![]() |
![]() |
![]() |
GLib Reference Manual | ![]() |
---|---|---|---|---|
Top | Description |
#include <glib.h> GMainLoop; GMainLoop * g_main_loop_new (GMainContext *context, gboolean is_running); GMainLoop * g_main_loop_ref (GMainLoop *loop); void g_main_loop_unref (GMainLoop *loop); void g_main_loop_run (GMainLoop *loop); void g_main_loop_quit (GMainLoop *loop); gboolean g_main_loop_is_running (GMainLoop *loop); GMainContext * g_main_loop_get_context (GMainLoop *loop); #define g_main_new (is_running) #define g_main_destroy (loop) #define g_main_run (loop) #define g_main_quit (loop) #define g_main_is_running (loop) #define G_PRIORITY_HIGH #define G_PRIORITY_DEFAULT #define G_PRIORITY_HIGH_IDLE #define G_PRIORITY_DEFAULT_IDLE #define G_PRIORITY_LOW GMainContext; GMainContext * g_main_context_new (void); GMainContext * g_main_context_ref (GMainContext *context); void g_main_context_unref (GMainContext *context); GMainContext * g_main_context_default (void); gboolean g_main_context_iteration (GMainContext *context, gboolean may_block); #define g_main_iteration (may_block) gboolean g_main_context_pending (GMainContext *context); #define g_main_pending () GSource * g_main_context_find_source_by_id (GMainContext *context, guint source_id); GSource * g_main_context_find_source_by_user_data (GMainContext *context, gpointer user_data); GSource * g_main_context_find_source_by_funcs_user_data (GMainContext *context, GSourceFuncs *funcs, gpointer user_data); void g_main_context_wakeup (GMainContext *context); gboolean g_main_context_acquire (GMainContext *context); void g_main_context_release (GMainContext *context); gboolean g_main_context_is_owner (GMainContext *context); gboolean g_main_context_wait (GMainContext *context, GCond *cond, GMutex *mutex); gboolean g_main_context_prepare (GMainContext *context, gint *priority); gint g_main_context_query (GMainContext *context, gint max_priority, gint *timeout_, GPollFD *fds, gint n_fds); gint g_main_context_check (GMainContext *context, gint max_priority, GPollFD *fds, gint n_fds); void g_main_context_dispatch (GMainContext *context); void g_main_context_set_poll_func (GMainContext *context, GPollFunc func); GPollFunc g_main_context_get_poll_func (GMainContext *context); gint (*GPollFunc) (GPollFD *ufds, guint nfsd, gint timeout_); void g_main_context_add_poll (GMainContext *context, GPollFD *fd, gint priority); void g_main_context_remove_poll (GMainContext *context, GPollFD *fd); gint g_main_depth (void); GSource * g_main_current_source (void); #define g_main_set_poll_func (func) GSource * g_timeout_source_new (guint interval); GSource * g_timeout_source_new_seconds (guint interval); guint g_timeout_add (guint interval, GSourceFunc function, gpointer data); guint g_timeout_add_full (gint priority, guint interval, GSourceFunc function, gpointer data, GDestroyNotify notify); guint g_timeout_add_seconds (guint interval, GSourceFunc function, gpointer data); guint g_timeout_add_seconds_full (gint priority, guint interval, GSourceFunc function, gpointer data, GDestroyNotify notify); GSource * g_idle_source_new (void); guint g_idle_add (GSourceFunc function, gpointer data); guint g_idle_add_full (gint priority, GSourceFunc function, gpointer data, GDestroyNotify notify); gboolean g_idle_remove_by_data (gpointer data); typedef GPid; void (*GChildWatchFunc) (GPid pid, gint status, gpointer data); GSource * g_child_watch_source_new (GPid pid); guint g_child_watch_add (GPid pid, GChildWatchFunc function, gpointer data); guint g_child_watch_add_full (gint priority, GPid pid, GChildWatchFunc function, gpointer data, GDestroyNotify notify); GPollFD; gint g_poll (GPollFD *fds, guint nfds, gint timeout); GSource; void (*GSourceDummyMarshal) (void); GSourceFuncs; GSourceCallbackFuncs; GSource * g_source_new (GSourceFuncs *source_funcs, guint struct_size); GSource * g_source_ref (GSource *source); void g_source_unref (GSource *source); void g_source_set_funcs (GSource *source, GSourceFuncs *funcs); guint g_source_attach (GSource *source, GMainContext *context); void g_source_destroy (GSource *source); gboolean g_source_is_destroyed (GSource *source); void g_source_set_priority (GSource *source, gint priority); gint g_source_get_priority (GSource *source); void g_source_set_can_recurse (GSource *source, gboolean can_recurse); gboolean g_source_get_can_recurse (GSource *source); guint g_source_get_id (GSource *source); GMainContext * g_source_get_context (GSource *source); void g_source_set_callback (GSource *source, GSourceFunc func, gpointer data, GDestroyNotify notify); gboolean (*GSourceFunc) (gpointer data); void g_source_set_callback_indirect (GSource *source, gpointer callback_data, GSourceCallbackFuncs *callback_funcs); void g_source_add_poll (GSource *source, GPollFD *fd); void g_source_remove_poll (GSource *source, GPollFD *fd); void g_source_get_current_time (GSource *source, GTimeVal *timeval); gboolean g_source_remove (guint tag); gboolean g_source_remove_by_funcs_user_data (GSourceFuncs *funcs, gpointer user_data); gboolean g_source_remove_by_user_data (gpointer user_data);
The main event loop manages all the available sources of events for
GLib and GTK+ applications. These events can come from any number of
different types of sources such as file descriptors (plain files,
pipes or sockets) and timeouts. New types of event sources can also
be added using g_source_attach()
.
To allow multiple independent sets of sources to be handled in different threads, each source is associated with a GMainContext. A GMainContext can only be running in a single thread, but sources can be added to it and removed from it from other threads.
Each event source is assigned a priority. The default priority, G_PRIORITY_DEFAULT, is 0. Values less than 0 denote higher priorities. Values greater than 0 denote lower priorities. Events from high priority sources are always processed before events from lower priority sources.
Idle functions can also be added, and assigned a priority. These will be run whenever no events with a higher priority are ready to be processed.
The GMainLoop data type represents a main event loop. A GMainLoop
is created with g_main_loop_new()
. After adding the initial event sources,
g_main_loop_run()
is called. This continuously checks for new events from
each of the event sources and dispatches them. Finally, the
processing of an event from one of the sources leads to a call to
g_main_loop_quit()
to exit the main loop, and g_main_loop_run()
returns.
It is possible to create new instances of GMainLoop recursively. This is often used in GTK+ applications when showing modal dialog boxes. Note that event sources are associated with a particular GMainContext, and will be checked and dispatched for all main loops associated with that GMainContext.
GTK+ contains wrappers of some of these functions, e.g. gtk_main()
,
gtk_main_quit()
and gtk_events_pending()
.
One of the unusual features of the GTK+ main loop functionality
is that new types of event source can be created and used in
addition to the builtin type of event source. A new event source
type is used for handling GDK events. A new source type is
created by deriving from the GSource
structure. The derived type of source is represented by a
structure that has the GSource structure as a first element,
and other elements specific to the new source type. To create
an instance of the new source type, call g_source_new()
passing
in the size of the derived structure and a table of functions.
These GSourceFuncs determine the behavior of the new source
types.
New source types basically interact with the main context
in two ways. Their prepare function in GSourceFuncs can set
a timeout to determine the maximum amount of time that the
main loop will sleep before checking the source again. In
addition, or as well, the source can add file descriptors to
the set that the main context checks using g_source_add_poll()
.
Single iterations of a GMainContext can be run with
g_main_context_iteration()
. In some cases, more detailed control
of exactly how the details of the main loop work is desired,
for instance, when integrating the GMainLoop with an external
main loop. In such cases, you can call the component functions
of g_main_context_iteration()
directly. These functions
are g_main_context_prepare()
, g_main_context_query()
,
g_main_context_check()
and g_main_context_dispatch()
.
The operation of these functions can best be seen in terms of a state diagram, as shown in Figure 1, “States of a Main Context”.
typedef struct _GMainLoop GMainLoop;
The GMainLoop struct is an opaque data type representing the main event loop of a GLib or GTK+ application.
GMainLoop * g_main_loop_new (GMainContext *context, gboolean is_running);
Creates a new GMainLoop structure.
|
a GMainContext (if NULL , the default context will be used).
|
|
set to TRUE to indicate that the loop is running. This
is not very important since calling g_main_loop_run() will set this to
TRUE anyway.
|
Returns : |
a new GMainLoop. |
GMainLoop * g_main_loop_ref (GMainLoop *loop);
Increases the reference count on a GMainLoop object by one.
|
a GMainLoop |
Returns : |
loop
|
void g_main_loop_unref (GMainLoop *loop);
Decreases the reference count on a GMainLoop object by one. If the result is zero, free the loop and free all associated memory.
|
a GMainLoop |
void g_main_loop_run (GMainLoop *loop);
Runs a main loop until g_main_loop_quit()
is called on the loop.
If this is called for the thread of the loop's GMainContext,
it will process events from the loop, otherwise it will
simply wait.
|
a GMainLoop |
void g_main_loop_quit (GMainLoop *loop);
Stops a GMainLoop from running. Any calls to g_main_loop_run()
for the loop will return.
Note that sources that have already been dispatched when
g_main_loop_quit()
is called will still be executed.
|
a GMainLoop |
gboolean g_main_loop_is_running (GMainLoop *loop);
Checks to see if the main loop is currently being run via g_main_loop_run()
.
GMainContext * g_main_loop_get_context (GMainLoop *loop);
Returns the GMainContext of loop
.
|
a GMainLoop. |
Returns : |
the GMainContext of loop
|
#define g_main_new(is_running)
g_main_new
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_loop_new()
instead.
Creates a new GMainLoop for the default main loop.
|
set to TRUE to indicate that the loop is running. This is not
very important since calling g_main_run() will set this to TRUE anyway.
|
Returns : |
a new GMainLoop. |
#define g_main_destroy(loop)
g_main_destroy
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_loop_unref()
instead.
Frees the memory allocated for the GMainLoop.
|
a GMainLoop. |
#define g_main_run(loop)
g_main_run
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_loop_run()
instead.
Runs a main loop until it stops running.
|
a GMainLoop. |
#define g_main_quit(loop)
g_main_quit
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_loop_quit()
instead.
Stops the GMainLoop. If g_main_run()
was called to run the GMainLoop,
it will now return.
|
a GMainLoop. |
#define g_main_is_running(loop)
g_main_is_running
has been deprecated since version 2.2 and should not be used in newly-written code. USe g_main_loop_is_running()
instead.
Checks if the main loop is running.
|
a GMainLoop. |
Returns : |
%TRUE if the main loop is running. |
#define G_PRIORITY_HIGH -100
Use this for high priority event sources. It is not used within GLib or GTK+.
#define G_PRIORITY_DEFAULT 0
Use this for default priority event sources.
In GLib this priority is used when adding timeout functions with
g_timeout_add()
.
In GDK this priority is used for events from the X server.
#define G_PRIORITY_HIGH_IDLE 100
Use this for high priority idle functions. GTK+ uses G_PRIORITY_HIGH_IDLE + 10 for resizing operations, and G_PRIORITY_HIGH_IDLE + 20 for redrawing operations. (This is done to ensure that any pending resizes are processed before any pending redraws, so that widgets are not redrawn twice unnecessarily.)
#define G_PRIORITY_DEFAULT_IDLE 200
Use this for default priority idle functions.
In GLib this priority is used when adding idle functions with g_idle_add()
.
#define G_PRIORITY_LOW 300
Use this for very low priority background tasks. It is not used within GLib or GTK+.
typedef struct _GMainContext GMainContext;
The GMainContext struct is an opaque data type representing a set of sources to be handled in a main loop.
GMainContext * g_main_context_new (void);
Creates a new GMainContext structure.
Returns : |
the new GMainContext |
GMainContext * g_main_context_ref (GMainContext *context);
Increases the reference count on a GMainContext object by one.
|
a GMainContext |
Returns : |
the context that was passed in (since 2.6)
|
void g_main_context_unref (GMainContext *context);
Decreases the reference count on a GMainContext object by one. If the result is zero, free the context and free all associated memory.
|
a GMainContext |
GMainContext * g_main_context_default (void);
Returns the default main context. This is the main context used for main loop functions when a main loop is not explicitly specified.
Returns : |
the default main context. |
gboolean g_main_context_iteration (GMainContext *context, gboolean may_block);
Runs a single iteration for the given main loop. This involves
checking to see if any event sources are ready to be processed,
then if no events sources are ready and may_block
is TRUE
, waiting
for a source to become ready, then dispatching the highest priority
events sources that are ready. Otherwise, if may_block
is FALSE
sources are not waited to become ready, only those highest priority
events sources will be dispatched (if any), that are ready at this
given moment without further waiting.
Note that even when may_block
is TRUE
, it is still possible for
g_main_context_iteration()
to return FALSE
, since the the wait may
be interrupted for other reasons than an event source becoming ready.
|
a GMainContext (if NULL , the default context will be used)
|
|
whether the call may block. |
Returns : |
TRUE if events were dispatched.
|
#define g_main_iteration(may_block)
g_main_iteration
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_context_iteration()
instead.
Runs a single iteration for the default GMainContext.
gboolean g_main_context_pending (GMainContext *context);
Checks if any sources have pending events for the given context.
|
a GMainContext (if NULL , the default context will be used)
|
Returns : |
TRUE if events are pending.
|
#define g_main_pending()
g_main_pending
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_context_pending()
instead.
Checks if any events are pending for the default GMainContext (i.e. ready to be processed).
Returns : |
%TRUE if any events are pending. |
GSource * g_main_context_find_source_by_id (GMainContext *context, guint source_id);
Finds a GSource given a pair of context and ID.
|
a GMainContext (if NULL , the default context will be used)
|
|
the source ID, as returned by g_source_get_id() .
|
Returns : |
the GSource if found, otherwise, NULL
|
GSource * g_main_context_find_source_by_user_data (GMainContext *context, gpointer user_data);
Finds a source with the given user data for the callback. If multiple sources exist with the same user data, the first one found will be returned.
|
a GMainContext |
|
the user_data for the callback. |
Returns : |
the source, if one was found, otherwise NULL
|
GSource * g_main_context_find_source_by_funcs_user_data (GMainContext *context, GSourceFuncs *funcs, gpointer user_data);
Finds a source with the given source functions and user data. If multiple sources exist with the same source function and user data, the first one found will be returned.
|
a GMainContext (if NULL , the default context will be used).
|
|
the source_funcs passed to g_source_new() .
|
|
the user data from the callback. |
Returns : |
the source, if one was found, otherwise NULL
|
void g_main_context_wakeup (GMainContext *context);
If context
is currently waiting in a poll()
, interrupt
the poll()
, and continue the iteration process.
|
a GMainContext |
gboolean g_main_context_acquire (GMainContext *context);
Tries to become the owner of the specified context.
If some other thread is the owner of the context,
returns FALSE
immediately. Ownership is properly
recursive: the owner can require ownership again
and will release ownership when g_main_context_release()
is called as many times as g_main_context_acquire()
.
You must be the owner of a context before you
can call g_main_context_prepare()
, g_main_context_query()
,
g_main_context_check()
, g_main_context_dispatch()
.
|
a GMainContext |
Returns : |
TRUE if the operation succeeded, and
this thread is now the owner of context .
|
void g_main_context_release (GMainContext *context);
Releases ownership of a context previously acquired by this thread
with g_main_context_acquire()
. If the context was acquired multiple
times, the ownership will be released only when g_main_context_release()
is called as many times as it was acquired.
|
a GMainContext |
gboolean g_main_context_is_owner (GMainContext *context);
Determines whether this thread holds the (recursive)
ownership of this GMaincontext. This is useful to
know before waiting on another thread that may be
blocking to get ownership of context
.
|
a GMainContext |
Returns : |
TRUE if current thread is owner of context .
|
Since 2.10
gboolean g_main_context_wait (GMainContext *context, GCond *cond, GMutex *mutex);
Tries to become the owner of the specified context,
as with g_main_context_acquire()
. But if another thread
is the owner, atomically drop mutex
and wait on cond
until
that owner releases ownership or until cond
is signaled, then
try again (once) to become the owner.
|
a GMainContext |
|
a condition variable |
|
a mutex, currently held |
Returns : |
TRUE if the operation succeeded, and
this thread is now the owner of context .
|
gboolean g_main_context_prepare (GMainContext *context, gint *priority);
Prepares to poll sources within a main loop. The resulting information
for polling is determined by calling g_main_context_query()
.
|
a GMainContext |
|
location to store priority of highest priority source already ready. |
Returns : |
TRUE if some source is ready to be dispatched
prior to polling.
|
gint g_main_context_query (GMainContext *context, gint max_priority, gint *timeout_, GPollFD *fds, gint n_fds);
Determines information necessary to poll this main loop.
|
a GMainContext |
|
maximum priority source to check |
|
location to store timeout to be used in polling |
|
location to store GPollFD records that need to be polled. |
|
length of fds .
|
Returns : |
the number of records actually stored in fds ,
or, if more than n_fds records need to be stored, the number
of records that need to be stored.
|
gint g_main_context_check (GMainContext *context, gint max_priority, GPollFD *fds, gint n_fds);
Passes the results of polling back to the main loop.
|
a GMainContext |
|
the maximum numerical priority of sources to check |
|
array of GPollFD's that was passed to the last call to
g_main_context_query()
|
|
return value of g_main_context_query()
|
Returns : |
TRUE if some sources are ready to be dispatched.
|
void g_main_context_dispatch (GMainContext *context);
Dispatches all pending sources.
|
a GMainContext |
void g_main_context_set_poll_func (GMainContext *context, GPollFunc func);
Sets the function to use to handle polling of file descriptors. It
will be used instead of the poll()
system call
(or GLib's replacement function, which is used where
poll()
isn't available).
This function could possibly be used to integrate the GLib event loop with an external event loop.
|
a GMainContext |
|
the function to call to poll all file descriptors |
GPollFunc g_main_context_get_poll_func (GMainContext *context);
Gets the poll function set by g_main_context_set_poll_func()
.
|
a GMainContext |
Returns : |
the poll function |
gint (*GPollFunc) (GPollFD *ufds, guint nfsd, gint timeout_);
Specifies the type of function passed to g_main_context_set_poll_func()
.
The semantics of the function should match those of the
system call.
poll()
|
an array of GPollFD elements. |
|
the number of elements in ufds .
|
|
the maximum time to wait for an event of the file descriptors. A negative value indicates an infinite timeout. |
Returns : |
the number of GPollFD elements which have events or errors reported, or -1 if an error occurred. |
void g_main_context_add_poll (GMainContext *context, GPollFD *fd, gint priority);
Adds a file descriptor to the set of file descriptors polled for
this context. This will very seldomly be used directly. Instead
a typical event source will use g_source_add_poll()
instead.
|
a GMainContext (or NULL for the default context)
|
|
a GPollFD structure holding information about a file descriptor to watch. |
|
the priority for this file descriptor which should be
the same as the priority used for g_source_attach() to ensure that the
file descriptor is polled whenever the results may be needed.
|
void g_main_context_remove_poll (GMainContext *context, GPollFD *fd);
Removes file descriptor from the set of file descriptors to be polled for a particular context.
|
a GMainContext |
|
a GPollFD descriptor previously added with g_main_context_add_poll()
|
gint g_main_depth (void);
Returns the depth of the stack of calls to
g_main_context_dispatch()
on any GMainContext in the current thread.
That is, when called from the toplevel, it gives 0. When
called from within a callback from g_main_context_iteration()
(or g_main_loop_run()
, etc.) it returns 1. When called from within
a callback to a recursive call to g_main_context_iterate()
,
it returns 2. And so forth.
This function is useful in a situation like the following: Imagine an extremely simple "garbage collected" system.
static GList *free_list; gpointer allocate_memory (gsize size) { gpointer result = g_malloc (size); free_list = g_list_prepend (free_list, result); return result; } void free_allocated_memory (void) { GList *l; for (l = free_list; l; l = l->next); g_free (l->data); g_list_free (free_list); free_list = NULL; } [...] while (TRUE); { g_main_context_iteration (NULL, TRUE); free_allocated_memory(); }
This works from an application, however, if you want to do the same
thing from a library, it gets more difficult, since you no longer
control the main loop. You might think you can simply use an idle
function to make the call to free_allocated_memory()
, but that
doesn't work, since the idle function could be called from a
recursive callback. This can be fixed by using g_main_depth()
gpointer allocate_memory (gsize size) { FreeListBlock *block = g_new (FreeListBlock, 1); block->mem = g_malloc (size); block->depth = g_main_depth (); free_list = g_list_prepend (free_list, block); return block->mem; } void free_allocated_memory (void) { GList *l; int depth = g_main_depth (); for (l = free_list; l; ); { GList *next = l->next; FreeListBlock *block = l->data; if (block->depth > depth) { g_free (block->mem); g_free (block); free_list = g_list_delete_link (free_list, l); } l = next; } }
There is a temptation to use g_main_depth()
to solve
problems with reentrancy. For instance, while waiting for data
to be received from the network in response to a menu item,
the menu item might be selected again. It might seem that
one could make the menu item's callback return immediately
and do nothing if g_main_depth()
returns a value greater than 1.
However, this should be avoided since the user then sees selecting
the menu item do nothing. Furthermore, you'll find yourself adding
these checks all over your code, since there are doubtless many,
many things that the user could do. Instead, you can use the
following techniques:
Use gtk_widget_set_sensitive()
or modal dialogs to prevent
the user from interacting with elements while the main
loop is recursing.
Avoid main loop recursion in situations where you can't handle arbitrary callbacks. Instead, structure your code so that you simply return to the main loop and then get called again when there is more work to do.
Returns : |
The main loop recursion level in the current thread |
GSource * g_main_current_source (void);
Returns the currently firing source for this thread.
Returns : |
The currently firing source or NULL .
|
Since 2.12
#define g_main_set_poll_func(func)
g_main_set_poll_func
has been deprecated since version 2.2 and should not be used in newly-written code. Use g_main_context_set_poll_func()
instead.
Sets the function to use for the handle polling of file descriptors for the default main context.
|
the function to call to poll all file descriptors. |
GSource * g_timeout_source_new (guint interval);
Creates a new timeout source.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed.
|
the timeout interval in milliseconds. |
Returns : |
the newly-created timeout source |
GSource * g_timeout_source_new_seconds (guint interval);
Creates a new timeout source.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed.
The scheduling granularity/accuracy of this timeout source will be in seconds.
|
the timeout interval in seconds |
Returns : |
the newly-created timeout source |
Since 2.14
guint g_timeout_add (guint interval, GSourceFunc function, gpointer data);
Sets a function to be called at regular intervals, with the default
priority, G_PRIORITY_DEFAULT. The function is called repeatedly
until it returns FALSE
, at which point the timeout is automatically
destroyed and the function will not be called again. The first call
to the function will be at the end of the first interval
.
Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval (it does not try to 'catch up' time lost in delays).
If you want to have a timer in the "seconds" range and do not care
about the exact time of the first call of the timer, use the
g_timeout_add_seconds()
function; this function allows for more
optimizations and more efficient system power usage.
This internally creates a main loop source using g_timeout_source_new()
and attaches it to the main loop context using g_source_attach()
. You can
do these steps manually if you need greater control.
|
the time between calls to the function, in milliseconds (1/1000ths of a second) |
|
function to call |
|
data to pass to function
|
Returns : |
the ID (greater than 0) of the event source. |
guint g_timeout_add_full (gint priority, guint interval, GSourceFunc function, gpointer data, GDestroyNotify notify);
Sets a function to be called at regular intervals, with the given
priority. The function is called repeatedly until it returns
FALSE
, at which point the timeout is automatically destroyed and
the function will not be called again. The notify
function is
called when the timeout is destroyed. The first call to the
function will be at the end of the first interval
.
Note that timeout functions may be delayed, due to the processing of other event sources. Thus they should not be relied on for precise timing. After each call to the timeout function, the time of the next timeout is recalculated based on the current time and the given interval (it does not try to 'catch up' time lost in delays).
This internally creates a main loop source using g_timeout_source_new()
and attaches it to the main loop context using g_source_attach()
. You can
do these steps manually if you need greater control.
|
the priority of the timeout source. Typically this will be in the range between G_PRIORITY_DEFAULT and G_PRIORITY_HIGH. |
|
the time between calls to the function, in milliseconds (1/1000ths of a second) |
|
function to call |
|
data to pass to function
|
|
function to call when the timeout is removed, or NULL
|
Returns : |
the ID (greater than 0) of the event source. |
guint g_timeout_add_seconds (guint interval, GSourceFunc function, gpointer data);
Sets a function to be called at regular intervals with the default
priority, G_PRIORITY_DEFAULT. The function is called repeatedly until
it returns FALSE
, at which point the timeout is automatically destroyed
and the function will not be called again.
This internally creates a main loop source using
g_timeout_source_new_seconds()
and attaches it to the main loop context
using g_source_attach()
. You can do these steps manually if you need
greater control. Also see g_timout_add_seconds_full()
.
|
the time between calls to the function, in seconds |
|
function to call |
|
data to pass to function
|
Returns : |
the ID (greater than 0) of the event source. |
Since 2.14
guint g_timeout_add_seconds_full (gint priority, guint interval, GSourceFunc function, gpointer data, GDestroyNotify notify);
Sets a function to be called at regular intervals, with priority
.
The function is called repeatedly until it returns FALSE
, at which
point the timeout is automatically destroyed and the function will
not be called again.
Unlike g_timeout_add()
, this function operates at whole second granularity.
The initial starting point of the timer is determined by the implementation
and the implementation is expected to group multiple timers together so that
they fire all at the same time.
To allow this grouping, the interval
to the first timer is rounded
and can deviate up to one second from the specified interval.
Subsequent timer iterations will generally run at the specified interval.
Note that timeout functions may be delayed, due to the processing of other
event sources. Thus they should not be relied on for precise timing.
After each call to the timeout function, the time of the next
timeout is recalculated based on the current time and the given interval
If you want timing more precise than whole seconds, use g_timeout_add()
instead.
The grouping of timers to fire at the same time results in a more power
and CPU efficient behavior so if your timer is in multiples of seconds
and you don't require the first timer exactly one second from now, the
use of g_timeout_add_seconds()
is preferred over g_timeout_add()
.
This internally creates a main loop source using
g_timeout_source_new_seconds()
and attaches it to the main loop context
using g_source_attach()
. You can do these steps manually if you need
greater control.
|
the priority of the timeout source. Typically this will be in the range between G_PRIORITY_DEFAULT and G_PRIORITY_HIGH. |
|
the time between calls to the function, in seconds |
|
function to call |
|
data to pass to function
|
|
function to call when the timeout is removed, or NULL
|
Returns : |
the ID (greater than 0) of the event source. |
Since 2.14
GSource * g_idle_source_new (void);
Creates a new idle source.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed. Note that the default priority for idle sources is
G_PRIORITY_DEFAULT_IDLE
, as compared to other sources which
have a default priority of G_PRIORITY_DEFAULT
.
Returns : |
the newly-created idle source |
guint g_idle_add (GSourceFunc function, gpointer data);
Adds a function to be called whenever there are no higher priority
events pending to the default main loop. The function is given the
default idle priority, G_PRIORITY_DEFAULT_IDLE. If the function
returns FALSE
it is automatically removed from the list of event
sources and will not be called again.
This internally creates a main loop source using g_idle_source_new()
and attaches it to the main loop context using g_source_attach()
.
You can do these steps manually if you need greater control.
|
function to call |
|
data to pass to function .
|
Returns : |
the ID (greater than 0) of the event source. |
guint g_idle_add_full (gint priority, GSourceFunc function, gpointer data, GDestroyNotify notify);
Adds a function to be called whenever there are no higher priority
events pending. If the function returns FALSE
it is automatically
removed from the list of event sources and will not be called again.
This internally creates a main loop source using g_idle_source_new()
and attaches it to the main loop context using g_source_attach()
.
You can do these steps manually if you need greater control.
|
the priority of the idle source. Typically this will be in the range between G_PRIORITY_DEFAULT_IDLE and G_PRIORITY_HIGH_IDLE. |
|
function to call |
|
data to pass to function
|
|
function to call when the idle is removed, or NULL
|
Returns : |
the ID (greater than 0) of the event source. |
gboolean g_idle_remove_by_data (gpointer data);
Removes the idle function with the given data.
|
the data for the idle source's callback. |
Returns : |
TRUE if an idle source was found and removed.
|
typedef int GPid;
A type which is used to hold a process identification. On Unix, processes are identified by a process id (an integer), while Windows uses process handles (which are pointers).
void (*GChildWatchFunc) (GPid pid, gint status, gpointer data);
The type of functions to be called when a child exists.
|
the process id of the child process |
|
Status information about the child process, see waitpid(2) for more information about this field |
|
user data passed to g_child_watch_add()
|
GSource * g_child_watch_source_new (GPid pid);
Creates a new child_watch source.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed.
Note that child watch sources can only be used in conjunction with
g_spawn...
when the G_SPAWN_DO_NOT_REAP_CHILD
flag is used.
Note that on platforms where GPid must be explicitly closed
(see g_spawn_close_pid()
) pid
must not be closed while the
source is still active. Typically, you will want to call
g_spawn_close_pid()
in the callback function for the source.
Note further that using g_child_watch_source_new()
is not
compatible with calling waitpid(-1)
in
the application. Calling waitpid()
for individual pids will
still work fine.
|
process to watch. On POSIX the pid of a child process. On Windows a handle for a process (which doesn't have to be a child). |
Returns : |
the newly-created child watch source |
Since 2.4
guint g_child_watch_add (GPid pid, GChildWatchFunc function, gpointer data);
Sets a function to be called when the child indicated by pid
exits, at a default priority, G_PRIORITY_DEFAULT.
If you obtain pid
from g_spawn_async()
or g_spawn_async_with_pipes()
you will need to pass G_SPAWN_DO_NOT_REAP_CHILD as flag to
the spawn function for the child watching to work.
Note that on platforms where GPid must be explicitly closed
(see g_spawn_close_pid()
) pid
must not be closed while the
source is still active. Typically, you will want to call
g_spawn_close_pid()
in the callback function for the source.
GLib supports only a single callback per process id.
This internally creates a main loop source using
g_child_watch_source_new()
and attaches it to the main loop context
using g_source_attach()
. You can do these steps manually if you
need greater control.
|
process id to watch. On POSIX the pid of a child process. On Windows a handle for a process (which doesn't have to be a child). |
|
function to call |
|
data to pass to function
|
Returns : |
the ID (greater than 0) of the event source. |
Since 2.4
guint g_child_watch_add_full (gint priority, GPid pid, GChildWatchFunc function, gpointer data, GDestroyNotify notify);
Sets a function to be called when the child indicated by pid
exits, at the priority priority
.
If you obtain pid
from g_spawn_async()
or g_spawn_async_with_pipes()
you will need to pass G_SPAWN_DO_NOT_REAP_CHILD as flag to
the spawn function for the child watching to work.
Note that on platforms where GPid must be explicitly closed
(see g_spawn_close_pid()
) pid
must not be closed while the
source is still active. Typically, you will want to call
g_spawn_close_pid()
in the callback function for the source.
GLib supports only a single callback per process id.
This internally creates a main loop source using
g_child_watch_source_new()
and attaches it to the main loop context
using g_source_attach()
. You can do these steps manually if you
need greater control.
|
the priority of the idle source. Typically this will be in the range between G_PRIORITY_DEFAULT_IDLE and G_PRIORITY_HIGH_IDLE. |
|
process to watch. On POSIX the pid of a child process. On Windows a handle for a process (which doesn't have to be a child). |
|
function to call |
|
data to pass to function
|
|
function to call when the idle is removed, or NULL
|
Returns : |
the ID (greater than 0) of the event source. |
Since 2.4
typedef struct { #if defined (G_OS_WIN32) && GLIB_SIZEOF_VOID_P == 8 gint64 fd; #else gint fd; #endif gushort events; gushort revents; } GPollFD;
gint fd; | the file descriptor to poll (or a HANDLE on Win32 platforms). |
gushort events; | a bitwise combination of flags from GIOCondition, specifying which
events should be polled for. Typically for reading from a file descriptor
you would use G_IO_IN | G_IO_HUP | G_IO_ERR , and for writing you would use
G_IO_OUT | G_IO_ERR .
|
gushort revents; | a bitwise combination of flags from GIOCondition, returned from the
function to indicate which events occurred.
|
gint g_poll (GPollFD *fds, guint nfds, gint timeout);
Polls fds
, as with the poll()
system call, but portably. (On
systems that don't have poll()
, it is emulated using select()
.)
This is used internally by GMainContext, but it can be called
directly if you need to block until a file descriptor is ready, but
don't want to run the full main loop.
Each element of fds
is a GPollFD describing a single file
descriptor to poll. The fd
field indicates the file descriptor,
and the events
field indicates the events to poll for. On return,
the revents
fields will be filled with the events that actually
occurred.
On POSIX systems, the file descriptors in fds
can be any sort of
file descriptor, but the situation is much more complicated on
Windows. If you need to use g_poll()
in code that has to run on
Windows, the easiest solution is to construct all of your
GPollFDs with g_io_channel_win32_make_pollfd()
.
|
file descriptors to poll |
|
the number of file descriptors in fds
|
|
amount of time to wait, in milliseconds, or -1 to wait forever |
Returns : |
the number of entries in fds whose revents fields
were filled in, or 0 if the operation timed out, or -1 on error or
if the call was interrupted.
|
Since 2.20
typedef struct { } GSource;
The GSource struct is an opaque data type representing an event source.
void (*GSourceDummyMarshal) (void);
This is just a placeholder for GClosureMarshal, which cannot be used here for dependency reasons.
typedef struct { gboolean (*prepare) (GSource *source, gint *timeout_); gboolean (*check) (GSource *source); gboolean (*dispatch) (GSource *source, GSourceFunc callback, gpointer user_data); void (*finalize) (GSource *source); /* Can be NULL */ /* For use by g_source_set_closure */ GSourceFunc closure_callback; GSourceDummyMarshal closure_marshal; /* Really is of type GClosureMarshal */ } GSourceFuncs;
The GSourceFuncs struct contains a table of functions used to handle event sources in a generic manner.
For idle sources, the prepare and check functions always return TRUE
to
indicate that the source is always ready to be processed.
The prepare function also returns a timeout value of 0 to ensure that the
poll()
call doesn't block (since that would be time
wasted which could have been spent running the idle function).
For timeout sources, the prepare and check functions both return TRUE
if the
timeout interval has expired. The prepare function also returns a timeout
value to ensure that the poll()
call doesn't block too
long and miss the next timeout.
For file descriptor sources, the prepare function typically returns FALSE
,
since it must wait until poll()
has been called before
it knows whether any events need to be processed. It sets the returned
timeout to -1 to indicate that it doesn't mind how long the
poll()
call blocks.
In the check function, it tests the results of the poll()
call to see if the required condition has been met, and returns TRUE
if so.
|
Called before all the file descriptors are polled.
If the source can determine that it is ready here (without waiting for the
results of the poll() call) it should return TRUE .
It can also return a timeout_ value which should be the maximum timeout
(in milliseconds) which should be passed to the poll() call.
The actual timeout used will be -1 if all sources returned -1, or it will
be the minimum of all the timeout_ values returned which were >= 0.
|
|
Called after all the file descriptors are polled.
The source should return TRUE if it is ready to be dispatched.
Note that some time may have passed since the previous prepare function was
called, so the source should be checked again here.
|
|
Called to dispatch the event source, after it has returned TRUE in
either its prepare or its check function. The dispatch function is
passed in a callback function and data. The callback function may be
NULL if the source was never connected to a callback using
g_source_set_callback() . The dispatch function should call the
callback function with user_data and whatever additional parameters are
needed for this type of event source.
|
|
Called when the source is finalized. |
GSourceFunc |
|
GSourceDummyMarshal |
typedef struct { void (*ref) (gpointer cb_data); void (*unref) (gpointer cb_data); void (*get) (gpointer cb_data, GSource *source, GSourceFunc *func, gpointer *data); } GSourceCallbackFuncs;
The GSourceCallbackFuncs struct contains functions for managing callback objects.
|
Called when a reference is added to the callback object. |
|
Called when a reference to the callback object is dropped. |
|
Called to extract the callback function and data from the callback object. |
GSource * g_source_new (GSourceFuncs *source_funcs, guint struct_size);
Creates a new GSource structure. The size is specified to
allow creating structures derived from GSource that contain
additional data. The size passed in must be at least
sizeof (GSource)
.
The source will not initially be associated with any GMainContext
and must be added to one with g_source_attach()
before it will be
executed.
GSource * g_source_ref (GSource *source);
Increases the reference count on a source by one.
|
a GSource |
Returns : |
source
|
void g_source_unref (GSource *source);
Decreases the reference count of a source by one. If the resulting reference count is zero the source and associated memory will be destroyed.
|
a GSource |
void g_source_set_funcs (GSource *source, GSourceFuncs *funcs);
Sets the source functions (can be used to override default implementations) of an unattached source.
|
a GSource |
|
the new GSourceFuncs |
Since 2.12
guint g_source_attach (GSource *source, GMainContext *context);
Adds a GSource to a context
so that it will be executed within
that context. Remove it by calling g_source_destroy()
.
|
a GSource |
|
a GMainContext (if NULL , the default context will be used)
|
Returns : |
the ID (greater than 0) for the source within the GMainContext. |
void g_source_destroy (GSource *source);
Removes a source from its GMainContext, if any, and mark it as destroyed. The source cannot be subsequently added to another context.
|
a GSource |
gboolean g_source_is_destroyed (GSource *source);
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 FALSE; } 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; }
Since 2.12
void g_source_set_priority (GSource *source, gint 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 GSource |
|
the new priority. |
gint g_source_get_priority (GSource *source);
Gets the priority of a source.
|
a GSource |
Returns : |
the priority of the source |
void g_source_set_can_recurse (GSource *source, gboolean 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.
|
a GSource |
|
whether recursion is allowed for this source |
gboolean g_source_get_can_recurse (GSource *source);
Checks whether a source is allowed to be called recursively.
see g_source_set_can_recurse()
.
|
a GSource |
Returns : |
whether recursion is allowed. |
guint g_source_get_id (GSource *source);
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()
.
|
a GSource |
Returns : |
the ID (greater than 0) for the source |
GMainContext * g_source_get_context (GSource *source);
Gets the GMainContext with which the source is associated. Calling this function on a destroyed source is an error.
|
a GSource |
Returns : |
the GMainContext with which the source is associated,
or NULL if the context has not yet been added
to a source.
|
void g_source_set_callback (GSource *source, GSourceFunc func, gpointer data, GDestroyNotify 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.
Typically, you won't use this function. Instead use functions specific to the type of source you are using.
|
the source |
|
a callback function |
|
the data to pass to callback function |
|
a function to call when data is no longer in use, or NULL .
|
gboolean (*GSourceFunc) (gpointer data);
Specifies the type of function passed to g_timeout_add()
, g_timeout_add_full()
,
g_idle_add()
, and g_idle_add_full()
.
|
data passed to the function, set when the source was created with one of the above functions. |
Returns : |
it should return FALSE if the source should be removed.
|
void g_source_set_callback_indirect (GSource *source, gpointer callback_data, GSourceCallbackFuncs *callback_funcs);
Sets the callback function storing the data as a refcounted callback
"object". This is used internally. Note that calling
g_source_set_callback_indirect()
assumes
an initial reference count on callback_data
, and thus
callback_funcs->unref
will eventually be called once more
than callback_funcs->ref
.
|
the source |
|
pointer to callback data "object" |
|
functions for reference counting callback_data
and getting the callback and data
|
void g_source_add_poll (GSource *source, GPollFD *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.
void g_source_remove_poll (GSource *source, GPollFD *fd);
Removes a file descriptor from the set of file descriptors polled for this source.
|
a GSource |
|
a GPollFD structure previously passed to g_source_add_poll() .
|
void g_source_get_current_time (GSource *source, GTimeVal *timeval);
Gets the "current time" to be used when checking
this source. The advantage of calling this function over
calling g_get_current_time()
directly is that when
checking multiple sources, GLib can cache a single value
instead of having to repeatedly get the system time.
gboolean g_source_remove (guint tag);
Removes the source with the given id from the 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()
.
See also g_source_destroy()
. You must use g_source_destroy()
for sources
added to a non-default main context.
|
the ID of the source to remove. |
Returns : |
TRUE if the source was found and removed.
|
gboolean g_source_remove_by_funcs_user_data (GSourceFuncs *funcs, gpointer user_data);
Removes a source from the default main loop context given the source functions and user data. If multiple sources exist with the same source functions and user data, only one will be destroyed.
|
The source_funcs passed to g_source_new()
|
|
the user data for the callback |
Returns : |
TRUE if a source was found and removed.
|
gboolean g_source_remove_by_user_data (gpointer 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.
|
the user_data for the callback. |
Returns : |
TRUE if a source was found and removed.
|