wireplumber/lib/wp/core.c

/* WirePlumber
 *
 * Copyright © 2019 Collabora Ltd.
 *    @author George Kiagiadakis <george.kiagiadakis@collabora.com>
 *
 * SPDX-License-Identifier: MIT
 */

#define G_LOG_DOMAIN "wp-core"

#include "core.h"
#include "wp.h"
#include "private/registry.h"

#include <pipewire/pipewire.h>

#include <spa/utils/result.h>
#include <spa/debug/types.h>

/*
 * Integration between the PipeWire main loop and GMainLoop
 */

#define WP_LOOP_SOURCE(x) ((WpLoopSource *) x)

typedef struct _WpLoopSource WpLoopSource;
struct _WpLoopSource
{
  GSource parent;
  struct pw_loop *loop;
};

static gboolean
wp_loop_source_dispatch (GSource * s, GSourceFunc callback, gpointer user_data)
{
  int result;

  wp_trace_boxed (G_TYPE_SOURCE, s, "entering pw main loop");

  pw_loop_enter (WP_LOOP_SOURCE(s)->loop);
  result = pw_loop_iterate (WP_LOOP_SOURCE(s)->loop, 0);
  pw_loop_leave (WP_LOOP_SOURCE(s)->loop);

  wp_trace_boxed (G_TYPE_SOURCE, s, "leaving pw main loop");

  if (G_UNLIKELY (result < 0))
    wp_warning_boxed (G_TYPE_SOURCE, s,
        "pw_loop_iterate failed: %s", spa_strerror (result));

  return G_SOURCE_CONTINUE;
}

static void
wp_loop_source_finalize (GSource * s)
{
  pw_loop_destroy (WP_LOOP_SOURCE(s)->loop);
}

static GSourceFuncs source_funcs = {
  NULL,
  NULL,
  wp_loop_source_dispatch,
  wp_loop_source_finalize
};

static GSource *
wp_loop_source_new (void)
{
  GSource *s = g_source_new (&source_funcs, sizeof (WpLoopSource));
  WP_LOOP_SOURCE(s)->loop = pw_loop_new (NULL);

  g_source_add_unix_fd (s,
      pw_loop_get_fd (WP_LOOP_SOURCE(s)->loop),
      G_IO_IN | G_IO_ERR | G_IO_HUP);

  return (GSource *) s;
}

/*! \defgroup wpcore WpCore */
/*!
 * \struct WpCore
 *
 * The core is the central object around which everything operates. It is
 * essential to create a WpCore before using any other WirePlumber API.
 *
 * The core object has the following responsibilities:
 *  * it initializes the PipeWire library
 *  * it creates a `pw_context` and allows connecting to the PipeWire server,
 *    creating a local `pw_core`
 *  * it glues the PipeWire library's event loop system with GMainLoop
 *  * it maintains a list of registered objects, which other classes use
 *    to keep objects loaded permanently into memory
 *  * it watches the PipeWire registry and keeps track of remote and local
 *    objects that appear in the registry, making them accessible through
 *    the WpObjectManager API.
 *
 * \gproperties
 *
 * \gproperty{g-main-context, GMainContext *, G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY,
 *   A GMainContext to attach to}
 *
 * \gproperty{properties, WpProperties *, G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY,
 *   The pipewire properties of the pw_core}
 *
 * \gproperty{pw-context, gpointer (struct pw_context *), G_PARAM_READABLE,
 *   The pipewire context}
 *
 * \gproperty{pw-core, gpointer (struct pw_core *), G_PARAM_READABLE,
 *   The pipewire core}
 *
 * \gsignals
 *
 * \par connected
 * \parblock
 * \code
 * void
 * connected_callback (WpCore * self,
 *                     gpointer user_data)
 * \endcode
 * Emitted when the core is successfully connected to the PipeWire server
 * \endparblock
 *
 * \par disconnected
 * \parblock
 * \code
 * void
 * disconnected_callback (WpCore * self,
 *                        gpointer user_data)
 * \endcode
 * Emitted when the core is disconnected from the PipeWire server
 * \endparblock
 */
struct _WpCore
{
  GObject parent;

  /* main loop integration */
  GMainContext *g_main_context;

  /* extra properties */
  WpProperties *properties;

  /* pipewire main objects */
  struct pw_context *pw_context;
  struct pw_core *pw_core;
  struct pw_core_info *info;

  /* pipewire main listeners */
  struct spa_hook core_listener;
  struct spa_hook proxy_core_listener;

  WpRegistry registry;
  GHashTable *async_tasks; // <int seq, GTask*>
};

enum {
  PROP_0,
  PROP_G_MAIN_CONTEXT,
  PROP_PROPERTIES,
  PROP_PW_CONTEXT,
  PROP_PW_CORE,
};

enum {
  SIGNAL_CONNECTED,
  SIGNAL_DISCONNECTED,
  NUM_SIGNALS
};

static guint32 signals[NUM_SIGNALS];

G_DEFINE_TYPE (WpCore, wp_core, G_TYPE_OBJECT)

static void
core_info (void *data, const struct pw_core_info * info)
{
  WpCore *self = WP_CORE (data);
  gboolean new_connection = (self->info == NULL);

  self->info = pw_core_info_update (self->info, info);

  wp_info_object (self, "connected to server: %s, cookie: %u",
      self->info->name, self->info->cookie);

  if (new_connection)
    g_signal_emit (self, signals[SIGNAL_CONNECTED], 0);
}

static void
core_done (void *data, uint32_t id, int seq)
{
  WpCore *self = WP_CORE (data);
  g_autoptr (GTask) task = NULL;

  g_hash_table_steal_extended (self->async_tasks, GINT_TO_POINTER (seq), NULL,
      (gpointer *) &task);
  wp_debug_object (self, "done, seq 0x%x, task " WP_OBJECT_FORMAT,
      seq, WP_OBJECT_ARGS (task));

  if (task)
    g_task_return_boolean (task, TRUE);
}

static gboolean
core_disconnect_async (WpCore * self)
{
  wp_core_disconnect (self);
  return G_SOURCE_REMOVE;
}

static void
core_error (void *data, uint32_t id, int seq, int res, const char *message)
{
  WpCore *self = WP_CORE (data);

  /* protocol socket disconnected; schedule disconnecting our core */
  if (id == 0 && res == -EPIPE) {
    wp_core_idle_add_closure (self, NULL, g_cclosure_new_object (
            G_CALLBACK (core_disconnect_async), G_OBJECT (self)));
  }
}

static const struct pw_core_events core_events = {
  PW_VERSION_CORE_EVENTS,
  .info = core_info,
  .done = core_done,
  .error = core_error,
};

static gboolean
async_tasks_finish (gpointer key, gpointer value, gpointer user_data)
{
  GTask *task = G_TASK (value);
  g_return_val_if_fail (task, FALSE);

  g_task_return_new_error (task, WP_DOMAIN_LIBRARY,
        WP_LIBRARY_ERROR_INVARIANT, "core disconnected");
  return TRUE;
}

static void
proxy_core_destroy (void *data)
{
  WpCore *self = WP_CORE (data);
  g_hash_table_foreach_remove (self->async_tasks, async_tasks_finish, NULL);
  g_clear_pointer (&self->info, pw_core_info_free);
  self->pw_core = NULL;
  wp_debug_object (self, "emit disconnected");
  g_signal_emit (self, signals[SIGNAL_DISCONNECTED], 0);
}

static const struct pw_proxy_events proxy_core_events = {
  PW_VERSION_PROXY_EVENTS,
  .destroy = proxy_core_destroy,
};

static void
wp_core_init (WpCore * self)
{
  wp_registry_init (&self->registry);
  self->async_tasks = g_hash_table_new_full (g_direct_hash, g_direct_equal,
      NULL, g_object_unref);
}

static void
wp_core_constructed (GObject *object)
{
  WpCore *self = WP_CORE (object);
  g_autoptr (GSource) source = NULL;

  /* loop */
  source = wp_loop_source_new ();
  g_source_attach (source, self->g_main_context);

  /* context */
  if (!self->pw_context) {
    struct pw_properties *p = NULL;
    const gchar *str = NULL;

    /* properties are fully stored in the pw_context, no need to keep a copy */
    p = self->properties ?
        wp_properties_unref_and_take_pw_properties (self->properties) : NULL;
    self->properties = NULL;

    self->pw_context = pw_context_new (WP_LOOP_SOURCE(source)->loop, p,
        sizeof (grefcount));
    g_return_if_fail (self->pw_context);

    /* use the same config option as pipewire to set the log level */
    p = (struct pw_properties *) pw_context_get_properties (self->pw_context);
    if (!g_getenv("WIREPLUMBER_DEBUG") &&
        (str = pw_properties_get(p, "log.level")) != NULL)
      wp_log_set_level (str);

    /* Init refcount */
    grefcount *rc = pw_context_get_user_data (self->pw_context);
    g_return_if_fail (rc);
    g_ref_count_init (rc);
  } else {
    /* Increase refcount */
    grefcount *rc = pw_context_get_user_data (self->pw_context);
    g_return_if_fail (rc);
    g_ref_count_inc (rc);
  }

  G_OBJECT_CLASS (wp_core_parent_class)->constructed (object);
}

static void
wp_core_dispose (GObject * obj)
{
  WpCore *self = WP_CORE (obj);

  wp_registry_clear (&self->registry);

  G_OBJECT_CLASS (wp_core_parent_class)->dispose (obj);
}

static void
wp_core_finalize (GObject * obj)
{
  WpCore *self = WP_CORE (obj);
  grefcount *rc = pw_context_get_user_data (self->pw_context);
  g_return_if_fail (rc);

  wp_core_disconnect (self);

  /* Clear pw-context if refcount reaches 0 */
  if (g_ref_count_dec (rc))
    g_clear_pointer (&self->pw_context, pw_context_destroy);

  g_clear_pointer (&self->properties, wp_properties_unref);
  g_clear_pointer (&self->g_main_context, g_main_context_unref);
  g_clear_pointer (&self->async_tasks, g_hash_table_unref);

  wp_debug_object (self, "WpCore destroyed");

  G_OBJECT_CLASS (wp_core_parent_class)->finalize (obj);
}

static void
wp_core_get_property (GObject * object, guint property_id,
    GValue * value, GParamSpec * pspec)
{
  WpCore *self = WP_CORE (object);

  switch (property_id) {
  case PROP_G_MAIN_CONTEXT:
    g_value_set_boxed (value, self->g_main_context);
    break;
  case PROP_PROPERTIES:
    g_value_take_boxed (value, wp_core_get_properties (self));
    break;
  case PROP_PW_CONTEXT:
    g_value_set_pointer (value, self->pw_context);
    break;
  case PROP_PW_CORE:
    g_value_set_pointer (value, self->pw_core);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
    break;
  }
}

static void
wp_core_set_property (GObject * object, guint property_id,
    const GValue * value, GParamSpec * pspec)
{
  WpCore *self = WP_CORE (object);

  switch (property_id) {
  case PROP_G_MAIN_CONTEXT:
    self->g_main_context = g_value_dup_boxed (value);
    break;
  case PROP_PROPERTIES:
    self->properties = g_value_dup_boxed (value);
    break;
  case PROP_PW_CONTEXT:
    self->pw_context = g_value_get_pointer (value);
    break;
  default:
    G_OBJECT_WARN_INVALID_PROPERTY_ID (object, property_id, pspec);
    break;
  }
}

static void
wp_core_class_init (WpCoreClass * klass)
{
  GObjectClass *object_class = (GObjectClass *) klass;

  object_class->constructed = wp_core_constructed;
  object_class->dispose = wp_core_dispose;
  object_class->finalize = wp_core_finalize;
  object_class->get_property = wp_core_get_property;
  object_class->set_property = wp_core_set_property;

  g_object_class_install_property (object_class, PROP_G_MAIN_CONTEXT,
      g_param_spec_boxed ("g-main-context", "g-main-context",
          "A GMainContext to attach to", G_TYPE_MAIN_CONTEXT,
          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (object_class, PROP_PROPERTIES,
      g_param_spec_boxed ("properties", "properties", "Extra properties",
          WP_TYPE_PROPERTIES,
          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (object_class, PROP_PW_CONTEXT,
      g_param_spec_pointer ("pw-context", "pw-context", "The pipewire context",
          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY | G_PARAM_STATIC_STRINGS));

  g_object_class_install_property (object_class, PROP_PW_CORE,
      g_param_spec_pointer ("pw-core", "pw-core", "The pipewire core",
          G_PARAM_READABLE | G_PARAM_STATIC_STRINGS));

  signals[SIGNAL_CONNECTED] = g_signal_new ("connected",
      G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL,
      G_TYPE_NONE, 0);

  signals[SIGNAL_DISCONNECTED] = g_signal_new ("disconnected",
      G_TYPE_FROM_CLASS (klass), G_SIGNAL_RUN_LAST, 0, NULL, NULL, NULL,
      G_TYPE_NONE, 0);
}

/*!
 * \brief Creates a new core object
 *
 * \ingroup wpcore
 * \param context (transfer none) (nullable): the GMainContext to use for events
 * \param properties (transfer full) (nullable): additional properties, which are
 *   passed to pw_context_new() and pw_context_connect()
 * \returns (transfer full): a new WpCore
 */
WpCore *
wp_core_new (GMainContext *context, WpProperties * properties)
{
  g_autoptr (WpProperties) props = properties;
  return g_object_new (WP_TYPE_CORE,
      "g-main-context", context,
      "properties", properties,
      "pw-context", NULL,
      NULL);
}

/*!
 * \brief Clones a core with the same context as \a self
 *
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer full): the clone WpCore
 */
WpCore *
wp_core_clone (WpCore * self)
{
  return g_object_new (WP_TYPE_CORE,
      "g-main-context", self->g_main_context,
      "properties", self->properties,
      "pw-context", self->pw_context,
      NULL);
}

/*!
 * \brief Gets the GMainContext of the core
 *
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer none) (nullable): the GMainContext that is in
 *   use by this core for events
 */
GMainContext *
wp_core_get_g_main_context (WpCore * self)
{
  g_return_val_if_fail (WP_IS_CORE (self), NULL);
  return self->g_main_context;
}

/*!
 * \brief Gets the internal PipeWire context of the core
 *
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer none): the internal pw_context object
 */
struct pw_context *
wp_core_get_pw_context (WpCore * self)
{
  g_return_val_if_fail (WP_IS_CORE (self), NULL);
  return self->pw_context;
}

/*!
 * \brief Gets the internal PipeWire core of the core
 *
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer none) (nullable): the internal pw_core object,
 *   or NULL if the core is not connected to PipeWire
 */
struct pw_core *
wp_core_get_pw_core (WpCore * self)
{
  g_return_val_if_fail (WP_IS_CORE (self), NULL);
  return self->pw_core;
}

/*!
 * \brief Connects this core to the PipeWire server.
 *
 * When connection succeeds, the WpCore \c "connected" signal is emitted.
 *
 * \ingroup wpcore
 * \param self the core
 * \returns TRUE if the core is effectively connected or FALSE if
 *   connection failed
 */
gboolean
wp_core_connect (WpCore *self)
{
  struct pw_properties *p = NULL;

  g_return_val_if_fail (WP_IS_CORE (self), FALSE);

  /* Don't do anything if core is already connected */
  if (self->pw_core)
    return TRUE;

  /* Connect */
  p = self->properties ? wp_properties_to_pw_properties (self->properties) : NULL;
  self->pw_core = pw_context_connect (self->pw_context, p, 0);
  if (!self->pw_core)
    return FALSE;

  /* Add the core listeners */
  pw_core_add_listener (self->pw_core, &self->core_listener, &core_events, self);
  pw_proxy_add_listener((struct pw_proxy*)self->pw_core,
      &self->proxy_core_listener, &proxy_core_events, self);

  /* Add the registry listener */
  wp_registry_attach (&self->registry, self->pw_core);

  return TRUE;
}

/*!
 * \brief Disconnects this core from the PipeWire server.
 *
 * This also effectively destroys all WpCore objects that were created through
 * the registry, destroys the pw_core and finally emits the WpCore
 * \c "disconnected" signal.
 *
 * \ingroup wpcore
 * \param self the core
 */
void
wp_core_disconnect (WpCore *self)
{
  wp_registry_detach (&self->registry);

  /* pw_core_disconnect destroys the core proxy
    and we continue in proxy_core_destroy() */
  if (self->pw_core)
    pw_core_disconnect (self->pw_core);
}

/*!
 * \brief Checks if the core is connected to PipeWire
 *
 * \ingroup wpcore
 * \param self the core
 * \returns TRUE if the core is connected to PipeWire, FALSE otherwise
 */
gboolean
wp_core_is_connected (WpCore * self)
{
  g_return_val_if_fail (WP_IS_CORE (self), FALSE);
  return self->pw_core != NULL;
}

/*!
 * \brief Gets the cookie of the core's connected PipeWire instance
 *
 * \ingroup wpcore
 * \param self the core
 * \returns The cookie of the PipeWire instance that \a self is connected to.
 *     The cookie is a unique random number for identifying an instance of
 *     PipeWire
 */
guint32
wp_core_get_remote_cookie (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), 0);
  g_return_val_if_fail (self->info, 0);

  return self->info->cookie;
}

/*!
 * \brief Gets the name of the core's connected PipeWire instance
 * \ingroup wpcore
 * \param self the core
 * \returns The name of the PipeWire instance that \a self is connected to
 */
const gchar *
wp_core_get_remote_name (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), NULL);
  g_return_val_if_fail (self->info, NULL);

  return self->info->name;
}

/*!
 * \brief Gets the user name of the core's connected PipeWire instance
 * \ingroup wpcore
 * \param self the core
 * \returns The name of the user that started the PipeWire instance that
 *     \a self is connected to
 */
const gchar *
wp_core_get_remote_user_name (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), NULL);
  g_return_val_if_fail (self->info, NULL);

  return self->info->user_name;
}

/*!
 * \brief Gets the host name of the core's connected PipeWire instance
 * \ingroup wpcore
 * \param self the core
 * \returns The name of the host where the PipeWire instance that
 *     \a self is connected to is running on
 */
const gchar *
wp_core_get_remote_host_name (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), NULL);
  g_return_val_if_fail (self->info, NULL);

  return self->info->host_name;
}

/*!
 * \brief Gets the version of the core's connected PipeWire instance
 * \ingroup wpcore
 * \param self the core
 * \returns The version of the PipeWire instance that \a self is connected to
 */
const gchar *
wp_core_get_remote_version (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), NULL);
  g_return_val_if_fail (self->info, NULL);

  return self->info->version;
}

/*!
 * \brief Gets the properties of the core's connected PipeWire instance
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer full): the properties of the PipeWire instance that
 *     \a self is connected to
 */
WpProperties *
wp_core_get_remote_properties (WpCore * self)
{
  g_return_val_if_fail (wp_core_is_connected (self), NULL);
  g_return_val_if_fail (self->info, NULL);

  return wp_properties_new_wrap_dict (self->info->props);
}

/*!
 * \brief Gets the properties of the core
 * \ingroup wpcore
 * \param self the core
 * \returns (transfer full): the properties of \a self
 */
WpProperties *
wp_core_get_properties (WpCore * self)
{
  g_return_val_if_fail (WP_IS_CORE (self), NULL);

  /* pw_core has all the properties of the pw_context,
     plus our updates, passed in pw_context_connect() */
  if (self->pw_core)
    return wp_properties_new_wrap (pw_core_get_properties (self->pw_core));

  /* if there is no connection yet, return the properties of the context */
  else if (!self->properties)
    return wp_properties_new_wrap (pw_context_get_properties (self->pw_context));

  /* ... plus any further updates that we got from wp_core_update_properties() */
  else {
    /* we need to copy here in order to augment with the updates */
    WpProperties *ret =
        wp_properties_new_copy (pw_context_get_properties (self->pw_context));
    wp_properties_update (ret, self->properties);
    return ret;
  }
}

/*!
 * \brief Updates the properties of \a self on the connection, making them
 * appear on the client object that represents this connection.
 *
 * If \a self is not connected yet, these properties are stored and passed to
 * pw_context_connect() when connecting.
 *
 * \ingroup wpcore
 * \param self the core
 * \param updates (transfer full): updates to apply to the properties of
 *    \a self; this does not need to include properties that have not changed
 */
void
wp_core_update_properties (WpCore * self, WpProperties * updates)
{
  g_autoptr (WpProperties) upd = updates;

  g_return_if_fail (WP_IS_CORE (self));
  g_return_if_fail (updates != NULL);

  /* store updates locally so that
    - they persist after disconnection
    - we can pass them to pw_context_connect */
  if (!self->properties)
    self->properties = wp_properties_new_empty ();
  wp_properties_update (self->properties, upd);

  if (self->pw_core)
    pw_core_update_properties (self->pw_core, wp_properties_peek_dict (upd));
}

/*!
 * \brief Adds an idle callback to be called in the same GMainContext as the
 * one used by this core.
 *
 * This is essentially the same as g_idle_add_full(), but it adds the created
 * GSource on the GMainContext used by this core instead of the default context.
 *
 * \ingroup wpcore
 * \param self the core
 * \param source (out) (optional): the source
 * \param function (scope notified): the function to call
 * \param data (closure): data to pass to \a function
 * \param destroy (nullable): a function to destroy \a data
 */
void
wp_core_idle_add (WpCore * self, GSource **source, GSourceFunc function,
    gpointer data, GDestroyNotify destroy)
{
  g_autoptr (GSource) s = NULL;

  g_return_if_fail (WP_IS_CORE (self));

  s = g_idle_source_new ();
  g_source_set_callback (s, function, data, destroy);
  g_source_attach (s, self->g_main_context);

  if (source)
    *source = g_source_ref (s);
}

/*!
 * \brief Adds an idle callback to be called in the same GMainContext as
 * the one used by this core.
 *
 * This is the same as wp_core_idle_add(), but it allows you to specify a
 * GClosure instead of a C callback.
 *
 * \ingroup wpcore
 * \param self the core
 * \param source (out) (optional): the source
 * \param closure the closure to invoke
 */
void
wp_core_idle_add_closure (WpCore * self, GSource **source, GClosure * closure)
{
  g_autoptr (GSource) s = NULL;

  g_return_if_fail (WP_IS_CORE (self));
  g_return_if_fail (closure != NULL);

  s = g_idle_source_new ();
  g_source_set_closure (s, closure);
  g_source_attach (s, self->g_main_context);

  if (source)
    *source = g_source_ref (s);
}

/*!
 * \brief Adds a timeout callback to be called at regular intervals in the same
 * GMainContext as the one used by this core.
 *
 * 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.

 * This is essentially the same as g_timeout_add_full(), but it adds
 * the created GSource on the GMainContext used by this core instead of the
 * default context.
 *
 * \ingroup wpcore
 * \param self the core
 * \param source (out) (optional): the source
 * \param timeout_ms the timeout in milliseconds
 * \param function (scope notified): the function to call
 * \param data (closure): data to pass to \a function
 * \param destroy (nullable): a function to destroy \a data
 */
void
wp_core_timeout_add (WpCore * self, GSource **source, guint timeout_ms,
    GSourceFunc function, gpointer data, GDestroyNotify destroy)
{
  g_autoptr (GSource) s = NULL;

  g_return_if_fail (WP_IS_CORE (self));

  s = g_timeout_source_new (timeout_ms);
  g_source_set_callback (s, function, data, destroy);
  g_source_attach (s, self->g_main_context);

  if (source)
    *source = g_source_ref (s);
}

/*!
 * \brief Adds a timeout callback to be called at regular intervals in the same
 * GMainContext as the one used by this core.
 *
 * This is the same as wp_core_timeout_add(), but it allows you to specify a
 * GClosure instead of a C callback.
 *
 * \ingroup wpcore
 * \param self the core
 * \param source (out) (optional): the source
 * \param timeout_ms the timeout in milliseconds
 * \param closure the closure to invoke
 */
void
wp_core_timeout_add_closure (WpCore * self, GSource **source, guint timeout_ms,
    GClosure * closure)
{
  g_autoptr (GSource) s = NULL;

  g_return_if_fail (WP_IS_CORE (self));
  g_return_if_fail (closure != NULL);

  s = g_timeout_source_new (timeout_ms);
  g_source_set_closure (s, closure);
  g_source_attach (s, self->g_main_context);

  if (source)
    *source = g_source_ref (s);
}

/*!
 * \brief Asks the PipeWire server to call the \a callback via an event.
 *
 * Since methods are handled in-order and events are delivered
 * in-order, this can be used as a barrier to ensure all previous
 * methods and the resulting events have been handled.
 *
 * In both success and error cases, \a callback is always called.
 * Use wp_core_sync_finish() from within the \a callback to determine whether
 * the operation completed successfully or if an error occurred.
 *
 * \ingroup wpcore
 * \param self the core
 * \param cancellable (nullable): a GCancellable to cancel the operation
 * \param callback (scope async): a function to call when the operation is done
 * \param user_data (closure): data to pass to \a callback
 * \returns TRUE if the sync operation was started, FALSE if an error
 *   occurred before returning from this function
 */
gboolean
wp_core_sync (WpCore * self, GCancellable * cancellable,
    GAsyncReadyCallback callback, gpointer user_data)
{
  g_autoptr (GTask) task = NULL;
  int seq;

  g_return_val_if_fail (WP_IS_CORE (self), FALSE);

  task = g_task_new (self, cancellable, callback, user_data);

  if (G_UNLIKELY (!self->pw_core)) {
    g_warn_if_reached ();
    g_task_return_new_error (task, WP_DOMAIN_LIBRARY,
        WP_LIBRARY_ERROR_INVARIANT, "No pipewire core");
    return FALSE;
  }

  seq = pw_core_sync (self->pw_core, 0, 0);
  if (G_UNLIKELY (seq < 0)) {
    g_task_return_new_error (task, WP_DOMAIN_LIBRARY,
        WP_LIBRARY_ERROR_OPERATION_FAILED, "pw_core_sync failed: %s",
        g_strerror (-seq));
    return FALSE;
  }

  wp_debug_object (self, "sync, seq 0x%x, task " WP_OBJECT_FORMAT,
      seq, WP_OBJECT_ARGS (task));

  g_hash_table_insert (self->async_tasks, GINT_TO_POINTER (seq),
      g_steal_pointer (&task));
  return TRUE;
}

/*!
 * \brief This function is meant to be called from within the callback of
 * wp_core_sync() in order to determine the success or failure of the operation.
 *
 * \ingroup wpcore
 * \param self the core
 * \param res a GAsyncResult
 * \param error (out) (optional): the error that occurred, if any
 * \returns TRUE if the operation succeeded, FALSE otherwise
 */
gboolean
wp_core_sync_finish (WpCore * self, GAsyncResult * res, GError ** error)
{
  g_return_val_if_fail (WP_IS_CORE (self), FALSE);
  g_return_val_if_fail (g_task_is_valid (res, self), FALSE);

  return g_task_propagate_boolean (G_TASK (res), error);
}

WpRegistry *
wp_core_get_registry (WpCore * self)
{
  return &self->registry;
}

WpCore *
wp_registry_get_core (WpRegistry * self)
{
  return SPA_CONTAINER_OF (self, WpCore, registry);
}