gio/
pollable_input_stream.rs

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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
// Take a look at the license at the top of the repository in the LICENSE file.

use std::{cell::RefCell, io, mem::transmute, pin::Pin, ptr};

use futures_core::{
    stream::Stream,
    task::{Context, Poll},
};
use futures_io::AsyncRead;
use glib::{prelude::*, translate::*};

use crate::{ffi, prelude::*, Cancellable, PollableInputStream};

mod sealed {
    pub trait Sealed {}
    impl<T: super::IsA<super::PollableInputStream>> Sealed for T {}
}

pub trait PollableInputStreamExtManual: sealed::Sealed + IsA<PollableInputStream> + Sized {
    /// Creates a #GSource that triggers when @self can be read, or
    /// @cancellable is triggered or an error occurs. The callback on the
    /// source is of the #GPollableSourceFunc type.
    ///
    /// As with g_pollable_input_stream_is_readable(), it is possible that
    /// the stream may not actually be readable even after the source
    /// triggers, so you should use g_pollable_input_stream_read_nonblocking()
    /// rather than g_input_stream_read() from the callback.
    ///
    /// The behaviour of this method is undefined if
    /// g_pollable_input_stream_can_poll() returns [`false`] for @self.
    /// ## `cancellable`
    /// a #GCancellable, or [`None`]
    ///
    /// # Returns
    ///
    /// a new #GSource
    #[doc(alias = "g_pollable_input_stream_create_source")]
    fn create_source<F, C>(
        &self,
        cancellable: Option<&C>,
        name: Option<&str>,
        priority: glib::Priority,
        func: F,
    ) -> glib::Source
    where
        F: FnMut(&Self) -> glib::ControlFlow + 'static,
        C: IsA<Cancellable>,
    {
        unsafe extern "C" fn trampoline<
            O: IsA<PollableInputStream>,
            F: FnMut(&O) -> glib::ControlFlow + 'static,
        >(
            stream: *mut ffi::GPollableInputStream,
            func: glib::ffi::gpointer,
        ) -> glib::ffi::gboolean {
            let func: &RefCell<F> = &*(func as *const RefCell<F>);
            let mut func = func.borrow_mut();
            (*func)(PollableInputStream::from_glib_borrow(stream).unsafe_cast_ref()).into_glib()
        }
        unsafe extern "C" fn destroy_closure<F>(ptr: glib::ffi::gpointer) {
            let _ = Box::<RefCell<F>>::from_raw(ptr as *mut _);
        }
        let cancellable = cancellable.map(|c| c.as_ref());
        let gcancellable = cancellable.to_glib_none();
        unsafe {
            let source = ffi::g_pollable_input_stream_create_source(
                self.as_ref().to_glib_none().0,
                gcancellable.0,
            );

            let trampoline = trampoline::<Self, F> as glib::ffi::gpointer;
            glib::ffi::g_source_set_callback(
                source,
                Some(transmute::<
                    glib::ffi::gpointer,
                    unsafe extern "C" fn(glib::ffi::gpointer) -> glib::ffi::gboolean,
                >(trampoline)),
                Box::into_raw(Box::new(RefCell::new(func))) as glib::ffi::gpointer,
                Some(destroy_closure::<F>),
            );
            glib::ffi::g_source_set_priority(source, priority.into_glib());

            if let Some(name) = name {
                glib::ffi::g_source_set_name(source, name.to_glib_none().0);
            }

            from_glib_full(source)
        }
    }

    fn create_source_future<C: IsA<Cancellable>>(
        &self,
        cancellable: Option<&C>,
        priority: glib::Priority,
    ) -> Pin<Box<dyn std::future::Future<Output = ()> + 'static>> {
        let cancellable: Option<Cancellable> = cancellable.map(|c| c.as_ref()).cloned();

        let obj = self.clone();
        Box::pin(glib::SourceFuture::new(move |send| {
            let mut send = Some(send);
            obj.create_source(cancellable.as_ref(), None, priority, move |_| {
                let _ = send.take().unwrap().send(());
                glib::ControlFlow::Break
            })
        }))
    }

    fn create_source_stream<C: IsA<Cancellable>>(
        &self,
        cancellable: Option<&C>,
        priority: glib::Priority,
    ) -> Pin<Box<dyn Stream<Item = ()> + 'static>> {
        let cancellable: Option<Cancellable> = cancellable.map(|c| c.as_ref()).cloned();

        let obj = self.clone();
        Box::pin(glib::SourceStream::new(move |send| {
            obj.create_source(cancellable.as_ref(), None, priority, move |_| {
                if send.unbounded_send(()).is_err() {
                    glib::ControlFlow::Break
                } else {
                    glib::ControlFlow::Continue
                }
            })
        }))
    }

    /// Attempts to read up to @count bytes from @self into @buffer, as
    /// with g_input_stream_read(). If @self is not currently readable,
    /// this will immediately return [`IOErrorEnum::WouldBlock`][crate::IOErrorEnum::WouldBlock], and you can
    /// use g_pollable_input_stream_create_source() to create a #GSource
    /// that will be triggered when @self is readable.
    ///
    /// Note that since this method never blocks, you cannot actually
    /// use @cancellable to cancel it. However, it will return an error
    /// if @cancellable has already been cancelled when you call, which
    /// may happen if you call this method after a source triggers due
    /// to having been cancelled.
    ///
    /// The behaviour of this method is undefined if
    /// g_pollable_input_stream_can_poll() returns [`false`] for @self.
    /// ## `cancellable`
    /// a #GCancellable, or [`None`]
    ///
    /// # Returns
    ///
    /// the number of bytes read, or -1 on error (including
    ///   [`IOErrorEnum::WouldBlock`][crate::IOErrorEnum::WouldBlock]).
    ///
    /// ## `buffer`
    /// a
    ///     buffer to read data into (which should be at least @count bytes long).
    #[doc(alias = "g_pollable_input_stream_read_nonblocking")]
    fn read_nonblocking<C: IsA<Cancellable>>(
        &self,
        buffer: &mut [u8],
        cancellable: Option<&C>,
    ) -> Result<isize, glib::Error> {
        let cancellable = cancellable.map(|c| c.as_ref());
        let gcancellable = cancellable.to_glib_none();
        let count = buffer.len();
        unsafe {
            let mut error = ptr::null_mut();
            let ret = ffi::g_pollable_input_stream_read_nonblocking(
                self.as_ref().to_glib_none().0,
                buffer.to_glib_none().0,
                count,
                gcancellable.0,
                &mut error,
            );
            if error.is_null() {
                Ok(ret)
            } else {
                Err(from_glib_full(error))
            }
        }
    }

    fn into_async_read(self) -> Result<InputStreamAsyncRead<Self>, Self>
    where
        Self: IsA<PollableInputStream>,
    {
        if self.can_poll() {
            Ok(InputStreamAsyncRead(self))
        } else {
            Err(self)
        }
    }
}

impl<O: IsA<PollableInputStream>> PollableInputStreamExtManual for O {}

#[derive(Debug)]
pub struct InputStreamAsyncRead<T: IsA<PollableInputStream>>(T);

impl<T: IsA<PollableInputStream>> InputStreamAsyncRead<T> {
    pub fn into_input_stream(self) -> T {
        self.0
    }

    pub fn input_stream(&self) -> &T {
        &self.0
    }
}

impl<T: IsA<PollableInputStream>> AsyncRead for InputStreamAsyncRead<T> {
    fn poll_read(
        self: Pin<&mut Self>,
        cx: &mut Context,
        buf: &mut [u8],
    ) -> Poll<io::Result<usize>> {
        let stream = Pin::get_ref(self.as_ref());
        let gio_result = stream
            .0
            .as_ref()
            .read_nonblocking(buf, crate::Cancellable::NONE);

        match gio_result {
            Ok(size) => Poll::Ready(Ok(size as usize)),
            Err(err) => {
                let kind = err
                    .kind::<crate::IOErrorEnum>()
                    .unwrap_or(crate::IOErrorEnum::Failed);
                if kind == crate::IOErrorEnum::WouldBlock {
                    let mut waker = Some(cx.waker().clone());
                    let source = stream.0.as_ref().create_source(
                        crate::Cancellable::NONE,
                        None,
                        glib::Priority::default(),
                        move |_| {
                            if let Some(waker) = waker.take() {
                                waker.wake();
                            }
                            glib::ControlFlow::Break
                        },
                    );
                    let main_context = glib::MainContext::ref_thread_default();
                    source.attach(Some(&main_context));

                    Poll::Pending
                } else {
                    Poll::Ready(Err(io::Error::new(io::ErrorKind::from(kind), err)))
                }
            }
        }
    }
}