#!/usr/bin/env python3
# Copyright 2024 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import os
import sys
from collections import defaultdict
DESCRIPTION = \
'''This script takes in a Chromium trace file and extracts info about Mojo
messages that were sent/received.
Trace files can be created using chrome://tracing or from passing
'--enable-tracing' to a Chrome or browser test executable. In the
chrome://tracing UI, ensure that the 'mojom' and 'toplevel' categories are
selected when setting up a new trace. Also, the trace events available will
have much more information (including message contents and return values) if
the executable generating the trace file is built with the
`extended_tracing_enabled = true` gn arg.
'''
PERFETTO_NOT_FOUND_HELP_TEXT = \
'''Error: perfetto module not found.
This script requires the perfetto Python module. To install it, use something
like `pip install perfetto`, or for Googlers on gLinux use the following (in a
Chromium checkout):
```
sudo apt-get install python3-venv
python3 -m venv venv
./venv/bin/python3 -mpip install perfetto
./venv/bin/python3 tools/mojo_messages_log.py <script args>
```
'''
# Note: Ignore 'mojo::Message::Message' (from the disabled by default 'mojom'
# category) because there is usually higher-level information that's more
# helpful, even in release builds.
# TODO(awillia): The 'Send mojo message' and 'Receive mojo sync reply' trace
# events (both from the toplevel.flow category) should have a message ID
# associated with them but I'm not sure how to access it. With the former we
# could figure out the sender of a message, but without the message ID the
# events aren't very helpful.
MOJO_EVENTS_QUERY = \
'''INCLUDE PERFETTO MODULE slices.with_context;
SELECT
(ts - (SELECT start_ts FROM trace_bounds)) / 1000000000.0 AS ts_delta,
process_name,
pid, -- Useful for distinguishing renderer processes
thread_name,
name,
category AS event_category,
GROUP_CONCAT(args.key || ": " ||
COALESCE(args.int_value,
args.string_value,
args.real_value)) AS parameters
-- Note that we could get argument type info as well if that's worthwhile
FROM thread_slice
LEFT JOIN args on args.arg_set_id = thread_slice.arg_set_id
WHERE (category IS 'mojom' AND name GLOB 'Send *') OR
(category IS 'mojom' AND name GLOB 'Call *') OR
(category IS 'toplevel' AND name GLOB 'Receive *') OR
(category IS 'toplevel' AND name IS 'Closed mojo endpoint')
GROUP BY thread_slice.id, args.arg_set_id
ORDER BY ts;
'''
SUMMARY_FIELDS = ['ts_delta', 'process_name', 'name']
VERBOSE_FIELDS = ['ts_delta', 'process_name', 'pid', 'thread_name', 'name']
ADDITIONAL_DATA_FIELDS = ['name', 'event_category', 'parameters']
def is_valid_path(parser, path):
if not os.path.exists(path):
parser.error("Invalid path: %s" % (path))
else:
return path
def process_mojo_msg_info(extra, spacing=2):
if not extra or len(extra) != len(ADDITIONAL_DATA_FIELDS):
return
output = ''
spacer = ' ' * spacing
event_name, event_category, parameters = extra
# The parameters exist as a single comma separated line, so break it into
# separate lines. Each if statement block here corresponds to a WHERE
# condition in the SQL query.
if (event_category == 'mojom' and event_name.startswith("Send ")) or \
(event_category == 'mojom' and event_name.startswith("Call ")):
if parameters is None:
# The call has no parameters
parameters = []
else:
assert (parameters.startswith('debug.'))
parameters = parameters.replace('debug.', '', 1)
parameters = parameters.split(',debug.')
elif (event_category == 'toplevel' and event_name.startswith("Receive ")) or \
(event_category == 'toplevel' and event_name == "Closed mojo endpoint"):
if parameters is None:
parameters = []
elif parameters.startswith('chrome_mojo_event_info.'):
parameters = parameters.replace('chrome_mojo_event_info.', '', 1)
parameters = parameters.split(',chrome_mojo_event_info.')
parameters = ['chrome_mojo_event_info.' + x for x in parameters]
else:
assert (parameters.startswith('args.'))
parameters = parameters.replace('args.', '', 1)
parameters = parameters.split(',args.')
results = defaultdict(lambda: [])
for parameter in parameters:
info_type, info = parameter.split('.', 1)
results[info_type].append(info)
for info_type in results:
output += spacer + info_type + ':\n'
for entry in results[info_type]:
output += spacer * 2 + entry + '\n'
return output
# Formats the event data into the structured data that can be shown in the
# displayed table and additional unstructured data that should be shown
# underneath each event.
def process_events(args, events):
rows = []
extras = []
for row_data in events:
row = []
extra = []
if args.summary:
for field in SUMMARY_FIELDS:
row.append(str(getattr(row_data, field)))
else:
for field in VERBOSE_FIELDS:
row.append(str(getattr(row_data, field)))
for field in ADDITIONAL_DATA_FIELDS:
extra.append(getattr(row_data, field))
extra = process_mojo_msg_info(extra)
rows.append(row)
extras.append(extra)
return rows, extras
try:
from perfetto.trace_processor import TraceProcessor
except ModuleNotFoundError:
print(PERFETTO_NOT_FOUND_HELP_TEXT)
sys.exit(1)
def main():
import argparse
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
description=DESCRIPTION)
parser.add_argument('tracefile',
type=lambda path: is_valid_path(parser, path))
parser.add_argument('--summary', action="store_true")
args = parser.parse_args()
tp = TraceProcessor(file_path=args.tracefile)
results = tp.query(MOJO_EVENTS_QUERY)
rows, extras = process_events(args, results)
# Add headers for the table.
if args.summary:
rows.insert(0, SUMMARY_FIELDS)
else:
rows.insert(0, VERBOSE_FIELDS)
# Keep `extras` the same length as `rows`.
extras.insert(0, None)
# Calculate the appropriate widths of each column.
widths = [max(map(len, column)) for column in zip(*rows)]
for i in range(len(rows)):
row = rows[i]
extra = extras[i]
# Format the structured data so the fields align with the table headers.
out = (value.ljust(width) for value, width in zip(row, widths))
out = " ".join(out).rstrip()
print(out)
if extra:
print(extra)
if __name__ == '__main__':
sys.exit(main())
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