Add subscribe-performance test app (#126)

Author: Chrylo

examples/performance-subscribe/AppManifest.json

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+{
+    "manifestVersion": "v1",
+    "name": "performance-subscribe",
+    "interfaces": [
+        {
+            "type": "vehicle-signal-interface",
+            "config": {
+                "src": "https://github.com/COVESA/vehicle_signal_specification/releases/download/v4.1/vss_rel_4.1.json",
+                "datapoints": {
+                    "required": [
+                    ]
+                }
+            }
+        }
+    ]
+}

examples/performance-subscribe/README.md

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+## Usage
+
+1) Create a .json file named: "subscription_signals.json"
+2) Place it in the same folder as the binary
+3) Exeucute the binary e.g. "./sampleapp"
+4) Check the console output for the timestamps: "<Timestamp> - <Signal_Name> - <Value>"
+
+## .json format
+
+The following format is mandatory for the input file:
+
+```
+{
+  "signals": [
+    {
+      "path": "Vehicle.LowVoltageBattery.CurrentVoltage"
+    },
+    {
+      "path": "Vehicle.LowVoltageBattery.CurrentCurrent"
+    },
+    {
+      "path": "Vehicle.Speed"
+    },
+    ...
+  ]
+}
+```
+
+Signals which are not available will be printed in the console as a warning.

examples/performance-subscribe/src/main.py

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+# Copyright (c) 2022-2024 Contributors to the Eclipse Foundation
+#
+# This program and the accompanying materials are made available under the
+# terms of the Apache License, Version 2.0 which is available at
+# https://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.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import asyncio
+import json
+import logging
+import signal
+from datetime import datetime
+
+from sdv_model import Vehicle, vehicle  # type: ignore
+
+from velocitas_sdk.model import DataPoint
+from velocitas_sdk.util.log import (  # type: ignore
+    get_opentelemetry_log_factory,
+    get_opentelemetry_log_format,
+)
+from velocitas_sdk.vdb.reply import DataPointReply
+from velocitas_sdk.vehicle_app import VehicleApp
+
+# Configure the VehicleApp logger with the necessary log config and level.
+logging.setLogRecordFactory(get_opentelemetry_log_factory())
+logging.basicConfig(format=get_opentelemetry_log_format())
+logging.getLogger().setLevel("DEBUG")
+logger = logging.getLogger(__name__)
+
+# The file path may need to be updated based on the location of the file.
+SIGNALS_JSON = "subscription_signals.json"
+
+
+class PerformanceTestApp(VehicleApp):
+    """
+    A sample vehicle app that subscribes to a list of signals (from a file) and prints
+    the values + timestamps of the signals.
+    """
+
+    def __init__(self, vehicle_client: Vehicle):
+        super().__init__()
+        self.Vehicle = vehicle_client
+
+    async def on_start(self):
+        signals_paths = self.read_signals_paths()
+        for signal_str in signals_paths:
+            await self.subscribe(signal_str)
+
+    def read_signals_paths(self) -> list[str]:
+        test_signals_json = self.read_json(SIGNALS_JSON)
+        signals_json = test_signals_json["signals"]
+
+        signal_paths: list[str] = []
+        for signal_json in signals_json:
+            signal_path = signal_json["path"]
+            signal_paths.append(signal_path)
+
+        return signal_paths
+
+    def read_json(self, file_path: str) -> dict:
+        with open(file_path, "r") as file:
+            return json.load(file)
+
+    async def subscribe(self, signal_str: str):
+        try:
+            node: DataPoint = self.Vehicle.getNode(signal_str)  # type: ignore
+            await node.subscribe(self.on_node_change)
+        except AttributeError:
+            print(f"Signal {signal_str} not found in the vehicle model.")
+
+    async def on_node_change(self, data: DataPointReply):
+        current_timestamp = datetime.now()
+
+        datapoint_str = data.reply.fields.popitem()[
+            0
+        ]  # The key of the first field is the datapoint path
+        node = self.Vehicle.getNode(datapoint_str)
+        data_point = data.get(node)  # type: ignore
+        data_point_value = data_point.value
+
+        print(f"{current_timestamp.time()} - {node.name} - {data_point_value}")
+
+
+async def main():
+    """Main function"""
+    logger.info("Starting the subscribe-performance test app")
+    vehicle_app = PerformanceTestApp(vehicle)
+    await vehicle_app.run()
+
+
+LOOP = asyncio.get_event_loop()
+LOOP.add_signal_handler(signal.SIGTERM, LOOP.stop)
+LOOP.run_until_complete(main())
+LOOP.close()