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bpo-42064: Pass module state to sqlite3 UDF callbacks #27456

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Merged
miss-islington merged 6 commits into from
Aug 24, 2021
Merged

bpo-42064: Pass module state to sqlite3 UDF callbacks #27456

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bebc47a
Add stubs for managing callback context
Jul 29, 2021
48a954d
Adapt create_*() functions
Jul 29, 2021
c5da5ab
Hold GIL when allocating/freeing context
Jul 30, 2021
506390f
Improve naming and remove some unneeded temporary variables
Aug 6, 2021
b5355d6
Merge branch 'main' into sqlite-callback-state/part1
Aug 24, 2021
271b9b5
Address review: protect incref with GIL
Aug 24, 2021
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89 changes: 58 additions & 31 deletions Modules/_sqlite/connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -612,8 +612,10 @@ set_sqlite_error(sqlite3_context *context, const char *msg)
else {
sqlite3_result_error(context, msg, -1);
}
pysqlite_state *state = pysqlite_get_state(NULL);
if (state->enable_callback_tracebacks) {
callback_context *ctx = (callback_context *)sqlite3_user_data(context);
assert(ctx != NULL);
assert(ctx->state != NULL);
if (ctx->state->enable_callback_tracebacks) {
PyErr_Print();
}
else {
Expand All @@ -625,19 +627,18 @@ static void
_pysqlite_func_callback(sqlite3_context *context, int argc, sqlite3_value **argv)
{
PyObject* args;
PyObject* py_func;
PyObject* py_retval = NULL;
int ok;

PyGILState_STATE threadstate;

threadstate = PyGILState_Ensure();

py_func = (PyObject*)sqlite3_user_data(context);

args = _pysqlite_build_py_params(context, argc, argv);
if (args) {
py_retval = PyObject_CallObject(py_func, args);
callback_context *ctx = (callback_context *)sqlite3_user_data(context);
assert(ctx != NULL);
py_retval = PyObject_CallObject(ctx->callable, args);
Py_DECREF(args);
}

Expand All @@ -657,20 +658,19 @@ static void _pysqlite_step_callback(sqlite3_context *context, int argc, sqlite3_
{
PyObject* args;
PyObject* function_result = NULL;
PyObject* aggregate_class;
PyObject** aggregate_instance;
PyObject* stepmethod = NULL;

PyGILState_STATE threadstate;

threadstate = PyGILState_Ensure();

aggregate_class = (PyObject*)sqlite3_user_data(context);

aggregate_instance = (PyObject**)sqlite3_aggregate_context(context, sizeof(PyObject*));

if (*aggregate_instance == NULL) {
*aggregate_instance = _PyObject_CallNoArg(aggregate_class);
callback_context *ctx = (callback_context *)sqlite3_user_data(context);
assert(ctx != NULL);
*aggregate_instance = _PyObject_CallNoArg(ctx->callable);
if (!*aggregate_instance) {
set_sqlite_error(context,
"user-defined aggregate's '__init__' method raised error");
Expand Down Expand Up @@ -784,14 +784,35 @@ static void _pysqlite_drop_unused_cursor_references(pysqlite_Connection* self)
Py_SETREF(self->cursors, new_list);
}

static void _destructor(void* args)
static callback_context *
create_callback_context(pysqlite_state *state, PyObject *callable)
{
// This function may be called without the GIL held, so we need to ensure
// that we destroy 'args' with the GIL
PyGILState_STATE gstate;
gstate = PyGILState_Ensure();
Py_DECREF((PyObject*)args);
PyGILState_STATE gstate = PyGILState_Ensure();
callback_context *ctx = PyMem_Malloc(sizeof(callback_context));
if (ctx != NULL) {
ctx->callable = Py_NewRef(callable);
ctx->state = state;
}
PyGILState_Release(gstate);
return ctx;
}

static void
free_callback_context(callback_context *ctx)
{
if (ctx != NULL) {
// This function may be called without the GIL held, so we need to
// ensure that we destroy 'ctx' with the GIL held.
PyGILState_STATE gstate = PyGILState_Ensure();
Py_DECREF(ctx->callable);
PyMem_Free(ctx);
PyGILState_Release(gstate);
}
}

static void _destructor(void* args)
{
free_callback_context((callback_context *)args);
}

/*[clinic input]
Expand Down Expand Up @@ -833,11 +854,11 @@ pysqlite_connection_create_function_impl(pysqlite_Connection *self,
flags |= SQLITE_DETERMINISTIC;
#endif
}
rc = sqlite3_create_function_v2(self->db,
name,
narg,
flags,
(void*)Py_NewRef(func),
callback_context *ctx = create_callback_context(self->state, func);
if (ctx == NULL) {
return NULL;
}
rc = sqlite3_create_function_v2(self->db, name, narg, flags, ctx,
_pysqlite_func_callback,
NULL,
NULL,
Expand Down Expand Up @@ -873,11 +894,12 @@ pysqlite_connection_create_aggregate_impl(pysqlite_Connection *self,
return NULL;
}

rc = sqlite3_create_function_v2(self->db,
name,
n_arg,
SQLITE_UTF8,
(void*)Py_NewRef(aggregate_class),
callback_context *ctx = create_callback_context(self->state,
aggregate_class);
if (ctx == NULL) {
return NULL;
}
rc = sqlite3_create_function_v2(self->db, name, n_arg, SQLITE_UTF8, ctx,
0,
&_pysqlite_step_callback,
&_pysqlite_final_callback,
Expand Down Expand Up @@ -1439,7 +1461,6 @@ pysqlite_collation_callback(
int text1_length, const void* text1_data,
int text2_length, const void* text2_data)
{
PyObject* callback = (PyObject*)context;
PyObject* string1 = 0;
PyObject* string2 = 0;
PyGILState_STATE gilstate;
Expand All @@ -1459,8 +1480,10 @@ pysqlite_collation_callback(
goto finally; /* failed to allocate strings */
}

callback_context *ctx = (callback_context *)context;
assert(ctx != NULL);
PyObject *args[] = { string1, string2 }; // Borrowed refs.
retval = PyObject_Vectorcall(callback, args, 2, NULL);
retval = PyObject_Vectorcall(ctx->callable, args, 2, NULL);
if (retval == NULL) {
/* execution failed */
goto finally;
Expand Down Expand Up @@ -1690,6 +1713,7 @@ pysqlite_connection_create_collation_impl(pysqlite_Connection *self,
return NULL;
}

callback_context *ctx = NULL;
int rc;
int flags = SQLITE_UTF8;
if (callable == Py_None) {
Expand All @@ -1701,8 +1725,11 @@ pysqlite_connection_create_collation_impl(pysqlite_Connection *self,
PyErr_SetString(PyExc_TypeError, "parameter must be callable");
return NULL;
}
rc = sqlite3_create_collation_v2(self->db, name, flags,
Py_NewRef(callable),
ctx = create_callback_context(self->state, callable);
if (ctx == NULL) {
return NULL;
}
rc = sqlite3_create_collation_v2(self->db, name, flags, ctx,
&pysqlite_collation_callback,
&_destructor);
}
Expand All @@ -1713,7 +1740,7 @@ pysqlite_connection_create_collation_impl(pysqlite_Connection *self,
* the context before returning.
*/
if (callable != Py_None) {
Py_DECREF(callable);
free_callback_context(ctx);
}
_pysqlite_seterror(self->state, self->db);
return NULL;
Expand Down
6 changes: 6 additions & 0 deletions Modules/_sqlite/connection.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,12 @@

#include "sqlite3.h"

typedef struct _callback_context
{
PyObject *callable;
pysqlite_state *state;
} callback_context;

typedef struct
{
PyObject_HEAD
Expand Down