[libcamera-devel] [RFC PATCH 1/2] libcamera: tracing: Implement tracing infrastructure

Paul Elder paul.elder at ideasonboard.com
Mon Oct 19 12:25:28 CEST 2020


Implement tracing infrastructure in libcamera. It takes .tp files, as
required by lttng, and generates a tracepoint header and C file, as lttng
requires. meson is updated accordingly to get it to compile with the
rest of libcamera. Update the documentation accordingly.

Signed-off-by: Paul Elder <paul.elder at ideasonboard.com>
---
 Documentation/Doxyfile.in                     |  2 +
 README.rst                                    |  3 ++
 include/libcamera/internal/meson.build        |  9 +++++
 .../internal/tracepoints/meson.build          |  4 ++
 meson.build                                   |  3 ++
 meson_options.txt                             |  5 +++
 src/libcamera/meson.build                     |  7 ++++
 src/libcamera/tracepoints.cpp                 | 10 +++++
 utils/meson.build                             |  1 +
 utils/tracepoints/generate_header.py          | 40 +++++++++++++++++++
 utils/tracepoints/header.tmpl                 | 40 +++++++++++++++++++
 utils/tracepoints/meson.build                 |  5 +++
 12 files changed, 129 insertions(+)
 create mode 100644 include/libcamera/internal/tracepoints/meson.build
 create mode 100644 src/libcamera/tracepoints.cpp
 create mode 100644 utils/tracepoints/generate_header.py
 create mode 100644 utils/tracepoints/header.tmpl
 create mode 100644 utils/tracepoints/meson.build

diff --git a/Documentation/Doxyfile.in b/Documentation/Doxyfile.in
index 5ccd0d05..9a7a3fb4 100644
--- a/Documentation/Doxyfile.in
+++ b/Documentation/Doxyfile.in
@@ -842,6 +842,8 @@ EXCLUDE                = @TOP_SRCDIR@/include/libcamera/span.h \
 			 @TOP_SRCDIR@/src/libcamera/ipa_ipc_unixsocket.cpp \
 			 @TOP_SRCDIR@/src/libcamera/pipeline/ \
 			 @TOP_SRCDIR@/src/libcamera/proxy/ \
+			 @TOP_SRCDIR@/src/libcamera/tracepoints.cpp \
+			 @TOP_BUILDDIR@/include/libcamera/internal/tracepoints.h \
 			 @TOP_BUILDDIR@/include/libcamera/ipa/ \
 			 @TOP_BUILDDIR@/src/libcamera/proxy/
 
diff --git a/README.rst b/README.rst
index fc8f4948..039015ac 100644
--- a/README.rst
+++ b/README.rst
@@ -81,6 +81,9 @@ for gstreamer: [optional]
 for qcam: [optional]
 	qtbase5-dev libqt5core5a libqt5gui5 libqt5widgets5 qttools5-dev-tools libtiff-dev
 
+for tracing with lttng: [optional]
+        lttng-ust-dev
+
 Using GStreamer plugin
 ~~~~~~~~~~~~~~~~~~~~~~
 
diff --git a/include/libcamera/internal/meson.build b/include/libcamera/internal/meson.build
index 8dd744fd..21805edd 100644
--- a/include/libcamera/internal/meson.build
+++ b/include/libcamera/internal/meson.build
@@ -1,5 +1,14 @@
 # SPDX-License-Identifier: CC0-1.0
 
+subdir('tracepoints')
+
+libcamera_tracepoint_header = custom_target(
+    'tp_header',
+    input: [ tracepoints_header_template, tracepoint_files ],
+    output: 'tracepoints.h',
+    command: [ tracepoints_header_generator, '@OUTPUT@', '@INPUT@' ],
+)
+
 libcamera_internal_headers = files([
     'byte_stream_buffer.h',
     'camera_controls.h',
diff --git a/include/libcamera/internal/tracepoints/meson.build b/include/libcamera/internal/tracepoints/meson.build
new file mode 100644
index 00000000..2dd6733e
--- /dev/null
+++ b/include/libcamera/internal/tracepoints/meson.build
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: CC0-1.0
+
+tracepoint_files = files([
+])
diff --git a/meson.build b/meson.build
index de15cc16..b6a8c2d2 100644
--- a/meson.build
+++ b/meson.build
@@ -103,6 +103,9 @@ libcamera_includes = include_directories('include')
 # Sub-directories fill py_modules with their dependencies.
 py_modules = []
 
+# We need to check in include/ if we need to generate the tracepoint header
+liblttng = cc.find_library('lttng-ust', required : get_option('tracepoints'))
+
 # Utilities are parsed first to provide support for other components.
 subdir('utils')
 
diff --git a/meson_options.txt b/meson_options.txt
index 7f7b3e59..9e768beb 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -28,6 +28,11 @@ option('test',
         type : 'boolean',
         description: 'Compile and include the tests')
 
+option('tracepoints',
+        type : 'feature',
+        value : 'auto',
+        description: 'Compile libcamera with lttng tracepoints')
+
 option('v4l2',
         type : 'boolean',
         value : false,
diff --git a/src/libcamera/meson.build b/src/libcamera/meson.build
index 42340eae..7dc77c67 100644
--- a/src/libcamera/meson.build
+++ b/src/libcamera/meson.build
@@ -58,6 +58,7 @@ libcamera_sources = files([
 
 libcamera_sources += libcamera_public_headers
 libcamera_sources += libcamera_generated_headers
+libcamera_sources += libcamera_tracepoint_header
 
 includes = [
     libcamera_includes,
@@ -75,6 +76,11 @@ if libgnutls.found()
     config_h.set('HAVE_GNUTLS', 1)
 endif
 
+if liblttng.found()
+    config_h.set('TRACING_ENABLED', 1)
+    libcamera_sources += files(['tracepoints.cpp'])
+endif
+
 if libudev.found()
     config_h.set('HAVE_LIBUDEV', 1)
     libcamera_sources += files([
@@ -117,6 +123,7 @@ libcamera_deps = [
     libatomic,
     libdl,
     libgnutls,
+    liblttng,
     libudev,
     dependency('threads'),
 ]
diff --git a/src/libcamera/tracepoints.cpp b/src/libcamera/tracepoints.cpp
new file mode 100644
index 00000000..0173b75a
--- /dev/null
+++ b/src/libcamera/tracepoints.cpp
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) 2020, Google Inc.
+ *
+ * tracepoints.cpp - Tracepoints with lttng
+ */
+#define TRACEPOINT_CREATE_PROBES
+#define TRACEPOINT_DEFINE
+
+#include "libcamera/internal/tracepoints.h"
diff --git a/utils/meson.build b/utils/meson.build
index 383d5285..8e28ada7 100644
--- a/utils/meson.build
+++ b/utils/meson.build
@@ -2,6 +2,7 @@
 
 subdir('ipc')
 subdir('ipu3')
+subdir('tracepoints')
 
 ## Code generation
 py_modules += ['yaml']
diff --git a/utils/tracepoints/generate_header.py b/utils/tracepoints/generate_header.py
new file mode 100644
index 00000000..52268eba
--- /dev/null
+++ b/utils/tracepoints/generate_header.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (C) 2020, Google Inc.
+#
+# Author: Paul Elder <paul.elder at ideasonboard.com>
+#
+# generate_header.py - Generate header file to contain lttng tracepoints
+
+import datetime
+import jinja2
+import os
+import sys
+
+def main(argv):
+    if len(argv) < 3:
+        print(f'Usage: {argv[0]} output template tp_files...')
+        return 1
+
+    output = argv[1]
+    template = argv[2]
+
+    year = datetime.datetime.now().year
+    path = output.replace('include/', '', 1)
+
+    source = ''
+    for fname in argv[3:]:
+        source += open(fname, 'r').read() + '\n\n'
+
+    template = jinja2.Template(open(template, 'r').read())
+    string = template.render(year=year, path=path, source=source)
+
+    f = open(output, 'w')
+    f.write(string)
+    f.close()
+
+    return 0
+
+
+if __name__ == '__main__':
+    sys.exit(main(sys.argv))
diff --git a/utils/tracepoints/header.tmpl b/utils/tracepoints/header.tmpl
new file mode 100644
index 00000000..b1595656
--- /dev/null
+++ b/utils/tracepoints/header.tmpl
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+/*
+ * Copyright (C) {{year}}, Google Inc.
+ *
+ * tracepoints.h - Tracepoints with lttng
+ *
+ * This file is auto-generated. Do not edit.
+ */
+#ifndef __LIBCAMERA_INTERNAL_TRACEPOINTS_H__
+#define __LIBCAMERA_INTERNAL_TRACEPOINTS_H__
+
+#if TRACING_ENABLED
+#define LIBCAMERA_TRACEPOINT(...) tracepoint(libcamera, __VA_ARGS__)
+#else
+#define LIBCAMERA_TRACEPOINT(...) do {} while (0)
+#endif
+
+#endif /* __LIBCAMERA_INTERNAL_TRACEPOINTS_H__ */
+
+
+#if TRACING_ENABLED
+
+#undef TRACEPOINT_PROVIDER
+#define TRACEPOINT_PROVIDER libcamera
+
+#undef TRACEPOINT_INCLUDE
+#define TRACEPOINT_INCLUDE "{{path}}"
+
+#if !defined(INCLUDE_LIBCAMERA_INTERNAL_TRACEPOINTS_TP_H) || defined(TRACEPOINT_HEADER_MULTI_READ)
+#define INCLUDE_LIBCAMERA_INTERNAL_TRACEPOINTS_TP_H
+
+#include <lttng/tracepoint.h>
+
+{{source}}
+
+#endif /* INCLUDE_LIBCAMERA_INTERNAL_TRACEPOINTS_TP_H */
+
+#include <lttng/tracepoint-event.h>
+
+#endif /* TRACING_ENABLED */
diff --git a/utils/tracepoints/meson.build b/utils/tracepoints/meson.build
new file mode 100644
index 00000000..7294287b
--- /dev/null
+++ b/utils/tracepoints/meson.build
@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: CC0-1.0
+
+tracepoints_header_template = files(['header.tmpl'])
+
+tracepoints_header_generator = find_program('./generate_header.py')
-- 
2.27.0



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