Update mix python script for new log format (#53)

* Update mix python script for new log format

* remove unused imports

scripts/latency.py

@@ -1,17 +1,12 @@
 # !/usr/bin/env python
+import argparse
 import json
-import sys
+import statistics
 from collections.abc import Iterable
 from typing import Dict, Optional
-import statistics
-import argparse
 
 import mixlog
 
-from json_stream.base import TransientStreamingJSONObject
-
-JsonStream = Iterable[TransientStreamingJSONObject]
-
 
 class Message:
     def __init__(self, message_id: str, step_a: Optional[int]):
@@ -73,8 +68,13 @@ def parse_record_stream(record_stream: Iterable[str]) -> MessageStorage:
     storage: MessageStorage = {}
 
     for record in record_stream:
-        json_record = json.loads(record)
-        payload_id = json_record["payload_id"]
+        try:
+            json_record = json.loads(record)
+        except json.decoder.JSONDecodeError:
+            continue
+
+        if (payload_id := json_record.get("payload_id")) is None:
+            continue
         step_id = json_record["step_id"]
 
         if (stored_message := storage.get(payload_id)) is None:
@@ -91,12 +91,12 @@ def build_argument_parser() -> argparse.ArgumentParser:
         "--step-duration",
         type=int,
         default=100,
-        help="Duration (in ms) of each step in the simulation."
+        help="Duration (in ms) of each step in the simulation.",
     )
     parser.add_argument(
         "input_file",
         nargs="?",
-        help="The file to parse. If not provided, input will be read from stdin."
+        help="The file to parse. If not provided, input will be read from stdin.",
     )
     return parser