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
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
// Take a look at the license at the top of the repository in the LICENSE file.

use crate::source::Priority;
use crate::translate::*;
use crate::MainContext;
use crate::Source;
use crate::SourceId;
use ffi::{self, gboolean, gpointer};
use std::mem;

impl MainContext {
    #[doc(alias = "g_main_context_prepare")]
    pub fn prepare(&self) -> (bool, i32) {
        unsafe {
            let mut priority = mem::MaybeUninit::uninit();

            let res = from_glib(ffi::g_main_context_prepare(
                self.to_glib_none().0,
                priority.as_mut_ptr(),
            ));
            let priority = priority.assume_init();
            (res, priority)
        }
    }

    #[doc(alias = "g_main_context_find_source_by_id")]
    pub fn find_source_by_id(&self, source_id: &SourceId) -> Option<Source> {
        unsafe {
            from_glib_none(ffi::g_main_context_find_source_by_id(
                self.to_glib_none().0,
                source_id.as_raw(),
            ))
        }
    }

    // rustdoc-stripper-ignore-next
    /// Invokes `func` on the main context.
    ///
    /// If the current thread is the owner of the main context or the main context currently has no
    /// owner then `func` will be called directly from inside this function. If this behaviour is
    /// not desired and `func` should always be called asynchronously then use [`MainContext::spawn`]
    /// [`glib::idle_add`](crate::idle_add) instead.
    #[doc(alias = "g_main_context_invoke")]
    pub fn invoke<F>(&self, func: F)
    where
        F: FnOnce() + Send + 'static,
    {
        self.invoke_with_priority(crate::PRIORITY_DEFAULT_IDLE, func);
    }

    // rustdoc-stripper-ignore-next
    /// Invokes `func` on the main context with the given priority.
    ///
    /// If the current thread is the owner of the main context or the main context currently has no
    /// owner then `func` will be called directly from inside this function. If this behaviour is
    /// not desired and `func` should always be called asynchronously then use [`MainContext::spawn`]
    /// [`glib::idle_add`](crate::idle_add) instead.
    #[doc(alias = "g_main_context_invoke_full")]
    pub fn invoke_with_priority<F>(&self, priority: Priority, func: F)
    where
        F: FnOnce() + Send + 'static,
    {
        unsafe {
            self.invoke_unsafe(priority, func);
        }
    }

    // rustdoc-stripper-ignore-next
    /// Invokes `func` on the main context.
    ///
    /// Different to `invoke()`, this does not require `func` to be
    /// `Send` but can only be called from the thread that owns the main context.
    ///
    /// This function panics if called from a different thread than the one that
    /// owns the main context.
    ///
    /// Note that this effectively means that `func` is called directly from inside this function
    /// or otherwise panics immediately. If this behaviour is not desired and `func` should always
    /// be called asynchronously then use [`MainContext::spawn_local`]
    /// [`glib::idle_add_local`](crate::idle_add_local) instead.
    pub fn invoke_local<F>(&self, func: F)
    where
        F: FnOnce() + 'static,
    {
        self.invoke_local_with_priority(crate::PRIORITY_DEFAULT_IDLE, func);
    }

    // rustdoc-stripper-ignore-next
    /// Invokes `func` on the main context with the given priority.
    ///
    /// Different to `invoke_with_priority()`, this does not require `func` to be
    /// `Send` but can only be called from the thread that owns the main context.
    ///
    /// This function panics if called from a different thread than the one that
    /// owns the main context.
    ///
    /// Note that this effectively means that `func` is called directly from inside this function
    /// or otherwise panics immediately. If this behaviour is not desired and `func` should always
    /// be called asynchronously then use [`MainContext::spawn_local`]
    /// [`glib::idle_add_local`](crate::idle_add_local) instead.
    #[allow(clippy::if_same_then_else)]
    pub fn invoke_local_with_priority<F>(&self, _priority: Priority, func: F)
    where
        F: FnOnce() + 'static,
    {
        // Checks from `g_main_context_invoke_full()`
        // FIXME: Combine the first two cases somehow
        if self.is_owner() {
            func();
        } else if let Ok(_acquire) = self.acquire() {
            func();
        } else {
            panic!("Must be called from a thread that owns the main context");
        }
    }

    unsafe fn invoke_unsafe<F>(&self, priority: Priority, func: F)
    where
        F: FnOnce() + 'static,
    {
        unsafe extern "C" fn trampoline<F: FnOnce() + 'static>(func: gpointer) -> gboolean {
            let func: &mut Option<F> = &mut *(func as *mut Option<F>);
            let func = func
                .take()
                .expect("MainContext::invoke() closure called multiple times");
            func();
            ffi::G_SOURCE_REMOVE
        }
        unsafe extern "C" fn destroy_closure<F: FnOnce() + 'static>(ptr: gpointer) {
            let _ = Box::<Option<F>>::from_raw(ptr as *mut _);
        }
        let func = Box::into_raw(Box::new(Some(func)));
        ffi::g_main_context_invoke_full(
            self.to_glib_none().0,
            priority.into_glib(),
            Some(trampoline::<F>),
            func as gpointer,
            Some(destroy_closure::<F>),
        )
    }

    // rustdoc-stripper-ignore-next
    /// Call closure with the main context configured as the thread default one.
    ///
    /// The thread default main context is changed in a panic-safe manner before calling `func` and
    /// released again afterwards regardless of whether closure panicked or not.
    ///
    /// This will fail if the main context is owned already by another thread.
    #[doc(alias = "g_main_context_push_thread_default")]
    pub fn with_thread_default<R, F: Sized>(&self, func: F) -> Result<R, crate::BoolError>
    where
        F: FnOnce() -> R,
    {
        let _acquire = self.acquire()?;
        let _thread_default = ThreadDefaultContext::new(self);
        Ok(func())
    }

    // rustdoc-stripper-ignore-next
    /// Acquire ownership of the main context.
    ///
    /// Ownership will automatically be released again once the returned acquire guard is dropped.
    ///
    /// This will fail if the main context is owned already by another thread.
    #[doc(alias = "g_main_context_acquire")]
    pub fn acquire(&self) -> Result<MainContextAcquireGuard, crate::BoolError> {
        unsafe {
            let ret: bool = from_glib(ffi::g_main_context_acquire(self.to_glib_none().0));
            if ret {
                Ok(MainContextAcquireGuard(self))
            } else {
                Err(bool_error!("Failed to acquire ownership of main context, already acquired by another thread"))
            }
        }
    }
}

#[must_use = "if unused the main context will be released immediately"]
pub struct MainContextAcquireGuard<'a>(&'a MainContext);

impl<'a> Drop for MainContextAcquireGuard<'a> {
    #[doc(alias = "g_main_context_release")]
    fn drop(&mut self) {
        unsafe {
            ffi::g_main_context_release(self.0.to_glib_none().0);
        }
    }
}

struct ThreadDefaultContext<'a>(&'a MainContext);

impl<'a> ThreadDefaultContext<'a> {
    fn new(ctx: &MainContext) -> ThreadDefaultContext {
        unsafe {
            ffi::g_main_context_push_thread_default(ctx.to_glib_none().0);
        }
        ThreadDefaultContext(ctx)
    }
}

impl<'a> Drop for ThreadDefaultContext<'a> {
    fn drop(&mut self) {
        unsafe {
            ffi::g_main_context_pop_thread_default(self.0.to_glib_none().0);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::panic;
    use std::ptr;
    use std::thread;

    #[test]
    fn test_invoke() {
        let c = MainContext::new();
        let l = crate::MainLoop::new(Some(&c), false);

        let l_clone = l.clone();
        thread::spawn(move || {
            c.invoke(move || l_clone.quit());
        });

        l.run();
    }

    fn is_same_context(a: &MainContext, b: &MainContext) -> bool {
        ptr::eq(a.to_glib_none().0, b.to_glib_none().0)
    }

    #[test]
    fn test_with_thread_default() {
        let a = MainContext::new();
        let b = MainContext::new();

        assert!(!is_same_context(&a, &b));

        a.with_thread_default(|| {
            let t = MainContext::thread_default().unwrap();
            assert!(is_same_context(&a, &t));

            b.with_thread_default(|| {
                let t = MainContext::thread_default().unwrap();
                assert!(is_same_context(&b, &t));
            })
            .unwrap();

            let t = MainContext::thread_default().unwrap();
            assert!(is_same_context(&a, &t));
        })
        .unwrap();
    }

    #[test]
    fn test_with_thread_default_is_panic_safe() {
        let a = MainContext::new();
        let b = MainContext::new();

        assert!(!is_same_context(&a, &b));

        a.with_thread_default(|| {
            let t = MainContext::thread_default().unwrap();
            assert!(is_same_context(&a, &t));

            let result = panic::catch_unwind(|| {
                b.with_thread_default(|| {
                    panic!();
                })
                .unwrap();
            });
            assert!(result.is_err());

            let t = MainContext::thread_default().unwrap();
            assert!(is_same_context(&a, &t));
        })
        .unwrap();
    }
}