87617b9ae6
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>
295 lines
10 KiB
Python
Executable File
295 lines
10 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# Pretty-printer for simple trace backend binary trace files
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#
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# Copyright IBM, Corp. 2010
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#
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# This work is licensed under the terms of the GNU GPL, version 2. See
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# the COPYING file in the top-level directory.
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#
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# For help see docs/devel/tracing.rst
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import sys
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import struct
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import inspect
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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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# 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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# not guaranteed to be stable. Trace files must be parsed with the
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# same trace-events-all file and the same simpletrace.py file that
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# QEMU was built with.
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header_event_id = 0xffffffffffffffff
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header_magic = 0xf2b177cb0aa429b4
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dropped_event_id = 0xfffffffffffffffe
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record_type_mapping = 0
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record_type_event = 1
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log_header_fmt = '=QQQ'
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rec_header_fmt = '=QQII'
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class SimpleException(Exception):
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pass
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def read_header(fobj, hfmt):
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'''Read a trace record header'''
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hlen = struct.calcsize(hfmt)
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hdr = fobj.read(hlen)
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if len(hdr) != hlen:
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raise SimpleException('Error reading header. Wrong filetype provided?')
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return struct.unpack(hfmt, hdr)
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def get_record(event_mapping, event_id_to_name, rechdr, fobj):
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"""Deserialize a trace record from a file into a tuple
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(name, timestamp, pid, arg1, ..., arg6)."""
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event_id, timestamp_ns, length, pid = rechdr
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if event_id != dropped_event_id:
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name = event_id_to_name[event_id]
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try:
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event = event_mapping[name]
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except KeyError as e:
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raise SimpleException(
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f'{e} event is logged but is not declared in the trace events'
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'file, try using trace-events-all instead.'
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)
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rec = (name, timestamp_ns, pid)
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for type, name in event.args:
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if is_string(type):
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l = fobj.read(4)
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(len,) = struct.unpack('=L', l)
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s = fobj.read(len)
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rec = rec + (s,)
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else:
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(value,) = struct.unpack('=Q', fobj.read(8))
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rec = rec + (value,)
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else:
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(dropped_count,) = struct.unpack('=Q', fobj.read(8))
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rec = ("dropped", timestamp_ns, pid, dropped_count)
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return rec
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def get_mapping(fobj):
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(event_id, ) = struct.unpack('=Q', fobj.read(8))
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(len, ) = struct.unpack('=L', fobj.read(4))
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name = fobj.read(len).decode()
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return (event_id, name)
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def read_record(event_mapping, event_id_to_name, fobj):
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"""Deserialize a trace record from a file into a tuple (event_num, timestamp, pid, arg1, ..., arg6)."""
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rechdr = read_header(fobj, rec_header_fmt)
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return get_record(event_mapping, event_id_to_name, rechdr, fobj)
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def read_trace_header(fobj):
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"""Read and verify trace file header"""
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_header_event_id, _header_magic, log_version = read_header(fobj, log_header_fmt)
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if _header_event_id != header_event_id:
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raise ValueError(f'Not a valid trace file, header id {_header_event_id} != {header_event_id}')
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if _header_magic != header_magic:
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raise ValueError(f'Not a valid trace file, header magic {_header_magic} != {header_magic}')
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if log_version not in [0, 2, 3, 4]:
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raise ValueError(f'Unknown version {log_version} of tracelog format!')
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if log_version != 4:
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raise ValueError(f'Log format {log_version} not supported with this QEMU release!')
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def read_trace_records(event_mapping, event_id_to_name, fobj):
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"""Deserialize trace records from a file, yielding record tuples (event_num, timestamp, pid, arg1, ..., arg6).
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Note that `event_id_to_name` is modified if the file contains mapping records.
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Args:
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event_mapping (str -> Event): events dict, indexed by name
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event_id_to_name (int -> str): event names dict, indexed by event ID
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fobj (file): input file
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"""
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while True:
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t = fobj.read(8)
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if len(t) == 0:
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break
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(rectype, ) = struct.unpack('=Q', t)
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if rectype == record_type_mapping:
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event_id, name = get_mapping(fobj)
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event_id_to_name[event_id] = name
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else:
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rec = read_record(event_mapping, event_id_to_name, fobj)
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yield rec
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class 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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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):
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...
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The method can also take a timestamp argument before the trace event
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arguments::
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def runstate_set(self, timestamp, new_state):
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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, timestamp, pid, new_state):
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...
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"""
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def begin(self):
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"""Called at the start of the trace."""
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pass
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def catchall(self, event, rec):
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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 end(self):
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"""Called at the end of the trace."""
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pass
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def __enter__(self):
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self.begin()
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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if exc_type is None:
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self.end()
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return False
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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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events (file-object or list or str): events list or file-like object or file path as str to read event data from
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log (file-object or str): file-like object or file path as str to read log data from
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analyzer (Analyzer): Instance of Analyzer to interpret the event data
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read_header (bool, optional): Whether to read header data from the log data. Defaults to True.
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"""
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if isinstance(events, str):
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with open(events, 'r') as f:
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events_list = read_events(f, events)
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elif isinstance(events, list):
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# Treat as a list of events already produced by tracetool.read_events
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events_list = events
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else:
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# Treat as an already opened file-object
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events_list = read_events(events, events.name)
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close_log = False
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if isinstance(log, str):
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log = open(log, 'rb')
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close_log = True
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if read_header:
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read_trace_header(log)
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frameinfo = inspect.getframeinfo(inspect.currentframe())
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dropped_event = Event.build("Dropped_Event(uint64_t num_events_dropped)",
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frameinfo.lineno + 1, frameinfo.filename)
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event_mapping = {"dropped": dropped_event}
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event_id_to_name = {dropped_event_id: "dropped"}
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for event in events_list:
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event_mapping[event.name] = event
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# If there is no header assume event ID mapping matches events list
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if not read_header:
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for event_id, event in enumerate(events_list):
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event_id_to_name[event_id] = event.name
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def build_fn(analyzer, event):
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if isinstance(event, str):
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return analyzer.catchall
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fn = getattr(analyzer, event.name, None)
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if fn is None:
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return analyzer.catchall
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event_argcount = len(event.args)
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fn_argcount = len(inspect.getfullargspec(fn)[0]) - 1
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if fn_argcount == event_argcount + 1:
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# Include timestamp as first argument
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return lambda _, rec: fn(*(rec[1:2] + rec[3:3 + event_argcount]))
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elif fn_argcount == event_argcount + 2:
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# Include timestamp and pid
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return lambda _, rec: fn(*rec[1:3 + event_argcount])
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else:
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# Just arguments, no timestamp or pid
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return lambda _, rec: fn(*rec[3:3 + event_argcount])
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with analyzer:
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fn_cache = {}
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for rec in read_trace_records(event_mapping, event_id_to_name, log):
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event_num = rec[0]
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event = event_mapping[event_num]
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if event_num not in fn_cache:
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fn_cache[event_num] = build_fn(analyzer, event)
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fn_cache[event_num](event, rec)
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if close_log:
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log.close()
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def run(analyzer):
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"""Execute an analyzer on a trace file given on the command-line.
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This function is useful as a driver for simple analysis scripts. More
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advanced scripts will want to call process() instead."""
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try:
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# NOTE: See built-in `argparse` module for a more robust cli interface
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*no_header, trace_event_path, trace_file_path = sys.argv[1:]
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assert no_header == [] or no_header == ['--no-header'], 'Invalid no-header argument'
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except (AssertionError, ValueError):
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raise SimpleException(f'usage: {sys.argv[0]} [--no-header] <trace-events> <trace-file>\n')
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with open(trace_event_path, 'r') as events_fobj, open(trace_file_path, 'rb') as log_fobj:
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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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def __init__(self):
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self.last_timestamp = 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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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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try:
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run(Formatter())
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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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