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
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183

#[doc(hidden)]
#[cfg(not(feature = "fault_injection"))]
pub async fn debug_delay() {}

mod bitset;
#[cfg(feature = "fault_injection")]
mod debug_delay;
mod network;
mod paxos;
mod serialization;
mod simulator;
mod udp_net;
mod versioned_storage;

pub use {
    network::Net,
    paxos::{Client, Server},
    simulator::simulate,
};

use std::{io, net::ToSocketAddrs};

#[cfg(feature = "fault_injection")]
pub use debug_delay::debug_delay;

/// A possibly present value with an associated version number.
#[derive(Default, Debug, Clone, Eq, PartialEq, PartialOrd, Ord)]
pub struct VersionedValue {
    pub ballot: u64,
    pub value: Option<Vec<u8>>,
}

impl std::ops::Deref for VersionedValue {
    type Target = Option<Vec<u8>>;

    fn deref(&self) -> &Option<Vec<u8>> {
        &self.value
    }
}

impl std::ops::DerefMut for VersionedValue {
    fn deref_mut(&mut self) -> &mut Option<Vec<u8>> {
        &mut self.value
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum Message {
    Request(Request),
    Response(Response),
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum Request {
    // discriminant 1
    Ping,
    // discriminant 2
    Prepare { ballot: u64, key: Vec<u8> },
    // discriminant 3
    Accept { key: Vec<u8>, value: VersionedValue },
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum Response {
    // discriminant 4
    Pong,
    // discriminant 5
    Promise {
        success: Result<VersionedValue, u64>,
    },
    // discriminant 6
    Accepted {
        success: Result<(), u64>,
    },
}

impl Response {
    fn to_promise(self) -> Result<VersionedValue, u64> {
        if let Response::Promise { success } = self {
            success
        } else {
            panic!("called to_promise on {:?}", self);
        }
    }

    fn to_accepted(self) -> Result<(), u64> {
        if let Response::Accepted { success } = self {
            success
        } else {
            panic!("called to_promise on {:?}", self);
        }
    }

    fn is_pong(self) -> bool {
        if let Response::Pong = self {
            true
        } else {
            false
        }
    }

    fn is_success(&self) -> bool {
        match self {
            Response::Pong => true,
            Response::Accepted { success } => success.is_ok(),
            Response::Promise { success } => success.is_ok(),
        }
    }
}

#[derive(Debug, Clone, PartialEq, Eq)]
struct Envelope {
    uuid: uuid::Uuid,
    message: Message,
}
pub fn start_udp_client<
    A: ToSocketAddrs + std::fmt::Display,
    B: ToSocketAddrs + std::fmt::Display,
>(
    listen_addr: A,
    servers: &[B],
    timeout: std::time::Duration,
) -> std::io::Result<Client> {
    let mut known_servers = vec![];

    for server in servers {
        let mut addrs_iter = server.to_socket_addrs()?;
        // NB we only use the first address. this is buggy.
        if let Some(addr) = addrs_iter.next() {
            known_servers.push(addr);
        } else {
            return Err(io::Error::new(
                io::ErrorKind::AddrNotAvailable,
                format!("the address {} could not be resolved", server),
            ));
        }
    }

    let (process_task, net) = Net::new_udp(listen_addr, timeout)?;

    let processor = smol::Task::spawn(process_task);

    Ok(Client {
        known_servers,
        net,
        cache: Default::default(),
        processor: Some(processor),
    })
}

pub fn start_udp_server<
    A: ToSocketAddrs + std::fmt::Display,
    P: AsRef<std::path::Path>,
>(
    listen_addr: A,
    storage_directory: P,
    timeout: std::time::Duration,
) -> std::io::Result<Server> {
    let db = match sled::open(&storage_directory) {
        Ok(db) => versioned_storage::VersionedStorage { db },
        Err(e) => {
            return Err(io::Error::new(
                io::ErrorKind::Other,
                format!(
                    "failed to open database at {:?}: {:?}",
                    storage_directory.as_ref(),
                    e
                ),
            ))
        }
    };

    let (process_task, net) = Net::new_udp(listen_addr, timeout)?;

    let processor = smol::Task::spawn(process_task);

    Ok(Server {
        net,
        db,
        processor: Some(processor),
        promises: Default::default(),
    })
}