/* GObject - GLib Type, Object, Parameter and Signal Library * * Copyright (C) 2015-2022 Christian Hergert * Copyright (C) 2015 Garrett Regier * * 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 . * * SPDX-License-Identifier: LGPL-2.1-or-later */ #include "config.h" #include "glib.h" #include "glibintl.h" #include "gparamspecs.h" #include "gsignalgroup.h" #include "gvaluetypes.h" /** * SECTION:gsignalgroup * @Title: GSignalGroup * @Short_description: Manage a collection of signals on a GObject * * #GSignalGroup manages to simplify the process of connecting * many signals to a #GObject as a group. As such there is no API * to disconnect a signal from the group. * * In particular, this allows you to: * * - Change the target instance, which automatically causes disconnection * of the signals from the old instance and connecting to the new instance. * - Block and unblock signals as a group * - Ensuring that blocked state transfers across target instances. * * One place you might want to use such a structure is with #GtkTextView and * #GtkTextBuffer. Often times, you'll need to connect to many signals on * #GtkTextBuffer from a #GtkTextView subclass. This allows you to create a * signal group during instance construction, simply bind the * #GtkTextView:buffer property to #GSignalGroup:target and connect * all the signals you need. When the #GtkTextView:buffer property changes * all of the signals will be transitioned correctly. * * Since: 2.72 */ struct _GSignalGroup { GObject parent_instance; GWeakRef target_ref; GRecMutex mutex; GPtrArray *handlers; GType target_type; gssize block_count; guint has_bound_at_least_once : 1; }; typedef struct _GSignalGroupClass { GObjectClass parent_class; void (*bind) (GSignalGroup *self, GObject *target); } GSignalGroupClass; typedef struct { GSignalGroup *group; gulong handler_id; GClosure *closure; guint signal_id; GQuark signal_detail; guint connect_after : 1; } SignalHandler; G_DEFINE_TYPE (GSignalGroup, g_signal_group, G_TYPE_OBJECT) typedef enum { PROP_TARGET = 1, PROP_TARGET_TYPE, LAST_PROP } GSignalGroupProperty; enum { BIND, UNBIND, LAST_SIGNAL }; static GParamSpec *properties[LAST_PROP]; static guint signals[LAST_SIGNAL]; static void g_signal_group_set_target_type (GSignalGroup *self, GType target_type) { g_assert (G_IS_SIGNAL_GROUP (self)); g_assert (g_type_is_a (target_type, G_TYPE_OBJECT)); self->target_type = target_type; /* The class must be created at least once for the signals * to be registered, otherwise g_signal_parse_name() will fail */ if (G_TYPE_IS_INTERFACE (target_type)) { if (g_type_default_interface_peek (target_type) == NULL) g_type_default_interface_unref (g_type_default_interface_ref (target_type)); } else { if (g_type_class_peek (target_type) == NULL) g_type_class_unref (g_type_class_ref (target_type)); } } static void g_signal_group_gc_handlers (GSignalGroup *self) { guint i; g_assert (G_IS_SIGNAL_GROUP (self)); /* * Remove any handlers for which the closures have become invalid. We do * this cleanup lazily to avoid situations where we could have disposal * active on both the signal group and the peer object. */ for (i = self->handlers->len; i > 0; i--) { const SignalHandler *handler = g_ptr_array_index (self->handlers, i - 1); g_assert (handler != NULL); g_assert (handler->closure != NULL); if (handler->closure->is_invalid) g_ptr_array_remove_index (self->handlers, i - 1); } } static void g_signal_group__target_weak_notify (gpointer data, GObject *where_object_was) { GSignalGroup *self = data; guint i; g_assert (G_IS_SIGNAL_GROUP (self)); g_assert (where_object_was != NULL); g_rec_mutex_lock (&self->mutex); g_weak_ref_set (&self->target_ref, NULL); for (i = 0; i < self->handlers->len; i++) { SignalHandler *handler = g_ptr_array_index (self->handlers, i); handler->handler_id = 0; } g_signal_emit (self, signals[UNBIND], 0); g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TARGET]); g_rec_mutex_unlock (&self->mutex); } static void g_signal_group_bind_handler (GSignalGroup *self, SignalHandler *handler, GObject *target) { gssize i; g_assert (self != NULL); g_assert (G_IS_OBJECT (target)); g_assert (handler != NULL); g_assert (handler->signal_id != 0); g_assert (handler->closure != NULL); g_assert (handler->closure->is_invalid == 0); g_assert (handler->handler_id == 0); handler->handler_id = g_signal_connect_closure_by_id (target, handler->signal_id, handler->signal_detail, handler->closure, handler->connect_after); g_assert (handler->handler_id != 0); for (i = 0; i < self->block_count; i++) g_signal_handler_block (target, handler->handler_id); } static void g_signal_group_bind (GSignalGroup *self, GObject *target) { GObject *hold; guint i; g_assert (G_IS_SIGNAL_GROUP (self)); g_assert (!target || G_IS_OBJECT (target)); if (target == NULL) return; self->has_bound_at_least_once = TRUE; hold = g_object_ref (target); g_weak_ref_set (&self->target_ref, hold); g_object_weak_ref (hold, g_signal_group__target_weak_notify, self); g_signal_group_gc_handlers (self); for (i = 0; i < self->handlers->len; i++) { SignalHandler *handler = g_ptr_array_index (self->handlers, i); g_signal_group_bind_handler (self, handler, hold); } g_signal_emit (self, signals [BIND], 0, hold); g_object_unref (hold); } static void g_signal_group_unbind (GSignalGroup *self) { GObject *target; guint i; g_return_if_fail (G_IS_SIGNAL_GROUP (self)); target = g_weak_ref_get (&self->target_ref); /* * Target may be NULL by this point, as we got notified of its destruction. * However, if we're early enough, we may get a full reference back and can * cleanly disconnect our connections. */ if (target != NULL) { g_weak_ref_set (&self->target_ref, NULL); /* * Let go of our weak reference now that we have a full reference * for the life of this function. */ g_object_weak_unref (target, g_signal_group__target_weak_notify, self); } g_signal_group_gc_handlers (self); for (i = 0; i < self->handlers->len; i++) { SignalHandler *handler; gulong handler_id; handler = g_ptr_array_index (self->handlers, i); g_assert (handler != NULL); g_assert (handler->signal_id != 0); g_assert (handler->closure != NULL); handler_id = handler->handler_id; handler->handler_id = 0; /* * If @target is NULL, we lost a race to cleanup the weak * instance and the signal connections have already been * finalized and therefore nothing to do. */ if (target != NULL && handler_id != 0) g_signal_handler_disconnect (target, handler_id); } g_signal_emit (self, signals [UNBIND], 0); g_clear_object (&target); } static gboolean g_signal_group_check_target_type (GSignalGroup *self, gpointer target) { if ((target != NULL) && !g_type_is_a (G_OBJECT_TYPE (target), self->target_type)) { g_critical ("Failed to set GSignalGroup of target type %s " "using target %p of type %s", g_type_name (self->target_type), target, G_OBJECT_TYPE_NAME (target)); return FALSE; } return TRUE; } /** * g_signal_group_block: * @self: the #GSignalGroup * * Blocks all signal handlers managed by @self so they will not * be called during any signal emissions. Must be unblocked exactly * the same number of times it has been blocked to become active again. * * This blocked state will be kept across changes of the target instance. * * Since: 2.72 */ void g_signal_group_block (GSignalGroup *self) { GObject *target; guint i; g_return_if_fail (G_IS_SIGNAL_GROUP (self)); g_return_if_fail (self->block_count >= 0); g_rec_mutex_lock (&self->mutex); self->block_count++; target = g_weak_ref_get (&self->target_ref); if (target == NULL) goto unlock; for (i = 0; i < self->handlers->len; i++) { const SignalHandler *handler = g_ptr_array_index (self->handlers, i); g_assert (handler != NULL); g_assert (handler->signal_id != 0); g_assert (handler->closure != NULL); g_assert (handler->handler_id != 0); g_signal_handler_block (target, handler->handler_id); } g_object_unref (target); unlock: g_rec_mutex_unlock (&self->mutex); } /** * g_signal_group_unblock: * @self: the #GSignalGroup * * Unblocks all signal handlers managed by @self so they will be * called again during any signal emissions unless it is blocked * again. Must be unblocked exactly the same number of times it * has been blocked to become active again. * * Since: 2.72 */ void g_signal_group_unblock (GSignalGroup *self) { GObject *target; guint i; g_return_if_fail (G_IS_SIGNAL_GROUP (self)); g_return_if_fail (self->block_count > 0); g_rec_mutex_lock (&self->mutex); self->block_count--; target = g_weak_ref_get (&self->target_ref); if (target == NULL) goto unlock; for (i = 0; i < self->handlers->len; i++) { const SignalHandler *handler = g_ptr_array_index (self->handlers, i); g_assert (handler != NULL); g_assert (handler->signal_id != 0); g_assert (handler->closure != NULL); g_assert (handler->handler_id != 0); g_signal_handler_unblock (target, handler->handler_id); } g_object_unref (target); unlock: g_rec_mutex_unlock (&self->mutex); } /** * g_signal_group_dup_target: * @self: the #GSignalGroup * * Gets the target instance used when connecting signals. * * Returns: (nullable) (transfer full) (type GObject): The target instance * * Since: 2.72 */ gpointer g_signal_group_dup_target (GSignalGroup *self) { GObject *target; g_return_val_if_fail (G_IS_SIGNAL_GROUP (self), NULL); g_rec_mutex_lock (&self->mutex); target = g_weak_ref_get (&self->target_ref); g_rec_mutex_unlock (&self->mutex); return target; } /** * g_signal_group_set_target: * @self: the #GSignalGroup. * @target: (nullable) (type GObject) (transfer none): The target instance used * when connecting signals. * * Sets the target instance used when connecting signals. Any signal * that has been registered with g_signal_group_connect_object() or * similar functions will be connected to this object. * * If the target instance was previously set, signals will be * disconnected from that object prior to connecting to @target. * * Since: 2.72 */ void g_signal_group_set_target (GSignalGroup *self, gpointer target) { GObject *object; g_return_if_fail (G_IS_SIGNAL_GROUP (self)); g_rec_mutex_lock (&self->mutex); object = g_weak_ref_get (&self->target_ref); if (object == (GObject *)target) goto cleanup; if (!g_signal_group_check_target_type (self, target)) goto cleanup; /* Only emit unbind if we've ever called bind */ if (self->has_bound_at_least_once) g_signal_group_unbind (self); g_signal_group_bind (self, target); g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_TARGET]); cleanup: g_clear_object (&object); g_rec_mutex_unlock (&self->mutex); } static void signal_handler_free (gpointer data) { SignalHandler *handler = data; if (handler->closure != NULL) g_closure_invalidate (handler->closure); handler->handler_id = 0; handler->signal_id = 0; handler->signal_detail = 0; g_clear_pointer (&handler->closure, g_closure_unref); g_slice_free (SignalHandler, handler); } static void g_signal_group_constructed (GObject *object) { GSignalGroup *self = (GSignalGroup *)object; GObject *target; g_rec_mutex_lock (&self->mutex); target = g_weak_ref_get (&self->target_ref); if (!g_signal_group_check_target_type (self, target)) g_signal_group_set_target (self, NULL); G_OBJECT_CLASS (g_signal_group_parent_class)->constructed (object); g_clear_object (&target); g_rec_mutex_unlock (&self->mutex); } static void g_signal_group_dispose (GObject *object) { GSignalGroup *self = (GSignalGroup *)object; g_rec_mutex_lock (&self->mutex); g_signal_group_gc_handlers (self); if (self->has_bound_at_least_once) g_signal_group_unbind (self); g_clear_pointer (&self->handlers, g_ptr_array_unref); g_rec_mutex_unlock (&self->mutex); G_OBJECT_CLASS (g_signal_group_parent_class)->dispose (object); } static void g_signal_group_finalize (GObject *object) { GSignalGroup *self = (GSignalGroup *)object; g_weak_ref_clear (&self->target_ref); g_rec_mutex_clear (&self->mutex); G_OBJECT_CLASS (g_signal_group_parent_class)->finalize (object); } static void g_signal_group_get_property (GObject *object, guint prop_id, GValue *value, GParamSpec *pspec) { GSignalGroup *self = G_SIGNAL_GROUP (object); switch ((GSignalGroupProperty) prop_id) { case PROP_TARGET: g_value_take_object (value, g_signal_group_dup_target (self)); break; case PROP_TARGET_TYPE: g_value_set_gtype (value, self->target_type); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); } } static void g_signal_group_set_property (GObject *object, guint prop_id, const GValue *value, GParamSpec *pspec) { GSignalGroup *self = G_SIGNAL_GROUP (object); switch ((GSignalGroupProperty) prop_id) { case PROP_TARGET: g_signal_group_set_target (self, g_value_get_object (value)); break; case PROP_TARGET_TYPE: g_signal_group_set_target_type (self, g_value_get_gtype (value)); break; default: G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec); } } static void g_signal_group_class_init (GSignalGroupClass *klass) { GObjectClass *object_class = G_OBJECT_CLASS (klass); object_class->constructed = g_signal_group_constructed; object_class->dispose = g_signal_group_dispose; object_class->finalize = g_signal_group_finalize; object_class->get_property = g_signal_group_get_property; object_class->set_property = g_signal_group_set_property; /** * GSignalGroup:target * * The target instance used when connecting signals. * * Since: 2.72 */ properties[PROP_TARGET] = g_param_spec_object ("target", "Target", "The target instance used when connecting signals.", G_TYPE_OBJECT, (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS)); /** * GSignalGroup:target-type * * The #GType of the target property. * * Since: 2.72 */ properties[PROP_TARGET_TYPE] = g_param_spec_gtype ("target-type", "Target Type", "The GType of the target property.", G_TYPE_OBJECT, (G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS)); g_object_class_install_properties (object_class, LAST_PROP, properties); /** * GSignalGroup::bind: * @self: the #GSignalGroup * @instance: a #GObject containing the new value for #GSignalGroup:target * * This signal is emitted when #GSignalGroup:target is set to a new value * other than %NULL. It is similar to #GObject::notify on `target` except it * will not emit when #GSignalGroup:target is %NULL and also allows for * receiving the #GObject without a data-race. * * Since: 2.72 */ signals[BIND] = g_signal_new ("bind", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL, G_TYPE_NONE, 1, G_TYPE_OBJECT); /** * GSignalGroup::unbind: * @self: a #GSignalGroup * * This signal is emitted when the target instance of @self is set to a * new #GObject. * * This signal will only be emitted if the previous target of @self is * non-%NULL. * * Since: 2.72 */ signals[UNBIND] = g_signal_new ("unbind", G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL, G_TYPE_NONE, 0); } static void g_signal_group_init (GSignalGroup *self) { g_rec_mutex_init (&self->mutex); self->handlers = g_ptr_array_new_with_free_func (signal_handler_free); self->target_type = G_TYPE_OBJECT; } /** * g_signal_group_new: * @target_type: the #GType of the target instance. * * Creates a new #GSignalGroup for target instances of @target_type. * * Returns: (transfer full): a new #GSignalGroup * * Since: 2.72 */ GSignalGroup * g_signal_group_new (GType target_type) { g_return_val_if_fail (g_type_is_a (target_type, G_TYPE_OBJECT), NULL); return g_object_new (G_TYPE_SIGNAL_GROUP, "target-type", target_type, NULL); } /** * g_signal_group_connect_closure: * @self: a #GSignalGroup * @detailed_signal: a string of the form `signal-name` with optional `::signal-detail` * @closure: (not nullable): the closure to connect. * @after: whether the handler should be called before or after the * default handler of the signal. * * Connects @closure to the signal @detailed_signal on #GSignalGroup:target. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.74 */ void g_signal_group_connect_closure (GSignalGroup *self, const gchar *detailed_signal, GClosure *closure, gboolean after) { GObject *target; SignalHandler *handler; guint signal_id; GQuark signal_detail; g_return_if_fail (G_IS_SIGNAL_GROUP (self)); g_return_if_fail (detailed_signal != NULL); g_return_if_fail (g_signal_parse_name (detailed_signal, self->target_type, &signal_id, &signal_detail, TRUE) != 0); g_return_if_fail (closure != NULL); g_rec_mutex_lock (&self->mutex); if (self->has_bound_at_least_once) { g_critical ("Cannot add signals after setting target"); g_rec_mutex_unlock (&self->mutex); return; } handler = g_slice_new0 (SignalHandler); handler->group = self; handler->signal_id = signal_id; handler->signal_detail = signal_detail; handler->closure = g_closure_ref (closure); handler->connect_after = after; g_closure_sink (closure); g_ptr_array_add (self->handlers, handler); target = g_weak_ref_get (&self->target_ref); if (target != NULL) { g_signal_group_bind_handler (self, handler, target); g_object_unref (target); } /* Lazily remove any old handlers on connect */ g_signal_group_gc_handlers (self); g_rec_mutex_unlock (&self->mutex); } static void g_signal_group_connect_full (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer data, GClosureNotify notify, GConnectFlags flags, gboolean is_object) { GClosure *closure; g_return_if_fail (c_handler != NULL); g_return_if_fail (!is_object || G_IS_OBJECT (data)); if ((flags & G_CONNECT_SWAPPED) != 0) closure = g_cclosure_new_swap (c_handler, data, notify); else closure = g_cclosure_new (c_handler, data, notify); if (is_object) { /* Set closure->is_invalid when data is disposed. We only track this to avoid * reconnecting in the future. However, we do a round of cleanup when ever we * connect a new object or the target changes to GC the old handlers. */ g_object_watch_closure (data, closure); } g_signal_group_connect_closure (self, detailed_signal, closure, (flags & G_CONNECT_AFTER) != 0); } /** * g_signal_group_connect_object: (skip) * @self: a #GSignalGroup * @detailed_signal: a string of the form `signal-name` with optional `::signal-detail` * @c_handler: (scope notified): the #GCallback to connect * @object: (not nullable) (transfer none): the #GObject to pass as data to @c_handler calls * @flags: #GConnectFlags for the signal connection * * Connects @c_handler to the signal @detailed_signal on #GSignalGroup:target. * * Ensures that the @object stays alive during the call to @c_handler * by temporarily adding a reference count. When the @object is destroyed * the signal handler will automatically be removed. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.72 */ void g_signal_group_connect_object (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer object, GConnectFlags flags) { g_return_if_fail (G_IS_OBJECT (object)); g_signal_group_connect_full (self, detailed_signal, c_handler, object, NULL, flags, TRUE); } /** * g_signal_group_connect_data: * @self: a #GSignalGroup * @detailed_signal: a string of the form "signal-name::detail" * @c_handler: (scope notified) (closure data) (destroy notify): the #GCallback to connect * @data: the data to pass to @c_handler calls * @notify: function to be called when disposing of @self * @flags: the flags used to create the signal connection * * Connects @c_handler to the signal @detailed_signal * on the target instance of @self. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.72 */ void g_signal_group_connect_data (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer data, GClosureNotify notify, GConnectFlags flags) { g_signal_group_connect_full (self, detailed_signal, c_handler, data, notify, flags, FALSE); } /** * g_signal_group_connect: (skip) * @self: a #GSignalGroup * @detailed_signal: a string of the form "signal-name::detail" * @c_handler: (scope notified): the #GCallback to connect * @data: the data to pass to @c_handler calls * * Connects @c_handler to the signal @detailed_signal * on the target instance of @self. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.72 */ void g_signal_group_connect (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer data) { g_signal_group_connect_full (self, detailed_signal, c_handler, data, NULL, 0, FALSE); } /** * g_signal_group_connect_after: (skip) * @self: a #GSignalGroup * @detailed_signal: a string of the form "signal-name::detail" * @c_handler: (scope notified): the #GCallback to connect * @data: the data to pass to @c_handler calls * * Connects @c_handler to the signal @detailed_signal * on the target instance of @self. * * The @c_handler will be called after the default handler of the signal. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.72 */ void g_signal_group_connect_after (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer data) { g_signal_group_connect_full (self, detailed_signal, c_handler, data, NULL, G_CONNECT_AFTER, FALSE); } /** * g_signal_group_connect_swapped: * @self: a #GSignalGroup * @detailed_signal: a string of the form "signal-name::detail" * @c_handler: (scope async): the #GCallback to connect * @data: the data to pass to @c_handler calls * * Connects @c_handler to the signal @detailed_signal * on the target instance of @self. * * The instance on which the signal is emitted and @data * will be swapped when calling @c_handler. * * You cannot connect a signal handler after #GSignalGroup:target has been set. * * Since: 2.72 */ void g_signal_group_connect_swapped (GSignalGroup *self, const gchar *detailed_signal, GCallback c_handler, gpointer data) { g_signal_group_connect_full (self, detailed_signal, c_handler, data, NULL, G_CONNECT_SWAPPED, FALSE); }