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

use std::collections::HashMap;
use std::fmt::{self, Debug};
use std::hash::Hash;
use std::io;
use std::time::Duration;

use may::sync::Mutex;
use Waiter;

#[derive(Debug)]
pub struct WaiterGuard<'a, K: Hash + Eq + 'a, T: 'a> {
    owner: &'a WaiterMap<K, T>,
    id: K,
}

impl<'a, K: Hash + Eq + Debug, T> WaiterGuard<'a, K, T> {
    // wait for response
    pub fn wait_rsp<D: Into<Option<Duration>>>(&self, timeout: D) -> io::Result<T> {
        self.owner.wait_rsp(&self.id, timeout.into())
    }
}

impl<'a, K: Hash + Eq, T> Drop for WaiterGuard<'a, K, T> {
    fn drop(&mut self) {
        // remove the entry
        self.owner.del_waiter(&self.id);
    }
}

pub struct WaiterMap<K, T> {
    // TODO: use atomic hashmap instead
    map: Mutex<HashMap<K, Box<Waiter<T>>>>,
}

impl<K: Hash + Eq, T> Debug for WaiterMap<K, T> {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "WaiterMap{{ ... }}")
    }
}

impl<K: Hash + Eq, T> Default for WaiterMap<K, T> {
    fn default() -> Self {
        WaiterMap::new()
    }
}

unsafe impl<K, T> Send for WaiterMap<K, T> {}
unsafe impl<K, T> Sync for WaiterMap<K, T> {}

impl<K: Hash + Eq, T> WaiterMap<K, T> {
    pub fn new() -> Self {
        WaiterMap {
            map: Mutex::new(HashMap::new()),
        }
    }

    /// return a waiter on the stack!
    pub fn new_waiter(&self, id: K) -> WaiterGuard<K, T>
    where
        K: Clone,
    {
        let mut m = self.map.lock().unwrap();
        // if we add a same key, the old waiter would be lost!
        m.insert(id.clone(), Box::new(Waiter::new()));
        WaiterGuard { owner: self, id }
    }

    // used internally
    fn del_waiter(&self, id: &K) -> Option<Box<Waiter<T>>> {
        let mut m = self.map.lock().unwrap();
        m.remove(id)
    }

    fn wait_rsp(&self, id: &K, timeout: Option<Duration>) -> io::Result<T>
    where
        K: Debug,
    {
        fn extend_lifetime<'a, T>(r: &T) -> &'a T {
            unsafe { ::std::mem::transmute(r) }
        }

        let map = self.map.lock().unwrap();
        let waiter = match map.get(id) {
            // extends the lifetime of the waiter ref
            Some(v) => extend_lifetime(v.as_ref()),
            None => unreachable!("can't find id in waiter map!"),
        };

        //release the mutex
        drop(map);

        waiter.wait_rsp(timeout)
    }

    /// set rsp for the corresponding waiter
    pub fn set_rsp(&self, id: &K, rsp: T) -> Result<(), T>
    where
        K: Debug,
    {
        let m = self.map.lock().unwrap();
        match m.get(id) {
            Some(waiter) => {
                waiter.set_rsp(rsp);
                Ok(())
            }
            None => Err(rsp),
        }
    }

    /// cancel all the waiting waiter, all wait would return NotFound error
    pub fn cancel_all(&self) {
        let m = self.map.lock().unwrap();
        for (_k, waiter) in m.iter() {
            waiter.cancel_wait();
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_waiter_map() {
        use std::sync::Arc;
        let req_map = Arc::new(WaiterMap::<usize, usize>::new());
        let rmap = req_map.clone();

        let key = 1234;

        // one coroutine wait data send from another coroutine
        // prepare the waiter first
        let waiter = req_map.new_waiter(key);

        // trigger the rsp in another coroutine
        go!(move || rmap.set_rsp(&key, 100).ok());

        // this will block until the rsp was set
        let result = waiter.wait_rsp(None).unwrap();
        assert_eq!(result, 100);
    }
}