collector: Add PerfettoCollector

Add a Collector for accessing Google's Perfetto tracing infrastructure.
The Collector takes a path to an on-device config file, starts tracing
in the background using the perfetto binary and then stops by killing
the tracing process.

Signed-off-by: Kajetan Puchalski <kajetan.puchalski@arm.com>

devlib/__init__.py

@@ -46,6 +46,7 @@ from devlib.derived.energy import DerivedEnergyMeasurements
 from devlib.derived.fps import DerivedGfxInfoStats, DerivedSurfaceFlingerStats
 
 from devlib.collector.ftrace import FtraceCollector
+from devlib.collector.perfetto import PerfettoCollector
 from devlib.collector.perf import PerfCollector
 from devlib.collector.serial_trace import SerialTraceCollector
 from devlib.collector.dmesg import DmesgCollector

devlib/collector/perfetto.py

@@ -0,0 +1,120 @@
+#    Copyright 2023 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+import os
+import subprocess
+from shlex import quote
+
+from devlib.host import PACKAGE_BIN_DIRECTORY
+from devlib.collector import (CollectorBase, CollectorOutput,
+                              CollectorOutputEntry)
+from devlib.exception import TargetStableError, HostError
+
+OUTPUT_PERFETTO_TRACE = 'devlib-trace.perfetto-trace'
+
+
+class PerfettoCollector(CollectorBase):
+    """
+    Perfetto is a production-grade open-source stack for performance instrumentation
+    and trace analysis developed by Google. It offers services and libraries for
+    recording system-level and app-level traces, native + java heap profiling,
+    a library for analyzing traces using SQL and a web-based UI to visualize and
+    explore multi-GB traces.
+
+    This collector takes a path to a perfetto config file saved on disk and passes
+    it directly to the tool.
+
+    On Android platfroms Perfetto is included in the framework starting with Android 9.
+    On Android 8 and below, follow the Linux instructions below to build and include
+    the standalone tracebox binary.
+
+    On Linux platforms, either traced (Perfetto tracing daemon) needs to be running
+    in the background or the tracebox binary needs to be built from source and placed
+    in the Package Bin directory. The build instructions can be found here:
+
+    It is also possible to force using the prebuilt tracebox binary on platforms which
+    already have traced running using the force_tracebox collector parameter.
+
+    https://perfetto.dev/docs/contributing/build-instructions
+
+    After building the 'tracebox' binary should be copied to devlib/bin/<arch>/.
+
+    For more information consult the official documentation:
+    https://perfetto.dev/docs/
+    """
+
+    def __init__(self, target, config=None, force_tracebox=False):
+        super().__init__(target)
+        self.bg_cmd = None
+        self.config = config
+        self.target_binary = 'perfetto'
+        target_output_path = self.target.working_directory
+
+        install_tracebox = force_tracebox or (target.os in ['linux', 'android'] and not target.is_running('traced'))
+
+        # Install Perfetto through tracebox
+        if install_tracebox:
+            self.target_binary = 'tracebox'
+            if not self.target.get_installed(self.target_binary):
+                host_executable = os.path.join(PACKAGE_BIN_DIRECTORY,
+                                               self.target.abi, self.target_binary)
+                if not os.path.exists(host_executable):
+                    raise HostError("{} not found on the host".format(self.target_binary))
+                self.target.install(host_executable)
+        # Use Android's built-in Perfetto
+        elif target.os == 'android':
+            os_version = target.os_version['release']
+            if int(os_version) >= 9:
+                # Android requires built-in Perfetto to write to this directory
+                target_output_path = '/data/misc/perfetto-traces'
+                # Android 9 and 10 require traced to be enabled manually
+                if int(os_version) <= 10:
+                    target.execute('setprop persist.traced.enable 1')
+
+        self.target_output_file = target.path.join(target_output_path, OUTPUT_PERFETTO_TRACE)
+
+    def start(self):
+        cmd = "cat {} | {} --txt -c - -o {}".format(
+            quote(self.config), quote(self.target_binary), quote(self.target_output_file)
+        )
+        # start tracing
+        if self.bg_cmd is None:
+            self.bg_cmd = self.target.background(cmd, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        else:
+            raise TargetStableError('Perfetto collector is not re-entrant')
+
+    def stop(self):
+        # stop tracing
+        self.bg_cmd.cancel()
+        self.bg_cmd = None
+
+    def set_output(self, output_path):
+        if os.path.isdir(output_path):
+            output_path = os.path.join(output_path, os.path.basename(self.target_output_file))
+        self.output_path = output_path
+
+    def get_data(self):
+        if self.output_path is None:
+            raise RuntimeError("Output path was not set.")
+        if not self.target.file_exists(self.target_output_file):
+            raise RuntimeError("Output file not found on the device")
+        self.target.pull(self.target_output_file, self.output_path)
+        output = CollectorOutput()
+        if not os.path.isfile(self.output_path):
+            self.logger.warning('Perfetto trace not pulled from device.')
+        else:
+            output.append(CollectorOutputEntry(self.output_path, 'file'))
+        return output
+