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gobject/gclosure: cache libffi plans for closures

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If we are using libffi to trampoline then there is opportunity to cache
the ffi_call_plan introduced in newer libffi releases. A rather contrived
test introduced in the previous commit includes a basic performance test
that can compare between versions.

For my system, the average call time dropped from 200ns/call to 145ns/call
for cached GClosure. Since the previous version did no caching, the
uncached GClosure use was also just slightly slower around 205ns/call. For
the cached form (since it can reuse a global plan cache via GMutex) it
drops to 180ns/call. So that is 27.5% savings and a 10% savings in runtime
duration.

Closes: #4002
Co-authored-by: Philip Withnall <pwithnall@gnome.org>
This commit is contained in:
Christian Hergert
2026-07-24 15:51:57 +02:00
parent c4d9e92e11
commit 30dfead61b
8 changed files with 317 additions and 24 deletions
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10
.gitlab-ci.yml
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@@ -41,12 +41,12 @@ cache:
- _ccache/
variables:
FEDORA_IMAGE: "registry.gitlab.gnome.org/gnome/glib/fedora:v41.5"
FEDORA_IMAGE: "registry.gitlab.gnome.org/gnome/glib/fedora:v41.6"
COVERITY_IMAGE: "registry.gitlab.gnome.org/gnome/glib/coverity:v7"
DEBIAN_IMAGE: "registry.gitlab.gnome.org/gnome/glib/debian-stable:v25"
DEBIAN_I386_IMAGE: "registry.gitlab.gnome.org/gnome/glib/debian-stable-i386:v5"
ALPINE_IMAGE: "registry.gitlab.gnome.org/gnome/glib/alpine:v8"
MINGW_IMAGE: "registry.gitlab.gnome.org/gnome/glib/mingw:v41.3"
DEBIAN_IMAGE: "registry.gitlab.gnome.org/gnome/glib/debian-stable:v25.1"
DEBIAN_I386_IMAGE: "registry.gitlab.gnome.org/gnome/glib/debian-stable-i386:v5.1"
ALPINE_IMAGE: "registry.gitlab.gnome.org/gnome/glib/alpine:v8.1"
MINGW_IMAGE: "registry.gitlab.gnome.org/gnome/glib/mingw:v41.4"
GOBJECT_INTROSPECTION_TAG: "1.80.1"
MESON_TEST_TIMEOUT_MULTIPLIER: 4
G_MESSAGES_DEBUG: all

2
.gitlab-ci/mingw.Dockerfile
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@@ -1,4 +1,4 @@
FROM registry.gitlab.gnome.org/gnome/glib/fedora:v41.3
FROM registry.gitlab.gnome.org/gnome/glib/fedora:v41.6
USER root

3
INSTALL.md
View File

@@ -74,7 +74,8 @@ Some of the mimetype-related functionality in GIO requires the
`update-mime-database` and `update-desktop-database` utilities, which
are part of shared-mime-info and desktop-file-utils, respectively.
GObject uses libffi to implement generic marshalling functionality.
GObject uses libffi to implement generic marshalling functionality. With
libffi 3.7.0 or newer, GObject also caches call plans for generic marshalling.
The Nitty-Gritty
================

3
docs/reference/glib/building.md
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@@ -90,6 +90,9 @@ libraries.
expression matching. The system version of PCRE is used, unless not available
(which is the case on Android), in which case a fallback subproject is used.
- GObject uses libffi to implement generic marshalling functionality. With
libffi 3.7.0 or newer, GObject also caches call plans for generic marshalling.
- The optional extended attribute support in GIO requires the `getxattr()`
family of functions that may be provided by the C library or by the
standalone libattr library. To build GLib without extended attribute

282
gobject/gclosure.c
View File

@@ -170,6 +170,230 @@ enum {
POST_NOTIFY
};
#if defined(FFI_VERSION_NUMBER) && FFI_VERSION_NUMBER >= 30700
typedef struct
{
ffi_cif cif;
ffi_call_plan *plan;
ffi_type **atypes;
ffi_type *rtype;
ffi_abi abi;
guint n_args;
} GClosureMarshalCallPlan;
typedef struct
{
GMutex lock;
GHashTable *plans;
} GClosureMarshalPlanCache;
/* Like quarks, the cache and its entries live for the lifetime of the process. */
static GClosureMarshalPlanCache marshal_plan_cache;
static void
closure_marshal_call_plan_free (GClosureMarshalCallPlan *call_plan)
{
g_clear_pointer (&call_plan->plan, ffi_call_plan_free);
g_clear_pointer (&call_plan->atypes, g_free);
g_free (call_plan);
}
static GClosureMarshalCallPlan *
closure_marshal_call_plan_new (ffi_abi abi,
guint n_args,
ffi_type *rtype,
ffi_type **atypes)
{
GClosureMarshalCallPlan *call_plan;
g_assert (rtype != NULL);
g_assert (atypes != NULL);
call_plan = g_new0 (GClosureMarshalCallPlan, 1);
call_plan->atypes = g_new0 (ffi_type *, n_args);
memcpy (call_plan->atypes, atypes, sizeof (*atypes) * n_args);
call_plan->rtype = rtype;
call_plan->abi = abi;
call_plan->n_args = n_args;
if (ffi_prep_cif (&call_plan->cif,
call_plan->abi,
call_plan->n_args,
call_plan->rtype,
call_plan->atypes) != FFI_OK)
{
closure_marshal_call_plan_free (call_plan);
return NULL;
}
if (!(call_plan->plan = ffi_call_plan_alloc (&call_plan->cif)))
{
closure_marshal_call_plan_free (call_plan);
return NULL;
}
return call_plan;
}
static gboolean
closure_marshal_call_plan_matches (const GClosureMarshalCallPlan *call_plan,
ffi_abi abi,
guint n_args,
ffi_type *rtype,
ffi_type **atypes)
{
g_assert (call_plan != NULL);
g_assert (rtype != NULL);
g_assert (atypes != NULL);
return call_plan->abi == abi &&
call_plan->n_args == n_args &&
call_plan->rtype == rtype &&
memcmp (call_plan->atypes, atypes, sizeof (*atypes) * n_args) == 0;
}
static guint
closure_marshal_call_plan_hash (gconstpointer data)
{
const GClosureMarshalCallPlan *call_plan = data;
guint hash;
guint i;
hash = (guint) call_plan->abi;
hash = (hash * 33) ^ call_plan->n_args;
hash = (hash * 33) ^ g_direct_hash (call_plan->rtype);
for (i = 0; i < call_plan->n_args; i++)
hash = (hash * 33) ^ g_direct_hash (call_plan->atypes[i]);
return hash;
}
static gboolean
closure_marshal_call_plan_equal (gconstpointer data_a,
gconstpointer data_b)
{
const GClosureMarshalCallPlan *call_plan_a = data_a;
const GClosureMarshalCallPlan *call_plan_b = data_b;
return closure_marshal_call_plan_matches (call_plan_a,
call_plan_b->abi,
call_plan_b->n_args,
call_plan_b->rtype,
call_plan_b->atypes);
}
static GClosureMarshalCallPlan *
closure_marshal_plan_cache_lookup_unlocked (GClosureMarshalPlanCache *cache,
ffi_abi abi,
guint n_args,
ffi_type *rtype,
ffi_type **atypes)
{
GClosureMarshalCallPlan lookup = { 0, };
if (cache->plans == NULL)
return NULL;
lookup.atypes = atypes;
lookup.rtype = rtype;
lookup.abi = abi;
lookup.n_args = n_args;
return g_hash_table_lookup (cache->plans, &lookup);
}
static GClosureMarshalCallPlan *
closure_marshal_plan_cache_get (ffi_abi abi,
guint n_args,
ffi_type *rtype,
ffi_type **atypes)
{
GClosureMarshalCallPlan *call_plan;
GClosureMarshalCallPlan *candidate;
g_mutex_lock (&marshal_plan_cache.lock);
call_plan = closure_marshal_plan_cache_lookup_unlocked (&marshal_plan_cache,
abi,
n_args,
rtype,
atypes);
g_mutex_unlock (&marshal_plan_cache.lock);
if (call_plan != NULL)
return call_plan;
if (!(candidate = closure_marshal_call_plan_new (abi, n_args, rtype, atypes)))
return NULL;
g_mutex_lock (&marshal_plan_cache.lock);
if (marshal_plan_cache.plans == NULL)
marshal_plan_cache.plans =
g_hash_table_new_full (closure_marshal_call_plan_hash,
closure_marshal_call_plan_equal,
(GDestroyNotify) closure_marshal_call_plan_free,
NULL);
call_plan = closure_marshal_plan_cache_lookup_unlocked (&marshal_plan_cache,
abi,
n_args,
rtype,
atypes);
if (call_plan == NULL)
{
call_plan = g_steal_pointer (&candidate);
g_hash_table_add (marshal_plan_cache.plans, call_plan);
}
g_mutex_unlock (&marshal_plan_cache.lock);
g_clear_pointer (&candidate, closure_marshal_call_plan_free);
return call_plan;
}
static gboolean
closure_marshal_call_plan_invoke (GClosure *closure,
ffi_abi abi,
guint n_args,
ffi_type *rtype,
ffi_type **atypes,
void (*callback) (void),
void *rvalue,
void **args)
{
GRealClosure *real_closure;
GClosureMarshalCallPlan *call_plan;
g_assert (closure != NULL);
g_assert (rtype != NULL);
g_assert (atypes != NULL);
g_assert (callback != NULL);
g_assert (args != NULL);
real_closure = G_REAL_CLOSURE (closure);
call_plan = g_atomic_pointer_get (&real_closure->marshal_call_plan);
if (call_plan == NULL ||
!closure_marshal_call_plan_matches (call_plan, abi, n_args, rtype, atypes))
{
if (!(call_plan = closure_marshal_plan_cache_get (abi, n_args, rtype, atypes)))
return FALSE;
/* Concurrent invocations may cache different signatures; each uses its
* own local plan, and the next invocation checks the cached signature. */
g_atomic_pointer_set (&real_closure->marshal_call_plan, call_plan);
}
ffi_call_plan_invoke (call_plan->plan, callback, rvalue, args);
return TRUE;
}
#endif /* FFI_VERSION_NUMBER >= 30700 */
/* --- functions --- */
/**
@@ -1696,10 +1920,30 @@ g_cclosure_marshal_generic (GClosure *closure,
g_assert (n_args <= UINT_MAX);
#if defined(FFI_VERSION_NUMBER) && FFI_VERSION_NUMBER >= 30700
if (!closure_marshal_call_plan_invoke (closure,
FFI_DEFAULT_ABI,
(guint) n_args,
rtype,
atypes,
FFI_FN (marshal_data ? marshal_data : cc->callback),
rvalue,
args))
{
if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, (unsigned int) n_args, rtype, atypes) != FFI_OK)
return;
ffi_call (&cif,
FFI_FN (marshal_data ? marshal_data : cc->callback),
rvalue,
args);
}
#else
if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, (unsigned int) n_args, rtype, atypes) != FFI_OK)
return;
ffi_call (&cif, marshal_data ? marshal_data : cc->callback, rvalue, args);
ffi_call (&cif, FFI_FN (marshal_data ? marshal_data : cc->callback), rvalue, args);
#endif
if (return_gvalue && G_VALUE_TYPE (return_gvalue))
value_from_ffi_type (return_gvalue, rvalue);
@@ -1748,6 +1992,7 @@ g_cclosure_marshal_generic_va (GClosure *closure,
gint *enum_tmpval;
gpointer *pointer_tmpval;
gboolean tmpval_used = FALSE;
gboolean call_succeeded = FALSE;
va_list args_copy;
GValue *value_storage;
@@ -1828,10 +2073,33 @@ g_cclosure_marshal_generic_va (GClosure *closure,
g_assert (n_args <= UINT_MAX);
if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, (unsigned int) n_args, rtype, atypes) != FFI_OK)
return;
ffi_call (&cif, marshal_data ? marshal_data : cc->callback, rvalue, args);
#if defined(FFI_VERSION_NUMBER) && FFI_VERSION_NUMBER >= 30700
if (closure_marshal_call_plan_invoke (closure,
FFI_DEFAULT_ABI,
(guint) n_args,
rtype,
atypes,
FFI_FN (marshal_data ? marshal_data : cc->callback),
rvalue,
args))
{
call_succeeded = TRUE;
}
else if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, (unsigned int) n_args, rtype, atypes) == FFI_OK)
{
ffi_call (&cif,
FFI_FN (marshal_data ? marshal_data : cc->callback),
rvalue,
args);
call_succeeded = TRUE;
}
#else
if (ffi_prep_cif (&cif, FFI_DEFAULT_ABI, (unsigned int) n_args, rtype, atypes) == FFI_OK)
{
ffi_call (&cif, FFI_FN (marshal_data ? marshal_data : cc->callback), rvalue, args);
call_succeeded = TRUE;
}
#endif
/* Unbox non-primitive arguments */
for (i = 0; i < unsigned_n_params; i++)
@@ -1855,7 +2123,7 @@ g_cclosure_marshal_generic_va (GClosure *closure,
if (fundamental == G_TYPE_OBJECT && storage[i]._gpointer != NULL)
g_object_unref (storage[i]._gpointer);
}
if (return_value && G_VALUE_TYPE (return_value))
if (call_succeeded && return_value && G_VALUE_TYPE (return_value))
value_from_ffi_type (return_value, rvalue);
}

1
gobject/gtype-private.h
View File

@@ -58,6 +58,7 @@ struct _GRealClosure
gpointer meta_marshal_data;
GVaClosureMarshal va_meta_marshal;
GVaClosureMarshal va_marshal;
gpointer marshal_call_plan; /* (atomic) */
GClosure closure;
};

19
subprojects/libffi.wrap
View File

@@ -1,13 +1,14 @@
[wrap-file]
directory = libffi-3.5.2
source_url = https://github.com/libffi/libffi/releases/download/v3.5.2/libffi-3.5.2.tar.gz
source_filename = libffi-3.5.2.tar.gz
source_hash = f3a3082a23b37c293a4fcd1053147b371f2ff91fa7ea1b2a52e335676bac82dc
patch_filename = libffi_3.5.2-1_patch.zip
patch_url = https://wrapdb.mesonbuild.com/v2/libffi_3.5.2-1/get_patch
patch_hash = 1ee3035d92e4df3541d0b2b8d192d2fa183b46e4a3d68c00d8f71ede354bee74
source_fallback_url = https://github.com/mesonbuild/wrapdb/releases/download/libffi_3.5.2-1/libffi-3.5.2.tar.gz
wrapdb_version = 3.5.2-1
directory = libffi-3.7.1
source_url = https://github.com/libffi/libffi/releases/download/v3.7.1/libffi-3.7.1.tar.gz
source_filename = libffi-3.7.1.tar.gz
source_hash = d5e9a6638ddbd2513ddb54518eb67e4bbe6fa707bcc01c10f6212f0a088d819d
source_fallback_url = https://wrapdb.mesonbuild.com/v2/libffi_3.7.1-1/get_source/libffi-3.7.1.tar.gz
patch_filename = libffi_3.7.1-1_patch.zip
patch_url = https://wrapdb.mesonbuild.com/v2/libffi_3.7.1-1/get_patch
patch_fallback_url = https://github.com/mesonbuild/wrapdb/releases/download/libffi_3.7.1-1/libffi_3.7.1-1_patch.zip
patch_hash = 7c5397bbfd026a5b9aac87e8aea58a6098329b4ee13243e3a9c8f49978418fac
wrapdb_version = 3.7.1-1
[provide]
dependency_names = libffi

21
tools/glib.supp
View File

@@ -84,6 +84,25 @@
fun:g_quark_init
}
# Cached libffi call plans and their hash table live for the process lifetime.
{
gobject-marshal-plan-cache-malloc
Memcheck:Leak
match-leak-kinds:reachable
fun:malloc
...
fun:closure_marshal_plan_cache_get
}
{
gobject-marshal-plan-cache-calloc
Memcheck:Leak
match-leak-kinds:reachable
fun:calloc
...
fun:closure_marshal_plan_cache_get
}
{
gobject-init-malloc
Memcheck:Leak
@@ -1362,4 +1381,4 @@
fun:malloc
...
fun:g_test_print_handler_full
}
}