gio/auto/

cancellable.rs

// This file was generated by gir (https://github.com/gtk-rs/gir)
// from gir-files (https://github.com/gtk-rs/gir-files)
// DO NOT EDIT

use crate::ffi;
use glib::{prelude::*, translate::*};

glib::wrapper! {
    /// `GCancellable` allows operations to be cancelled.
    ///
    /// `GCancellable` is a thread-safe operation cancellation stack used
    /// throughout GIO to allow for cancellation of synchronous and
    /// asynchronous operations.
    ///
    /// ## Signals
    ///
    ///
    /// #### `cancelled`
    ///  Emitted when the operation has been cancelled.
    ///
    /// Can be used by implementations of cancellable operations. If the
    /// operation is cancelled from another thread, the signal will be
    /// emitted in the thread that cancelled the operation, not the
    /// thread that is running the operation.
    ///
    /// Note that disconnecting from this signal (or any signal) in a
    /// multi-threaded program is prone to race conditions. For instance
    /// it is possible that a signal handler may be invoked even after
    /// a call to g_signal_handler_disconnect() for that handler has
    /// already returned.
    ///
    /// There is also a problem when cancellation happens right before
    /// connecting to the signal. If this happens the signal will
    /// unexpectedly not be emitted, and checking before connecting to
    /// the signal leaves a race condition where this is still happening.
    ///
    /// In order to make it safe and easy to connect handlers there
    /// are two helper functions: g_cancellable_connect() and
    /// g_cancellable_disconnect() which protect against problems
    /// like this.
    ///
    /// An example of how to us this:
    ///
    ///
    /// **⚠️ The following code is in C ⚠️**
    ///
    /// ```C
    ///     // Make sure we don't do unnecessary work if already cancelled
    ///     if (g_cancellable_set_error_if_cancelled (cancellable, error))
    ///       return;
    ///
    ///     // Set up all the data needed to be able to handle cancellation
    ///     // of the operation
    ///     my_data = my_data_new (...);
    ///
    ///     id = 0;
    ///     if (cancellable)
    ///       id = g_cancellable_connect (cancellable,
    ///                       G_CALLBACK (cancelled_handler)
    ///                       data, NULL);
    ///
    ///     // cancellable operation here...
    ///
    ///     g_cancellable_disconnect (cancellable, id);
    ///
    ///     // cancelled_handler is never called after this, it is now safe
    ///     // to free the data
    ///     my_data_free (my_data);
    /// ```
    ///
    /// Note that the cancelled signal is emitted in the thread that
    /// the user cancelled from, which may be the main thread. So, the
    /// cancellable signal should not do something that can block.
    ///
    ///
    ///
    /// # Implements
    ///
    /// [`CancellableExt`][trait@crate::prelude::CancellableExt], [`trait@glib::ObjectExt`], [`CancellableExtManual`][trait@crate::prelude::CancellableExtManual]
    #[doc(alias = "GCancellable")]
    pub struct Cancellable(Object<ffi::GCancellable, ffi::GCancellableClass>);

    match fn {
        type_ => || ffi::g_cancellable_get_type(),
    }
}

impl Cancellable {
    pub const NONE: Option<&'static Cancellable> = None;

    /// Creates a new #GCancellable object.
    ///
    /// Applications that want to start one or more operations
    /// that should be cancellable should create a #GCancellable
    /// and pass it to the operations.
    ///
    /// One #GCancellable can be used in multiple consecutive
    /// operations or in multiple concurrent operations.
    ///
    /// # Returns
    ///
    /// a #GCancellable.
    #[doc(alias = "g_cancellable_new")]
    pub fn new() -> Cancellable {
        unsafe { from_glib_full(ffi::g_cancellable_new()) }
    }

    /// Gets the top cancellable from the stack.
    ///
    /// # Returns
    ///
    /// a #GCancellable from the top
    /// of the stack, or [`None`] if the stack is empty.
    #[doc(alias = "g_cancellable_get_current")]
    #[doc(alias = "get_current")]
    pub fn current() -> Option<Cancellable> {
        unsafe { from_glib_none(ffi::g_cancellable_get_current()) }
    }
}

impl Default for Cancellable {
    fn default() -> Self {
        Self::new()
    }
}

unsafe impl Send for Cancellable {}
unsafe impl Sync for Cancellable {}

/// Trait containing all [`struct@Cancellable`] methods.
///
/// # Implementors
///
/// [`Cancellable`][struct@crate::Cancellable]
pub trait CancellableExt: IsA<Cancellable> + 'static {
    /// Will set @self to cancelled, and will emit the
    /// #GCancellable::cancelled signal. (However, see the warning about
    /// race conditions in the documentation for that signal if you are
    /// planning to connect to it.)
    ///
    /// This function is thread-safe. In other words, you can safely call
    /// it from a thread other than the one running the operation that was
    /// passed the @self.
    ///
    /// If @self is [`None`], this function returns immediately for convenience.
    ///
    /// The convention within GIO is that cancelling an asynchronous
    /// operation causes it to complete asynchronously. That is, if you
    /// cancel the operation from the same thread in which it is running,
    /// then the operation's #GAsyncReadyCallback will not be invoked until
    /// the application returns to the main loop.
    #[doc(alias = "g_cancellable_cancel")]
    fn cancel(&self) {
        unsafe {
            ffi::g_cancellable_cancel(self.as_ref().to_glib_none().0);
        }
    }

    /// Gets the file descriptor for a cancellable job. This can be used to
    /// implement cancellable operations on Unix systems. The returned fd will
    /// turn readable when @self is cancelled.
    ///
    /// You are not supposed to read from the fd yourself, just check for
    /// readable status. Reading to unset the readable status is done
    /// with g_cancellable_reset().
    ///
    /// After a successful return from this function, you should use
    /// g_cancellable_release_fd() to free up resources allocated for
    /// the returned file descriptor.
    ///
    /// See also g_cancellable_make_pollfd().
    ///
    /// # Returns
    ///
    /// A valid file descriptor. `-1` if the file descriptor
    /// is not supported, or on errors.
    #[doc(alias = "g_cancellable_get_fd")]
    #[doc(alias = "get_fd")]
    fn fd(&self) -> i32 {
        unsafe { ffi::g_cancellable_get_fd(self.as_ref().to_glib_none().0) }
    }

    /// Checks if a cancellable job has been cancelled.
    ///
    /// # Returns
    ///
    /// [`true`] if @self is cancelled,
    /// FALSE if called with [`None`] or if item is not cancelled.
    #[doc(alias = "g_cancellable_is_cancelled")]
    fn is_cancelled(&self) -> bool {
        unsafe {
            from_glib(ffi::g_cancellable_is_cancelled(
                self.as_ref().to_glib_none().0,
            ))
        }
    }

    //#[doc(alias = "g_cancellable_make_pollfd")]
    //fn make_pollfd(&self, pollfd: /*Ignored*/&mut glib::PollFD) -> bool {
    //    unsafe { TODO: call ffi:g_cancellable_make_pollfd() }
    //}

    /// Pops @self off the cancellable stack (verifying that @self
    /// is on the top of the stack).
    #[doc(alias = "g_cancellable_pop_current")]
    fn pop_current(&self) {
        unsafe {
            ffi::g_cancellable_pop_current(self.as_ref().to_glib_none().0);
        }
    }

    /// Pushes @self onto the cancellable stack. The current
    /// cancellable can then be received using g_cancellable_get_current().
    ///
    /// This is useful when implementing cancellable operations in
    /// code that does not allow you to pass down the cancellable object.
    ///
    /// This is typically called automatically by e.g. #GFile operations,
    /// so you rarely have to call this yourself.
    #[doc(alias = "g_cancellable_push_current")]
    fn push_current(&self) {
        unsafe {
            ffi::g_cancellable_push_current(self.as_ref().to_glib_none().0);
        }
    }

    /// Releases a resources previously allocated by g_cancellable_get_fd()
    /// or g_cancellable_make_pollfd().
    ///
    /// For compatibility reasons with older releases, calling this function
    /// is not strictly required, the resources will be automatically freed
    /// when the @self is finalized. However, the @self will
    /// block scarce file descriptors until it is finalized if this function
    /// is not called. This can cause the application to run out of file
    /// descriptors when many #GCancellables are used at the same time.
    #[doc(alias = "g_cancellable_release_fd")]
    fn release_fd(&self) {
        unsafe {
            ffi::g_cancellable_release_fd(self.as_ref().to_glib_none().0);
        }
    }
}

impl<O: IsA<Cancellable>> CancellableExt for O {}