[PATCH 32/52] perf tools: Add helpers for calling Python objects

Adrian Hunter
2014-07-22T13:27:40Z

The Python script API repeatedly uses the same
lines of code to get and call objects. Make that
into helper functions instead. A side-effect is
that some reference counting bugs disappear because
the new call_object() function always decrements
the reference count of 'retval'.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
---
.../util/scripting-engines/trace-event-python.c | 114 +++++++++------------
1 file changed, 47 insertions(+), 67 deletions(-)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index cbce254..26e5f14 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -73,6 +73,35 @@ static void pydict_set_item_string_decref(PyObject *dict, const char *key, PyObj
Py_DECREF(val);
}

+static PyObject *get_handler(const char *handler_name)
+{
+ PyObject *handler;
+
+ handler = PyDict_GetItemString(main_dict, handler_name);
+ if (handler && !PyCallable_Check(handler))
+ return NULL;
+ return handler;
+}
+
+static void call_object(PyObject *handler, PyObject *args, const char *die_msg)
+{
+ PyObject *retval;
+
+ retval = PyObject_CallObject(handler, args);
+ if (retval == NULL)
+ handler_call_die(die_msg);
+ Py_DECREF(retval);
+}
+
+static void try_call_object(const char *handler_name, PyObject *args)
+{
+ PyObject *handler;
+
+ handler = get_handler(handler_name);
+ if (handler)
+ call_object(handler, args, handler_name);
+}
+
static void define_value(enum print_arg_type field_type,
const char *ev_name,
const char *field_name,
@@ -80,7 +109,7 @@ static void define_value(enum print_arg_type field_type,
const char *field_str)
{
const char *handler_name = "define_flag_value";
- PyObject *handler, *t, *retval;
+ PyObject *t;
unsigned long long value;
unsigned n = 0;

@@ -98,13 +127,7 @@ static void define_value(enum print_arg_type field_type,
PyTuple_SetItem(t, n++, PyInt_FromLong(value));
PyTuple_SetItem(t, n++, PyString_FromString(field_str));

- handler = PyDict_GetItemString(main_dict, handler_name);
- if (handler && PyCallable_Check(handler)) {
- retval = PyObject_CallObject(handler, t);
- if (retval == NULL)
- handler_call_die(handler_name);
- Py_DECREF(retval);
- }
+ try_call_object(handler_name, t);

Py_DECREF(t);
}
@@ -127,7 +150,7 @@ static void define_field(enum print_arg_type field_type,
const char *delim)
{
const char *handler_name = "define_flag_field";
- PyObject *handler, *t, *retval;
+ PyObject *t;
unsigned n = 0;

if (field_type == PRINT_SYMBOL)
@@ -145,13 +168,7 @@ static void define_field(enum print_arg_type field_type,
if (field_type == PRINT_FLAGS)
PyTuple_SetItem(t, n++, PyString_FromString(delim));

- handler = PyDict_GetItemString(main_dict, handler_name);
- if (handler && PyCallable_Check(handler)) {
- retval = PyObject_CallObject(handler, t);
- if (retval == NULL)
- handler_call_die(handler_name);
- Py_DECREF(retval);
- }
+ try_call_object(handler_name, t);

Py_DECREF(t);
}
@@ -362,7 +379,7 @@ static void python_process_tracepoint(struct perf_sample *sample,
struct thread *thread,
struct addr_location *al)
{
- PyObject *handler, *retval, *context, *t, *obj, *callchain;
+ PyObject *handler, *context, *t, *obj, *callchain;
PyObject *dict = NULL;
static char handler_name[256];
struct format_field *field;
@@ -387,9 +404,7 @@ static void python_process_tracepoint(struct perf_sample *sample,

sprintf(handler_name, "%s__%s", event->system, event->name);

- handler = PyDict_GetItemString(main_dict, handler_name);
- if (handler && !PyCallable_Check(handler))
- handler = NULL;
+ handler = get_handler(handler_name);
if (!handler) {
dict = PyDict_New();
if (!dict)
@@ -450,19 +465,9 @@ static void python_process_tracepoint(struct perf_sample *sample,
Py_FatalError("error resizing Python tuple");

if (handler) {
- retval = PyObject_CallObject(handler, t);
- if (retval == NULL)
- handler_call_die(handler_name);
- Py_DECREF(retval);
+ call_object(handler, t, handler_name);
} else {
- handler = PyDict_GetItemString(main_dict, "trace_unhandled");
- if (handler && PyCallable_Check(handler)) {
-
- retval = PyObject_CallObject(handler, t);
- if (retval == NULL)
- handler_call_die("trace_unhandled");
- Py_DECREF(retval);
- }
+ try_call_object("trace_unhandled", t);
Py_DECREF(dict);
}

@@ -474,7 +479,7 @@ static void python_process_general_event(struct perf_sample *sample,
struct thread *thread,
struct addr_location *al)
{
- PyObject *handler, *retval, *t, *dict, *callchain, *dict_sample;
+ PyObject *handler, *t, *dict, *callchain, *dict_sample;
static char handler_name[64];
unsigned n = 0;

@@ -496,8 +501,8 @@ static void python_process_general_event(struct perf_sample *sample,

snprintf(handler_name, sizeof(handler_name), "%s", "process_event");

- handler = PyDict_GetItemString(main_dict, handler_name);
- if (!handler || !PyCallable_Check(handler))
+ handler = get_handler(handler_name);
+ if (!handler)
goto exit;

pydict_set_item_string_decref(dict, "ev_name", PyString_FromString(perf_evsel__name(evsel)));
@@ -539,10 +544,7 @@ static void python_process_general_event(struct perf_sample *sample,
if (_PyTuple_Resize(&t, n) == -1)
Py_FatalError("error resizing Python tuple");

- retval = PyObject_CallObject(handler, t);
- if (retval == NULL)
- handler_call_die(handler_name);
- Py_DECREF(retval);
+ call_object(handler, t, handler_name);
exit:
Py_DECREF(dict);
Py_DECREF(t);
@@ -566,36 +568,24 @@ static void python_process_event(union perf_event *event __maybe_unused,

static int run_start_sub(void)
{
- PyObject *handler, *retval;
- int err = 0;
-
main_module = PyImport_AddModule("__main__");
if (main_module == NULL)
return -1;
Py_INCREF(main_module);

main_dict = PyModule_GetDict(main_module);
- if (main_dict == NULL) {
- err = -1;
+ if (main_dict == NULL)
goto error;
- }
Py_INCREF(main_dict);

- handler = PyDict_GetItemString(main_dict, "trace_begin");
- if (handler == NULL || !PyCallable_Check(handler))
- goto out;
+ try_call_object("trace_begin", NULL);

- retval = PyObject_CallObject(handler, NULL);
- if (retval == NULL)
- handler_call_die("trace_begin");
+ return 0;

- Py_DECREF(retval);
- return err;
error:
Py_XDECREF(main_dict);
Py_XDECREF(main_module);
-out:
- return err;
+ return -1;
}

/*
@@ -654,23 +644,13 @@ error:
*/
static int python_stop_script(void)
{
- PyObject *handler, *retval;
- int err = 0;
+ try_call_object("trace_end", NULL);

- handler = PyDict_GetItemString(main_dict, "trace_end");
- if (handler == NULL || !PyCallable_Check(handler))
- goto out;
-
- retval = PyObject_CallObject(handler, NULL);
- if (retval == NULL)
- handler_call_die("trace_end");
- Py_DECREF(retval);
-out:
Py_XDECREF(main_dict);
Py_XDECREF(main_module);
Py_Finalize();

- return err;
+ return 0;
}

static int python_generate_script(struct pevent *pevent, const char *outfile)
--
1.8.3.2