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

Author: Erlend E. Aasland

Modules/_sqlite/connection.c

@@ -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);
@@ -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);

Modules/_sqlite/cursor.c

@@ -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 script_length;
     PyObject* result;
 
     if (!check_cursor(self)) {
@@ -690,7 +691,7 @@ 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, &script_length);
         if (!script_cstr) {
             return NULL;
         }
@@ -706,13 +707,16 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
     }
     Py_DECREF(result);
 
+    Py_ssize_t size_incl_null = script_length + 1;
     while (1) {
+        const char *tail;
+
         Py_BEGIN_ALLOW_THREADS
         rc = sqlite3_prepare_v2(self->connection->db,
                                 script_cstr,
-                                -1,
+                                size_incl_null,
                                 &statement,
-                                &script_cstr);
+                                &tail);
         Py_END_ALLOW_THREADS
         if (rc != SQLITE_OK) {
             _pysqlite_seterror(self->connection->db);
@@ -740,9 +744,11 @@ pysqlite_cursor_executescript(pysqlite_Cursor *self, PyObject *script_obj)
             goto error;
         }
 
-        if (*script_cstr == (char)0) {
+        if (*tail == (char)0) {
             break;
         }
+        size_incl_null -= (tail - script_cstr);
+        script_cstr = tail;
     }
 
 error:

Modules/_sqlite/statement.c

@@ -96,7 +96,7 @@ int pysqlite_statement_create(pysqlite_Statement* self, pysqlite_Connection* con
     Py_BEGIN_ALLOW_THREADS
     rc = sqlite3_prepare_v2(connection->db,
                             sql_cstr,
-                            -1,
+                            sql_cstr_len + 1,
                             &self->st,
                             &tail);
     Py_END_ALLOW_THREADS