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Diffstat (limited to 'shell/cc-object-storage.c')
| -rw-r--r-- | shell/cc-object-storage.c | 444 |
1 files changed, 444 insertions, 0 deletions
diff --git a/shell/cc-object-storage.c b/shell/cc-object-storage.c new file mode 100644 index 0000000..f52ba59 --- /dev/null +++ b/shell/cc-object-storage.c @@ -0,0 +1,444 @@ +/* cc-object-storage.h + * + * Copyright 2018 Georges Basile Stavracas Neto <georges.stavracas@gmail.com> + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ + +#define G_LOG_DOMAIN "cc-object-storage" + +#include "cc-object-storage.h" + +struct _CcObjectStorage +{ + GObject parent_instance; + + GHashTable *id_to_object; +}; + +G_DEFINE_TYPE (CcObjectStorage, cc_object_storage, G_TYPE_OBJECT) + +/* Singleton instance */ +static CcObjectStorage *_instance = NULL; + +/* GTask API to create a new D-Bus proxy */ +typedef struct +{ + GBusType bus_type; + GDBusProxyFlags flags; + gchar *name; + gchar *path; + gchar *interface; + gboolean cached; +} TaskData; + +static TaskData* +task_data_new (GBusType bus_type, + GDBusProxyFlags flags, + const gchar *name, + const gchar *path, + const gchar *interface) +{ + TaskData *data = g_slice_new (TaskData); + data->bus_type = bus_type; + data->flags =flags; + data->name = g_strdup (name); + data->path = g_strdup (path); + data->interface = g_strdup (interface); + data->cached = FALSE; + + return data; +} + +static void +task_data_free (TaskData *data) +{ + g_free (data->name); + g_free (data->path); + g_free (data->interface); + g_slice_free (TaskData, data); +} + +static void +create_dbus_proxy_in_thread_cb (GTask *task, + gpointer source_object, + gpointer task_data, + GCancellable *cancellable) +{ + g_autoptr(GDBusProxy) proxy = NULL; + g_autoptr(GError) local_error = NULL; + TaskData *data = task_data; + + proxy = g_dbus_proxy_new_for_bus_sync (data->bus_type, + data->flags, + NULL, + data->name, + data->path, + data->interface, + cancellable, + &local_error); + + if (local_error) + { + g_task_return_error (task, local_error); + return; + } + + g_task_return_pointer (task, g_object_ref (g_steal_pointer (&proxy)), g_object_unref); +} + +static void +cc_object_storage_finalize (GObject *object) +{ + CcObjectStorage *self = (CcObjectStorage *)object; + + g_debug ("Destroying cached objects"); + + g_clear_pointer (&self->id_to_object, g_hash_table_destroy); + + G_OBJECT_CLASS (cc_object_storage_parent_class)->finalize (object); +} + +static void +cc_object_storage_class_init (CcObjectStorageClass *klass) +{ + GObjectClass *object_class = G_OBJECT_CLASS (klass); + + object_class->finalize = cc_object_storage_finalize; +} + +static void +cc_object_storage_init (CcObjectStorage *self) +{ + self->id_to_object = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_object_unref); +} + +/** + * cc_object_storage_has_object: + * @key: the unique string identifier of the object + * + * Checks whether there is an object associated with @key. + * + * Returns: %TRUE if the object is stored, %FALSE otherwise. + */ +gboolean +cc_object_storage_has_object (const gchar *key) +{ + g_assert (CC_IS_OBJECT_STORAGE (_instance)); + g_assert (key != NULL); + + return g_hash_table_contains (_instance->id_to_object, key); +} + +/** + * cc_object_storage_add_object: + * @key: the unique string identifier of the object + * @object: (type GObject): the object to be stored + * + * Adds @object to the object storage. It is a programming error to try to + * add an object that was already added. + * + * @object must be a GObject. + * + * Always check if the object is stored with cc_object_storage_has_object() + * before calling this function. + */ +void +cc_object_storage_add_object (const gchar *key, + gpointer object) +{ + /* Trying to add an object that was already added is a hard error. Each + * object must be added once, and only once, over the entire lifetime + * of the application. + */ + g_assert (CC_IS_OBJECT_STORAGE (_instance)); + g_assert (key != NULL); + g_assert (G_IS_OBJECT (object)); + g_assert (!g_hash_table_contains (_instance->id_to_object, key)); + + g_debug ("Adding object %s (%s → %p) to the storage", + g_type_name (G_OBJECT_TYPE (object)), + key, + object); + + g_hash_table_insert (_instance->id_to_object, g_strdup (key), g_object_ref (object)); +} + +/** + * cc_object_storage_get_object: + * @key: the unique string identifier of the object + * + * Retrieves the object associated with @key. It is a programming error to + * try to retrieve an object before adding it. + * + * Always check if the object is stored with cc_object_storage_has_object() + * before calling this function. + * + * Returns: (transfer full): the GObject associated with @key. + */ +gpointer +cc_object_storage_get_object (const gchar *key) +{ + /* Trying to peek an object that was not yet added is a hard error. Users + * of this API need to first check if the object is available with + * cc_object_storage_has_object(). + */ + g_assert (CC_IS_OBJECT_STORAGE (_instance)); + g_assert (key != NULL); + g_assert (g_hash_table_contains (_instance->id_to_object, key)); + + return g_object_ref (g_hash_table_lookup (_instance->id_to_object, key)); +} + +/** + * cc_object_storage_create_dbus_proxy_sync: + * @name: the D-Bus name + * @flags: the D-Bus proxy flags + * @path: the D-Bus object path + * @interface: the D-Bus interface name + * @cancellable: (nullable): #GCancellable to cancel the operation + * @error: (nullable): return location for a #GError + * + * Synchronously create a #GDBusProxy with @name, @path and @interface, + * stores it in the cache, and returns the newly created proxy. + * + * If a proxy with that signature is already created, it will be used + * instead of creating a new one. + * + * Returns: (transfer full)(nullable): the new #GDBusProxy. + */ +gpointer +cc_object_storage_create_dbus_proxy_sync (GBusType bus_type, + GDBusProxyFlags flags, + const gchar *name, + const gchar *path, + const gchar *interface, + GCancellable *cancellable, + GError **error) +{ + g_autoptr(GDBusProxy) proxy = NULL; + g_autoptr(GError) local_error = NULL; + g_autofree gchar *key = NULL; + + g_assert (CC_IS_OBJECT_STORAGE (_instance)); + g_assert (name && *name); + g_assert (path && *path); + g_assert (interface && *interface); + g_assert (!error || !*error); + + key = g_strdup_printf ("CcObjectStorage::dbus-proxy(%s,%s,%s)", name, path, interface); + + g_debug ("Creating D-Bus proxy for %s", key); + + /* Check if a DBus proxy with that signature is already available; if it is, + * return that instead of a new one. + */ + if (g_hash_table_contains (_instance->id_to_object, key)) + return cc_object_storage_get_object (key); + + proxy = g_dbus_proxy_new_for_bus_sync (bus_type, + flags, + NULL, + name, + path, + interface, + cancellable, + &local_error); + + if (local_error) + { + g_propagate_error (error, g_steal_pointer (&local_error)); + return NULL; + } + + /* Store the newly created D-Bus proxy */ + cc_object_storage_add_object (key, proxy); + + return g_steal_pointer (&proxy); +} + + +/** + * cc_object_storage_create_dbus_proxy: + * @name: the D-Bus name + * @flags: the D-Bus proxy flags + * @path: the D-Bus object path + * @interface: the D-Bus interface name + * @cancellable: (nullable): #GCancellable to cancel the operation + * @callback: callback for when the async operation is finished + * @user_data: user data for @callback + * + * Asynchronously create a #GDBusProxy with @name, @path and @interface. + * + * If a proxy with that signature is already created, it will be used instead of + * creating a new one. + * + * It is a programming error to create the an identical proxy while asynchronously + * creating one. Not cancelling this operation will result in an assertion failure + * when calling cc_object_storage_create_dbus_proxy_finish(). + */ +void +cc_object_storage_create_dbus_proxy (GBusType bus_type, + GDBusProxyFlags flags, + const gchar *name, + const gchar *path, + const gchar *interface, + GCancellable *cancellable, + GAsyncReadyCallback callback, + gpointer user_data) +{ + g_autoptr(GTask) task = NULL; + g_autofree gchar *key = NULL; + TaskData *data = NULL; + + g_assert (CC_IS_OBJECT_STORAGE (_instance)); + g_assert (name && *name); + g_assert (path && *path); + g_assert (interface && *interface); + g_assert (!cancellable || G_IS_CANCELLABLE (cancellable)); + + data = task_data_new (bus_type, flags, name, path, interface); + + task = g_task_new (_instance, cancellable, callback, user_data); + g_task_set_source_tag (task, cc_object_storage_create_dbus_proxy); + g_task_set_task_data (task, data, (GDestroyNotify) task_data_free); + + /* Check if the D-Bus proxy is already created */ + key = g_strdup_printf ("CcObjectStorage::dbus-proxy(%s,%s,%s)", name, path, interface); + + g_debug ("Asynchronously creating D-Bus proxy for %s", key); + + if (g_hash_table_contains (_instance->id_to_object, key)) + { + /* Mark this GTask as already cached, so we can call the right assertions + * on the callback + * */ + data->cached = TRUE; + + g_debug ("Found in cache the D-Bus proxy %s", key); + + g_task_return_pointer (task, cc_object_storage_get_object (key), g_object_unref); + return; + } + + g_task_run_in_thread (task, create_dbus_proxy_in_thread_cb); +} + +/** + * cc_object_storage_create_dbus_proxy_finish: + * @result: + * @error: (nullable): return location for a #GError + * + * Finishes a D-Bus proxy creation started by cc_object_storage_create_dbus_proxy(). + * + * Synchronously create a #GDBusProxy with @name, @path and @interface, + * stores it in the cache, and returns the newly created proxy. + * + * If a proxy with that signature is already created, it will be used + * instead of creating a new one. + * + * Returns: (transfer full)(nullable): the new #GDBusProxy. + */ +gpointer +cc_object_storage_create_dbus_proxy_finish (GAsyncResult *result, + GError **error) +{ + g_autoptr(GDBusProxy) proxy = NULL; + g_autoptr(GError) local_error = NULL; + g_autofree gchar *key = NULL; + TaskData *task_data; + GTask *task; + + task = G_TASK (result); + + g_assert (task && G_TASK (result)); + g_assert (!error || !*error); + + task_data = g_task_get_task_data (task); + g_assert (task_data != NULL); + + key = g_strdup_printf ("CcObjectStorage::dbus-proxy(%s,%s,%s)", + task_data->name, + task_data->path, + task_data->interface); + + g_debug ("Finished creating D-Bus proxy for %s", key); + + /* Retrieve the newly created proxy */ + proxy = g_task_propagate_pointer (task, &local_error); + + /* If the proxy is not cached, do the normal caching routine */ + if (local_error) + { + g_propagate_error (error, g_steal_pointer (&local_error)); + return NULL; + } + + /* Either we have the object stored right when trying to create it - in which case, + * task_data->cached == TRUE and cc_object_storage_has_object (key) == TRUE - or we + * didn't have a cached proxy before, and we shouldn't have it now. + * + * This is to force consumers of this code to *never* try to create the same D-Bus + * proxy asynchronously multiple times. Trying to do so is considered a programming + * error. + */ + g_assert (task_data->cached == cc_object_storage_has_object (key)); + + /* If the proxy is already cached, destroy the newly created and used the cached proxy + * instead. + */ + if (cc_object_storage_has_object (key)) + return cc_object_storage_get_object (key); + + /* Store the newly created D-Bus proxy */ + cc_object_storage_add_object (key, proxy); + + return g_steal_pointer (&proxy); +} + +/** + * cc_object_storage_initialize: + * + * Initializes the single CcObjectStorage. This must be called only once, + * and before every other method of this object. + */ +void +cc_object_storage_initialize (void) +{ + g_assert (_instance == NULL); + + if (g_once_init_enter (&_instance)) + { + CcObjectStorage *instance = g_object_new (CC_TYPE_OBJECT_STORAGE, NULL); + + g_debug ("Initializing object storage"); + + g_once_init_leave (&_instance, instance); + } +} + +/** + * cc_object_storage_destroy: + * + * Destroys the instance of #CcObjectStorage. This must be called only + * once during the application lifetime. It is a programming error to + * call this function multiple times + */ +void +cc_object_storage_destroy (void) +{ + g_assert (_instance != NULL); + + g_clear_object (&_instance); +} |