postgres/src/pl/plpython/plpy_cursorobject.c

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/*
* the PLyCursor class
*
* src/pl/plpython/plpy_cursorobject.c
*/
#include "postgres.h"
#include <limits.h>
#include "access/xact.h"
#include "mb/pg_wchar.h"
#include "utils/memutils.h"
#include "plpython.h"
#include "plpy_cursorobject.h"
#include "plpy_elog.h"
#include "plpy_main.h"
#include "plpy_planobject.h"
#include "plpy_procedure.h"
#include "plpy_resultobject.h"
#include "plpy_spi.h"
static PyObject *PLy_cursor_query(const char *query);
static void PLy_cursor_dealloc(PyObject *arg);
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);
static char PLy_cursor_doc[] = {
"Wrapper around a PostgreSQL cursor"
};
static PyMethodDef PLy_cursor_methods[] = {
{"fetch", PLy_cursor_fetch, METH_VARARGS, NULL},
{"close", PLy_cursor_close, METH_NOARGS, NULL},
{NULL, NULL, 0, NULL}
};
static PyTypeObject PLy_CursorType = {
PyVarObject_HEAD_INIT(NULL, 0)
"PLyCursor", /* tp_name */
sizeof(PLyCursorObject), /* tp_size */
0, /* tp_itemsize */
/*
* methods
*/
PLy_cursor_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
0, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_ITER, /* tp_flags */
PLy_cursor_doc, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
PLy_cursor_iternext, /* tp_iternext */
PLy_cursor_methods, /* tp_tpmethods */
};
void
PLy_cursor_init_type(void)
{
if (PyType_Ready(&PLy_CursorType) < 0)
elog(ERROR, "could not initialize PLy_CursorType");
}
PyObject *
PLy_cursor(PyObject *self, PyObject *args)
{
char *query;
PyObject *plan;
PyObject *planargs = NULL;
if (PyArg_ParseTuple(args, "s", &query))
return PLy_cursor_query(query);
PyErr_Clear();
if (PyArg_ParseTuple(args, "O|O", &plan, &planargs))
return PLy_cursor_plan(plan, planargs);
PLy_exception_set(PLy_exc_error, "plpy.cursor expected a query or a plan");
return NULL;
}
static PyObject *
PLy_cursor_query(const char *query)
{
PLyCursorObject *cursor;
volatile MemoryContext oldcontext;
volatile ResourceOwner oldowner;
if ((cursor = PyObject_New(PLyCursorObject, &PLy_CursorType)) == NULL)
return NULL;
cursor->portalname = NULL;
cursor->closed = false;
cursor->mcxt = AllocSetContextCreate(TopMemoryContext,
"PL/Python cursor context",
Add macros to make AllocSetContextCreate() calls simpler and safer. I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
2016-08-27 17:50:38 -04:00
ALLOCSET_DEFAULT_SIZES);
PLy_typeinfo_init(&cursor->result, cursor->mcxt);
oldcontext = CurrentMemoryContext;
oldowner = CurrentResourceOwner;
PLy_spi_subtransaction_begin(oldcontext, oldowner);
PG_TRY();
{
PLyExecutionContext *exec_ctx = PLy_current_execution_context();
SPIPlanPtr plan;
Portal portal;
pg_verifymbstr(query, strlen(query), false);
plan = SPI_prepare(query, 0, NULL);
if (plan == NULL)
elog(ERROR, "SPI_prepare failed: %s",
SPI_result_code_string(SPI_result));
portal = SPI_cursor_open(NULL, plan, NULL, NULL,
exec_ctx->curr_proc->fn_readonly);
SPI_freeplan(plan);
if (portal == NULL)
2012-01-10 22:49:17 +02:00
elog(ERROR, "SPI_cursor_open() failed: %s",
SPI_result_code_string(SPI_result));
cursor->portalname = MemoryContextStrdup(cursor->mcxt, portal->name);
PLy_spi_subtransaction_commit(oldcontext, oldowner);
}
PG_CATCH();
{
PLy_spi_subtransaction_abort(oldcontext, oldowner);
return NULL;
}
PG_END_TRY();
Assert(cursor->portalname != NULL);
return (PyObject *) cursor;
}
PyObject *
PLy_cursor_plan(PyObject *ob, PyObject *args)
{
PLyCursorObject *cursor;
volatile int nargs;
int i;
PLyPlanObject *plan;
volatile MemoryContext oldcontext;
volatile ResourceOwner oldowner;
if (args)
{
if (!PySequence_Check(args) || PyString_Check(args) || PyUnicode_Check(args))
{
PLy_exception_set(PyExc_TypeError, "plpy.cursor takes a sequence as its second argument");
return NULL;
}
nargs = PySequence_Length(args);
}
else
nargs = 0;
plan = (PLyPlanObject *) ob;
if (nargs != plan->nargs)
{
char *sv;
PyObject *so = PyObject_Str(args);
if (!so)
PLy_elog(ERROR, "could not execute plan");
sv = PyString_AsString(so);
PLy_exception_set_plural(PyExc_TypeError,
"Expected sequence of %d argument, got %d: %s",
"Expected sequence of %d arguments, got %d: %s",
plan->nargs,
plan->nargs, nargs, sv);
Py_DECREF(so);
return NULL;
}
if ((cursor = PyObject_New(PLyCursorObject, &PLy_CursorType)) == NULL)
return NULL;
cursor->portalname = NULL;
cursor->closed = false;
cursor->mcxt = AllocSetContextCreate(TopMemoryContext,
"PL/Python cursor context",
Add macros to make AllocSetContextCreate() calls simpler and safer. I found that half a dozen (nearly 5%) of our AllocSetContextCreate calls had typos in the context-sizing parameters. While none of these led to especially significant problems, they did create minor inefficiencies, and it's now clear that expecting people to copy-and-paste those calls accurately is not a great idea. Let's reduce the risk of future errors by introducing single macros that encapsulate the common use-cases. Three such macros are enough to cover all but two special-purpose contexts; those two calls can be left as-is, I think. While this patch doesn't in itself improve matters for third-party extensions, it doesn't break anything for them either, and they can gradually adopt the simplified notation over time. In passing, change TopMemoryContext to use the default allocation parameters. Formerly it could only be extended 8K at a time. That was probably reasonable when this code was written; but nowadays we create many more contexts than we did then, so that it's not unusual to have a couple hundred K in TopMemoryContext, even without considering various dubious code that sticks other things there. There seems no good reason not to let it use growing blocks like most other contexts. Back-patch to 9.6, mostly because that's still close enough to HEAD that it's easy to do so, and keeping the branches in sync can be expected to avoid some future back-patching pain. The bugs fixed by these changes don't seem to be significant enough to justify fixing them further back. Discussion: <21072.1472321324@sss.pgh.pa.us>
2016-08-27 17:50:38 -04:00
ALLOCSET_DEFAULT_SIZES);
PLy_typeinfo_init(&cursor->result, cursor->mcxt);
oldcontext = CurrentMemoryContext;
oldowner = CurrentResourceOwner;
PLy_spi_subtransaction_begin(oldcontext, oldowner);
PG_TRY();
{
PLyExecutionContext *exec_ctx = PLy_current_execution_context();
Portal portal;
char *volatile nulls;
volatile int j;
if (nargs > 0)
nulls = palloc(nargs * sizeof(char));
else
nulls = NULL;
for (j = 0; j < nargs; j++)
{
PyObject *elem;
elem = PySequence_GetItem(args, j);
if (elem != Py_None)
{
PG_TRY();
{
plan->values[j] =
plan->args[j].out.d.func(&(plan->args[j].out.d),
-1,
elem,
false);
}
PG_CATCH();
{
Py_DECREF(elem);
PG_RE_THROW();
}
PG_END_TRY();
Py_DECREF(elem);
nulls[j] = ' ';
}
else
{
Py_DECREF(elem);
plan->values[j] =
InputFunctionCall(&(plan->args[j].out.d.typfunc),
NULL,
plan->args[j].out.d.typioparam,
-1);
nulls[j] = 'n';
}
}
portal = SPI_cursor_open(NULL, plan->plan, plan->values, nulls,
exec_ctx->curr_proc->fn_readonly);
if (portal == NULL)
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elog(ERROR, "SPI_cursor_open() failed: %s",
SPI_result_code_string(SPI_result));
cursor->portalname = MemoryContextStrdup(cursor->mcxt, portal->name);
PLy_spi_subtransaction_commit(oldcontext, oldowner);
}
PG_CATCH();
{
int k;
/* cleanup plan->values array */
for (k = 0; k < nargs; k++)
{
if (!plan->args[k].out.d.typbyval &&
(plan->values[k] != PointerGetDatum(NULL)))
{
pfree(DatumGetPointer(plan->values[k]));
plan->values[k] = PointerGetDatum(NULL);
}
}
Py_DECREF(cursor);
PLy_spi_subtransaction_abort(oldcontext, oldowner);
return NULL;
}
PG_END_TRY();
for (i = 0; i < nargs; i++)
{
if (!plan->args[i].out.d.typbyval &&
(plan->values[i] != PointerGetDatum(NULL)))
{
pfree(DatumGetPointer(plan->values[i]));
plan->values[i] = PointerGetDatum(NULL);
}
}
Assert(cursor->portalname != NULL);
return (PyObject *) cursor;
}
static void
PLy_cursor_dealloc(PyObject *arg)
{
PLyCursorObject *cursor;
Portal portal;
cursor = (PLyCursorObject *) arg;
if (!cursor->closed)
{
portal = GetPortalByName(cursor->portalname);
if (PortalIsValid(portal))
SPI_cursor_close(portal);
cursor->closed = true;
}
if (cursor->mcxt)
{
MemoryContextDelete(cursor->mcxt);
cursor->mcxt = NULL;
}
arg->ob_type->tp_free(arg);
}
static PyObject *
PLy_cursor_iternext(PyObject *self)
{
PLyCursorObject *cursor;
PyObject *ret;
volatile MemoryContext oldcontext;
volatile ResourceOwner oldowner;
Portal portal;
cursor = (PLyCursorObject *) self;
if (cursor->closed)
{
PLy_exception_set(PyExc_ValueError, "iterating a closed cursor");
return NULL;
}
portal = GetPortalByName(cursor->portalname);
if (!PortalIsValid(portal))
{
PLy_exception_set(PyExc_ValueError,
"iterating a cursor in an aborted subtransaction");
return NULL;
}
oldcontext = CurrentMemoryContext;
oldowner = CurrentResourceOwner;
PLy_spi_subtransaction_begin(oldcontext, oldowner);
PG_TRY();
{
SPI_cursor_fetch(portal, true, 1);
if (SPI_processed == 0)
{
PyErr_SetNone(PyExc_StopIteration);
ret = NULL;
}
else
{
if (cursor->result.is_rowtype != 1)
PLy_input_tuple_funcs(&cursor->result, SPI_tuptable->tupdesc);
ret = PLyDict_FromTuple(&cursor->result, SPI_tuptable->vals[0],
SPI_tuptable->tupdesc);
}
SPI_freetuptable(SPI_tuptable);
PLy_spi_subtransaction_commit(oldcontext, oldowner);
}
PG_CATCH();
{
PLy_spi_subtransaction_abort(oldcontext, oldowner);
return NULL;
}
PG_END_TRY();
return ret;
}
static PyObject *
PLy_cursor_fetch(PyObject *self, PyObject *args)
{
PLyCursorObject *cursor;
int count;
PLyResultObject *ret;
volatile MemoryContext oldcontext;
volatile ResourceOwner oldowner;
Portal portal;
if (!PyArg_ParseTuple(args, "i:fetch", &count))
return NULL;
cursor = (PLyCursorObject *) self;
if (cursor->closed)
{
PLy_exception_set(PyExc_ValueError, "fetch from a closed cursor");
return NULL;
}
portal = GetPortalByName(cursor->portalname);
if (!PortalIsValid(portal))
{
PLy_exception_set(PyExc_ValueError,
"iterating a cursor in an aborted subtransaction");
return NULL;
}
ret = (PLyResultObject *) PLy_result_new();
if (ret == NULL)
return NULL;
oldcontext = CurrentMemoryContext;
oldowner = CurrentResourceOwner;
PLy_spi_subtransaction_begin(oldcontext, oldowner);
PG_TRY();
{
SPI_cursor_fetch(portal, true, count);
if (cursor->result.is_rowtype != 1)
PLy_input_tuple_funcs(&cursor->result, SPI_tuptable->tupdesc);
Py_DECREF(ret->status);
ret->status = PyInt_FromLong(SPI_OK_FETCH);
Py_DECREF(ret->nrows);
ret->nrows = (SPI_processed > (uint64) LONG_MAX) ?
PyFloat_FromDouble((double) SPI_processed) :
PyInt_FromLong((long) SPI_processed);
if (SPI_processed != 0)
{
uint64 i;
/*
* PyList_New() and PyList_SetItem() use Py_ssize_t for list size
* and list indices; so we cannot support a result larger than
* PY_SSIZE_T_MAX.
*/
if (SPI_processed > (uint64) PY_SSIZE_T_MAX)
ereport(ERROR,
(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
errmsg("query result has too many rows to fit in a Python list")));
Py_DECREF(ret->rows);
ret->rows = PyList_New(SPI_processed);
for (i = 0; i < SPI_processed; i++)
{
PyObject *row = PLyDict_FromTuple(&cursor->result,
SPI_tuptable->vals[i],
SPI_tuptable->tupdesc);
PyList_SetItem(ret->rows, i, row);
}
}
SPI_freetuptable(SPI_tuptable);
PLy_spi_subtransaction_commit(oldcontext, oldowner);
}
PG_CATCH();
{
PLy_spi_subtransaction_abort(oldcontext, oldowner);
return NULL;
}
PG_END_TRY();
return (PyObject *) ret;
}
static PyObject *
PLy_cursor_close(PyObject *self, PyObject *unused)
{
PLyCursorObject *cursor = (PLyCursorObject *) self;
if (!cursor->closed)
{
Portal portal = GetPortalByName(cursor->portalname);
if (!PortalIsValid(portal))
{
PLy_exception_set(PyExc_ValueError,
"closing a cursor in an aborted subtransaction");
return NULL;
}
SPI_cursor_close(portal);
cursor->closed = true;
}
Py_INCREF(Py_None);
return Py_None;
}