gio.Cancellable
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gio.Cancellable

gio.Cancellable — Thread-safe Operation Cancellation Stack.

Synopsis

class gio.Cancellable(gobject.GObject):
    gio.Cancellable()
    def cancel()
    def get_fd()
    def is_cancelled()
    def pop_current()
    def push_current()
    def reset()
    def set_error_if_cancelled()
Functions
 
    def gio.cancellable_get_current()

Ancestry

+-- gobject.GObject
  +-- gio.Cancellable

Description

The gio.Cancellable is a thread-safe operation cancellation stack used throughout GIO to allow for cancellation of synchronous and asynchronous operations.

Constructor

    gio.Cancellable()

Returns :

a new gio.Cancellable.

Creates a new gio.Cancellable object.

Applications that want to start one or more operations that should be cancellable should create a gio.Cancellable and pass it to the operations.

One gio.Cancellable can be used in multiple consecutive operations, but not in multiple concurrent operations.

Methods

gio.Cancellable.cancel

    def cancel()

The cancel() method will set cancellable to cancelled, and will emit the "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 cancellable.

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.

gio.Cancellable.get_fd

    def get_fd()

Returns :

A valid file descriptor. -1 if the file descriptor is not supported, or on errors.

The get_fd() method 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 cancellable is cancelled.

gio.Cancellable.is_cancelled

    def is_cancelled()

Returns :

True if cancellable is cancelled, False if called with None or if item is not cancelled.

The get_fd() method 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 cancellable is cancelled.

gio.Cancellable.pop_current

    def pop_current()

The pop_current() method pops cancellable off the cancellable stack (verifying that cancellable is on the top of the stack).

gio.Cancellable.push_current

    def push_current()

The push_current() method pushes cancellable onto the cancellable stack. The current cancllable can then be recieved using gio.cancellable_get_current().

gio.Cancellable.reset

    def reset()

The reset() method resets cancellable to its uncancelled state.

gio.Cancellable.set_error_if_cancelled

    def set_error_if_cancelled()

Returns :

True if cancellable was cancelled, False if it was not.

The set_error_if_cancelled() method, if the cancellable is cancelled, sets the error to notify that the operation was cancelled.

Functions

gio.cancellable_get_current

    def cancellable_get_current()

Returns :

A gio.Cancellable from the top of the stack, or None if the stack is empty.

The cancellable_get_current() function gets the top cancellable from the stack.

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