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SubjectRe: [PATCH v5 1/5] perf script: Add general python handler to process non-tracepoint events
Date
Hi, Feng

On Wed, 8 Aug 2012 17:57:51 +0800, Feng Tang wrote:
> This patch just follows Robert Richter's idea and the commit 37a058ea0
> "perf script: Add generic perl handler to process events"
> to similarly add a python handler for general events other than tracepoints.
>
> For non-tracepoint events, this patch will try to find a function named
> "process_event" in the python script, and pass the event attribute,
> perf_sample, raw_data in format of raw string. And the python script can
> use "struct" module's unpack function to disasemble the needed info and process.
>
> Signed-off-by: Feng Tang <feng.tang@intel.com>
> Cc: Andi Kleen <andi@firstfloor.org>
> Cc: David Ahern <dsahern@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Robert Richter <robert.richter@amd.com>
> Cc: Stephane Eranian <eranian@google.com>
> http://lkml.kernel.org/r/1339999839-14007-2-git-send-email-feng.tang@intel.com
> [ committer note: Fixed up wrt da37896, i.e. pevent parm in script event handlers ]
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> .../util/scripting-engines/trace-event-python.c | 59 +++++++++++++++++++-
> 1 files changed, 58 insertions(+), 1 deletions(-)
>
> diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
> index df7d33d..b9010d8 100644
> --- a/tools/perf/util/scripting-engines/trace-event-python.c
> +++ b/tools/perf/util/scripting-engines/trace-event-python.c
> @@ -32,6 +32,7 @@
> #include "../event.h"
> #include "../thread.h"
> #include "../trace-event.h"
> +#include "../evsel.h"
>
> PyMODINIT_FUNC initperf_trace_context(void);
>
> @@ -220,7 +221,7 @@ static inline struct event_format *find_cache_event(struct perf_evsel *evsel)
> return event;
> }
>
> -static void python_process_event(union perf_event *perf_event __unused,
> +static void python_process_tracepoint(union perf_event *perf_event __unused,
> struct perf_sample *sample,
> struct perf_evsel *evsel,
> struct machine *machine __unused,
> @@ -337,6 +338,62 @@ static void python_process_event(union perf_event *perf_event __unused,
> Py_DECREF(t);
> }
>
> +static void python_process_general_event(union perf_event *perf_event __unused,
> + struct perf_sample *sample,
> + struct perf_evsel *evsel,
> + struct machine *machine __unused,
> + struct thread *thread __unused)
> +{
> + PyObject *handler, *retval, *t;
> + static char handler_name[64];
> + unsigned n = 0;
> + void *data = sample->raw_data;
> +
> + t = PyTuple_New(MAX_FIELDS);
> + if (!t)
> + Py_FatalError("couldn't create Python tuple");
> +
> + snprintf(handler_name, sizeof(handler_name), "%s", "process_event");
> +
> + handler = PyDict_GetItemString(main_dict, handler_name);
> + if (handler && !PyCallable_Check(handler)) {

Shouldn't it be like below?

if (!handler || !PyCallable_Check(handler))
goto exit;

Otherwise we can end up calling PyObject_CallObject with NULL handler
if PyDict_GetItemString() returns NULL. And the handler won't be used
anymore so no need to set it to NULL (again).

Thanks,
Namhyung


> + handler = NULL;
> + goto exit;
> + }
> +
> + /* Pass 3 parameters: event_attr, perf_sample, raw data */
> + PyTuple_SetItem(t, n++, PyString_FromStringAndSize((void *)&evsel->attr, sizeof(evsel->attr)));
> + PyTuple_SetItem(t, n++, PyString_FromStringAndSize((void *)sample, sizeof(*sample)));
> + PyTuple_SetItem(t, n++, PyString_FromStringAndSize(data, sample->raw_size));
> +
> + 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);
> +exit:
> + Py_DECREF(t);
> +}
> +
> +static void python_process_event(union perf_event *perf_event,
> + struct perf_sample *sample,
> + struct perf_evsel *evsel,
> + struct machine *machine,
> + struct thread *thread)
> +{
> + switch (evsel->attr.type) {
> + case PERF_TYPE_TRACEPOINT:
> + python_process_tracepoint(perf_event, sample, evsel,
> + machine, thread);
> + break;
> + /* Reserve for future process_hw/sw/raw APIs */
> + default:
> + python_process_general_event(perf_event, sample, evsel,
> + machine, thread);
> + }
> +}
> +
> static int run_start_sub(void)
> {
> PyObject *handler, *retval;


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