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Merge branch 'gatomic-exchange' into 'main'

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gatomic: Add APIs to perform atomic int / pointer exchanges

See merge request GNOME/glib!2726
This commit is contained in:
Philip Withnall 2022-06-07 15:30:34 +00:00
commit d7c3b0fbf2
6 changed files with 235 additions and 0 deletions
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2
docs/reference/glib/glib-sections.txt
View File

@ -1273,6 +1273,7 @@ g_atomic_int_set
g_atomic_int_inc
g_atomic_int_dec_and_test
g_atomic_int_compare_and_exchange
g_atomic_int_exchange
g_atomic_int_add
g_atomic_int_and
g_atomic_int_or
@ -1282,6 +1283,7 @@ g_atomic_int_xor
g_atomic_pointer_get
g_atomic_pointer_set
g_atomic_pointer_compare_and_exchange
g_atomic_pointer_exchange
g_atomic_pointer_add
g_atomic_pointer_and
g_atomic_pointer_or

94
glib/gatomic.c
View File

@ -218,6 +218,31 @@ gboolean
return g_atomic_int_compare_and_exchange (atomic, oldval, newval);
}
/**
* g_atomic_int_exchange:
* @atomic: a pointer to a #gint or #guint
* @newval: the value to replace with
*
* Sets the @atomic to @newval and returns the old value from @atomic.
*
* This exchange is done atomically.
*
* Think of this operation as an atomic version of
* `{ tmp = *atomic; *atomic = val; return tmp; }`.
*
* This call acts as a full compiler and hardware memory barrier.
*
* Returns: the value of @atomic before the exchange, signed
*
* Since: 2.74
**/
gint
(g_atomic_int_exchange) (gint *atomic,
gint newval)
{
return g_atomic_int_exchange (atomic, newval);
}
/**
* g_atomic_int_add:
* @atomic: a pointer to a #gint or #guint
@ -405,6 +430,31 @@ gboolean
oldval, newval);
}
/**
* g_atomic_pointer_exchange:
* @atomic: a pointer to a #gint or #guint
* @newval: the value to replace with
*
* Sets the @atomic to @newval and returns the old value from @atomic.
*
* This exchange is done atomically.
*
* Think of this operation as an atomic version of
* `{ tmp = *atomic; *atomic = val; return tmp; }`.
*
* This call acts as a full compiler and hardware memory barrier.
*
* Returns: the value of @atomic before the exchange, signed
*
* Since: 2.74
**/
gpointer
(g_atomic_pointer_exchange) (void *atomic,
gpointer newval)
{
return g_atomic_pointer_exchange ((gpointer *) atomic, newval);
}
/**
* g_atomic_pointer_add:
* @atomic: (not nullable): a pointer to a #gpointer-sized value
@ -609,6 +659,13 @@ gboolean
return InterlockedCompareExchange (atomic, newval, oldval) == oldval;
}
gint
(g_atomic_int_exchange) (gint *atomic,
gint newval)
{
return InterlockedExchange (atomic, newval);
}
gint
(g_atomic_int_add) (volatile gint *atomic,
gint val)
@ -665,6 +722,13 @@ gboolean
return InterlockedCompareExchangePointer (atomic, newval, oldval) == oldval;
}
gpointer
(g_atomic_pointer_exchange) (void *atomic,
gpointer newval)
{
return InterlockedExchangePointer (atomic, newval);
}
gssize
(g_atomic_pointer_add) (volatile void *atomic,
gssize val)
@ -787,6 +851,21 @@ gboolean
return success;
}
gint
(g_atomic_int_exchange) (gint *atomic,
gint newval)
{
gint *ptr = atomic;
gint oldval;
pthread_mutex_lock (&g_atomic_lock);
oldval = *ptr;
*ptr = newval;
pthread_mutex_unlock (&g_atomic_lock);
return oldval;
}
gint
(g_atomic_int_add) (volatile gint *atomic,
gint val)
@ -886,6 +965,21 @@ gboolean
return success;
}
gpointer
(g_atomic_pointer_exchange) (void *atomic,
gpointer newval)
{
gpointer *ptr = atomic;
gpointer oldval;
pthread_mutex_lock (&g_atomic_lock);
oldval = *ptr;
*ptr = newval;
pthread_mutex_unlock (&g_atomic_lock);
return oldval;
}
gssize
(g_atomic_pointer_add) (volatile void *atomic,
gssize val)

62
glib/gatomic.h
View File

@ -44,6 +44,9 @@ GLIB_AVAILABLE_IN_ALL
gboolean g_atomic_int_compare_and_exchange (volatile gint *atomic,
gint oldval,
gint newval);
GLIB_AVAILABLE_IN_2_74
gint g_atomic_int_exchange (gint *atomic,
gint newval);
GLIB_AVAILABLE_IN_ALL
gint g_atomic_int_add (volatile gint *atomic,
gint val);
@ -66,6 +69,9 @@ GLIB_AVAILABLE_IN_ALL
gboolean g_atomic_pointer_compare_and_exchange (volatile void *atomic,
gpointer oldval,
gpointer newval);
GLIB_AVAILABLE_IN_2_74
gpointer g_atomic_pointer_exchange (void *atomic,
gpointer newval);
GLIB_AVAILABLE_IN_ALL
gssize g_atomic_pointer_add (volatile void *atomic,
gssize val);
@ -173,6 +179,12 @@ G_END_DECLS
__atomic_compare_exchange_n ((atomic), (void *) (&(gaicae_oldval)), (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \
}))
#endif /* defined(glib_typeof) */
#define g_atomic_int_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) : 1); \
(gint) __atomic_exchange_n ((atomic), (newval), __ATOMIC_SEQ_CST); \
}))
#define g_atomic_int_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
@ -225,6 +237,12 @@ G_END_DECLS
__atomic_compare_exchange_n ((atomic), (void *) (&(gapcae_oldval)), (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \
}))
#endif /* defined(glib_typeof) */
#define g_atomic_pointer_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(gpointer) __atomic_exchange_n ((atomic), (newval), __ATOMIC_SEQ_CST); \
}))
#define g_atomic_pointer_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
@ -355,6 +373,26 @@ G_END_DECLS
(void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \
__sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \
}))
#if defined(__GCC_HAVE_SYNC_SWAP)
#define g_atomic_int_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) : 1); \
(gint) __sync_swap ((atomic), (newval)); \
}))
#else /* defined(__GCC_HAVE_SYNC_SWAP) */
#define g_atomic_int_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
gint oldval; \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
(void) (0 ? *(atomic) ^ (newval) : 1); \
do \
{ \
oldval = *atomic; \
} while (!__sync_bool_compare_and_swap (atomic, oldval, newval)); \
oldval; \
}))
#endif /* defined(__GCC_HAVE_SYNC_SWAP) */
#define g_atomic_int_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \
@ -386,6 +424,26 @@ G_END_DECLS
(void) (0 ? (gpointer) *(atomic) : NULL); \
__sync_bool_compare_and_swap ((atomic), (oldval), (newval)) ? TRUE : FALSE; \
}))
#if defined(__GCC_HAVE_SYNC_SWAP)
#define g_atomic_pointer_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
(gpointer) __sync_swap ((atomic), (newval)); \
}))
#else
#define g_atomic_pointer_exchange(atomic, newval) \
(G_GNUC_EXTENSION ({ \
gpointer oldval; \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
(void) (0 ? (gpointer) *(atomic) : NULL); \
do \
{ \
oldval = (gpointer) *atomic; \
} while (!__sync_bool_compare_and_swap (atomic, oldval, newval)); \
oldval; \
}))
#endif /* defined(__GCC_HAVE_SYNC_SWAP) */
#define g_atomic_pointer_add(atomic, val) \
(G_GNUC_EXTENSION ({ \
G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gpointer)); \
@ -425,6 +483,8 @@ G_END_DECLS
(g_atomic_int_set ((gint *) (atomic), (gint) (newval)))
#define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \
(g_atomic_int_compare_and_exchange ((gint *) (atomic), (oldval), (newval)))
#define g_atomic_int_exchange(atomic, newval) \
(g_atomic_int_exchange ((gint *) (atomic), (newval)))
#define g_atomic_int_add(atomic, val) \
(g_atomic_int_add ((gint *) (atomic), (val)))
#define g_atomic_int_and(atomic, val) \
@ -458,6 +518,8 @@ G_END_DECLS
#define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
(g_atomic_pointer_compare_and_exchange ((atomic), (gpointer) (oldval), (gpointer) (newval)))
#define g_atomic_pointer_exchange(atomic, newval) \
(g_atomic_pointer_exchange ((atomic), (gpointer) (newval)))
#define g_atomic_pointer_add(atomic, val) \
(g_atomic_pointer_add ((atomic), (gssize) (val)))
#define g_atomic_pointer_and(atomic, val) \

30
glib/tests/atomic.c
View File

@ -56,6 +56,9 @@ test_types (void)
u2 = g_atomic_int_xor (&u, 4);
g_assert_cmpint (u2, ==, 12);
g_assert_cmpint (u, ==, 8);
u2 = g_atomic_int_exchange (&u, 55);
g_assert_cmpint (u2, ==, 8);
g_assert_cmpint (u, ==, 55);
g_atomic_int_set (&s, 5);
s2 = g_atomic_int_get (&s);
@ -79,6 +82,9 @@ test_types (void)
s2 = (gint) g_atomic_int_xor (&s, 4);
g_assert_cmpint (s2, ==, 12);
g_assert_cmpint (s, ==, 8);
s2 = g_atomic_int_exchange (&s, 55);
g_assert_cmpint (s2, ==, 8);
g_assert_cmpint (s, ==, 55);
g_atomic_pointer_set (&vp, 0);
vp2 = g_atomic_pointer_get (&vp);
@ -89,10 +95,14 @@ test_types (void)
res = g_atomic_pointer_compare_and_exchange (&vp, NULL, NULL);
g_assert_true (res);
g_assert_true (vp == 0);
g_assert_null (g_atomic_pointer_exchange (&vp, &s));
g_assert_true (vp == &s);
g_atomic_pointer_set (&vp_str, NULL);
res = g_atomic_pointer_compare_and_exchange (&vp_str, NULL, str);
g_assert_true (res);
g_assert_cmpstr (g_atomic_pointer_exchange (&vp_str, NULL), ==, str);
g_assert_null (vp_str);
/* Note that atomic variables should almost certainly not be marked as
* `volatile` — see http://isvolatileusefulwiththreads.in/c/. This test exists
@ -130,6 +140,10 @@ test_types (void)
gs2 = g_atomic_pointer_xor (&gs, 4);
g_assert_cmpuint (gs2, ==, 12);
g_assert_cmpuint (gs, ==, 8);
vp2 = g_atomic_pointer_exchange ((gpointer*) &gs, NULL);
gs2 = (gsize) vp2;
g_assert_cmpuint (gs2, ==, 8);
g_assert_null ((gpointer) gs);
g_assert_cmpint (g_atomic_int_get (csp), ==, s);
g_assert_true (g_atomic_pointer_get ((const gint **) cspp) == csp);
@ -138,6 +152,7 @@ test_types (void)
#undef g_atomic_int_set
#undef g_atomic_int_get
#undef g_atomic_int_compare_and_exchange
#undef g_atomic_int_exchange
#undef g_atomic_int_add
#undef g_atomic_int_inc
#undef g_atomic_int_and
@ -147,6 +162,7 @@ test_types (void)
#undef g_atomic_pointer_set
#undef g_atomic_pointer_get
#undef g_atomic_pointer_compare_and_exchange
#undef g_atomic_pointer_exchange
#undef g_atomic_pointer_add
#undef g_atomic_pointer_and
#undef g_atomic_pointer_or
@ -173,6 +189,9 @@ test_types (void)
g_assert_cmpint (u, ==, 12);
u2 = g_atomic_int_xor (&u, 4);
g_assert_cmpint (u2, ==, 12);
u2 = g_atomic_int_exchange (&u, 55);
g_assert_cmpint (u2, ==, 8);
g_assert_cmpint (u, ==, 55);
g_atomic_int_set (&s, 5);
s2 = g_atomic_int_get (&s);
@ -201,6 +220,9 @@ G_GNUC_BEGIN_IGNORE_DEPRECATIONS
G_GNUC_END_IGNORE_DEPRECATIONS
g_assert_cmpint (s2, ==, 8);
g_assert_cmpint (s, ==, 9);
s2 = g_atomic_int_exchange (&s, 55);
g_assert_cmpint (s2, ==, 9);
g_assert_cmpint (s, ==, 55);
g_atomic_pointer_set (&vp, 0);
vp2 = g_atomic_pointer_get (&vp);
@ -211,6 +233,8 @@ G_GNUC_END_IGNORE_DEPRECATIONS
res = g_atomic_pointer_compare_and_exchange (&vp, NULL, NULL);
g_assert_true (res);
g_assert_true (vp == 0);
g_assert_null (g_atomic_pointer_exchange (&vp, &s));
g_assert_true (vp == &s);
g_atomic_pointer_set (&vp_str, NULL);
res = g_atomic_pointer_compare_and_exchange (&vp_str, NULL, (char *) str);
@ -222,6 +246,8 @@ G_GNUC_END_IGNORE_DEPRECATIONS
g_atomic_pointer_set (&vp_str_vol, NULL);
res = g_atomic_pointer_compare_and_exchange (&vp_str_vol, NULL, (char *) str);
g_assert_true (res);
g_assert_cmpstr (g_atomic_pointer_exchange (&vp_str, NULL), ==, str);
g_assert_null (vp_str);
g_atomic_pointer_set (&ip, 0);
ip2 = g_atomic_pointer_get (&ip);
@ -249,6 +275,10 @@ G_GNUC_END_IGNORE_DEPRECATIONS
gs2 = g_atomic_pointer_xor (&gs, 4);
g_assert_cmpuint (gs2, ==, 12);
g_assert_cmpuint (gs, ==, 8);
vp2 = g_atomic_pointer_exchange ((gpointer*) &gs, NULL);
gs2 = (gsize) vp2;
g_assert_cmpuint (gs2, ==, 8);
g_assert_null ((gpointer) gs);
g_assert_cmpint (g_atomic_int_get (csp), ==, s);
g_assert_true (g_atomic_pointer_get (cspp) == csp);

35
glib/tests/cxx.cpp
View File

@ -87,6 +87,39 @@ test_atomic_int_compare_and_exchange (void)
#endif
}
static void
test_atomic_pointer_exchange (void)
{
#if __cplusplus >= 201103L
const gchar *str1 = "str1";
const gchar *str2 = "str2";
const gchar *atomic_string = str1;
g_test_message ("Test that g_atomic_pointer_exchange() with a "
"non-void* pointer doesn’t have any compiler warnings in C++ mode");
g_assert_true (g_atomic_pointer_exchange (&atomic_string, str2) == str1);
g_assert_true (atomic_string == str2);
#else
g_test_skip ("This test requires a C++11 compiler");
#endif
}
static void
test_atomic_int_exchange (void)
{
#if __cplusplus >= 201103L
gint atomic_int = 5;
g_test_message ("Test that g_atomic_int_compare_and_exchange() doesn’t have "
"any compiler warnings in C++ mode");
g_assert_cmpint (g_atomic_int_exchange (&atomic_int, 50), ==, 5);
#else
g_test_skip ("This test requires a C++11 compiler");
#endif
}
int
main (int argc, char *argv[])
{
@ -99,6 +132,8 @@ main (int argc, char *argv[])
g_test_add_func ("/C++/typeof", test_typeof);
g_test_add_func ("/C++/atomic-pointer-compare-and-exchange", test_atomic_pointer_compare_and_exchange);
g_test_add_func ("/C++/atomic-int-compare-and-exchange", test_atomic_int_compare_and_exchange);
g_test_add_func ("/C++/atomic-pointer-exchange", test_atomic_pointer_exchange);
g_test_add_func ("/C++/atomic-int-exchange", test_atomic_int_exchange);
return g_test_run ();
}

12
meson.build
View File

@ -1840,6 +1840,18 @@ if cc.get_id() == 'msvc' or cc.get_id() == 'clang-cl' or cc.links(atomictest, na
# __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
glib_conf.set('__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4', true)
endif
if cc.get_id() == 'gcc' or cc.get_id() == 'clang'
sync_swap_test = '''
int main() {
int atomic = 2;
__sync_swap (&atomic, 2);
return 0;
}
'''
glib_conf.set('__GCC_HAVE_SYNC_SWAP', cc.links(sync_swap_test, name : 'sync swap'))
endif
else
have_atomic_lock_free = false
if host_machine.cpu_family() == 'x86' and cc.links(atomictest, args : '-march=i486')