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

use std::cell::RefCell;
use std::fmt;
#[cfg(feature = "futures")]
use std::future::Future;
use std::rc::Rc;

use wasm_bindgen_futures::spawn_local;

use crate::codec::Codec;
use crate::handler_id::HandlerId;
use crate::lifecycle::{WorkerLifecycleEvent, WorkerRunnable, WorkerState};
use crate::messages::FromWorker;
use crate::native_worker::{DedicatedWorker, NativeWorkerExt, WorkerSelf};
use crate::traits::Worker;
use crate::Shared;

/// A handle that closes the worker when it is dropped.
pub struct WorkerDestroyHandle<W: Worker> {
    scope: WorkerScope<W>,
}

impl<W: Worker> fmt::Debug for WorkerDestroyHandle<W> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("WorkerDestroyHandle<_>")
    }
}

impl<W> WorkerDestroyHandle<W>
where
    W: Worker,
{
    pub(crate) fn new(scope: WorkerScope<W>) -> Self {
        Self { scope }
    }
}

impl<W> Drop for WorkerDestroyHandle<W>
where
    W: Worker,
{
    fn drop(&mut self) {
        self.scope.send(WorkerLifecycleEvent::Destroy);
    }
}

/// This struct holds a reference to a component and to a global scheduler.
pub struct WorkerScope<W: Worker> {
    state: Shared<WorkerState<W>>,
    post_msg: Rc<dyn Fn(FromWorker<W>)>,
}

impl<W: Worker> fmt::Debug for WorkerScope<W> {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str("WorkerScope<_>")
    }
}

impl<W: Worker> Clone for WorkerScope<W> {
    fn clone(&self) -> Self {
        WorkerScope {
            state: self.state.clone(),
            post_msg: self.post_msg.clone(),
        }
    }
}

impl<W> WorkerScope<W>
where
    W: Worker,
{
    /// Create worker scope
    pub(crate) fn new<CODEC>() -> Self
    where
        CODEC: Codec,
    {
        let post_msg = move |msg: FromWorker<W>| {
            DedicatedWorker::worker_self().post_packed_message::<_, CODEC>(msg)
        };

        let state = Rc::new(RefCell::new(WorkerState::new()));
        WorkerScope {
            post_msg: Rc::new(post_msg),
            state,
        }
    }

    /// Schedule message for sending to worker
    pub(crate) fn send(&self, event: WorkerLifecycleEvent<W>) {
        let state = self.state.clone();

        // We can implement a custom scheduler,
        // but it's easier to borrow the one from wasm-bindgen-futures.
        spawn_local(async move {
            WorkerRunnable { state, event }.run();
        });
    }

    /// Send response to a worker bridge.
    pub fn respond(&self, id: HandlerId, output: W::Output) {
        let msg = FromWorker::<W>::ProcessOutput(id, output);
        (self.post_msg)(msg);
    }

    /// Send a message to the worker
    pub fn send_message<T>(&self, msg: T)
    where
        T: Into<W::Message>,
    {
        self.send(WorkerLifecycleEvent::Message(msg.into()));
    }

    /// Create a callback which will send a message to the worker when invoked.
    pub fn callback<F, IN, M>(&self, function: F) -> Rc<dyn Fn(IN)>
    where
        M: Into<W::Message>,
        F: Fn(IN) -> M + 'static,
    {
        let scope = self.clone();
        let closure = move |input| {
            let output = function(input).into();
            scope.send(WorkerLifecycleEvent::Message(output));
        };
        Rc::new(closure)
    }

    /// This method creates a callback which returns a Future which
    /// returns a message to be sent back to the worker
    ///
    /// # Panics
    /// If the future panics, then the promise will not resolve, and
    /// will leak.
    #[cfg(feature = "futures")]
    #[cfg_attr(docsrs, doc(cfg(feature = "futures")))]
    pub fn callback_future<FN, FU, IN, M>(&self, function: FN) -> Rc<dyn Fn(IN)>
    where
        M: Into<W::Message>,
        FU: Future<Output = M> + 'static,
        FN: Fn(IN) -> FU + 'static,
    {
        let scope = self.clone();

        let closure = move |input: IN| {
            let future: FU = function(input);
            scope.send_future(future);
        };

        Rc::new(closure)
    }

    /// This method processes a Future that returns a message and sends it back to the worker.
    ///
    /// # Panics
    /// If the future panics, then the promise will not resolve, and will leak.
    #[cfg(feature = "futures")]
    #[cfg_attr(docsrs, doc(cfg(feature = "futures")))]
    pub fn send_future<F, M>(&self, future: F)
    where
        M: Into<W::Message>,
        F: Future<Output = M> + 'static,
    {
        let scope = self.clone();
        let js_future = async move {
            let message: W::Message = future.await.into();
            let cb = scope.callback(|m: W::Message| m);
            (*cb)(message);
        };
        wasm_bindgen_futures::spawn_local(js_future);
    }
}