@@ -122,12 +122,13 @@ 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.
+ is invoked. When Analyzer is used as a context-manager (using the `with`
+ statement), begin() and end() are called automatically.
If a method matching a trace event name exists, it is invoked to process
that trace record. Otherwise the catchall() method is invoked.
@@ -165,6 +166,15 @@ def end(self):
"""Called at the end of the trace."""
pass
+ def __enter__(self):
+ self.begin()
+ return self
+
+ def __exit__(self, exc_type, exc_val, exc_tb):
+ if exc_type is None:
+ self.end()
+ return False
+
def process(events, log, analyzer, read_header=True):
"""Invoke an analyzer on each event in a log.
Args:
@@ -226,15 +236,14 @@ 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:
+ 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)
if close_log:
log.close()