giomodule: Don’t mandatorily cache GIOModule implementations

While all of the current callers of _g_io_module_get_default() want to
cache the returned GObject for the lifetime of the process, that doesn’t
necessarily have to be the case, so let callers make that decision on a
case-by-case basis.

Signed-off-by: Philip Withnall <withnall@endlessm.com>
This commit is contained in:
Philip Withnall 2019-01-23 16:07:51 +00:00 committed by Philip Withnall
parent b207965697
commit 22b924b64a
7 changed files with 121 additions and 31 deletions

View File

@ -884,6 +884,13 @@ try_implementation (const char *extension_point,
}
}
static void
weak_ref_free (GWeakRef *weak_ref)
{
g_weak_ref_clear (weak_ref);
g_free (weak_ref);
}
/**
* _g_io_module_get_default:
* @extension_point: the name of an extension point
@ -905,10 +912,11 @@ try_implementation (const char *extension_point,
* be called on each candidate implementation after construction, to
* check if it is actually usable or not.
*
* The result is cached after it is generated the first time, and
* The result is cached after it is generated the first time (but the cache does
* not keep a strong reference to the object), and
* the function is thread-safe.
*
* Returns: (transfer none): an object implementing
* Returns: (transfer full) (nullable): an object implementing
* @extension_point, or %NULL if there are no usable
* implementations.
*/
@ -923,25 +931,33 @@ _g_io_module_get_default (const gchar *extension_point,
GList *l;
GIOExtensionPoint *ep;
GIOExtension *extension = NULL, *preferred;
gpointer impl;
gpointer impl, value;
GWeakRef *impl_weak_ref = NULL;
g_rec_mutex_lock (&default_modules_lock);
if (default_modules)
{
gpointer key;
if (g_hash_table_lookup_extended (default_modules, extension_point,
&key, &impl))
{
NULL, &value))
{
/* Dont debug here, since were returning a cached object which was
* already printed earlier. */
g_rec_mutex_unlock (&default_modules_lock);
return impl;
}
impl_weak_ref = value;
impl = g_weak_ref_get (impl_weak_ref);
/* If the object has been finalised (impl == NULL), fall through and
* instantiate a new one. */
if (impl != NULL)
{
g_rec_mutex_unlock (&default_modules_lock);
return g_steal_pointer (&impl);
}
}
}
else
{
default_modules = g_hash_table_new (g_str_hash, g_str_equal);
default_modules = g_hash_table_new_full (g_str_hash, g_str_equal,
g_free, (GDestroyNotify) weak_ref_free);
}
_g_io_modules_ensure_loaded ();
@ -993,9 +1009,18 @@ _g_io_module_get_default (const gchar *extension_point,
impl = NULL;
done:
g_hash_table_insert (default_modules,
g_strdup (extension_point),
impl ? g_object_ref (impl) : NULL);
if (impl_weak_ref == NULL)
{
impl_weak_ref = g_new0 (GWeakRef, 1);
g_weak_ref_init (impl_weak_ref, impl);
g_hash_table_insert (default_modules, g_strdup (extension_point),
g_steal_pointer (&impl_weak_ref));
}
else
{
g_weak_ref_set (impl_weak_ref, impl);
}
g_rec_mutex_unlock (&default_modules_lock);
if (impl != NULL)
@ -1009,7 +1034,7 @@ _g_io_module_get_default (const gchar *extension_point,
g_debug ("%s: Failed to find default implementation for %s",
G_STRFUNC, extension_point);
return impl;
return g_steal_pointer (&impl);
}
G_LOCK_DEFINE_STATIC (registered_extensions);

View File

@ -77,6 +77,7 @@ enum {
};
static guint signals[LAST_SIGNAL] = { 0 };
static GNetworkMonitor *network_monitor_default_singleton = NULL; /* (owned) (atomic) */
/**
* g_network_monitor_get_default:
@ -91,9 +92,18 @@ static guint signals[LAST_SIGNAL] = { 0 };
GNetworkMonitor *
g_network_monitor_get_default (void)
{
return _g_io_module_get_default (G_NETWORK_MONITOR_EXTENSION_POINT_NAME,
"GIO_USE_NETWORK_MONITOR",
NULL);
if (g_once_init_enter (&network_monitor_default_singleton))
{
GNetworkMonitor *singleton;
singleton = _g_io_module_get_default (G_NETWORK_MONITOR_EXTENSION_POINT_NAME,
"GIO_USE_NETWORK_MONITOR",
NULL);
g_once_init_leave (&network_monitor_default_singleton, singleton);
}
return network_monitor_default_singleton;
}
/**

View File

@ -67,6 +67,8 @@ g_proxy_resolver_default_init (GProxyResolverInterface *iface)
{
}
static GProxyResolver *proxy_resolver_default_singleton = NULL; /* (owned) (atomic) */
/**
* g_proxy_resolver_get_default:
*
@ -80,9 +82,18 @@ g_proxy_resolver_default_init (GProxyResolverInterface *iface)
GProxyResolver *
g_proxy_resolver_get_default (void)
{
return _g_io_module_get_default (G_PROXY_RESOLVER_EXTENSION_POINT_NAME,
"GIO_USE_PROXY_RESOLVER",
(GIOModuleVerifyFunc)g_proxy_resolver_is_supported);
if (g_once_init_enter (&proxy_resolver_default_singleton))
{
GProxyResolver *singleton;
singleton = _g_io_module_get_default (G_PROXY_RESOLVER_EXTENSION_POINT_NAME,
"GIO_USE_PROXY_RESOLVER",
(GIOModuleVerifyFunc) g_proxy_resolver_is_supported);
g_once_init_leave (&proxy_resolver_default_singleton, singleton);
}
return proxy_resolver_default_singleton;
}
/**

View File

@ -992,6 +992,12 @@ g_settings_backend_verify (gpointer impl)
return TRUE;
}
/* We need to cache the default #GSettingsBackend for the entire process
* lifetime, especially if the backend is #GMemorySettingsBackend: it needs to
* keep the in-memory settings around even while there are no #GSettings
* instances alive. */
static GSettingsBackend *settings_backend_default_singleton = NULL; /* (owned) (atomic) */
/**
* g_settings_backend_get_default:
*
@ -1010,12 +1016,18 @@ g_settings_backend_verify (gpointer impl)
GSettingsBackend *
g_settings_backend_get_default (void)
{
GSettingsBackend *backend;
if (g_once_init_enter (&settings_backend_default_singleton))
{
GSettingsBackend *singleton;
backend = _g_io_module_get_default (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
"GSETTINGS_BACKEND",
g_settings_backend_verify);
return g_object_ref (backend);
singleton = _g_io_module_get_default (G_SETTINGS_BACKEND_EXTENSION_POINT_NAME,
"GSETTINGS_BACKEND",
g_settings_backend_verify);
g_once_init_leave (&settings_backend_default_singleton, singleton);
}
return g_object_ref (settings_backend_default_singleton);
}
/*< private >

View File

@ -93,6 +93,8 @@ g_tls_backend_default_init (GTlsBackendInterface *iface)
{
}
static GTlsBackend *tls_backend_default_singleton = NULL; /* (owned) (atomic) */
/**
* g_tls_backend_get_default:
*
@ -106,8 +108,18 @@ g_tls_backend_default_init (GTlsBackendInterface *iface)
GTlsBackend *
g_tls_backend_get_default (void)
{
return _g_io_module_get_default (G_TLS_BACKEND_EXTENSION_POINT_NAME,
"GIO_USE_TLS", NULL);
if (g_once_init_enter (&tls_backend_default_singleton))
{
GTlsBackend *singleton;
singleton = _g_io_module_get_default (G_TLS_BACKEND_EXTENSION_POINT_NAME,
"GIO_USE_TLS",
NULL);
g_once_init_leave (&tls_backend_default_singleton, singleton);
}
return tls_backend_default_singleton;
}
/**

View File

@ -337,6 +337,8 @@ g_vfs_parse_name (GVfs *vfs,
return (* class->parse_name) (vfs, parse_name);
}
static GVfs *vfs_default_singleton = NULL; /* (owned) (atomic) */
/**
* g_vfs_get_default:
*
@ -350,9 +352,19 @@ g_vfs_get_default (void)
{
if (GLIB_PRIVATE_CALL (g_check_setuid) ())
return g_vfs_get_local ();
return _g_io_module_get_default (G_VFS_EXTENSION_POINT_NAME,
"GIO_USE_VFS",
(GIOModuleVerifyFunc)g_vfs_is_active);
if (g_once_init_enter (&vfs_default_singleton))
{
GVfs *singleton;
singleton = _g_io_module_get_default (G_VFS_EXTENSION_POINT_NAME,
"GIO_USE_VFS",
(GIOModuleVerifyFunc) g_vfs_is_active);
g_once_init_leave (&vfs_default_singleton, singleton);
}
return vfs_default_singleton;
}
/**

View File

@ -421,6 +421,14 @@
fun:_g_io_module_get_default*
}
{
g-io-module-default-singleton-weak-ref
Memcheck:Leak
fun:calloc
...
fun:_g_io_module_get_default
}
{
g-get-language-names-malloc
Memcheck:Leak