simpletrace: added simplified Analyzer2 class
By moving the dynamic argument construction to keyword-arguments, we can remove all of the specialized handling, and streamline it. If a tracing method wants to access these, they can define the kwargs, or ignore it be placing `**kwargs` at the end of the function's arguments list. Added deprecation warning to Analyzer class to make users aware of the Analyzer2 class. No removal date is planned. Signed-off-by: Mads Ynddal <m.ynddal@samsung.com> Message-id: 20230926103436.25700-13-mads@ynddal.dk Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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@ -12,10 +12,11 @@
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import sys
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import struct
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import inspect
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import warnings
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from tracetool import read_events, Event
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from tracetool.backend.simple import is_string
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__all__ = ['Analyzer', 'process', 'run']
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__all__ = ['Analyzer', 'Analyzer2', 'process', 'run']
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# This is the binary format that the QEMU "simple" trace backend
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# emits. There is no specification documentation because the format is
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@ -130,7 +131,9 @@ def read_trace_records(events, fobj, read_header):
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yield (event_mapping[event_name], event_name, timestamp_ns, pid) + tuple(args)
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class Analyzer:
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"""A trace file analyzer which processes trace records.
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"""[Deprecated. Refer to Analyzer2 instead.]
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A trace file analyzer which processes trace records.
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An analyzer can be passed to run() or process(). The begin() method is
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invoked, then each trace record is processed, and finally the end() method
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@ -188,6 +191,11 @@ class Analyzer:
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return lambda _, rec: fn(*rec[3:3 + event_argcount])
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def _process_event(self, rec_args, *, event, event_id, timestamp_ns, pid, **kwargs):
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warnings.warn(
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"Use of deprecated Analyzer class. Refer to Analyzer2 instead.",
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DeprecationWarning,
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)
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if not hasattr(self, '_fn_cache'):
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# NOTE: Cannot depend on downstream subclasses to have
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# super().__init__() because of legacy.
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@ -211,6 +219,56 @@ class Analyzer:
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self.end()
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return False
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class Analyzer2(Analyzer):
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"""A trace file analyzer which processes trace records.
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An analyzer can be passed to run() or process(). The begin() method is
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invoked, then each trace record is processed, and finally the end() method
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is invoked. When Analyzer is used as a context-manager (using the `with`
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statement), begin() and end() are called automatically.
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If a method matching a trace event name exists, it is invoked to process
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that trace record. Otherwise the catchall() method is invoked.
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The methods are called with a set of keyword-arguments. These can be ignored
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using `**kwargs` or defined like any keyword-argument.
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The following keyword-arguments are available, but make sure to have an
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**kwargs to allow for unmatched arguments in the future:
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event: Event object of current trace
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event_id: The id of the event in the current trace file
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timestamp_ns: The timestamp in nanoseconds of the trace
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pid: The process id recorded for the given trace
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Example:
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The following method handles the runstate_set(int new_state) trace event::
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def runstate_set(self, new_state, **kwargs):
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...
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The method can also explicitly take a timestamp keyword-argument with the
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trace event arguments::
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def runstate_set(self, new_state, *, timestamp_ns, **kwargs):
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...
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Timestamps have the uint64_t type and are in nanoseconds.
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The pid can be included in addition to the timestamp and is useful when
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dealing with traces from multiple processes:
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def runstate_set(self, new_state, *, timestamp_ns, pid, **kwargs):
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...
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"""
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def catchall(self, *rec_args, event, timestamp_ns, pid, event_id, **kwargs):
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"""Called if no specific method for processing a trace event has been found."""
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pass
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def _process_event(self, rec_args, *, event, **kwargs):
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fn = getattr(self, event.name, self.catchall)
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fn(*rec_args, event=event, **kwargs)
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def process(events, log, analyzer, read_header=True):
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"""Invoke an analyzer on each event in a log.
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Args:
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@ -278,30 +336,24 @@ def run(analyzer):
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process(events_fobj, log_fobj, analyzer, read_header=not no_header)
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if __name__ == '__main__':
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class Formatter(Analyzer):
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class Formatter2(Analyzer2):
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def __init__(self):
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self.last_timestamp = None
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self.last_timestamp_ns = None
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def catchall(self, event, rec):
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timestamp = rec[1]
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if self.last_timestamp is None:
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self.last_timestamp = timestamp
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delta_ns = timestamp - self.last_timestamp
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self.last_timestamp = timestamp
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def catchall(self, *rec_args, event, timestamp_ns, pid, event_id):
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if self.last_timestamp_ns is None:
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self.last_timestamp_ns = timestamp_ns
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delta_ns = timestamp_ns - self.last_timestamp_ns
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self.last_timestamp_ns = timestamp_ns
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fields = [event.name, '%0.3f' % (delta_ns / 1000.0),
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'pid=%d' % rec[2]]
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i = 3
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for type, name in event.args:
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if is_string(type):
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fields.append('%s=%s' % (name, rec[i]))
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else:
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fields.append('%s=0x%x' % (name, rec[i]))
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i += 1
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print(' '.join(fields))
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fields = [
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f'{name}={r}' if is_string(type) else f'{name}=0x{r:x}'
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for r, (type, name) in zip(rec_args, event.args)
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]
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print(f'{event.name} {delta_ns / 1000:0.3f} {pid=} ' + ' '.join(fields))
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try:
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run(Formatter())
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run(Formatter2())
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except SimpleException as e:
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sys.stderr.write(str(e) + "\n")
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sys.exit(1)
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