bpo-43760: Add PyThreadState_EnterTracing() (GH-28542)

Add PyThreadState_EnterTracing() and PyThreadState_LeaveTracing()
functions to the limited C API to suspend and resume tracing and
profiling.

Add an unit test on the PyThreadState C API to _testcapi.

Add also internal _PyThreadState_DisableTracing() and
_PyThreadState_ResetTracing().

1 files changed, 61 insertions, 6 deletions

diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 82cfc04..6857241 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -18,29 +18,32 @@
 #define PY_SSIZE_T_CLEAN
 
 #include "Python.h"
-#include "datetime.h"
-#include "marshal.h"
+#include "frameobject.h"          // PyFrame_Check()
+#include "datetime.h"             // PyDateTimeAPI
+#include "marshal.h"              // PyMarshal_WriteLongToFile
 #include "structmember.h"         // PyMemberDef
-#include <float.h>
+#include <float.h>                // FLT_MAX
 #include <signal.h>
 
 #ifdef MS_WINDOWS
-#  include <winsock2.h>         /* struct timeval */
+#  include <winsock2.h>           // struct timeval
 #endif
 
 #ifdef HAVE_SYS_WAIT_H
-#include <sys/wait.h>           /* For W_STOPCODE */
+#include <sys/wait.h>             // W_STOPCODE
 #endif
 
 #ifdef Py_BUILD_CORE
 #  error "_testcapi must test the public Python C API, not CPython internal C API"
 #endif
 
+
+// Forward declarations
 static struct PyModuleDef _testcapimodule;
 static PyType_Spec HeapTypeNameType_Spec;
-
 static PyObject *TestError;     /* set to exception object in init */
 
+
 /* Raise TestError with test_name + ": " + msg, and return NULL. */
 
 static PyObject *
@@ -5674,6 +5677,57 @@ type_get_version(PyObject *self, PyObject *type)
 }
 
 
+// Test PyThreadState C API
+static PyObject *
+test_tstate_capi(PyObject *self, PyObject *Py_UNUSED(args))
+{
+    // PyThreadState_Get()
+    PyThreadState *tstate = PyThreadState_Get();
+    assert(tstate != NULL);
+
+    // PyThreadState_GET()
+    PyThreadState *tstate2 = PyThreadState_Get();
+    assert(tstate2 == tstate);
+
+    // private _PyThreadState_UncheckedGet()
+    PyThreadState *tstate3 = _PyThreadState_UncheckedGet();
+    assert(tstate3 == tstate);
+
+    // PyThreadState_EnterTracing(), PyThreadState_LeaveTracing()
+    PyThreadState_EnterTracing(tstate);
+    PyThreadState_LeaveTracing(tstate);
+
+    // PyThreadState_GetDict(): no tstate argument
+    PyObject *dict = PyThreadState_GetDict();
+    // PyThreadState_GetDict() API can return NULL if PyDict_New() fails,
+    // but it should not occur in practice.
+    assert(dict != NULL);
+    assert(PyDict_Check(dict));
+    // dict is a borrowed reference
+
+    // private _PyThreadState_GetDict()
+    PyObject *dict2 = _PyThreadState_GetDict(tstate);
+    assert(dict2 == dict);
+    // dict2 is a borrowed reference
+
+    // PyThreadState_GetInterpreter()
+    PyInterpreterState *interp = PyThreadState_GetInterpreter(tstate);
+    assert(interp != NULL);
+
+    // PyThreadState_GetFrame()
+    PyFrameObject*frame = PyThreadState_GetFrame(tstate);
+    assert(frame != NULL);
+    assert(PyFrame_Check(frame));
+    Py_DECREF(frame);
+
+    // PyThreadState_GetID()
+    uint64_t id = PyThreadState_GetID(tstate);
+    assert(id >= 1);
+
+    Py_RETURN_NONE;
+}
+
+
 static PyObject *test_buildvalue_issue38913(PyObject *, PyObject *);
 static PyObject *getargs_s_hash_int(PyObject *, PyObject *, PyObject*);
 
@@ -5957,6 +6011,7 @@ static PyMethodDef TestMethods[] = {
     {"fatal_error", test_fatal_error, METH_VARARGS,
      PyDoc_STR("fatal_error(message, release_gil=False): call Py_FatalError(message)")},
     {"type_get_version", type_get_version, METH_O, PyDoc_STR("type->tp_version_tag")},
+    {"test_tstate_capi", test_tstate_capi, METH_NOARGS, NULL},
     {NULL, NULL} /* sentinel */
 };