dope 0.12.0

The manifold runtime
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
155
156
157
158
159
160
161
162

use std::io;
use std::os::fd::AsRawFd;

use super::FileOutcome;
use super::raw::ReadRegion;
use super::raw::table::OperationTable;
use super::source::Source;
use dope::DriverContext;
use dope_core::backend::RawSqe;
use dope_core::driver::ready::CompletionWaker;
use dope_core::driver::token::kind::READ;
use dope_core::driver::token::{KeyTag, Token};
use dope_core::io::ReadEvent;
use std::io::Error;
use std::io::ErrorKind;
use std::mem::replace;
use std::process::abort;

pub enum ReadDone {
    Complete(usize),
    Failed(Error),
}

enum ReadFlight {
    Idle,
    Prepared(ReadRegion),
    Pending(ReadRegion),
}

struct ReadHold<'d> {
    buffer: Vec<u8>,
    source: Source<'d>,
    offset: u64,
    flight: ReadFlight,
}

impl ReadHold<'_> {
    fn prepare_submission(&mut self, token: Token) -> io::Result<RawSqe> {
        if !matches!(self.flight, ReadFlight::Idle) {
            return Err(Self::invalid_flight());
        }
        let region = ReadRegion::new(&mut self.buffer).ok_or_else(|| {
            Error::new(
                ErrorKind::InvalidInput,
                "dope::file: read buffer has no writable region",
            )
        })?;
        let (sqe, region) = region.submission(self.source.as_raw_fd(), self.offset, token);
        self.flight = ReadFlight::Prepared(region);
        Ok(sqe)
    }

    fn accept_submission(&mut self) {
        let ReadFlight::Prepared(region) = replace(&mut self.flight, ReadFlight::Idle) else {
            abort();
        };
        self.flight = ReadFlight::Pending(region);
    }

    fn abort_submission(&mut self) {
        if !matches!(
            std::mem::replace(&mut self.flight, ReadFlight::Idle),
            ReadFlight::Prepared(_)
        ) {
            abort();
        }
    }

    fn finish(&mut self, amount: u32) -> io::Result<()> {
        let ReadFlight::Pending(region) = replace(&mut self.flight, ReadFlight::Idle) else {
            return Err(Self::invalid_flight());
        };
        region.commit(&mut self.buffer, amount)
    }

    fn invalid_flight() -> Error {
        Error::new(
            ErrorKind::InvalidData,
            "dope::file: read completion does not match a pending region",
        )
    }
}

pub(crate) struct ReadTable<'d, const ID: u8> {
    operations: OperationTable<'d, ReadHold<'d>, ReadDone, KeyTag<ID, READ>>,
}

impl<'d, const ID: u8> ReadTable<'d, ID> {
    pub(crate) fn new(capacity: usize) -> Self {
        Self {
            operations: OperationTable::with_capacity(capacity),
        }
    }

    pub(crate) fn is_empty(&self) -> bool {
        self.operations.is_empty()
    }

    pub(crate) fn append_targets(&self, targets: &mut Vec<Token>) {
        self.operations.append_targets(targets);
    }

    pub(crate) fn begin(
        &self,
        source: Source<'d>,
        buffer: Vec<u8>,
        offset: u64,
        driver: &mut DriverContext<'_, 'd>,
    ) -> Result<Token, (Vec<u8>, Error)> {
        self.operations
            .begin_prepared(
                ReadHold {
                    buffer,
                    source,
                    offset,
                    flight: ReadFlight::Idle,
                },
                driver,
                |token, hold| Ok((token, hold.prepare_submission(token)?)),
                ReadHold::accept_submission,
                ReadHold::abort_submission,
            )
            .map_err(|(hold, error)| (hold.buffer, error))
    }

    pub(crate) fn poll(
        &self,
        token: Token,
        wake: CompletionWaker<'d>,
    ) -> FileOutcome<(Vec<u8>, ReadDone)> {
        match self.operations.poll(token, wake) {
            Some((hold, done)) => FileOutcome::Done((hold.buffer, done)),
            None => FileOutcome::Pending,
        }
    }

    pub(crate) fn cancel(&self, token: Token) {
        let _ = self.operations.request_cancel(token);
    }

    pub(crate) fn flush_cancellations(&self, driver: &mut DriverContext<'_, 'd>) -> bool {
        self.operations.flush_cancellations(driver)
    }

    pub(crate) fn complete(&self, token: Token, event: ReadEvent) {
        self.operations
            .complete(token, event, |hold, event| match event {
                ReadEvent::Read(amount) => match hold.finish(amount) {
                    Ok(()) => ReadDone::Complete(amount as usize),
                    Err(error) => ReadDone::Failed(error),
                },
                ReadEvent::Eof => match hold.finish(0) {
                    Ok(()) => ReadDone::Complete(0),
                    Err(error) => ReadDone::Failed(error),
                },
                ReadEvent::Failed(errno) => match hold.finish(0) {
                    Ok(()) => ReadDone::Failed(Error::from_raw_os_error(errno)),
                    Err(error) => ReadDone::Failed(error),
                },
            });
    }
}