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#include "Python.h"
#include "pycore_lock.h"
#include "pycore_critical_section.h"
static_assert(_Alignof(_PyCriticalSection) >= 4,
"critical section must be aligned to at least 4 bytes");
void
_PyCriticalSection_BeginSlow(_PyCriticalSection *c, PyMutex *m)
{
PyThreadState *tstate = _PyThreadState_GET();
c->mutex = NULL;
c->prev = (uintptr_t)tstate->critical_section;
tstate->critical_section = (uintptr_t)c;
_PyMutex_LockSlow(m);
c->mutex = m;
}
void
_PyCriticalSection2_BeginSlow(_PyCriticalSection2 *c, PyMutex *m1, PyMutex *m2,
int is_m1_locked)
{
PyThreadState *tstate = _PyThreadState_GET();
c->base.mutex = NULL;
c->mutex2 = NULL;
c->base.prev = tstate->critical_section;
tstate->critical_section = (uintptr_t)c | _Py_CRITICAL_SECTION_TWO_MUTEXES;
if (!is_m1_locked) {
PyMutex_Lock(m1);
}
PyMutex_Lock(m2);
c->base.mutex = m1;
c->mutex2 = m2;
}
static _PyCriticalSection *
untag_critical_section(uintptr_t tag)
{
return (_PyCriticalSection *)(tag & ~_Py_CRITICAL_SECTION_MASK);
}
// Release all locks held by critical sections. This is called by
// _PyThreadState_Detach.
void
_PyCriticalSection_SuspendAll(PyThreadState *tstate)
{
uintptr_t *tagptr = &tstate->critical_section;
while (_PyCriticalSection_IsActive(*tagptr)) {
_PyCriticalSection *c = untag_critical_section(*tagptr);
if (c->mutex) {
PyMutex_Unlock(c->mutex);
if ((*tagptr & _Py_CRITICAL_SECTION_TWO_MUTEXES)) {
_PyCriticalSection2 *c2 = (_PyCriticalSection2 *)c;
if (c2->mutex2) {
PyMutex_Unlock(c2->mutex2);
}
}
}
*tagptr |= _Py_CRITICAL_SECTION_INACTIVE;
tagptr = &c->prev;
}
}
void
_PyCriticalSection_Resume(PyThreadState *tstate)
{
uintptr_t p = tstate->critical_section;
_PyCriticalSection *c = untag_critical_section(p);
assert(!_PyCriticalSection_IsActive(p));
PyMutex *m1 = c->mutex;
c->mutex = NULL;
PyMutex *m2 = NULL;
_PyCriticalSection2 *c2 = NULL;
if ((p & _Py_CRITICAL_SECTION_TWO_MUTEXES)) {
c2 = (_PyCriticalSection2 *)c;
m2 = c2->mutex2;
c2->mutex2 = NULL;
}
if (m1) {
PyMutex_Lock(m1);
}
if (m2) {
PyMutex_Lock(m2);
}
c->mutex = m1;
if (m2) {
c2->mutex2 = m2;
}
tstate->critical_section &= ~_Py_CRITICAL_SECTION_INACTIVE;
}
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