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bpo-44165: optimise sqlite3 statement preparation by passing string size #26206

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Merged
merged 5 commits into from
Jun 2, 2021
Merged

bpo-44165: optimise sqlite3 statement preparation by passing string size #26206

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f901fd5
bpo-44165: optimise sqlite3 statement preparation by passing string size
May 18, 2021
9febd15
Pass -1 if size >= INT_MAX
May 19, 2021
081de33
Raise OverflowError if SQL string is too long
May 19, 2021
d981be6
Raise DataError iso. OverflowError to keep current behaviour
May 19, 2021
d0d0618
sqlite3_limit is cheap; use it directly iso. caching it in the connec…
May 19, 2021
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4 changes: 2 additions & 2 deletions Modules/_sqlite/connection.c
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Original file line number Diff line number Diff line change
Expand Up @@ -428,7 +428,7 @@ pysqlite_connection_commit_impl(pysqlite_Connection *self)
if (!sqlite3_get_autocommit(self->db)) {

Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(self->db, "COMMIT", -1, &statement, NULL);
rc = sqlite3_prepare_v2(self->db, "COMMIT", 7, &statement, NULL);
Py_END_ALLOW_THREADS
if (rc != SQLITE_OK) {
_pysqlite_seterror(self->db);
Expand Down Expand Up @@ -478,7 +478,7 @@ pysqlite_connection_rollback_impl(pysqlite_Connection *self)
pysqlite_do_all_statements(self, ACTION_RESET, 1);

Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(self->db, "ROLLBACK", -1, &statement, NULL);
rc = sqlite3_prepare_v2(self->db, "ROLLBACK", 9, &statement, NULL);
Py_END_ALLOW_THREADS
if (rc != SQLITE_OK) {
_pysqlite_seterror(self->db);
Expand Down
20 changes: 16 additions & 4 deletions Modules/_sqlite/cursor.c
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Original file line number Diff line number Diff line change
Expand Up @@ -681,6 +681,7 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
const char* script_cstr;
sqlite3_stmt* statement;
int rc;
Py_ssize_t sql_len;
PyObject* result;

if (!check_cursor(self)) {
Expand All @@ -690,10 +691,17 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
self->reset = 0;

if (PyUnicode_Check(script_obj)) {
script_cstr = PyUnicode_AsUTF8(script_obj);
script_cstr = PyUnicode_AsUTF8AndSize(script_obj, &sql_len);
if (!script_cstr) {
return NULL;
}

int max_length = sqlite3_limit(self->connection->db,
SQLITE_LIMIT_LENGTH, -1);
if (sql_len >= max_length) {
PyErr_SetString(pysqlite_DataError, "query string is too large");
return NULL;
}
} else {
PyErr_SetString(PyExc_ValueError, "script argument must be unicode.");
return NULL;
Expand All @@ -707,12 +715,14 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
Py_DECREF(result);

while (1) {
const char *tail;

Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(self->connection->db,
script_cstr,
-1,
(int)sql_len + 1,
&statement,
&script_cstr);
&tail);
Py_END_ALLOW_THREADS
if (rc != SQLITE_OK) {
_pysqlite_seterror(self->connection->db);
Expand Down Expand Up @@ -740,9 +750,11 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
goto error;
}

if (*script_cstr == (char)0) {
if (*tail == (char)0) {
break;
}
sql_len -= (tail - script_cstr);
script_cstr = tail;
}

error:
Expand Down
8 changes: 7 additions & 1 deletion Modules/_sqlite/statement.c
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Original file line number Diff line number Diff line change
Expand Up @@ -66,6 +66,12 @@ int pysqlite_statement_create(pysqlite_Statement* self, pysqlite_Connection* con
rc = PYSQLITE_SQL_WRONG_TYPE;
return rc;
}

int max_length = sqlite3_limit(connection->db, SQLITE_LIMIT_LENGTH, -1);
if (sql_cstr_len >= max_length) {
PyErr_SetString(pysqlite_DataError, "query string is too large");
return PYSQLITE_TOO_MUCH_SQL;
}
if (strlen(sql_cstr) != (size_t)sql_cstr_len) {
PyErr_SetString(PyExc_ValueError, "the query contains a null character");
return PYSQLITE_SQL_WRONG_TYPE;
Expand Down Expand Up @@ -96,7 +102,7 @@ int pysqlite_statement_create(pysqlite_Statement* self, pysqlite_Connection* con
Py_BEGIN_ALLOW_THREADS
rc = sqlite3_prepare_v2(connection->db,
sql_cstr,
-1,
(int)sql_cstr_len + 1,
&self->st,
&tail);
Py_END_ALLOW_THREADS
Expand Down