Include/cpython/pystate.h

#ifndef Py_CPYTHON_PYSTATE_H
#  error "this header file must not be included directly"
#endif

#ifdef __cplusplus
extern "C" {
#endif

/* Placeholders while working on the new configuration API
 *
 * See PEP 432 for final anticipated contents
 */
typedef struct {
    int install_signal_handlers;   /* Install signal handlers? -1 means unset */
    PyObject *argv;                /* sys.argv list, can be NULL */
    PyObject *executable;          /* sys.executable str */
    PyObject *prefix;              /* sys.prefix str */
    PyObject *base_prefix;         /* sys.base_prefix str, can be NULL */
    PyObject *exec_prefix;         /* sys.exec_prefix str */
    PyObject *base_exec_prefix;    /* sys.base_exec_prefix str, can be NULL */
    PyObject *warnoptions;         /* sys.warnoptions list, can be NULL */
    PyObject *xoptions;            /* sys._xoptions dict, can be NULL */
    PyObject *module_search_path;  /* sys.path list */
    PyObject *pycache_prefix;      /* sys.pycache_prefix str, can be NULL */
} _PyMainInterpreterConfig;

#define _PyMainInterpreterConfig_INIT \
    (_PyMainInterpreterConfig){.install_signal_handlers = -1}
/* Note: _PyMainInterpreterConfig_INIT sets other fields to 0/NULL */

PyAPI_FUNC(_PyCoreConfig *) _PyInterpreterState_GetCoreConfig(PyInterpreterState *);
PyAPI_FUNC(_PyMainInterpreterConfig *) _PyInterpreterState_GetMainConfig(PyInterpreterState *);


/* State unique per thread */

/* Py_tracefunc return -1 when raising an exception, or 0 for success. */
typedef int (*Py_tracefunc)(PyObject *, struct _frame *, int, PyObject *);

/* The following values are used for 'what' for tracefunc functions
 *
 * To add a new kind of trace event, also update "trace_init" in
 * Python/sysmodule.c to define the Python level event name
 */
#define PyTrace_CALL 0
#define PyTrace_EXCEPTION 1
#define PyTrace_LINE 2
#define PyTrace_RETURN 3
#define PyTrace_C_CALL 4
#define PyTrace_C_EXCEPTION 5
#define PyTrace_C_RETURN 6
#define PyTrace_OPCODE 7


typedef struct _err_stackitem {
    /* This struct represents an entry on the exception stack, which is a
     * per-coroutine state. (Coroutine in the computer science sense,
     * including the thread and generators).
     * This ensures that the exception state is not impacted by "yields"
     * from an except handler.
     */
    PyObject *exc_type, *exc_value, *exc_traceback;

    struct _err_stackitem *previous_item;

} _PyErr_StackItem;


// The PyThreadState typedef is in Include/pystate.h.
struct _ts {
    /* See Python/ceval.c for comments explaining most fields */

    struct _ts *prev;
    struct _ts *next;
    PyInterpreterState *interp;

    struct _frame *frame;
    int recursion_depth;
    char overflowed; /* The stack has overflowed. Allow 50 more calls
                        to handle the runtime error. */
    char recursion_critical; /* The current calls must not cause
                                a stack overflow. */
    int stackcheck_counter;

    /* 'tracing' keeps track of the execution depth when tracing/profiling.
       This is to prevent the actual trace/profile code from being recorded in
       the trace/profile. */
    int tracing;
    int use_tracing;

    Py_tracefunc c_profilefunc;
    Py_tracefunc c_tracefunc;
    PyObject *c_profileobj;
    PyObject *c_traceobj;

    /* The exception currently being raised */
    PyObject *curexc_type;
    PyObject *curexc_value;
    PyObject *curexc_traceback;

    /* The exception currently being handled, if no coroutines/generators
     * are present. Always last element on the stack referred to be exc_info.
     */
    _PyErr_StackItem exc_state;

    /* Pointer to the top of the stack of the exceptions currently
     * being handled */
    _PyErr_StackItem *exc_info;

    PyObject *dict;  /* Stores per-thread state */

    int gilstate_counter;

    PyObject *async_exc; /* Asynchronous exception to raise */
    unsigned long thread_id; /* Thread id where this tstate was created */

    int trash_delete_nesting;
    PyObject *trash_delete_later;

    /* Called when a thread state is deleted normally, but not when it
     * is destroyed after fork().
     * Pain:  to prevent rare but fatal shutdown errors (issue 18808),
     * Thread.join() must wait for the join'ed thread's tstate to be unlinked
     * from the tstate chain.  That happens at the end of a thread's life,
     * in pystate.c.
     * The obvious way doesn't quite work:  create a lock which the tstate
     * unlinking code releases, and have Thread.join() wait to acquire that
     * lock.  The problem is that we _are_ at the end of the thread's life:
     * if the thread holds the last reference to the lock, decref'ing the
     * lock will delete the lock, and that may trigger arbitrary Python code
     * if there's a weakref, with a callback, to the lock.  But by this time
     * _PyRuntime.gilstate.tstate_current is already NULL, so only the simplest
     * of C code can be allowed to run (in particular it must not be possible to
     * release the GIL).
     * So instead of holding the lock directly, the tstate holds a weakref to
     * the lock:  that's the value of on_delete_data below.  Decref'ing a
     * weakref is harmless.
     * on_delete points to _threadmodule.c's static release_sentinel() function.
     * After the tstate is unlinked, release_sentinel is called with the
     * weakref-to-lock (on_delete_data) argument, and release_sentinel releases
     * the indirectly held lock.
     */
    void (*on_delete)(void *);
    void *on_delete_data;

    int coroutine_origin_tracking_depth;

    PyObject *coroutine_wrapper;
    int in_coroutine_wrapper;

    PyObject *async_gen_firstiter;
    PyObject *async_gen_finalizer;

    PyObject *context;
    uint64_t context_ver;

    /* Unique thread state id. */
    uint64_t id;

    /* XXX signal handlers should also be here */

};

/* Get the current interpreter state.

   Issue a fatal error if there no current Python thread state or no current
   interpreter. It cannot return NULL.

   The caller must hold the GIL.*/
PyAPI_FUNC(PyInterpreterState *) _PyInterpreterState_Get(void);

PyAPI_FUNC(int) _PyState_AddModule(PyObject*, struct PyModuleDef*);
PyAPI_FUNC(void) _PyState_ClearModules(void);
PyAPI_FUNC(PyThreadState *) _PyThreadState_Prealloc(PyInterpreterState *);
PyAPI_FUNC(void) _PyThreadState_Init(PyThreadState *);
PyAPI_FUNC(void) _PyThreadState_DeleteExcept(PyThreadState *tstate);
PyAPI_FUNC(void) _PyGILState_Reinit(void);

/* Similar to PyThreadState_Get(), but don't issue a fatal error
 * if it is NULL. */
PyAPI_FUNC(PyThreadState *) _PyThreadState_UncheckedGet(void);

/* PyGILState */

/* Helper/diagnostic function - return 1 if the current thread
   currently holds the GIL, 0 otherwise.

   The function returns 1 if _PyGILState_check_enabled is non-zero. */
PyAPI_FUNC(int) PyGILState_Check(void);

/* Get the single PyInterpreterState used by this process' GILState
   implementation.

   This function doesn't check for error. Return NULL before _PyGILState_Init()
   is called and after _PyGILState_Fini() is called.

   See also _PyInterpreterState_Get() and _PyInterpreterState_GET_UNSAFE(). */
PyAPI_FUNC(PyInterpreterState *) _PyGILState_GetInterpreterStateUnsafe(void);

/* The implementation of sys._current_frames()  Returns a dict mapping
   thread id to that thread's current frame.
*/
PyAPI_FUNC(PyObject *) _PyThread_CurrentFrames(void);

/* Routines for advanced debuggers, requested by David Beazley.
   Don't use unless you know what you are doing! */
PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Main(void);
PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Head(void);
PyAPI_FUNC(PyInterpreterState *) PyInterpreterState_Next(PyInterpreterState *);
PyAPI_FUNC(PyThreadState *) PyInterpreterState_ThreadHead(PyInterpreterState *);
PyAPI_FUNC(PyThreadState *) PyThreadState_Next(PyThreadState *);

typedef struct _frame *(*PyThreadFrameGetter)(PyThreadState *self_);

#ifdef __cplusplus
}
#endif