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[PULL 08/14] simpletrace: made Analyzer into context-manager
From: |
Stefan Hajnoczi |
Subject: |
[PULL 08/14] simpletrace: made Analyzer into context-manager |
Date: |
Thu, 28 Sep 2023 09:44:01 -0400 |
From: Mads Ynddal <m.ynddal@samsung.com>
Instead of explicitly calling `begin` and `end`, we can change the class
to use the context-manager paradigm. This is mostly a styling choice,
used in modern Python code. But it also allows for more advanced analyzers
to handle exceptions gracefully in the `__exit__` method (not
demonstrated here).
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Mads Ynddal <m.ynddal@samsung.com>
Message-id: 20230926103436.25700-9-mads@ynddal.dk
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
scripts/simpletrace.py | 31 ++++++++++++++++++++-----------
1 file changed, 20 insertions(+), 11 deletions(-)
diff --git a/scripts/simpletrace.py b/scripts/simpletrace.py
index 229b10aa99..7f514d1577 100755
--- a/scripts/simpletrace.py
+++ b/scripts/simpletrace.py
@@ -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()
--
2.41.0
- [PULL 00/14] Tracing patches, Stefan Hajnoczi, 2023/09/28
- [PULL 02/14] simpletrace: annotate magic constants from QEMU code, Stefan Hajnoczi, 2023/09/28
- [PULL 03/14] simpletrace: improve parsing of sys.argv; fix files never closed., Stefan Hajnoczi, 2023/09/28
- [PULL 05/14] simpletrace: update code for Python 3.11, Stefan Hajnoczi, 2023/09/28
- [PULL 06/14] simpletrace: improved error handling on struct unpack, Stefan Hajnoczi, 2023/09/28
- [PULL 08/14] simpletrace: made Analyzer into context-manager,
Stefan Hajnoczi <=
- [PULL 01/14] simpletrace: add __all__ to define public interface, Stefan Hajnoczi, 2023/09/28
- [PULL 07/14] simpletrace: define exception and add handling, Stefan Hajnoczi, 2023/09/28
- [PULL 11/14] simpletrace: move event processing to Analyzer class, Stefan Hajnoczi, 2023/09/28
- [PULL 10/14] simpletrace: move logic of process into internal function, Stefan Hajnoczi, 2023/09/28
- [PULL 09/14] simpletrace: refactor to separate responsibilities, Stefan Hajnoczi, 2023/09/28
- [PULL 04/14] simpletrace: changed naming of edict and idtoname to improve readability, Stefan Hajnoczi, 2023/09/28
- [PULL 13/14] MAINTAINERS: add maintainer of simpletrace.py, Stefan Hajnoczi, 2023/09/28
- [PULL 12/14] simpletrace: added simplified Analyzer2 class, Stefan Hajnoczi, 2023/09/28
- [PULL 14/14] scripts/analyse-locks-simpletrace.py: changed iteritems() to items(), Stefan Hajnoczi, 2023/09/28