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gh-115432: Add critical section variant that handles a NULL object (#115433) 

This adds `Py_XBEGIN_CRITICAL_SECTION` and
`Py_XEND_CRITICAL_SECTION`, which accept a possibly NULL object as an
argument. If the argument is NULL, then nothing is locked or unlocked.
Otherwise, they behave like `Py_BEGIN/END_CRITICAL_SECTION`.
This commit is contained in:
Sam Gross 2024-02-15 08:37:54 -05:00 committed by GitHub
parent b0e5c35ded
commit ad4f909e0e
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2 changed files with 38 additions and 0 deletions
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29
Include/internal/pycore_critical_section.h
View File

@ -96,6 +96,15 @@ extern "C" {
_PyCriticalSection_End(&_cs); \
}
# define Py_XBEGIN_CRITICAL_SECTION(op) \
{ \
_PyCriticalSection _cs_opt = {0}; \
_PyCriticalSection_XBegin(&_cs_opt, _PyObject_CAST(op))
# define Py_XEND_CRITICAL_SECTION() \
_PyCriticalSection_XEnd(&_cs_opt); \
}
# define Py_BEGIN_CRITICAL_SECTION2(a, b) \
{ \
_PyCriticalSection2 _cs2; \
@ -131,6 +140,8 @@ extern "C" {
// The critical section APIs are no-ops with the GIL.
# define Py_BEGIN_CRITICAL_SECTION(op)
# define Py_END_CRITICAL_SECTION()
# define Py_XBEGIN_CRITICAL_SECTION(op)
# define Py_XEND_CRITICAL_SECTION()
# define Py_BEGIN_CRITICAL_SECTION2(a, b)
# define Py_END_CRITICAL_SECTION2()
# define _Py_CRITICAL_SECTION_ASSERT_MUTEX_LOCKED(mutex)
@ -187,6 +198,16 @@ _PyCriticalSection_Begin(_PyCriticalSection *c, PyMutex *m)
}
}
static inline void
_PyCriticalSection_XBegin(_PyCriticalSection *c, PyObject *op)
{
#ifdef Py_GIL_DISABLED
if (op != NULL) {
_PyCriticalSection_Begin(c, &_PyObject_CAST(op)->ob_mutex);
}
#endif
}
// Removes the top-most critical section from the thread's stack of critical
// sections. If the new top-most critical section is inactive, then it is
// resumed.
@ -209,6 +230,14 @@ _PyCriticalSection_End(_PyCriticalSection *c)
_PyCriticalSection_Pop(c);
}
static inline void
_PyCriticalSection_XEnd(_PyCriticalSection *c)
{
if (c->mutex) {
_PyCriticalSection_End(c);
}
}
static inline void
_PyCriticalSection2_Begin(_PyCriticalSection2 *c, PyMutex *m1, PyMutex *m2)
{

9
Modules/_testinternalcapi/test_critical_sections.c
View File

@ -49,6 +49,15 @@ test_critical_sections(PyObject *self, PyObject *Py_UNUSED(args))
Py_END_CRITICAL_SECTION2();
assert_nogil(!PyMutex_IsLocked(&d2->ob_mutex));
// Optional variant behaves the same if the object is non-NULL
Py_XBEGIN_CRITICAL_SECTION(d1);
assert_nogil(PyMutex_IsLocked(&d1->ob_mutex));
Py_XEND_CRITICAL_SECTION();
// No-op
Py_XBEGIN_CRITICAL_SECTION(NULL);
Py_XEND_CRITICAL_SECTION();
Py_DECREF(d2);
Py_DECREF(d1);
Py_RETURN_NONE;