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# coding: utf-8
"""
This module contains the generic :class:`LogReader` as
well as :class:`MessageSync` which plays back messages
in the recorded order an time intervals.
"""
from __future__ import absolute_import
from time import time, sleep
import logging
from .generic import BaseIOHandler
from .asc import ASCReader
from .blf import BLFReader
from .canutils import CanutilsLogReader
from .csv import CSVReader
from .sqlite import SqliteReader
log = logging.getLogger('can.io.player')
class LogReader(BaseIOHandler):
"""
Replay logged CAN messages from a file.
The format is determined from the file format which can be one of:
* .asc
* .blf
* .csv
* .db
* .log
Exposes a simple iterator interface, to use simply:
>>> for msg in LogReader("some/path/to/my_file.log"):
... print(msg)
.. note::
There are no time delays, if you want to reproduce the measured
delays between messages look at the :class:`can.MessageSync` class.
.. note::
This class itself is just a dispatcher, and any positional an keyword
arguments are passed on to the returned instance.
"""
@staticmethod
def __new__(cls, filename, *args, **kwargs):
"""
:param str filename: the filename/path the file to read from
"""
if filename.endswith(".asc"):
return ASCReader(filename, *args, **kwargs)
elif filename.endswith(".blf"):
return BLFReader(filename, *args, **kwargs)
elif filename.endswith(".csv"):
return CSVReader(filename, *args, **kwargs)
elif filename.endswith(".db"):
return SqliteReader(filename, *args, **kwargs)
elif filename.endswith(".log"):
return CanutilsLogReader(filename, *args, **kwargs)
else:
raise NotImplementedError("No read support for this log format: {}".format(filename))
class MessageSync(object):
"""
Used to iterate over some given messages in the recorded time.
"""
def __init__(self, messages, timestamps=True, gap=0.0001, skip=60):
"""Creates an new **MessageSync** instance.
:param Iterable[can.Message] messages: An iterable of :class:`can.Message` instances.
:param bool timestamps: Use the messages' timestamps. If False, uses the *gap* parameter as the time between messages.
:param float gap: Minimum time between sent messages in seconds
:param float skip: Skip periods of inactivity greater than this (in seconds).
"""
self.raw_messages = messages
self.timestamps = timestamps
self.gap = gap
self.skip = skip
def __iter__(self):
playback_start_time = time()
recorded_start_time = None
for message in self.raw_messages:
# Work out the correct wait time
if self.timestamps:
if recorded_start_time is None:
recorded_start_time = message.timestamp
now = time()
current_offset = now - playback_start_time
recorded_offset_from_start = message.timestamp - recorded_start_time
remaining_gap = max(0.0, recorded_offset_from_start - current_offset)
sleep_period = max(self.gap, min(self.skip, remaining_gap))
else:
sleep_period = self.gap
sleep(sleep_period)
yield message
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