wendelin_telecom_base: Add maximum data chunk size to KPI calculation

bt5/wendelin_telecom_base/PathTemplateItem/portal_callables/DataAnalysisLine_calculateOrsEnbKpi.py

 import json
 import numpy as np
 
+MAX_CHUNK_SIZE = 10000000 # bytes
 HISTORY_LINE_COUNT = 64
 T_PERIOD = 30 # seconds
 QCI_COUNT = 256
@@ -9,7 +10,7 @@ in_data_stream = in_stream['Data Stream']
 progress_indicator = in_stream['Progress Indicator']
 offset_index = progress_indicator.getIntOffsetIndex()
 start = 0
-end = in_data_stream.getSize()
+end = min(in_data_stream.getSize(), offset_index + MAX_CHUNK_SIZE)
 
 # No new data to process
 if offset_index >= end:
@@ -21,6 +22,15 @@ new_log_data = ''.join(in_data_stream.readChunkList(offset_index, end))
 previous_log_data_line_list = previous_log_data.splitlines()
 new_log_data_line_list = new_log_data.splitlines()
 
+# Last new log line may not be valid JSON due to MAX_CHUNK_SIZE:
+# In that case, leave it to the next KPI calculation
+last_new_log_data_line = new_log_data_line_list[-1]
+try:
+  json.loads(last_new_log_data_line)
+except ValueError:
+  end -= len(last_new_log_data_line)
+  new_log_data_line_list = new_log_data_line_list[:-1]
+
 log_data_line_list = previous_log_data_line_list + new_log_data_line_list
 
 # Remove duplicate log lines