glommio 0.3.0

A set of utilities to allow one to write thread per core applications
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

// Unless explicitly stated otherwise all files in this repository are licensed under the
// MIT/Apache-2.0 License, at your convenience
//
// This product includes software developed at Datadog (https://www.datadoghq.com/). Copyright 2020 Datadog, Inc.
//
use ahash::AHashMap;
use std::cell::RefCell;
use std::fs::{canonicalize, read_dir, read_to_string};
use std::io;
use std::path::{Path, PathBuf};
use std::str::FromStr;
use std::vec::Vec;

thread_local!(static DEV_MAP: RefCell<AHashMap<(usize, usize), BlockDevice>> = RefCell::new(AHashMap::new()));

#[derive(Debug)]
enum StorageCache {
    WriteBack,
    WriteThrough,
}

impl FromStr for StorageCache {
    type Err = String;
    fn from_str(data: &str) -> Result<Self, Self::Err> {
        let contents = data.trim_matches('\n');
        match contents {
            "write back" => Ok(StorageCache::WriteBack),
            "write through" => Ok(StorageCache::WriteThrough),
            _ => Err(format!("Invalid value {}", data)),
        }
    }
}

#[derive(Debug)]
pub(crate) struct BlockDevice {
    memory_device: bool,
    rotational: bool,
    minimum_io_size: usize,
    optimal_io_size: usize,
    logical_block_size: usize,
    physical_block_size: usize,
    cache: StorageCache,
    subcomponents: Vec<PathBuf>,
}

macro_rules! block_property {
    ( $map:expr, $property:tt, $major:expr, $minor:expr ) => {
        DEV_MAP.with(|x| {
            let key = ($major, $minor);
            let mut map = x.borrow_mut();
            let bdev = map.entry(key).or_insert_with(|| BlockDevice::new(key));

            bdev.$property.clone()
        });
    };
}

fn read_int<P: AsRef<Path>>(path: P) -> isize {
    let path = path.as_ref();
    let data =
        read_to_string(path).unwrap_or_else(|err| panic!("reading {} ({})", path.display(), err));
    let contents = data.trim_matches('\n');
    contents.parse::<isize>().unwrap()
}

#[allow(dead_code)]
impl BlockDevice {
    fn in_memory() -> BlockDevice {
        BlockDevice {
            memory_device: true,
            rotational: false,
            minimum_io_size: 512,
            optimal_io_size: 128 << 10,
            logical_block_size: 512,
            physical_block_size: 512,
            cache: StorageCache::WriteBack,
            subcomponents: Vec::new(),
        }
    }

    fn new(dev_id: (usize, usize)) -> BlockDevice {
        // /sys/dev/block/major:minor is a symlink to the device in /sys/devices/
        // However if this a partition, we actually want to look at the main device.
        // So minor is always zero.
        let dir_path = format!("/sys/dev/block/{}:{}", dev_id.0, 0);
        let dir = match canonicalize(Path::new(dir_path.as_str())) {
            Ok(path) => path,
            Err(x) => match x.kind() {
                io::ErrorKind::NotFound => return BlockDevice::in_memory(),
                _ => panic!("Unexpected error: {:?}", x),
            },
        };
        let queue = dir.join("queue");

        let rotational = read_int(&queue.join("rotational")) != 0;
        let minimum_io_size = read_int(&queue.join("minimum_io_size")) as _;
        let optimal_io_size = read_int(&queue.join("optimal_io_size")) as _;
        let logical_block_size = read_int(&queue.join("logical_block_size")) as _;
        let physical_block_size = read_int(&queue.join("physical_block_size")) as _;

        let cache_data = read_to_string(&queue.join("write_cache")).unwrap();
        let cache = cache_data.parse::<StorageCache>().unwrap();
        let subcomponents = read_dir(dir.join("slaves"))
            .unwrap()
            .map(|x| x.unwrap().path())
            .collect();

        BlockDevice {
            memory_device: false,
            rotational,
            minimum_io_size,
            optimal_io_size,
            logical_block_size,
            physical_block_size,
            cache,
            subcomponents,
        }
    }

    pub(crate) fn memory_device(major: usize, minor: usize) -> bool {
        block_property!(DEV_MAP, memory_device, major, minor)
    }

    pub(crate) fn is_rotational(major: usize, minor: usize) -> bool {
        block_property!(DEV_MAP, rotational, major, minor)
    }

    pub(crate) fn minimum_io_size(major: usize, minor: usize) -> usize {
        block_property!(DEV_MAP, minimum_io_size, major, minor)
    }

    pub(crate) fn optimal_io_size(major: usize, minor: usize) -> usize {
        block_property!(DEV_MAP, optimal_io_size, major, minor)
    }

    pub(crate) fn logical_block_size(major: usize, minor: usize) -> usize {
        block_property!(DEV_MAP, logical_block_size, major, minor)
    }

    pub(crate) fn physical_block_size(major: usize, minor: usize) -> usize {
        block_property!(DEV_MAP, physical_block_size, major, minor)
    }

    pub(crate) fn is_md(major: usize, minor: usize) -> bool {
        !block_property!(DEV_MAP, subcomponents, major, minor).is_empty()
    }
}