Prepare for Python "Limited API" in PL/Python

Using the Python Limited API would allow building PL/Python against
any Python 3.x version and using another Python 3.x version at run
time.  This commit does not activate that, but it prepares the code to
only use APIs supported by the Limited API.

Implementation details:

- Convert static types to heap types
  (https://docs.python.org/3/howto/isolating-extensions.html#heap-types).

- Replace PyRun_String() with component functions.

- Replace PyList_SET_ITEM() with PyList_SetItem().

Reviewed-by: Jakob Egger <jakob@eggerapps.at>
Discussion: https://www.postgresql.org/message-id/flat/ee410de1-1e0b-4770-b125-eeefd4726a24@eisentraut.org

diff --git a/src/pl/plpython/plpy_cursorobject.c b/src/pl/plpython/plpy_cursorobject.c
index bb3fa8a390990b002ffe256b97b90c8b8d72e2fe..2a370157f90fb2ea75df47b2827cf27f208a9ca9 100644 (file)
--- a/src/pl/plpython/plpy_cursorobject.c
+++ b/src/pl/plpython/plpy_cursorobject.c
@@ -20,7 +20,7 @@
 #include "utils/memutils.h"
 
 static PyObject *PLy_cursor_query(const char *query);
-static void PLy_cursor_dealloc(PyObject *arg);
+static void PLy_cursor_dealloc(PLyCursorObject *self);
 static PyObject *PLy_cursor_iternext(PyObject *self);
 static PyObject *PLy_cursor_fetch(PyObject *self, PyObject *args);
 static PyObject *PLy_cursor_close(PyObject *self, PyObject *unused);
@@ -33,22 +33,43 @@ static PyMethodDef PLy_cursor_methods[] = {
    {NULL, NULL, 0, NULL}
 };
 
-static PyTypeObject PLy_CursorType = {
-   PyVarObject_HEAD_INIT(NULL, 0)
-   .tp_name = "PLyCursor",
-   .tp_basicsize = sizeof(PLyCursorObject),
-   .tp_dealloc = PLy_cursor_dealloc,
-   .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
-   .tp_doc = PLy_cursor_doc,
-   .tp_iter = PyObject_SelfIter,
-   .tp_iternext = PLy_cursor_iternext,
-   .tp_methods = PLy_cursor_methods,
+static PyType_Slot PLyCursor_slots[] =
+{
+   {
+       Py_tp_dealloc, PLy_cursor_dealloc
+   },
+   {
+       Py_tp_doc, (char *) PLy_cursor_doc
+   },
+   {
+       Py_tp_iter, PyObject_SelfIter
+   },
+   {
+       Py_tp_iternext, PLy_cursor_iternext
+   },
+   {
+       Py_tp_methods, PLy_cursor_methods
+   },
+   {
+       0, NULL
+   }
 };
 
+static PyType_Spec PLyCursor_spec =
+{
+   .name = "PLyCursor",
+       .basicsize = sizeof(PLyCursorObject),
+       .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+       .slots = PLyCursor_slots,
+};
+
+static PyTypeObject *PLy_CursorType;
+
 void
 PLy_cursor_init_type(void)
 {
-   if (PyType_Ready(&PLy_CursorType) < 0)
+   PLy_CursorType = (PyTypeObject *) PyType_FromSpec(&PLyCursor_spec);
+   if (!PLy_CursorType)
        elog(ERROR, "could not initialize PLy_CursorType");
 }
 
@@ -80,7 +101,7 @@ PLy_cursor_query(const char *query)
    volatile MemoryContext oldcontext;
    volatile ResourceOwner oldowner;
 
-   if ((cursor = PyObject_New(PLyCursorObject, &PLy_CursorType)) == NULL)
+   if ((cursor = PyObject_New(PLyCursorObject, PLy_CursorType)) == NULL)
        return NULL;
    cursor->portalname = NULL;
    cursor->closed = false;
@@ -177,7 +198,7 @@ PLy_cursor_plan(PyObject *ob, PyObject *args)
        return NULL;
    }
 
-   if ((cursor = PyObject_New(PLyCursorObject, &PLy_CursorType)) == NULL)
+   if ((cursor = PyObject_New(PLyCursorObject, PLy_CursorType)) == NULL)
        return NULL;
    cursor->portalname = NULL;
    cursor->closed = false;
@@ -272,30 +293,30 @@ PLy_cursor_plan(PyObject *ob, PyObject *args)
 }
 
 static void
-PLy_cursor_dealloc(PyObject *arg)
+PLy_cursor_dealloc(PLyCursorObject *self)
 {
-   PLyCursorObject *cursor;
+   PyTypeObject *tp = Py_TYPE(self);
    Portal      portal;
 
-   cursor = (PLyCursorObject *) arg;
-
-   if (!cursor->closed)
+   if (!self->closed)
    {
-       portal = GetPortalByName(cursor->portalname);
+       portal = GetPortalByName(self->portalname);
 
        if (PortalIsValid(portal))
        {
            UnpinPortal(portal);
            SPI_cursor_close(portal);
        }
-       cursor->closed = true;
+       self->closed = true;
    }
-   if (cursor->mcxt)
+   if (self->mcxt)
    {
-       MemoryContextDelete(cursor->mcxt);
-       cursor->mcxt = NULL;
+       MemoryContextDelete(self->mcxt);
+       self->mcxt = NULL;
    }
-   arg->ob_type->tp_free(arg);
+
+   PyObject_Free(self);
+   Py_DECREF(tp);
 }
 
 static PyObject *

diff --git a/src/pl/plpython/plpy_planobject.c b/src/pl/plpython/plpy_planobject.c
index 9427674d2f4a6506ad7f6fb6f80d046e18eac903..1b97b5cbd2ad8416e3e979dd40f8b7f883f35a1f 100644 (file)
--- a/src/pl/plpython/plpy_planobject.c
+++ b/src/pl/plpython/plpy_planobject.c
@@ -12,7 +12,7 @@
 #include "plpython.h"
 #include "utils/memutils.h"
 
-static void PLy_plan_dealloc(PyObject *arg);
+static void PLy_plan_dealloc(PLyPlanObject *self);
 static PyObject *PLy_plan_cursor(PyObject *self, PyObject *args);
 static PyObject *PLy_plan_execute(PyObject *self, PyObject *args);
 static PyObject *PLy_plan_status(PyObject *self, PyObject *args);
@@ -26,20 +26,37 @@ static PyMethodDef PLy_plan_methods[] = {
    {NULL, NULL, 0, NULL}
 };
 
-static PyTypeObject PLy_PlanType = {
-   PyVarObject_HEAD_INIT(NULL, 0)
-   .tp_name = "PLyPlan",
-   .tp_basicsize = sizeof(PLyPlanObject),
-   .tp_dealloc = PLy_plan_dealloc,
-   .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
-   .tp_doc = PLy_plan_doc,
-   .tp_methods = PLy_plan_methods,
+static PyType_Slot PLyPlan_slots[] =
+{
+   {
+       Py_tp_dealloc, PLy_plan_dealloc
+   },
+   {
+       Py_tp_doc, (char *) PLy_plan_doc
+   },
+   {
+       Py_tp_methods, PLy_plan_methods
+   },
+   {
+       0, NULL
+   }
 };
 
+static PyType_Spec PLyPlan_spec =
+{
+   .name = "PLyPlan",
+       .basicsize = sizeof(PLyPlanObject),
+       .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+       .slots = PLyPlan_slots,
+};
+
+static PyTypeObject *PLy_PlanType;
+
 void
 PLy_plan_init_type(void)
 {
-   if (PyType_Ready(&PLy_PlanType) < 0)
+   PLy_PlanType = (PyTypeObject *) PyType_FromSpec(&PLyPlan_spec);
+   if (!PLy_PlanType)
        elog(ERROR, "could not initialize PLy_PlanType");
 }
 
@@ -48,7 +65,7 @@ PLy_plan_new(void)
 {
    PLyPlanObject *ob;
 
-   if ((ob = PyObject_New(PLyPlanObject, &PLy_PlanType)) == NULL)
+   if ((ob = PyObject_New(PLyPlanObject, PLy_PlanType)) == NULL)
        return NULL;
 
    ob->plan = NULL;
@@ -63,25 +80,27 @@ PLy_plan_new(void)
 bool
 is_PLyPlanObject(PyObject *ob)
 {
-   return ob->ob_type == &PLy_PlanType;
+   return ob->ob_type == PLy_PlanType;
 }
 
 static void
-PLy_plan_dealloc(PyObject *arg)
+PLy_plan_dealloc(PLyPlanObject *self)
 {
-   PLyPlanObject *ob = (PLyPlanObject *) arg;
+   PyTypeObject *tp = Py_TYPE(self);
 
-   if (ob->plan)
+   if (self->plan)
    {
-       SPI_freeplan(ob->plan);
-       ob->plan = NULL;
+       SPI_freeplan(self->plan);
+       self->plan = NULL;
    }
-   if (ob->mcxt)
+   if (self->mcxt)
    {
-       MemoryContextDelete(ob->mcxt);
-       ob->mcxt = NULL;
+       MemoryContextDelete(self->mcxt);
+       self->mcxt = NULL;
    }
-   arg->ob_type->tp_free(arg);
+
+   PyObject_Free(self);
+   Py_DECREF(tp);
 }
 
 

diff --git a/src/pl/plpython/plpy_procedure.c b/src/pl/plpython/plpy_procedure.c
index c35a3b801abbfd7672fd735f2406ff6531cd57f5..b494eeb474f36e0f2d51747b0564fe299eb88e48 100644 (file)
--- a/src/pl/plpython/plpy_procedure.c
+++ b/src/pl/plpython/plpy_procedure.c
@@ -350,6 +350,7 @@ PLy_procedure_compile(PLyProcedure *proc, const char *src)
 {
    PyObject   *crv = NULL;
    char       *msrc;
+   PyObject   *code0;
 
    proc->globals = PyDict_Copy(PLy_interp_globals);
 
@@ -368,7 +369,9 @@ PLy_procedure_compile(PLyProcedure *proc, const char *src)
    msrc = PLy_procedure_munge_source(proc->pyname, src);
    /* Save the mangled source for later inclusion in tracebacks */
    proc->src = MemoryContextStrdup(proc->mcxt, msrc);
-   crv = PyRun_String(msrc, Py_file_input, proc->globals, NULL);
+   code0 = Py_CompileString(msrc, "<string>", Py_file_input);
+   if (code0)
+       crv = PyEval_EvalCode(code0, proc->globals, NULL);
    pfree(msrc);
 
    if (crv != NULL)

diff --git a/src/pl/plpython/plpy_resultobject.c b/src/pl/plpython/plpy_resultobject.c
index 95acce654935c8743b544535402bb0c92c3f0165..f2628205669052f5d5fc9d7c891263ef670178cc 100644 (file)
--- a/src/pl/plpython/plpy_resultobject.c
+++ b/src/pl/plpython/plpy_resultobject.c
@@ -10,7 +10,7 @@
 #include "plpy_resultobject.h"
 #include "plpython.h"
 
-static void PLy_result_dealloc(PyObject *arg);
+static void PLy_result_dealloc(PLyResultObject *self);
 static PyObject *PLy_result_colnames(PyObject *self, PyObject *unused);
 static PyObject *PLy_result_coltypes(PyObject *self, PyObject *unused);
 static PyObject *PLy_result_coltypmods(PyObject *self, PyObject *unused);
@@ -24,17 +24,6 @@ static int   PLy_result_ass_subscript(PyObject *arg, PyObject *item, PyObject *val
 
 static char PLy_result_doc[] = "Results of a PostgreSQL query";
 
-static PySequenceMethods PLy_result_as_sequence = {
-   .sq_length = PLy_result_length,
-   .sq_item = PLy_result_item,
-};
-
-static PyMappingMethods PLy_result_as_mapping = {
-   .mp_length = PLy_result_length,
-   .mp_subscript = PLy_result_subscript,
-   .mp_ass_subscript = PLy_result_ass_subscript,
-};
-
 static PyMethodDef PLy_result_methods[] = {
    {"colnames", PLy_result_colnames, METH_NOARGS, NULL},
    {"coltypes", PLy_result_coltypes, METH_NOARGS, NULL},
@@ -44,23 +33,55 @@ static PyMethodDef PLy_result_methods[] = {
    {NULL, NULL, 0, NULL}
 };
 
-static PyTypeObject PLy_ResultType = {
-   PyVarObject_HEAD_INIT(NULL, 0)
-   .tp_name = "PLyResult",
-   .tp_basicsize = sizeof(PLyResultObject),
-   .tp_dealloc = PLy_result_dealloc,
-   .tp_as_sequence = &PLy_result_as_sequence,
-   .tp_as_mapping = &PLy_result_as_mapping,
-   .tp_str = &PLy_result_str,
-   .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
-   .tp_doc = PLy_result_doc,
-   .tp_methods = PLy_result_methods,
+static PyType_Slot PLyResult_slots[] =
+{
+   {
+       Py_tp_dealloc, PLy_result_dealloc
+   },
+   {
+       Py_sq_length, PLy_result_length
+   },
+   {
+       Py_sq_item, PLy_result_item
+   },
+   {
+       Py_mp_length, PLy_result_length
+   },
+   {
+       Py_mp_subscript, PLy_result_subscript
+   },
+   {
+       Py_mp_ass_subscript, PLy_result_ass_subscript
+   },
+   {
+       Py_tp_str, PLy_result_str
+   },
+   {
+       Py_tp_doc, (char *) PLy_result_doc
+   },
+   {
+       Py_tp_methods, PLy_result_methods
+   },
+   {
+       0, NULL
+   }
 };
 
+static PyType_Spec PLyResult_spec =
+{
+   .name = "PLyResult",
+       .basicsize = sizeof(PLyResultObject),
+       .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+       .slots = PLyResult_slots,
+};
+
+static PyTypeObject *PLy_ResultType;
+
 void
 PLy_result_init_type(void)
 {
-   if (PyType_Ready(&PLy_ResultType) < 0)
+   PLy_ResultType = (PyTypeObject *) PyType_FromSpec(&PLyResult_spec);
+   if (!PLy_ResultType)
        elog(ERROR, "could not initialize PLy_ResultType");
 }
 
@@ -69,7 +90,7 @@ PLy_result_new(void)
 {
    PLyResultObject *ob;
 
-   if ((ob = PyObject_New(PLyResultObject, &PLy_ResultType)) == NULL)
+   if ((ob = PyObject_New(PLyResultObject, PLy_ResultType)) == NULL)
        return NULL;
 
    /* ob->tuples = NULL; */
@@ -89,20 +110,21 @@ PLy_result_new(void)
 }
 
 static void
-PLy_result_dealloc(PyObject *arg)
+PLy_result_dealloc(PLyResultObject *self)
 {
-   PLyResultObject *ob = (PLyResultObject *) arg;
+   PyTypeObject *tp = Py_TYPE(self);
 
-   Py_XDECREF(ob->nrows);
-   Py_XDECREF(ob->rows);
-   Py_XDECREF(ob->status);
-   if (ob->tupdesc)
+   Py_XDECREF(self->nrows);
+   Py_XDECREF(self->rows);
+   Py_XDECREF(self->status);
+   if (self->tupdesc)
    {
-       FreeTupleDesc(ob->tupdesc);
-       ob->tupdesc = NULL;
+       FreeTupleDesc(self->tupdesc);
+       self->tupdesc = NULL;
    }
 
-   arg->ob_type->tp_free(arg);
+   PyObject_Free(self);
+   Py_DECREF(tp);
 }
 
 static PyObject *
@@ -125,7 +147,7 @@ PLy_result_colnames(PyObject *self, PyObject *unused)
    {
        Form_pg_attribute attr = TupleDescAttr(ob->tupdesc, i);
 
-       PyList_SET_ITEM(list, i, PLyUnicode_FromString(NameStr(attr->attname)));
+       PyList_SetItem(list, i, PLyUnicode_FromString(NameStr(attr->attname)));
    }
 
    return list;
@@ -151,7 +173,7 @@ PLy_result_coltypes(PyObject *self, PyObject *unused)
    {
        Form_pg_attribute attr = TupleDescAttr(ob->tupdesc, i);
 
-       PyList_SET_ITEM(list, i, PyLong_FromLong(attr->atttypid));
+       PyList_SetItem(list, i, PyLong_FromLong(attr->atttypid));
    }
 
    return list;
@@ -177,7 +199,7 @@ PLy_result_coltypmods(PyObject *self, PyObject *unused)
    {
        Form_pg_attribute attr = TupleDescAttr(ob->tupdesc, i);
 
-       PyList_SET_ITEM(list, i, PyLong_FromLong(attr->atttypmod));
+       PyList_SetItem(list, i, PyLong_FromLong(attr->atttypmod));
    }
 
    return list;
@@ -227,7 +249,7 @@ PLy_result_str(PyObject *arg)
    PLyResultObject *ob = (PLyResultObject *) arg;
 
    return PyUnicode_FromFormat("<%s status=%S nrows=%S rows=%S>",
-                               Py_TYPE(ob)->tp_name,
+                               "PLyResult",
                                ob->status,
                                ob->nrows,
                                ob->rows);

diff --git a/src/pl/plpython/plpy_subxactobject.c b/src/pl/plpython/plpy_subxactobject.c
index 5c92a0e089a1b214e61178328047ceaa534286d0..cc7ff3f9df7c2ef5cf3b68f19b640a878f930e5f 100644 (file)
--- a/src/pl/plpython/plpy_subxactobject.c
+++ b/src/pl/plpython/plpy_subxactobject.c
@@ -15,7 +15,6 @@
 List      *explicit_subtransactions = NIL;
 
 
-static void PLy_subtransaction_dealloc(PyObject *subxact);
 static PyObject *PLy_subtransaction_enter(PyObject *self, PyObject *unused);
 static PyObject *PLy_subtransaction_exit(PyObject *self, PyObject *args);
 
@@ -31,21 +30,35 @@ static PyMethodDef PLy_subtransaction_methods[] = {
    {NULL, NULL, 0, NULL}
 };
 
-static PyTypeObject PLy_SubtransactionType = {
-   PyVarObject_HEAD_INIT(NULL, 0)
-   .tp_name = "PLySubtransaction",
-   .tp_basicsize = sizeof(PLySubtransactionObject),
-   .tp_dealloc = PLy_subtransaction_dealloc,
-   .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
-   .tp_doc = PLy_subtransaction_doc,
-   .tp_methods = PLy_subtransaction_methods,
+static PyType_Slot PLySubtransaction_slots[] =
+{
+   {
+       Py_tp_doc, (char *) PLy_subtransaction_doc
+   },
+   {
+       Py_tp_methods, PLy_subtransaction_methods
+   },
+   {
+       0, NULL
+   }
+};
+
+static PyType_Spec PLySubtransaction_spec =
+{
+   .name = "PLySubtransaction",
+       .basicsize = sizeof(PLySubtransactionObject),
+       .flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+       .slots = PLySubtransaction_slots,
 };
 
+static PyTypeObject *PLy_SubtransactionType;
+
 
 void
 PLy_subtransaction_init_type(void)
 {
-   if (PyType_Ready(&PLy_SubtransactionType) < 0)
+   PLy_SubtransactionType = (PyTypeObject *) PyType_FromSpec(&PLySubtransaction_spec);
+   if (!PLy_SubtransactionType)
        elog(ERROR, "could not initialize PLy_SubtransactionType");
 }
 
@@ -55,7 +68,7 @@ PLy_subtransaction_new(PyObject *self, PyObject *unused)
 {
    PLySubtransactionObject *ob;
 
-   ob = PyObject_New(PLySubtransactionObject, &PLy_SubtransactionType);
+   ob = PyObject_New(PLySubtransactionObject, PLy_SubtransactionType);
 
    if (ob == NULL)
        return NULL;
@@ -66,12 +79,6 @@ PLy_subtransaction_new(PyObject *self, PyObject *unused)
    return (PyObject *) ob;
 }
 
-/* Python requires a dealloc function to be defined */
-static void
-PLy_subtransaction_dealloc(PyObject *subxact)
-{
-}
-
 /*
  * subxact.__enter__() or subxact.enter()
  *

diff --git a/src/pl/plpython/plpy_typeio.c b/src/pl/plpython/plpy_typeio.c
index 51e1d610259d4f2083540321120474ab69dddd2b..1d127ae3ffe37c7c697f4344d6854459523ba22e 100644 (file)
--- a/src/pl/plpython/plpy_typeio.c
+++ b/src/pl/plpython/plpy_typeio.c
@@ -723,7 +723,7 @@ PLyList_FromArray_recurse(PLyDatumToOb *elm, int *dims, int ndim, int dim,
 
            sublist = PLyList_FromArray_recurse(elm, dims, ndim, dim + 1,
                                                dataptr_p, bitmap_p, bitmask_p);
-           PyList_SET_ITEM(list, i, sublist);
+           PyList_SetItem(list, i, sublist);
        }
    }
    else
@@ -742,14 +742,14 @@ PLyList_FromArray_recurse(PLyDatumToOb *elm, int *dims, int ndim, int dim,
            if (bitmap && (*bitmap & bitmask) == 0)
            {
                Py_INCREF(Py_None);
-               PyList_SET_ITEM(list, i, Py_None);
+               PyList_SetItem(list, i, Py_None);
            }
            else
            {
                Datum       itemvalue;
 
                itemvalue = fetch_att(dataptr, elm->typbyval, elm->typlen);
-               PyList_SET_ITEM(list, i, elm->func(elm, itemvalue));
+               PyList_SetItem(list, i, elm->func(elm, itemvalue));
                dataptr = att_addlength_pointer(dataptr, elm->typlen, dataptr);
                dataptr = (char *) att_align_nominal(dataptr, elm->typalign);
            }