Gio::Cancellable Class Reference

Allows actions to be cancelled. More...

Inherits Glib::Object.

Collaboration diagram for Gio::Cancellable:
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List of all members.

Public Types

typedef sigc::slot< void > SlotCancelledCallback

Public Member Functions

virtual ~Cancellable ()
GCancellable* gobj ()
 Provides access to the underlying C GObject.
const GCancellable* gobj () const
 Provides access to the underlying C GObject.
GCancellable* gobj_copy ()
 Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.
bool is_cancelled () const
 Checks if a cancellable job has been cancelled.
int get_fd () const
 Gets the file descriptor for a cancellable job.
void cancel ()
 Will set cancellable to cancelled, and will emit the Cancellable::cancelled signal.
void push_current ()
 Pushes cancellable onto the cancellable stack.
void pop_current ()
 Pops cancellable off the cancellable stack (verifying that cancellable is on the top of the stack).
void reset ()
 Resets cancellable to its uncancelled state.
gulong connect (const SlotCancelledCallback& callback)
 Convenience function to connect to the Cancellable::cancelled signal.
void disconnect (gulong handler_id)
 Disconnects a handler from an cancellable instance similar to Glib::signal_handler_disconnect() but ensures that once this function returns the handler will not run anymore in any thread.
Glib::SignalProxy0< void > signal_cancelled ()

Static Public Member Functions

static Glib::RefPtr< Cancellablecreate ()
static Glib::RefPtr< Cancellableget_current ()
 Gets the top cancellable from the stack.

Protected Member Functions

 Cancellable ()
virtual void on_cancelled ()

Related Functions

(Note that these are not member functions.)



Glib::RefPtr< Gio::Cancellablewrap (GCancellable* object, bool take_copy=false)
 A Glib::wrap() method for this object.

Detailed Description

Allows actions to be cancelled.

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

Since glibmm 2.16:

Member Typedef Documentation

typedef sigc::slot<void> Gio::Cancellable::SlotCancelledCallback

Constructor & Destructor Documentation

virtual Gio::Cancellable::~Cancellable (  )  [virtual]
Gio::Cancellable::Cancellable (  )  [protected]

Member Function Documentation

void Gio::Cancellable::cancel (  ) 

Will set cancellable to cancelled, and will emit the Cancellable::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 AsyncReadyCallback will not be invoked until the application returns to the main loop.

gulong Gio::Cancellable::connect ( const SlotCancelledCallback callback  ) 

Convenience function to connect to the Cancellable::cancelled signal.

Also handles the race condition that may happen if the cancellable is cancelled right before connecting.

callback is called at most once, either directly at the time of the connect if cancellable is already cancelled, or when cancellable is cancelled in some thread.

data_destroy_func will be called when the handler is disconnected, or immediately if the cancellable is already cancelled.

See Cancellable::cancelled for details on how to use this.

Parameters:
callback The Callback to connect.
data Data to pass to callback.
data_destroy_func Free function for data or 0.
Returns:
The id of the signal handler or 0 if cancellable has already been cancelled.
Since glibmm 2.22:
static Glib::RefPtr<Cancellable> Gio::Cancellable::create (  )  [static]
void Gio::Cancellable::disconnect ( gulong  handler_id  ) 

Disconnects a handler from an cancellable instance similar to Glib::signal_handler_disconnect() but ensures that once this function returns the handler will not run anymore in any thread.

This avoids a race condition where a thread cancels at the same time as the cancellable operation is finished and the signal handler is removed. See Cancellable::cancelled for details on how to use this.

If cancellable is 0 or handler_id is 0 this function does nothing.

Since glibmm 2.22:
Parameters:
handler_id Handler id of the handler to be disconnected, or 0.
static Glib::RefPtr<Cancellable> Gio::Cancellable::get_current (  )  [static]

Gets the top cancellable from the stack.

Returns:
A Cancellable from the top of the stack, or 0 if the stack is empty.
int Gio::Cancellable::get_fd (  )  const

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.

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().

See also g_cancellable_make_pollfd().

Returns:
A valid file descriptor. -1 if the file descriptor is not supported, or on errors.
const GCancellable* Gio::Cancellable::gobj (  )  const [inline]

Provides access to the underlying C GObject.

Reimplemented from Glib::ObjectBase.

GCancellable* Gio::Cancellable::gobj (  )  [inline]

Provides access to the underlying C GObject.

Reimplemented from Glib::ObjectBase.

GCancellable* Gio::Cancellable::gobj_copy (  ) 

Provides access to the underlying C instance. The caller is responsible for unrefing it. Use when directly setting fields in structs.

bool Gio::Cancellable::is_cancelled (  )  const

Checks if a cancellable job has been cancelled.

Returns:
true if cancellable is cancelled, false if called with 0 or if item is not cancelled.
virtual void Gio::Cancellable::on_cancelled (  )  [protected, virtual]
void Gio::Cancellable::pop_current (  ) 

Pops cancellable off the cancellable stack (verifying that cancellable is on the top of the stack).

void Gio::Cancellable::push_current (  ) 

Pushes cancellable onto the cancellable stack.

The current cancllable can then be recieved 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. File operations, so you rarely have to call this yourself.

void Gio::Cancellable::reset (  ) 

Resets cancellable to its uncancelled state.

Glib::SignalProxy0< void > Gio::Cancellable::signal_cancelled (  ) 
Prototype:
void on_my_cancelled()

Friends And Related Function Documentation

Glib::RefPtr< Gio::Cancellable > wrap ( GCancellable *  object,
bool  take_copy = false 
) [related]

A Glib::wrap() method for this object.

Parameters:
object The C instance.
take_copy False if the result should take ownership of the C instance. True if it should take a new copy or ref.
Returns:
A C++ instance that wraps this C instance.

The documentation for this class was generated from the following file:

Generated on Mon Sep 21 09:04:27 2009 for glibmm by  doxygen 1.6.1