perf script python: Add helpers for calling Python objects

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>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1406786474-9306-19-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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 (file)
--- 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)