[RFC PATCH v1 11/15] perf python: Add python session abstraction wrapping perf's session

[Ian Rogers <irogers@google.com>]

Sessions are necessary to be able to use perf.data files within a
tool. Add a wrapper python type that incorporates the tool. Allow a
sample callback to be passed when creating the session. When
process_events is run this callback will be called, if supplied, for
sample events.

An example use looks like:
```
$ perf record -e cycles,instructions -a sleep 3
$ PYTHONPATH=..../perf/python python3
Python 3.13.7 (main, Aug 20 2025, 22:17:40) [GCC 14.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import perf
>>> count=0
... def handle_sample(x):
...   global count
...   if count < 3:
...     print(dir(x))
...   count = count + 1
... perf.session(perf.data("perf.data"),sample=handle_sample).process_events()
...
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'sample_addr', 'sample_cpu', 'sample_id', 'sample_ip', 'sample_period', 'sample_pid', 'sample_stream_id', 'sample_tid', 'sample_time', 'type']
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'sample_addr', 'sample_cpu', 'sample_id', 'sample_ip', 'sample_period', 'sample_pid', 'sample_stream_id', 'sample_tid', 'sample_time', 'type']
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getstate__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'sample_addr', 'sample_cpu', 'sample_id', 'sample_ip', 'sample_period', 'sample_pid', 'sample_stream_id', 'sample_tid', 'sample_time', 'type']
```

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/python.c | 114 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 113 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/python.c b/tools/perf/util/python.c
index f96c1f6dca56..dfc6e9299af9 100644
--- a/tools/perf/util/python.c
+++ b/tools/perf/util/python.c
@@ -19,8 +19,10 @@
 #include "pmus.h"
 #include "print_binary.h"
 #include "record.h"
+#include "session.h"
 #include "strbuf.h"
 #include "thread_map.h"
+#include "tool.h"
 #include "tp_pmu.h"
 #include "trace-event.h"
 #include "metricgroup.h"
@@ -2219,6 +2221,112 @@ static int pyrf_data__setup_types(void)
 	return PyType_Ready(&pyrf_data__type);
 }
 
+struct pyrf_session {
+	PyObject_HEAD
+
+	struct perf_session *session;
+	struct perf_tool tool;
+	struct pyrf_data *pdata;
+	PyObject *sample;
+	PyObject *stat;
+};
+
+static int pyrf_session_tool__sample(const struct perf_tool *tool,
+				     union perf_event *event,
+				     struct perf_sample *sample,
+				     struct evsel *evsel,
+				     struct machine *machine __maybe_unused)
+{
+	struct pyrf_session *psession = container_of(tool, struct pyrf_session, tool);
+	PyObject *pyevent = pyrf_event__new(event);
+	struct pyrf_event *pevent = (struct pyrf_event *)pyevent;
+
+	if (pyevent == NULL)
+		return -ENOMEM;
+
+	pevent->evsel = evsel;
+	memcpy(&pevent->sample, sample, sizeof(struct perf_sample));
+
+	PyObject_CallFunction(psession->sample, "O", pyevent);
+	Py_DECREF(pyevent);
+	return 0;
+}
+
+static int pyrf_session__init(struct pyrf_session *psession, PyObject *args, PyObject *kwargs)
+{
+	struct pyrf_data *pdata;
+	PyObject *sample = NULL;
+	static char *kwlist[] = { "data", "sample", NULL };
+
+	if (!PyArg_ParseTupleAndKeywords(args, kwargs, "O|O", kwlist, &pdata, &sample))
+		return -1;
+
+	Py_INCREF(pdata);
+	psession->pdata = pdata;
+	perf_tool__init(&psession->tool, /*ordered_events=*/true);
+
+	#define ADD_TOOL(name) \
+	if (name) {					\
+		if (!PyCallable_Check(name)) {\
+			PyErr_SetString(PyExc_TypeError, #name " must be callable"); \
+			return -1;\
+		}\
+		psession->tool.name = pyrf_session_tool__##name;	\
+		Py_INCREF(name); \
+		psession->name = name; \
+	}
+
+	ADD_TOOL(sample);
+	#undef ADD_TOOL
+
+	psession->session = perf_session__new(&pdata->data, &psession->tool);
+	return psession->session ? 0 : -1;
+}
+
+static void pyrf_session__delete(struct pyrf_session *psession)
+{
+	Py_XDECREF(psession->pdata);
+	Py_XDECREF(psession->sample);
+	perf_session__delete(psession->session);
+	Py_TYPE(psession)->tp_free((PyObject *)psession);
+}
+
+static PyObject *pyrf_session__process_events(struct pyrf_session *psession)
+{
+	perf_session__process_events(psession->session);
+	Py_INCREF(Py_None);
+	return Py_None;
+}
+
+static PyMethodDef pyrf_session__methods[] = {
+	{
+		.ml_name  = "process_events",
+		.ml_meth  = (PyCFunction)pyrf_session__process_events,
+		.ml_flags = METH_NOARGS,
+		.ml_doc	  = PyDoc_STR("Iterate and process events.")
+	},
+	{ .ml_name = NULL, }
+};
+
+static const char pyrf_session__doc[] = PyDoc_STR("perf session object.");
+
+static PyTypeObject pyrf_session__type = {
+	PyVarObject_HEAD_INIT(NULL, 0)
+	.tp_name	= "perf.session",
+	.tp_basicsize	= sizeof(struct pyrf_session),
+	.tp_dealloc	= (destructor)pyrf_session__delete,
+	.tp_flags	= Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE,
+	.tp_methods	= pyrf_session__methods,
+	.tp_doc		= pyrf_session__doc,
+	.tp_init	= (initproc)pyrf_session__init,
+};
+
+static int pyrf_session__setup_types(void)
+{
+	pyrf_session__type.tp_new = PyType_GenericNew;
+	return PyType_Ready(&pyrf_session__type);
+}
+
 static PyMethodDef perf__methods[] = {
 	{
 		.ml_name  = "metrics",
@@ -2282,7 +2390,8 @@ PyMODINIT_FUNC PyInit_perf(void)
 	    pyrf_pmu_iterator__setup_types() < 0 ||
 	    pyrf_pmu__setup_types() < 0 ||
 	    pyrf_counts_values__setup_types() < 0 ||
-	    pyrf_data__setup_types() < 0)
+	    pyrf_data__setup_types() < 0 ||
+	    pyrf_session__setup_types() < 0)
 		return module;
 
 	/* The page_size is placed in util object. */
@@ -2333,6 +2442,9 @@ PyMODINIT_FUNC PyInit_perf(void)
 	Py_INCREF(&pyrf_data__type);
 	PyModule_AddObject(module, "data", (PyObject *)&pyrf_data__type);
 
+	Py_INCREF(&pyrf_data__type);
+	PyModule_AddObject(module, "session", (PyObject *)&pyrf_session__type);
+
 	dict = PyModule_GetDict(module);
 	if (dict == NULL)
 		goto error;
-- 
2.51.1.851.g4ebd6896fd-goog