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

//! Write endpoint for a sequence of batches.
//!
//! A `TraceWriter` accepts a sequence of batches and distributes them
//! to both a shared trace and to a sequence of private queues.

use std::rc::{Rc, Weak};
use std::cell::RefCell;

use timely::progress::Antichain;

use crate::trace::{Trace, Batch, BatchReader};
use crate::trace::wrappers::rc::TraceBox;


use super::TraceAgentQueueWriter;
use super::TraceReplayInstruction;

/// Write endpoint for a sequence of batches.
///
/// A `TraceWriter` accepts a sequence of batches and distributes them
/// to both a shared trace and to a sequence of private queues.
pub struct TraceWriter<Tr>
where
    Tr: Trace,
    Tr::Batch: Batch,
{
    /// Current upper limit.
    upper: Antichain<Tr::Time>,
    /// Shared trace, possibly absent (due to weakness).
    trace: Weak<RefCell<TraceBox<Tr>>>,
    /// A sequence of private queues into which batches are written.
    queues: Rc<RefCell<Vec<TraceAgentQueueWriter<Tr>>>>,
}

impl<Tr> TraceWriter<Tr>
where
    Tr: Trace,
    Tr::Batch: Batch,
{
    /// Creates a new `TraceWriter`.
    pub fn new(
        upper: Vec<Tr::Time>,
        trace: Weak<RefCell<TraceBox<Tr>>>,
        queues: Rc<RefCell<Vec<TraceAgentQueueWriter<Tr>>>>
    ) -> Self
    {
        let mut temp = Antichain::new();
        temp.extend(upper);
        Self { upper: temp, trace, queues }
    }

    /// Exerts merge effort, even without additional updates.
    pub fn exert(&mut self) {
        if let Some(trace) = self.trace.upgrade() {
            trace.borrow_mut().trace.exert();
        }
    }

    /// Advances the trace by `batch`.
    ///
    /// The `hint` argument is either `None` in the case of an empty batch,
    /// or is `Some(time)` for a time less or equal to all updates in the
    /// batch and which is suitable for use as a capability.
    pub fn insert(&mut self, batch: Tr::Batch, hint: Option<Tr::Time>) {

        // Something is wrong if not a sequence.
        if !(&self.upper == batch.lower()) {
            println!("{:?} vs {:?}", self.upper, batch.lower());
        }
        assert!(&self.upper == batch.lower());
        assert!(batch.lower() != batch.upper());

        self.upper.clone_from(batch.upper());

        // push information to each listener that still exists.
        let mut borrow = self.queues.borrow_mut();
        for queue in borrow.iter_mut() {
            if let Some(pair) = queue.upgrade() {
                pair.1.borrow_mut().push_back(TraceReplayInstruction::Batch(batch.clone(), hint.clone()));
                pair.1.borrow_mut().push_back(TraceReplayInstruction::Frontier(batch.upper().clone()));
                pair.0.activate();
            }
        }
        borrow.retain(|w| w.upgrade().is_some());

        // push data to the trace, if it still exists.
        if let Some(trace) = self.trace.upgrade() {
            trace.borrow_mut().trace.insert(batch);
        }

    }

    /// Inserts an empty batch up to `upper`.
    pub fn seal(&mut self, upper: Antichain<Tr::Time>) {
        if self.upper != upper {
            self.insert(Tr::Batch::empty(self.upper.clone(), upper), None);
        }
    }
}

impl<Tr> Drop for TraceWriter<Tr>
where
    Tr: Trace,
    Tr::Batch: Batch,
{
    fn drop(&mut self) {
        self.seal(Antichain::new())
    }
}