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[3.13] gh-117511: Make PyMutex public in the non-limited API (GH-117731) (#120800)

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(cherry picked from commit 3af7263037)
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Sam Gross 2024-06-20 12:00:25 -04:00 • committed by GitHub
parent 7c7aa5a99c
commit 3cb6c4cd60
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GPG key ID: B5690EEEBB952194
18 changed files with 185 additions and 110 deletions
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52
Python/lock.c
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@ -47,18 +47,12 @@ _Py_yield(void)
#endif
}
void
_PyMutex_LockSlow(PyMutex *m)
{
_PyMutex_LockTimed(m, -1, _PY_LOCK_DETACH);
}
PyLockStatus
_PyMutex_LockTimed(PyMutex *m, PyTime_t timeout, _PyLockFlags flags)
{
uint8_t v = _Py_atomic_load_uint8_relaxed(&m->v);
uint8_t v = _Py_atomic_load_uint8_relaxed(&m->_bits);
if ((v & _Py_LOCKED) == 0) {
if (_Py_atomic_compare_exchange_uint8(&m->v, &v, v|_Py_LOCKED)) {
if (_Py_atomic_compare_exchange_uint8(&m->_bits, &v, v|_Py_LOCKED)) {
return PY_LOCK_ACQUIRED;
}
}
@ -83,7 +77,7 @@ _PyMutex_LockTimed(PyMutex *m, PyTime_t timeout, _PyLockFlags flags)
for (;;) {
if ((v & _Py_LOCKED) == 0) {
// The lock is unlocked. Try to grab it.
if (_Py_atomic_compare_exchange_uint8(&m->v, &v, v|_Py_LOCKED)) {
if (_Py_atomic_compare_exchange_uint8(&m->_bits, &v, v|_Py_LOCKED)) {
return PY_LOCK_ACQUIRED;
}
continue;
@ -104,17 +98,17 @@ _PyMutex_LockTimed(PyMutex *m, PyTime_t timeout, _PyLockFlags flags)
if (!(v & _Py_HAS_PARKED)) {
// We are the first waiter. Set the _Py_HAS_PARKED flag.
newv = v | _Py_HAS_PARKED;
if (!_Py_atomic_compare_exchange_uint8(&m->v, &v, newv)) {
if (!_Py_atomic_compare_exchange_uint8(&m->_bits, &v, newv)) {
continue;
}
}
int ret = _PyParkingLot_Park(&m->v, &newv, sizeof(newv), timeout,
int ret = _PyParkingLot_Park(&m->_bits, &newv, sizeof(newv), timeout,
&entry, (flags & _PY_LOCK_DETACH) != 0);
if (ret == Py_PARK_OK) {
if (entry.handed_off) {
// We own the lock now.
assert(_Py_atomic_load_uint8_relaxed(&m->v) & _Py_LOCKED);
assert(_Py_atomic_load_uint8_relaxed(&m->_bits) & _Py_LOCKED);
return PY_LOCK_ACQUIRED;
}
}
@ -136,7 +130,7 @@ _PyMutex_LockTimed(PyMutex *m, PyTime_t timeout, _PyLockFlags flags)
}
}
v = _Py_atomic_load_uint8_relaxed(&m->v);
v = _Py_atomic_load_uint8_relaxed(&m->_bits);
}
}
@ -158,13 +152,13 @@ mutex_unpark(PyMutex *m, struct mutex_entry *entry, int has_more_waiters)
v |= _Py_HAS_PARKED;
}
}
_Py_atomic_store_uint8(&m->v, v);
_Py_atomic_store_uint8(&m->_bits, v);
}
int
_PyMutex_TryUnlock(PyMutex *m)
{
uint8_t v = _Py_atomic_load_uint8(&m->v);
uint8_t v = _Py_atomic_load_uint8(&m->_bits);
for (;;) {
if ((v & _Py_LOCKED) == 0) {
// error: the mutex is not locked
@ -172,24 +166,16 @@ _PyMutex_TryUnlock(PyMutex *m)
}
else if ((v & _Py_HAS_PARKED)) {
// wake up a single thread
_PyParkingLot_Unpark(&m->v, (_Py_unpark_fn_t *)mutex_unpark, m);
_PyParkingLot_Unpark(&m->_bits, (_Py_unpark_fn_t *)mutex_unpark, m);
return 0;
}
else if (_Py_atomic_compare_exchange_uint8(&m->v, &v, _Py_UNLOCKED)) {
else if (_Py_atomic_compare_exchange_uint8(&m->_bits, &v, _Py_UNLOCKED)) {
// fast-path: no waiters
return 0;
}
}
}
void
_PyMutex_UnlockSlow(PyMutex *m)
{
if (_PyMutex_TryUnlock(m) < 0) {
Py_FatalError("unlocking mutex that is not locked");
}
}
// _PyRawMutex stores a linked list of `struct raw_mutex_entry`, one for each
// thread waiting on the mutex, directly in the mutex itself.
struct raw_mutex_entry {
@ -584,3 +570,19 @@ uint32_t _PySeqLock_AfterFork(_PySeqLock *seqlock)
return 0;
}
#undef PyMutex_Lock
void
PyMutex_Lock(PyMutex *m)
{
_PyMutex_LockTimed(m, -1, _PY_LOCK_DETACH);
}
#undef PyMutex_Unlock
void
PyMutex_Unlock(PyMutex *m)
{
if (_PyMutex_TryUnlock(m) < 0) {
Py_FatalError("unlocking mutex that is not locked");
}
}