ref(self) -> R {
        self.frozen.into_rb_ref()
    }
}

impl<R: RbRef, const P: bool, const C: bool> AsRef<Self> for Caching<R, P, C> {
    fn as_ref(&self) -> &Self {
        self
    }
}
impl<R: RbRef, const P: bool, const C: bool> AsMut<Self> for Caching<R, P, C> {
    fn as_mut(&mut self) -> &mut Self {
        self
    }
}

impl<R: RbRef, const P: bool, const C: bool> Observer for Caching<R, P, C> {
    type Item = <R::Rb as Observer>::Item;

    #[inline]
    fn capacity(&self) -> NonZeroUsize {
        self.frozen.capacity()
    }

    #[inline]
    fn read_index(&self) -> usize {
        if P {
            self.frozen.fetch();
        }
        self.frozen.read_index()
    }
    #[inline]
    fn write_index(&self) -> usize {
        if C {
            self.frozen.fetch();
        }
        self.frozen.write_index()
    }

    unsafe fn unsafe_slices(&self, start: usize, end: usize) -> (&[MaybeUninit<Self::Item>], &[MaybeUninit<Self::Item>]) {
        self.frozen.unsafe_slices(start, end)
    }
    unsafe fn unsafe_slices_mut(&self, start: usize, end: usize) -> (&mut [MaybeUninit<Self::Item>], &mut [MaybeUninit<Self::Item>]) {
        self.frozen.unsafe_slices_mut(start, end)
    }

    #[inline]
    fn read_is_held(&self) -> bool {
        self.frozen.read_is_held()
    }
    #[inline]
    fn write_is_held(&self) -> bool {
        self.frozen.write_is_held()
    }
}

impl<R: RbRef> Producer for CachingProd<R> {
    #[inline]
    unsafe fn set_write_index(&self, value: usize) {
        self.frozen.set_write_index(value);
        self.frozen.commit();
    }

    fn try_push(&mut self, elem: Self::Item) -> Result<(), Self::Item> {
        if self.frozen.is_full() {
            self.frozen.fetch();
        }
        let r = self.frozen.try_push(elem);
        if r.is_ok() {
            self.frozen.commit();
        }
        r
    }
}

impl<R: RbRef> Consumer for CachingCons<R> {
    #[inline]
    unsafe fn set_read_index(&self, value: usize) {
        self.frozen.set_read_index(value);
        self.frozen.commit();
    }

    fn try_pop(&mut self) -> Option<<Self as Observer>::Item> {
        if self.frozen.is_empty() {
            self.frozen.fetch();
        }
        let r = self.frozen.try_pop();
        if r.is_some() {
            self.frozen.commit();
        }
        r
    }
}

impl_producer_traits!(CachingProd<R: RbRef>);
impl_consumer_traits!(CachingCons<R: RbRef>);