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Move _PyCrossInterpreterData (and functions) to the public API.
  • Loading branch information
ericsnowcurrently committed Mar 15, 2019
commit e962a139764686bcfa175960b6b0a2d365a03003
57 changes: 57 additions & 0 deletions Include/cpython/pystate.h
Original file line number Diff line number Diff line change
Expand Up @@ -215,6 +215,63 @@ PyAPI_FUNC(PyThreadState *) PyThreadState_Next(PyThreadState *);

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

/* cross-interpreter data */

struct _xid;

// _PyCrossInterpreterData is similar to Py_buffer as an effectively
// opaque struct that holds data outside the object machinery. This
// is necessary to pass safely between interpreters in the same process.
typedef struct _xid {
// data is the cross-interpreter-safe derivation of a Python object
// (see _PyObject_GetCrossInterpreterData). It will be NULL if the
// new_object func (below) encodes the data.
void *data;
// obj is the Python object from which the data was derived. This
// is non-NULL only if the data remains bound to the object in some
// way, such that the object must be "released" (via a decref) when
// the data is released. In that case the code that sets the field,
// likely a registered "crossinterpdatafunc", is responsible for
// ensuring it owns the reference (i.e. incref).
PyObject *obj;
// interp is the ID of the owning interpreter of the original
// object. It corresponds to the active interpreter when
// _PyObject_GetCrossInterpreterData() was called. This should only
// be set by the cross-interpreter machinery.
//
// We use the ID rather than the PyInterpreterState to avoid issues
// with deleted interpreters.
int64_t interp;
// new_object is a function that returns a new object in the current
// interpreter given the data. The resulting object (a new
// reference) will be equivalent to the original object. This field
// is required.
PyObject *(*new_object)(struct _xid *);
// free is called when the data is released. If it is NULL then
// nothing will be done to free the data. For some types this is
// okay (e.g. bytes) and for those types this field should be set
// to NULL. However, for most the data was allocated just for
// cross-interpreter use, so it must be freed when
// _PyCrossInterpreterData_Release is called or the memory will
// leak. In that case, at the very least this field should be set
// to PyMem_RawFree (the default if not explicitly set to NULL).
// The call will happen with the original interpreter activated.
void (*free)(void *);
} _PyCrossInterpreterData;

PyAPI_FUNC(int) _PyObject_GetCrossInterpreterData(PyObject *, _PyCrossInterpreterData *);
PyAPI_FUNC(PyObject *) _PyCrossInterpreterData_NewObject(_PyCrossInterpreterData *);
PyAPI_FUNC(void) _PyCrossInterpreterData_Release(_PyCrossInterpreterData *);

PyAPI_FUNC(int) _PyObject_CheckCrossInterpreterData(PyObject *);

/* cross-interpreter data registry */

typedef int (*crossinterpdatafunc)(PyObject *, struct _xid *);

PyAPI_FUNC(int) _PyCrossInterpreterData_Register_Class(PyTypeObject *, crossinterpdatafunc);
PyAPI_FUNC(crossinterpdatafunc) _PyCrossInterpreterData_Lookup(PyObject *);

#ifdef __cplusplus
}
#endif
54 changes: 0 additions & 54 deletions Include/internal/pycore_pystate.h
Original file line number Diff line number Diff line change
Expand Up @@ -89,66 +89,12 @@ PyAPI_FUNC(void) _PyInterpreterState_IDIncref(struct _is *);
PyAPI_FUNC(void) _PyInterpreterState_IDDecref(struct _is *);


/* cross-interpreter data */

struct _xid;

// _PyCrossInterpreterData is similar to Py_buffer as an effectively
// opaque struct that holds data outside the object machinery. This
// is necessary to pass safely between interpreters in the same process.
typedef struct _xid {
// data is the cross-interpreter-safe derivation of a Python object
// (see _PyObject_GetCrossInterpreterData). It will be NULL if the
// new_object func (below) encodes the data.
void *data;
// obj is the Python object from which the data was derived. This
// is non-NULL only if the data remains bound to the object in some
// way, such that the object must be "released" (via a decref) when
// the data is released. In that case the code that sets the field,
// likely a registered "crossinterpdatafunc", is responsible for
// ensuring it owns the reference (i.e. incref).
PyObject *obj;
// interp is the ID of the owning interpreter of the original
// object. It corresponds to the active interpreter when
// _PyObject_GetCrossInterpreterData() was called. This should only
// be set by the cross-interpreter machinery.
//
// We use the ID rather than the PyInterpreterState to avoid issues
// with deleted interpreters.
int64_t interp;
// new_object is a function that returns a new object in the current
// interpreter given the data. The resulting object (a new
// reference) will be equivalent to the original object. This field
// is required.
PyObject *(*new_object)(struct _xid *);
// free is called when the data is released. If it is NULL then
// nothing will be done to free the data. For some types this is
// okay (e.g. bytes) and for those types this field should be set
// to NULL. However, for most the data was allocated just for
// cross-interpreter use, so it must be freed when
// _PyCrossInterpreterData_Release is called or the memory will
// leak. In that case, at the very least this field should be set
// to PyMem_RawFree (the default if not explicitly set to NULL).
// The call will happen with the original interpreter activated.
void (*free)(void *);
} _PyCrossInterpreterData;

typedef int (*crossinterpdatafunc)(PyObject *, _PyCrossInterpreterData *);
PyAPI_FUNC(int) _PyObject_CheckCrossInterpreterData(PyObject *);

PyAPI_FUNC(int) _PyObject_GetCrossInterpreterData(PyObject *, _PyCrossInterpreterData *);
PyAPI_FUNC(PyObject *) _PyCrossInterpreterData_NewObject(_PyCrossInterpreterData *);
PyAPI_FUNC(void) _PyCrossInterpreterData_Release(_PyCrossInterpreterData *);

/* cross-interpreter data registry */

/* For now we use a global registry of shareable classes. An
alternative would be to add a tp_* slot for a class's
crossinterpdatafunc. It would be simpler and more efficient. */

PyAPI_FUNC(int) _PyCrossInterpreterData_Register_Class(PyTypeObject *, crossinterpdatafunc);
PyAPI_FUNC(crossinterpdatafunc) _PyCrossInterpreterData_Lookup(PyObject *);

struct _xidregitem;

struct _xidregitem {
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