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bitlock: factor out duplicated futex wait/wake functions

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This commit is contained in:
Thomas Haller
2025-04-04 10:25:04 +02:00
parent 493b9c49af
commit 90e6e2b528
1 changed files with 40 additions and 49 deletions
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89
glib/gbitlock.c
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@@ -176,7 +176,7 @@ g_futex_wake (const gint *address)
static gint g_bit_lock_contended[CONTENTION_CLASSES]; /* (atomic) */
G_ALWAYS_INLINE static inline guint
bit_lock_contended_class (gpointer address)
bit_lock_contended_class (gconstpointer address)
{
return ((gsize) address) % G_N_ELEMENTS (g_bit_lock_contended);
}
@@ -187,6 +187,37 @@ bit_lock_contended_class (gpointer address)
#endif
#endif
static const gint *g_futex_int_address (const void *address);
G_ALWAYS_INLINE static inline void
bit_lock_futex_wait (gconstpointer address, gboolean is_pointer_pointer, gint value)
{
const guint CLASS = bit_lock_contended_class (address);
g_atomic_int_add (&g_bit_lock_contended[CLASS], +1);
if (is_pointer_pointer)
address = g_futex_int_address (address);
g_futex_wait (address, value);
g_atomic_int_add (&g_bit_lock_contended[CLASS], -1);
}
G_ALWAYS_INLINE static inline void
bit_lock_futex_maybe_wake (gconstpointer address, gboolean is_pointer_pointer)
{
const guint CLASS = bit_lock_contended_class (address);
/* Warning: unlocking may allow another thread to proceed and destroy the
* memory that @address points to. We thus must not dereference it anymore.
*/
if (g_atomic_int_get (&g_bit_lock_contended[CLASS]))
{
if (is_pointer_pointer)
address = g_futex_int_address (address);
g_futex_wake (address);
}
}
/**
* g_bit_lock_and_get:
* @address: a pointer to an integer
@@ -232,13 +263,7 @@ g_bit_lock_and_get (gint *address,
v = (guint) g_atomic_int_get (address);
if (v & MASK)
{
guint class = bit_lock_contended_class (address);
g_atomic_int_add (&g_bit_lock_contended[class], +1);
g_futex_wait (address, v);
g_atomic_int_add (&g_bit_lock_contended[class], -1);
}
bit_lock_futex_wait (address, FALSE, (gint) v);
}
}
}
@@ -247,14 +272,8 @@ g_bit_lock_and_get (gint *address,
retry:
v = g_atomic_int_or ((guint *) address, MASK);
if (v & MASK)
/* already locked */
{
guint class = bit_lock_contended_class (address);
g_atomic_int_add (&g_bit_lock_contended[class], +1);
g_futex_wait (address, v);
g_atomic_int_add (&g_bit_lock_contended[class], -1);
bit_lock_futex_wait (address, FALSE, (gint) v);
goto retry;
}
@@ -376,13 +395,7 @@ g_bit_unlock (volatile gint *address,
/* Warning: unlocking may allow another thread to proceed and destroy the
* memory that @address points to. We thus must not dereference it anymore.
*/
{
guint class = bit_lock_contended_class (address_nonvolatile);
if (g_atomic_int_get (&g_bit_lock_contended[class]))
g_futex_wake (address_nonvolatile);
}
bit_lock_futex_maybe_wake (address_nonvolatile, FALSE);
}
/**
@@ -436,13 +449,7 @@ g_bit_unlock_and_set (gint *address,
/* Warning: unlocking may allow another thread to proceed and destroy the
* memory that @address points to. We thus must not dereference it anymore.
*/
{
guint class = bit_lock_contended_class (address);
if (g_atomic_int_get (&g_bit_lock_contended[class]))
g_futex_wake (address);
}
bit_lock_futex_maybe_wake (address, FALSE);
}
/* We emulate pointer-sized futex(2) because the kernel API only
@@ -534,7 +541,6 @@ void
guint lock_bit,
guintptr *out_ptr)
{
guint class = bit_lock_contended_class (address);
guintptr mask;
guintptr v;
@@ -558,11 +564,7 @@ void
contended:
v = (guintptr) g_atomic_pointer_get ((gpointer *) address);
if (v & mask)
{
g_atomic_int_add (&g_bit_lock_contended[class], +1);
g_futex_wait (g_futex_int_address (address), v);
g_atomic_int_add (&g_bit_lock_contended[class], -1);
}
bit_lock_futex_wait (address, TRUE, (gint) v);
}
}
#endif
@@ -570,11 +572,8 @@ void
retry:
v = g_atomic_pointer_or ((gpointer *) address, mask);
if (v & mask)
/* already locked */
{
g_atomic_int_add (&g_bit_lock_contended[class], +1);
g_futex_wait (g_futex_int_address (address), (guint) v);
g_atomic_int_add (&g_bit_lock_contended[class], -1);
bit_lock_futex_wait (address, TRUE, (gint) v);
goto retry;
}
@@ -696,13 +695,7 @@ void
/* Warning: unlocking may allow another thread to proceed and destroy the
* memory that @address points to. We thus must not dereference it anymore.
*/
{
guint class = bit_lock_contended_class (address_nonvolatile);
if (g_atomic_int_get (&g_bit_lock_contended[class]))
g_futex_wake (g_futex_int_address (address_nonvolatile));
}
bit_lock_futex_maybe_wake (address_nonvolatile, TRUE);
}
}
@@ -762,7 +755,6 @@ void (g_pointer_bit_unlock_and_set) (void *address,
guintptr preserve_mask)
{
gpointer *pointer_address = address;
guint class = bit_lock_contended_class (address);
gpointer ptr2;
g_return_if_fail (lock_bit < 32u);
@@ -782,8 +774,7 @@ void (g_pointer_bit_unlock_and_set) (void *address,
g_atomic_pointer_set (pointer_address, ptr2);
}
if (g_atomic_int_get (&g_bit_lock_contended[class]) > 0)
g_futex_wake (g_futex_int_address (address));
bit_lock_futex_maybe_wake (address, TRUE);
/* It makes no sense, if unlocking mangles the pointer. Assert against
* that.