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gmain.c
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gmain.c
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/* GLIB - Library of useful routines for C programming
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* gmain.c: Main loop abstraction, timeouts, and idle functions
* Copyright 1998 Owen Taylor
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
/*
* Modified by the GLib Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GLib Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GLib at ftp://ftp.gtk.org/pub/gtk/.
*/
/*
* MT safe
*/
#include "config.h"
#include "glibconfig.h"
#include "glib_trace.h"
/* Uncomment the next line (and the corresponding line in gpoll.c) to
* enable debugging printouts if the environment variable
* G_MAIN_POLL_DEBUG is set to some value.
*/
/* #define G_MAIN_POLL_DEBUG */
#ifdef _WIN32
/* Always enable debugging printout on Windows, as it is more often
* needed there...
*/
#define G_MAIN_POLL_DEBUG
#endif
#ifdef G_OS_UNIX
#include "glib-unix.h"
#include <pthread.h>
#ifdef HAVE_EVENTFD
#include <sys/eventfd.h>
#endif
#endif
#include <signal.h>
#include <sys/types.h>
#include <time.h>
#include <stdlib.h>
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif /* HAVE_SYS_TIME_H */
#ifdef G_OS_UNIX
#include <unistd.h>
#endif /* G_OS_UNIX */
#include <errno.h>
#include <string.h>
#ifdef G_OS_WIN32
#define STRICT
#include <windows.h>
#endif /* G_OS_WIN32 */
#ifdef HAVE_MACH_MACH_TIME_H
#include <mach/mach_time.h>
#endif
#include "glib_trace.h"
#include "gmain.h"
#include "garray.h"
#include "giochannel.h"
#include "ghash.h"
#include "ghook.h"
#include "gqueue.h"
#include "gstrfuncs.h"
#include "gtestutils.h"
#include "gthreadprivate.h"
#ifdef G_OS_WIN32
#include "gwin32.h"
#endif
#ifdef G_MAIN_POLL_DEBUG
#include "gtimer.h"
#endif
#include "gwakeup.h"
#include "gmain-internal.h"
#include "glib-init.h"
#include "glib-private.h"
/**
* SECTION:main
* @title: The Main Event Loop
* @short_description: manages all available sources of events
*
* 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. All
* functions which operate on a #GMainContext or a built-in #GSource are
* thread-safe.
*
* 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().
*
* ## Creating new source types
*
* One of the unusual features of the #GMainLoop 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 type.
*
* 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().
*
* ## Customizing the main loop iteration
*
* 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().
*
* ## State of a Main Context # {#mainloop-states}
*
* The operation of these functions can best be seen in terms
* of a state diagram, as shown in this image.
*
* ![](mainloop-states.gif)
*
* On UNIX, the GLib mainloop is incompatible with fork(). Any program
* using the mainloop must either exec() or exit() from the child
* without returning to the mainloop.
*
* ## Memory management of sources # {#mainloop-memory-management}
*
* There are two options for memory management of the user data passed to a
* #GSource to be passed to its callback on invocation. This data is provided
* in calls to g_timeout_add(), g_timeout_add_full(), g_idle_add(), etc. and
* more generally, using g_source_set_callback(). This data is typically an
* object which ‘owns’ the timeout or idle callback, such as a widget or a
* network protocol implementation. In many cases, it is an error for the
* callback to be invoked after this owning object has been destroyed, as that
* results in use of freed memory.
*
* The first, and preferred, option is to store the source ID returned by
* functions such as g_timeout_add() or g_source_attach(), and explicitly
* remove that source from the main context using g_source_remove() when the
* owning object is finalized. This ensures that the callback can only be
* invoked while the object is still alive.
*
* The second option is to hold a strong reference to the object in the
* callback, and to release it in the callback’s #GDestroyNotify. This ensures
* that the object is kept alive until after the source is finalized, which is
* guaranteed to be after it is invoked for the final time. The #GDestroyNotify
* is another callback passed to the ‘full’ variants of #GSource functions (for
* example, g_timeout_add_full()). It is called when the source is finalized,
* and is designed for releasing references like this.
*
* One important caveat of this second approach is that it will keep the object
* alive indefinitely if the main loop is stopped before the #GSource is
* invoked, which may be undesirable.
*/
/* Types */
typedef struct _GTimeoutSource GTimeoutSource;
typedef struct _GChildWatchSource GChildWatchSource;
typedef struct _GUnixSignalWatchSource GUnixSignalWatchSource;
typedef struct _GPollRec GPollRec;
typedef struct _GSourceCallback GSourceCallback;
typedef enum
{
G_SOURCE_READY = 1 << G_HOOK_FLAG_USER_SHIFT,
G_SOURCE_CAN_RECURSE = 1 << (G_HOOK_FLAG_USER_SHIFT + 1),
G_SOURCE_BLOCKED = 1 << (G_HOOK_FLAG_USER_SHIFT + 2)
} GSourceFlags;
typedef struct _GSourceList GSourceList;
struct _GSourceList
{
GSource *head, *tail;
gint priority;
};
typedef struct _GMainWaiter GMainWaiter;
struct _GMainWaiter
{
GCond *cond;
GMutex *mutex;
};
typedef struct _GMainDispatch GMainDispatch;
struct _GMainDispatch
{
gint depth;
GSource *source;
};
#ifdef G_MAIN_POLL_DEBUG
gboolean _g_main_poll_debug = FALSE;
#endif
struct _GMainContext
{
/* The following lock is used for both the list of sources
* and the list of poll records
*/
GMutex mutex;
GCond cond;
GThread *owner;
guint owner_count;
GSList *waiters;
volatile gint ref_count;
GHashTable *sources; /* guint -> GSource */
GPtrArray *pending_dispatches;
gint timeout; /* Timeout for current iteration */
guint next_id;
GList *source_lists;
gint in_check_or_prepare;
GPollRec *poll_records;
guint n_poll_records;
GPollFD *cached_poll_array;
guint cached_poll_array_size;
GWakeup *wakeup;
GPollFD wake_up_rec;
/* Flag indicating whether the set of fd's changed during a poll */
gboolean poll_changed;
GPollFunc poll_func;
gint64 time;
gboolean time_is_fresh;
};
struct _GSourceCallback
{
volatile gint ref_count;
GSourceFunc func;
gpointer data;
GDestroyNotify notify;
};
struct _GMainLoop
{
GMainContext *context;
gboolean is_running; /* (atomic) */
volatile gint ref_count;
};
struct _GTimeoutSource
{
GSource source;
/* Measured in seconds if 'seconds' is TRUE, or milliseconds otherwise. */
guint interval;
gboolean seconds;
};
struct _GChildWatchSource
{
GSource source;
GPid pid;
gint child_status;
#ifdef G_OS_WIN32
GPollFD poll;
#else /* G_OS_WIN32 */
gboolean child_exited; /* (atomic) */
#endif /* G_OS_WIN32 */
};
struct _GUnixSignalWatchSource
{
GSource source;
int signum;
gboolean pending; /* (atomic) */
};
struct _GPollRec
{
GPollFD *fd;
GPollRec *prev;
GPollRec *next;
gint priority;
};
struct _GSourcePrivate
{
GSList *child_sources;
GSource *parent_source;
gint64 ready_time;
/* This is currently only used on UNIX, but we always declare it (and
* let it remain empty on Windows) to avoid #ifdef all over the place.
*/
GSList *fds;
};
typedef struct _GSourceIter
{
GMainContext *context;
gboolean may_modify;
GList *current_list;
GSource *source;
} GSourceIter;
#define LOCK_CONTEXT(context) g_mutex_lock (&context->mutex)
#define UNLOCK_CONTEXT(context) g_mutex_unlock (&context->mutex)
#define G_THREAD_SELF g_thread_self ()
#define SOURCE_DESTROYED(source) (((source)->flags & G_HOOK_FLAG_ACTIVE) == 0)
#define SOURCE_BLOCKED(source) (((source)->flags & G_SOURCE_BLOCKED) != 0)
/* Forward declarations */
static void g_source_unref_internal (GSource *source,
GMainContext *context,
gboolean have_lock);
static void g_source_destroy_internal (GSource *source,
GMainContext *context,
gboolean have_lock);
static void g_source_set_priority_unlocked (GSource *source,
GMainContext *context,
gint priority);
static void g_child_source_remove_internal (GSource *child_source,
GMainContext *context);
static void g_main_context_poll (GMainContext *context,
gint timeout,
gint priority,
GPollFD *fds,
gint n_fds);
static void g_main_context_add_poll_unlocked (GMainContext *context,
gint priority,
GPollFD *fd);
static void g_main_context_remove_poll_unlocked (GMainContext *context,
GPollFD *fd);
static void g_source_iter_init (GSourceIter *iter,
GMainContext *context,
gboolean may_modify);
static gboolean g_source_iter_next (GSourceIter *iter,
GSource **source);
static void g_source_iter_clear (GSourceIter *iter);
static gboolean g_timeout_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data);
static gboolean g_child_watch_prepare (GSource *source,
gint *timeout);
static gboolean g_child_watch_check (GSource *source);
static gboolean g_child_watch_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data);
static void g_child_watch_finalize (GSource *source);
#ifdef G_OS_UNIX
static void g_unix_signal_handler (int signum);
static gboolean g_unix_signal_watch_prepare (GSource *source,
gint *timeout);
static gboolean g_unix_signal_watch_check (GSource *source);
static gboolean g_unix_signal_watch_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data);
static void g_unix_signal_watch_finalize (GSource *source);
#endif
static gboolean g_idle_prepare (GSource *source,
gint *timeout);
static gboolean g_idle_check (GSource *source);
static gboolean g_idle_dispatch (GSource *source,
GSourceFunc callback,
gpointer user_data);
static void block_source (GSource *source);
static GMainContext *glib_worker_context;
#ifndef G_OS_WIN32
/* UNIX signals work by marking one of these variables then waking the
* worker context to check on them and dispatch accordingly.
*/
#ifdef HAVE_SIG_ATOMIC_T
static volatile sig_atomic_t unix_signal_pending[NSIG];
static volatile sig_atomic_t any_unix_signal_pending;
#else
static volatile int unix_signal_pending[NSIG];
static volatile int any_unix_signal_pending;
#endif
/* Guards all the data below */
G_LOCK_DEFINE_STATIC (unix_signal_lock);
static guint unix_signal_refcount[NSIG];
static GSList *unix_signal_watches;
static GSList *unix_child_watches;
GSourceFuncs g_unix_signal_funcs =
{
g_unix_signal_watch_prepare,
g_unix_signal_watch_check,
g_unix_signal_watch_dispatch,
g_unix_signal_watch_finalize,
NULL, NULL
};
#endif /* !G_OS_WIN32 */
G_LOCK_DEFINE_STATIC (main_context_list);
static GSList *main_context_list = NULL;
GSourceFuncs g_timeout_funcs =
{
NULL, /* prepare */
NULL, /* check */
g_timeout_dispatch,
NULL, NULL, NULL
};
GSourceFuncs g_child_watch_funcs =
{
g_child_watch_prepare,
g_child_watch_check,
g_child_watch_dispatch,
g_child_watch_finalize,
NULL, NULL
};
GSourceFuncs g_idle_funcs =
{
g_idle_prepare,
g_idle_check,
g_idle_dispatch,
NULL, NULL, NULL
};
/**
* g_main_context_ref:
* @context: a #GMainContext
*
* Increases the reference count on a #GMainContext object by one.
*
* Returns: the @context that was passed in (since 2.6)
**/
GMainContext *
g_main_context_ref (GMainContext *context)
{
g_return_val_if_fail (context != NULL, NULL);
g_return_val_if_fail (g_atomic_int_get (&context->ref_count) > 0, NULL);
g_atomic_int_inc (&context->ref_count);
return context;
}
static inline void
poll_rec_list_free (GMainContext *context,
GPollRec *list)
{
g_slice_free_chain (GPollRec, list, next);
}
/**
* g_main_context_unref:
* @context: a #GMainContext
*
* Decreases the reference count on a #GMainContext object by one. If
* the result is zero, free the context and free all associated memory.
**/
void
g_main_context_unref (GMainContext *context)
{
GSourceIter iter;
GSource *source;
GList *sl_iter;
GSourceList *list;
guint i;
g_return_if_fail (context != NULL);
g_return_if_fail (g_atomic_int_get (&context->ref_count) > 0);
if (!g_atomic_int_dec_and_test (&context->ref_count))
return;
G_LOCK (main_context_list);
main_context_list = g_slist_remove (main_context_list, context);
G_UNLOCK (main_context_list);
/* Free pending dispatches */
for (i = 0; i < context->pending_dispatches->len; i++)
g_source_unref_internal (context->pending_dispatches->pdata[i], context, FALSE);
/* g_source_iter_next() assumes the context is locked. */
LOCK_CONTEXT (context);
g_source_iter_init (&iter, context, TRUE);
while (g_source_iter_next (&iter, &source))
{
source->context = NULL;
g_source_destroy_internal (source, context, TRUE);
}
UNLOCK_CONTEXT (context);
for (sl_iter = context->source_lists; sl_iter; sl_iter = sl_iter->next)
{
list = sl_iter->data;
g_slice_free (GSourceList, list);
}
g_list_free (context->source_lists);
g_hash_table_destroy (context->sources);
g_mutex_clear (&context->mutex);
g_ptr_array_free (context->pending_dispatches, TRUE);
g_free (context->cached_poll_array);
poll_rec_list_free (context, context->poll_records);
g_wakeup_free (context->wakeup);
g_cond_clear (&context->cond);
g_free (context);
}
/* Helper function used by mainloop/overflow test.
*/
GMainContext *
g_main_context_new_with_next_id (guint next_id)
{
GMainContext *ret = g_main_context_new ();
ret->next_id = next_id;
return ret;
}
/**
* g_main_context_new:
*
* Creates a new #GMainContext structure.
*
* Returns: the new #GMainContext
**/
GMainContext *
g_main_context_new (void)
{
static gsize initialised;
GMainContext *context;
if (g_once_init_enter (&initialised))
{
#ifdef G_MAIN_POLL_DEBUG
if (getenv ("G_MAIN_POLL_DEBUG") != NULL)
_g_main_poll_debug = TRUE;
#endif
g_once_init_leave (&initialised, TRUE);
}
context = g_new0 (GMainContext, 1);
TRACE (GLIB_MAIN_CONTEXT_NEW (context));
g_mutex_init (&context->mutex);
g_cond_init (&context->cond);
context->sources = g_hash_table_new (NULL, NULL);
context->owner = NULL;
context->waiters = NULL;
context->ref_count = 1;
context->next_id = 1;
context->source_lists = NULL;
context->poll_func = g_poll;
context->cached_poll_array = NULL;
context->cached_poll_array_size = 0;
context->pending_dispatches = g_ptr_array_new ();
context->time_is_fresh = FALSE;
context->wakeup = g_wakeup_new ();
g_wakeup_get_pollfd (context->wakeup, &context->wake_up_rec);
g_main_context_add_poll_unlocked (context, 0, &context->wake_up_rec);
G_LOCK (main_context_list);
main_context_list = g_slist_append (main_context_list, context);
#ifdef G_MAIN_POLL_DEBUG
if (_g_main_poll_debug)
g_print ("created context=%p\n", context);
#endif
G_UNLOCK (main_context_list);
return context;
}
/**
* g_main_context_default:
*
* Returns the global default main context. This is the main context
* used for main loop functions when a main loop is not explicitly
* specified, and corresponds to the "main" main loop. See also
* g_main_context_get_thread_default().
*
* Returns: (transfer none): the global default main context.
**/
GMainContext *
g_main_context_default (void)
{
static GMainContext *default_main_context = NULL;
if (g_once_init_enter (&default_main_context))
{
GMainContext *context;
context = g_main_context_new ();
TRACE (GLIB_MAIN_CONTEXT_DEFAULT (context));
#ifdef G_MAIN_POLL_DEBUG
if (_g_main_poll_debug)
g_print ("default context=%p\n", context);
#endif
g_once_init_leave (&default_main_context, context);
}
return default_main_context;
}
static void
free_context (gpointer data)
{
GMainContext *context = data;
TRACE (GLIB_MAIN_CONTEXT_FREE (context));
g_main_context_release (context);
if (context)
g_main_context_unref (context);
}
static void
free_context_stack (gpointer data)
{
g_queue_free_full((GQueue *) data, (GDestroyNotify) free_context);
}
static GPrivate thread_context_stack = G_PRIVATE_INIT (free_context_stack);
/**
* g_main_context_push_thread_default:
* @context: (nullable): a #GMainContext, or %NULL for the global default context
*
* Acquires @context and sets it as the thread-default context for the
* current thread. This will cause certain asynchronous operations
* (such as most [gio][gio]-based I/O) which are
* started in this thread to run under @context and deliver their
* results to its main loop, rather than running under the global
* default context in the main thread. Note that calling this function
* changes the context returned by g_main_context_get_thread_default(),
* not the one returned by g_main_context_default(), so it does not affect
* the context used by functions like g_idle_add().
*
* Normally you would call this function shortly after creating a new
* thread, passing it a #GMainContext which will be run by a
* #GMainLoop in that thread, to set a new default context for all
* async operations in that thread. In this case you may not need to
* ever call g_main_context_pop_thread_default(), assuming you want the
* new #GMainContext to be the default for the whole lifecycle of the
* thread.
*
* If you don't have control over how the new thread was created (e.g.
* in the new thread isn't newly created, or if the thread life
* cycle is managed by a #GThreadPool), it is always suggested to wrap
* the logic that needs to use the new #GMainContext inside a
* g_main_context_push_thread_default() / g_main_context_pop_thread_default()
* pair, otherwise threads that are re-used will end up never explicitly
* releasing the #GMainContext reference they hold.
*
* In some cases you may want to schedule a single operation in a
* non-default context, or temporarily use a non-default context in
* the main thread. In that case, you can wrap the call to the
* asynchronous operation inside a
* g_main_context_push_thread_default() /
* g_main_context_pop_thread_default() pair, but it is up to you to
* ensure that no other asynchronous operations accidentally get
* started while the non-default context is active.
*
* Beware that libraries that predate this function may not correctly
* handle being used from a thread with a thread-default context. Eg,
* see g_file_supports_thread_contexts().
*
* Since: 2.22
**/
void
g_main_context_push_thread_default (GMainContext *context)
{
GQueue *stack;
gboolean acquired_context;
acquired_context = g_main_context_acquire (context);
g_return_if_fail (acquired_context);
if (context == g_main_context_default ())
context = NULL;
else if (context)
g_main_context_ref (context);
stack = g_private_get (&thread_context_stack);
if (!stack)
{
stack = g_queue_new ();
g_private_set (&thread_context_stack, stack);
}
g_queue_push_head (stack, context);
TRACE (GLIB_MAIN_CONTEXT_PUSH_THREAD_DEFAULT (context));
}
/**
* g_main_context_pop_thread_default:
* @context: (nullable): a #GMainContext object, or %NULL
*
* Pops @context off the thread-default context stack (verifying that
* it was on the top of the stack).
*
* Since: 2.22
**/
void
g_main_context_pop_thread_default (GMainContext *context)
{
GQueue *stack;
if (context == g_main_context_default ())
context = NULL;
stack = g_private_get (&thread_context_stack);
g_return_if_fail (stack != NULL);
g_return_if_fail (g_queue_peek_head (stack) == context);
TRACE (GLIB_MAIN_CONTEXT_POP_THREAD_DEFAULT (context));
g_queue_pop_head (stack);
g_main_context_release (context);
if (context)
g_main_context_unref (context);
}
/**
* g_main_context_get_thread_default:
*
* Gets the thread-default #GMainContext for this thread. Asynchronous
* operations that want to be able to be run in contexts other than
* the default one should call this method or
* g_main_context_ref_thread_default() to get a #GMainContext to add
* their #GSources to. (Note that even in single-threaded
* programs applications may sometimes want to temporarily push a
* non-default context, so it is not safe to assume that this will
* always return %NULL if you are running in the default thread.)
*
* If you need to hold a reference on the context, use
* g_main_context_ref_thread_default() instead.
*
* Returns: (transfer none): the thread-default #GMainContext, or
* %NULL if the thread-default context is the global default context.
*
* Since: 2.22
**/
GMainContext *
g_main_context_get_thread_default (void)
{
GQueue *stack;
stack = g_private_get (&thread_context_stack);
if (stack)
return g_queue_peek_head (stack);
else
return NULL;
}
/**
* g_main_context_ref_thread_default:
*
* Gets the thread-default #GMainContext for this thread, as with
* g_main_context_get_thread_default(), but also adds a reference to
* it with g_main_context_ref(). In addition, unlike
* g_main_context_get_thread_default(), if the thread-default context
* is the global default context, this will return that #GMainContext
* (with a ref added to it) rather than returning %NULL.
*
* Returns: (transfer full): the thread-default #GMainContext. Unref
* with g_main_context_unref() when you are done with it.
*
* Since: 2.32
*/
GMainContext *
g_main_context_ref_thread_default (void)
{
GMainContext *context;
context = g_main_context_get_thread_default ();
if (!context)
context = g_main_context_default ();
return g_main_context_ref (context);
}
/* Hooks for adding to the main loop */
/**
* g_source_new:
* @source_funcs: structure containing functions that implement
* the sources behavior.
* @struct_size: size of the #GSource structure to create.
*
* 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.
*
* Returns: the newly-created #GSource.
**/
GSource *
g_source_new (GSourceFuncs *source_funcs,
guint struct_size)
{
GSource *source;
g_return_val_if_fail (source_funcs != NULL, NULL);
g_return_val_if_fail (struct_size >= sizeof (GSource), NULL);
source = (GSource*) g_malloc0 (struct_size);
source->priv = g_slice_new0 (GSourcePrivate);
source->source_funcs = source_funcs;
source->ref_count = 1;
source->priority = G_PRIORITY_DEFAULT;
source->flags = G_HOOK_FLAG_ACTIVE;
source->priv->ready_time = -1;
/* NULL/0 initialization for all other fields */
TRACE (GLIB_SOURCE_NEW (source, source_funcs->prepare, source_funcs->check,
source_funcs->dispatch, source_funcs->finalize,
struct_size));
return source;
}
/* Holds context's lock */
static void
g_source_iter_init (GSourceIter *iter,
GMainContext *context,
gboolean may_modify)
{
iter->context = context;
iter->current_list = NULL;
iter->source = NULL;
iter->may_modify = may_modify;
}
/* Holds context's lock */
static gboolean
g_source_iter_next (GSourceIter *iter, GSource **source)
{
GSource *next_source;
if (iter->source)
next_source = iter->source->next;
else
next_source = NULL;
if (!next_source)
{
if (iter->current_list)
iter->current_list = iter->current_list->next;
else
iter->current_list = iter->context->source_lists;
if (iter->current_list)
{
GSourceList *source_list = iter->current_list->data;
next_source = source_list->head;
}
}
/* Note: unreffing iter->source could potentially cause its
* GSourceList to be removed from source_lists (if iter->source is
* the only source in its list, and it is destroyed), so we have to
* keep it reffed until after we advance iter->current_list, above.
*/
if (iter->source && iter->may_modify)
g_source_unref_internal (iter->source, iter->context, TRUE);
iter->source = next_source;
if (iter->source && iter->may_modify)
g_source_ref (iter->source);
*source = iter->source;
return *source != NULL;
}
/* Holds context's lock. Only necessary to call if you broke out of
* the g_source_iter_next() loop early.
*/
static void
g_source_iter_clear (GSourceIter *iter)
{
if (iter->source && iter->may_modify)
{
g_source_unref_internal (iter->source, iter->context, TRUE);
iter->source = NULL;
}
}
/* Holds context's lock
*/
static GSourceList *
find_source_list_for_priority (GMainContext *context,
gint priority,