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

use super::traits::*;

use std::sync::*;

// TODO: issue with new 'drop' behaviour is what to do when we clone, as if keep_alive is
// false on the clone then dropping the clone will also drop this object. Sometimes we
// want this behaviour and sometimes we don't.

///
/// A notifiable that can be released (and then tidied up later)
///
pub struct ReleasableNotifiable {
    /// Set to true if this object should not release on drop. Note this is not shared,
    /// so the first ReleasableNotifiable in a group to be dropped where keep_alive
    /// is false will mark all the others as done.
    keep_alive: bool,

    /// The notifiable object that should be released when it's done
    target: Arc<Mutex<Option<Arc<dyn Notifiable>>>>
}

impl ReleasableNotifiable {
    ///
    /// Creates a new releasable notifiable object
    ///
    pub fn new(target: Arc<dyn Notifiable>) -> ReleasableNotifiable {
        ReleasableNotifiable {
            keep_alive: false,
            target:     Arc::new(Mutex::new(Some(target)))
        }
    }

    ///
    /// Marks this as changed and returns whether or not the notification was called
    ///
    pub fn mark_as_changed(&self) -> bool {
        // Get a reference to the target via the lock
        let target = {
            // Reset the optional item so that it's 'None'
            let target = self.target.lock().unwrap();

            // Send to the target
            target.clone()
        };

        // Send to the target
        if let Some(ref target) = target {
            target.mark_as_changed();
            true
        } else {
            false
        }
    }

    ///
    /// True if this item is still in use
    ///
    pub fn is_in_use(&self) -> bool {
        self.target.lock().unwrap().is_some()
    }

    ///
    /// Creates a new 'owned' clone (which will expire this notifiable when dropped)
    /// 
    pub fn clone_as_owned(&self) -> ReleasableNotifiable {
        ReleasableNotifiable {
            keep_alive: self.keep_alive,
            target:     Arc::clone(&self.target)
        }
    }

    ///
    /// Creates a new 'inspection' clone (which can be dropped without ending
    /// the lifetime of the releasable object)
    ///
    pub fn clone_for_inspection(&self) -> ReleasableNotifiable {
        ReleasableNotifiable {
            keep_alive: true,
            target:     Arc::clone(&self.target)
        }
    }
}

impl Releasable for ReleasableNotifiable {
    fn done(&mut self) {
        // Reset the optional item so that it's 'None'
        let mut target = self.target.lock().unwrap();

        *target = None;
    }

    fn keep_alive(&mut self) {
        self.keep_alive = true;
    }
}

impl Notifiable for ReleasableNotifiable {
    fn mark_as_changed(&self) {
        // Get a reference to the target via the lock
        let target = {
            // Reset the optional item so that it's 'None'
            let target = self.target.lock().unwrap();

            // Send to the target
            target.clone()
        };

        // Make sure we're calling out to mark_as_changed outside of the lock
        if let Some(target) = target {
            target.mark_as_changed();
        }
    }
}

impl Drop for ReleasableNotifiable {
    fn drop(&mut self) {
        if !self.keep_alive {
            self.done();
        }
    }
}

impl Releasable for Vec<Box<dyn Releasable>> {
    fn done(&mut self) {
        for item in self.iter_mut() {
            item.done();
        }
    }

    fn keep_alive(&mut self) {
        for item in self.iter_mut() {
            item.keep_alive();
        }
    }
}