shadow_rs/host/
status_listener.rs

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1//! Compatibility wrappers for C-style event listeners.
2
3use crate::core::work::task::TaskRef;
4use crate::core::worker::Worker;
5use crate::cshadow;
6use crate::host::descriptor::FileState;
7use crate::utility::HostTreePointer;
8
9use super::host::Host;
10
11/// An object that listens for status changes.
12///
13/// ~Deprecated: In new code consider using [`crate::host::descriptor::listener::StateEventSource`],
14/// which supports Rust closures or directly takes [`crate::cshadow::StatusListener`].
15#[derive(Debug)]
16pub struct StatusListener {
17    ptr: HostTreePointer<cshadow::StatusListener>,
18}
19
20impl Ord for StatusListener {
21    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
22        Worker::with_active_host(|host| {
23            // SAFETY: These pointers do not escape the `with_active_host` closure.
24            let lhs = unsafe { self.ptr.ptr_with_host(host) };
25            let rhs = unsafe { other.ptr.ptr_with_host(host) };
26
27            match unsafe { cshadow::status_listener_compare(lhs.cast(), rhs.cast()) } {
28                -1 => std::cmp::Ordering::Less,
29                0 => std::cmp::Ordering::Equal,
30                1 => std::cmp::Ordering::Greater,
31                other => panic!("Unexpected comparison result: {other}"),
32            }
33        })
34        .unwrap()
35    }
36}
37
38impl PartialOrd for StatusListener {
39    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
40        Some(self.cmp(other))
41    }
42}
43
44impl Eq for StatusListener {}
45
46impl PartialEq for StatusListener {
47    fn eq(&self, other: &Self) -> bool {
48        matches!(self.cmp(other), std::cmp::Ordering::Equal)
49    }
50}
51
52impl StatusListener {
53    /// Create an owned reference from `ptr`. Reference count is incremented on
54    /// creation, and decremented on Drop.
55    ///
56    /// # Safety
57    ///
58    /// `ptr` must be safely dereferenceable.
59    pub unsafe fn clone_from_c(host: &Host, ptr: *mut cshadow::StatusListener) -> Self {
60        unsafe { cshadow::statuslistener_ref(ptr) };
61        let ptr = HostTreePointer::new_for_host(host.id(), ptr);
62        Self { ptr }
63    }
64
65    /// Create a [`StatusListener`] with the given notification function.
66    pub fn new(host: &Host, notify: impl Fn(&Host) + Send + Sync + 'static) -> Self {
67        extern "C-unwind" fn notify_fn(
68            callback_object: *mut std::ffi::c_void,
69            _callback_arg: *mut std::ffi::c_void,
70        ) {
71            let task: *const TaskRef = callback_object.cast();
72            let task = unsafe { &*task };
73            Worker::with_active_host(|host| task.execute(host)).unwrap()
74        }
75        extern "C-unwind" fn object_free_fn(callback_object: *mut std::ffi::c_void) {
76            let task: *mut TaskRef = callback_object.cast();
77            drop(unsafe { Box::from_raw(task) })
78        }
79
80        let callback_obj = Box::into_raw(Box::new(TaskRef::new(notify)));
81        let status_listener = unsafe {
82            cshadow::statuslistener_new(
83                Some(notify_fn),
84                callback_obj.cast::<std::ffi::c_void>(),
85                Some(object_free_fn),
86                std::ptr::null_mut(),
87                None,
88                host,
89            )
90        };
91        Self {
92            ptr: HostTreePointer::new_for_host(host.id(), status_listener),
93        }
94    }
95
96    /// Called when a transition (bit flip) occurred on
97    /// at least one of its status bits. (This function should only be called
98    /// by status owners, i.e., the descriptor or futex base classes.)
99    /// If this listener is monitoring (via setMonitorStatus) any of the status bits
100    /// that just transitioned, then this function will trigger a notification
101    /// via the callback supplied to the new func.
102    pub fn handle_status_change(&self, host: &Host, current: FileState, transitions: FileState) {
103        unsafe {
104            cshadow::statuslistener_onStatusChanged(
105                self.ptr.ptr_with_host(host),
106                current,
107                transitions,
108            )
109        }
110    }
111
112    /// Set the status bits that we should monitor for transitions (flips),
113    /// and a filter that specifies which flips should cause the callback
114    /// to be invoked.
115    pub fn set_monitor_status(
116        &self,
117        host: &Host,
118        status: FileState,
119        filter: cshadow::StatusListenerFilter,
120    ) {
121        unsafe {
122            cshadow::statuslistener_setMonitorStatus(self.ptr.ptr_with_host(host), status, filter)
123        }
124    }
125}
126
127impl Drop for StatusListener {
128    fn drop(&mut self) {
129        unsafe { cshadow::statuslistener_unref(self.ptr.ptr()) };
130    }
131}
shadow_rs/host/status_listener.rs

shadow_rs/host/
status_listener.rs
