@@ -121,12 +121,12 @@ def read_trace_records(event_mapping, event_id_to_name, fobj):
yield rec
-class Analyzer(object):
+class Analyzer:
"""A trace file analyzer which processes trace records.
- An analyzer can be passed to run() or process(). The begin() method is
- invoked, then each trace record is processed, and finally the end() method
- is invoked.
+ An analyzer can be passed to run() or process(). The __enter__() method is
+ invoked when opening the analyzer using the `with` statement, then each trace
+ record is processed, and finally the __exit__() method is invoked.
If a method matching a trace event name exists, it is invoked to process
that trace record. Otherwise the catchall() method is invoked.
@@ -152,19 +152,19 @@ def runstate_set(self, timestamp, pid, new_state):
...
"""
- def begin(self):
+ def __enter__(self):
"""Called at the start of the trace."""
- pass
+ return self
def catchall(self, event, rec):
"""Called if no specific method for processing a trace event has been found."""
pass
- def end(self):
+ def __exit__(self, _type, value, traceback):
"""Called at the end of the trace."""
pass
-def process(events, log, analyzer, read_header=True):
+def process(events, log, analyzer_class, read_header=True):
"""Invoke an analyzer on each event in a log."""
if read_header:
read_trace_header(log)
@@ -203,15 +203,15 @@ def build_fn(analyzer, event):
# Just arguments, no timestamp or pid
return lambda _, rec: fn(*rec[3:3 + event_argcount])
- analyzer.begin()
- fn_cache = {}
- for rec in read_trace_records(event_mapping, event_id_to_name, log):
- event_num = rec[0]
- event = event_mapping[event_num]
- if event_num not in fn_cache:
- fn_cache[event_num] = build_fn(analyzer, event)
- fn_cache[event_num](event, rec)
- analyzer.end()
+ with analyzer_class() as analyzer:
+ fn_cache = {}
+ for rec in read_trace_records(event_mapping, event_id_to_name, log):
+ event_num = rec[0]
+ event = event_mapping[event_num]
+ if event_num not in fn_cache:
+ fn_cache[event_num] = build_fn(analyzer, event)
+ fn_cache[event_num](event, rec)
+
def run(analyzer):
"""Execute an analyzer on a trace file given on the command-line.
@@ -254,4 +254,4 @@ def catchall(self, event, rec):
i += 1
print(' '.join(fields))
- run(Formatter())
+ run(Formatter)