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<GSource>
(define-values () (source:add-child-source self child-source))
Adds child_source
to source
as a "polled" source; when source
is
added to a GMainContext, child_source
will be automatically added
with the same priority, when child_source
is triggered, it will
cause source
to dispatch (in addition to calling its own
callback), and when source
is destroyed, it will destroy
child_source
as well. (source
will also still be dispatched if
its own prepare/check functions indicate that it is ready.)
If you don't need child_source
to do anything on its own when it
triggers, you can call g_source_set_dummy_callback()
on it to set a
callback that does nothing (except return TRUE
if appropriate).
source
will hold a reference on child_source
while child_source
is attached to it.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
(define-values () (source:add-poll self fd))
Adds a file descriptor to the set of file descriptors polled for
this source. This is usually combined with g_source_new()
to add an
event source. The event source's check function will typically test
the revents
field in the GPollFD struct and return TRUE
if events need
to be processed.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
Using this API forces the linear scanning of event sources on each
main loop iteration. Newly-written event sources should try to use
g_source_add_unix_fd()
instead of this API.
(define-values (%return) (source:add-unix-fd self fd events))
Monitors fd
for the IO events in events
.
The tag returned by this function can be used to remove or modify the
monitoring of the fd using g_source_remove_unix_fd()
or
g_source_modify_unix_fd()
.
It is not necessary to remove the fd before destroying the source; it will be cleaned up automatically.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
As the name suggests, this function is not available on Windows.
(define-values (%return) (source:attach self context))
Adds a GSource to a context
so that it will be executed within
that context. Remove it by calling g_source_destroy()
.
This function is safe to call from any thread, regardless of which thread
the context
is running in.
(define-values () (source:destroy self))
Removes a source from its GMainContext, if any, and mark it as destroyed. The source cannot be subsequently added to another context. It is safe to call this on sources which have already been removed from their context.
This does not unref the #GSource: if you still hold a reference, use
g_source_unref()
to drop it.
This function is safe to call from any thread, regardless of which thread the GMainContext is running in.
(define-values (%return) (source:get-can-recurse? self))
Checks whether a source is allowed to be called recursively.
see g_source_set_can_recurse()
.
(define-values (%return) (source:get-context self))
Gets the GMainContext with which the source is associated.
You can call this on a source that has been destroyed, provided
that the GMainContext it was attached to still exists (in which
case it will return that GMainContext). In particular, you can
always call this function on the source returned from
g_main_current_source()
. But calling this function on a source
whose GMainContext has been destroyed is an error.
(define-values (%return) (source:get-id self))
Returns the numeric ID for a particular source. The ID of a source
is a positive integer which is unique within a particular main loop
context. The reverse
mapping from ID to source is done by g_main_context_find_source_by_id()
.
You can only call this function while the source is associated to a
GMainContext instance; calling this function before g_source_attach()
or after g_source_destroy()
yields undefined behavior. The ID returned
is unique within the GMainContext instance passed to g_source_attach()
.
(define-values (%return) (source:get-name self))
Gets a name for the source, used in debugging and profiling. The
name may be NULL if it has never been set with g_source_set_name()
.
(define-values (%return) (source:get-ready-time self))
Gets the "ready time" of source
, as set by
g_source_set_ready_time()
.
Any time before the current monotonic time (including 0) is an indication that the source will fire immediately.
(define-values (%return) (source:get-time self))
Gets the time to be used when checking this source. The advantage of
calling this function over calling g_get_monotonic_time()
directly is
that when checking multiple sources, GLib can cache a single value
instead of having to repeatedly get the system monotonic time.
The time here is the system monotonic time, if available, or some
other reasonable alternative otherwise. See g_get_monotonic_time()
.
(define-values (%return) (source:is-destroyed? self))
Returns whether source
has been destroyed.
This is important when you operate upon your objects from within idle handlers, but may have freed the object before the dispatch of your idle handler.
static gboolean idle_callback (gpointer data) { SomeWidget *self = data; GDK_THREADS_ENTER (); // do stuff with self self->idle_id = 0; GDK_THREADS_LEAVE (); return G_SOURCE_REMOVE; } static void some_widget_do_stuff_later (SomeWidget *self) { self->idle_id = g_idle_add (idle_callback, self); } static void some_widget_finalize (GObject *object) { SomeWidget *self = SOME_WIDGET (object); if (self->idle_id) g_source_remove (self->idle_id); G_OBJECT_CLASS (parent_class)->finalize (object); }
This will fail in a multi-threaded application if the widget is destroyed before the idle handler fires due to the use after free in the callback. A solution, to this particular problem, is to check to if the source has already been destroy within the callback.
static gboolean idle_callback (gpointer data) { SomeWidget *self = data; GDK_THREADS_ENTER (); if (!g_source_is_destroyed (g_main_current_source ())) { // do stuff with self } GDK_THREADS_LEAVE (); return FALSE; }
Calls to this function from a thread other than the one acquired by the GMainContext the GSource is attached to are typically redundant, as the source could be destroyed immediately after this function returns. However, once a source is destroyed it cannot be un-destroyed, so this function can be used for opportunistic checks from any thread.
(define-values () (source:modify-unix-fd self tag new-events))
Updates the event mask to watch for the fd identified by tag
.
tag
is the tag returned from g_source_add_unix_fd()
.
If you want to remove a fd, don't set its event mask to zero.
Instead, call g_source_remove_unix_fd()
.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
As the name suggests, this function is not available on Windows.
(define-values (%return) (source:query-unix-fd self tag))
Queries the events reported for the fd corresponding to tag
on
source
during the last poll.
The return value of this function is only defined when the function
is called from the check or dispatch functions for source
.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
As the name suggests, this function is not available on Windows.
(define-values () (source:remove-child-source self child-source))
Detaches child_source
from source
and destroys it.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
(define-values () (source:remove-poll self fd))
Removes a file descriptor from the set of file descriptors polled for this source.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
(define-values () (source:remove-unix-fd self tag))
Reverses the effect of a previous call to g_source_add_unix_fd()
.
You only need to call this if you want to remove an fd from being watched while keeping the same source around. In the normal case you will just want to destroy the source.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
As the name suggests, this function is not available on Windows.
(define-values () (source:set-callback self func data notify))
Sets the callback function for a source. The callback for a source is called from the source's dispatch function.
The exact type of func
depends on the type of source; ie. you
should not count on func
being called with data
as its first
parameter. Cast func
with G_SOURCE_FUNC()
to avoid warnings about
incompatible function types.
See [memory management of sources][mainloop-memory-management] for details
on how to handle memory management of data
.
Typically, you won't use this function. Instead use functions specific
to the type of source you are using, such as g_idle_add()
or g_timeout_add()
.
It is safe to call this function multiple times on a source which has already been attached to a context. The changes will take effect for the next time the source is dispatched after this call returns.
(define-values () (source:set-can-recurse self can-recurse))
Sets whether a source can be called recursively. If can_recurse
is
TRUE
, then while the source is being dispatched then this source
will be processed normally. Otherwise, all processing of this
source is blocked until the dispatch function returns.
(define-values () (source:set-name self name))
Sets a name for the source, used in debugging and profiling. The name defaults to NULL.
The source name should describe in a human-readable way what the source does. For example, "X11 event queue" or "GTK+ repaint idle handler" or whatever it is.
It is permitted to call this function multiple times, but is not recommended due to the potential performance impact. For example, one could change the name in the "check" function of a GSourceFuncs to include details like the event type in the source name.
Use caution if changing the name while another thread may be
accessing it with g_source_get_name()
; that function does not copy
the value, and changing the value will free it while the other thread
may be attempting to use it.
(define-values () (source:set-priority self priority))
Sets the priority of a source. While the main loop is being run, a source will be dispatched if it is ready to be dispatched and no sources at a higher (numerically smaller) priority are ready to be dispatched.
A child source always has the same priority as its parent. It is not permitted to change the priority of a source once it has been added as a child of another source.
(define-values () (source:set-ready-time self ready-time))
Sets a GSource to be dispatched when the given monotonic time is
reached (or passed). If the monotonic time is in the past (as it
always will be if ready_time
is 0) then the source will be
dispatched immediately.
If ready_time
is -1 then the source is never woken up on the basis
of the passage of time.
Dispatching the source does not reset the ready time. You should do so yourself, from the source dispatch function.
Note that if you have a pair of sources where the ready time of one suggests that it will be delivered first but the priority for the other suggests that it would be delivered first, and the ready time for both sources is reached during the same main context iteration, then the order of dispatch is undefined.
It is a no-op to call this function on a GSource which has already been
destroyed with g_source_destroy()
.
This API is only intended to be used by implementations of GSource. Do not call this API on a GSource that you did not create.
(define-values () (source:unref self))
Decreases the reference count of a source by one. If the resulting reference count is zero the source and associated memory will be destroyed.
(define-values (%return) (source:remove? tag))
Removes the source with the given ID from the default main context. You must
use g_source_destroy()
for sources added to a non-default main context.
The ID of a GSource is given by g_source_get_id()
, or will be
returned by the functions g_source_attach()
, g_idle_add()
,
g_idle_add_full()
, g_timeout_add()
, g_timeout_add_full()
,
g_child_watch_add()
, g_child_watch_add_full()
, g_io_add_watch()
, and
g_io_add_watch_full()
.
It is a programmer error to attempt to remove a non-existent source.
More specifically: source IDs can be reissued after a source has been
destroyed and therefore it is never valid to use this function with a
source ID which may have already been removed. An example is when
scheduling an idle to run in another thread with g_idle_add()
: the
idle may already have run and been removed by the time this function
is called on its (now invalid) source ID. This source ID may have
been reissued, leading to the operation being performed against the
wrong source.
(define-values (%return) (source:remove-by-user-data? user-data))
Removes a source from the default main loop context given the user data for the callback. If multiple sources exist with the same user data, only one will be destroyed.
(define-values () (source:set-name-by-id tag name))
Sets the name of a source using its ID.
This is a convenience utility to set source names from the return
value of g_idle_add()
, g_timeout_add()
, etc.
It is a programmer error to attempt to set the name of a non-existent source.
More specifically: source IDs can be reissued after a source has been
destroyed and therefore it is never valid to use this function with a
source ID which may have already been removed. An example is when
scheduling an idle to run in another thread with g_idle_add()
: the
idle may already have run and been removed by the time this function
is called on its (now invalid) source ID. This source ID may have
been reissued, leading to the operation being performed against the
wrong source.