Python OSITrace message_offset contains actual messages instead of lengths

[tpajenkamp-dspace]

Describe the bug

After calling "from_file", the attribute "message_offsets" contains the itneger 0 and a bunch of message objects.

Describe how to reproduce the bug

Steps to reproduce the behavior:
t = OSITrace()
t.from_file(myPath)

Describe the expected behavior

"message_offsets" contains the lengths of individual messages.

Additional context

In line 145 of retrieve_message(): self.message_offsets.append(message) is incorrect

[vkresch]

Can you share your script or a minimal reproducable example on when the bug appears? Which format are you using *.osi or *.txt?

[tpajenkamp-dspace]

I am using the *.osi format. Below is my sample code. I would expect something like [0, 32] to be printed instead of [0, global_ground_truth { version { version_major: 3 version_minor: 1 version_patch: 2 } timestamp { seconds: 1 nanos: 100000 } moving_object { id { value: 114 } vehicle_classification { type: TYPE_SMALL_CAR } } } ].

from osi3.osi_sensorview_pb2 import SensorView
import struct
from OSITrace import OSITrace

def createDummyTrace(filePath):
    """Initialize SensorView"""
    f = open(filePath, "wb")
    sensorview = SensorView()

    sv_ground_truth = sensorview.global_ground_truth
    sv_ground_truth.version.version_major = 3
    sv_ground_truth.version.version_minor = 1
    sv_ground_truth.version.version_patch = 2

    sv_ground_truth.timestamp.seconds = 0
    sv_ground_truth.timestamp.nanos = 0

    moving_object = sv_ground_truth.moving_object.add()
    moving_object.id.value = 114

    # Generate 10 OSI messages for 9 seconds
    for i in range(2):

        # Increment the time
        sv_ground_truth.timestamp.seconds += 1
        sv_ground_truth.timestamp.nanos += 100000

        moving_object.vehicle_classification.type = 2

        """Serialize"""
        bytes_buffer = sensorview.SerializeToString()
        f.write(struct.pack("<L", len(bytes_buffer)) + bytes_buffer)

    f.close()

def main():
    tracePath = "test_trace.osi"

    # Create dummy file
    createDummyTrace(tracePath)

    # Read dummy file
    traceReader = OSITrace(tracePath, 'SensorView')
    traceReader.from_file(tracePath, 'SensorView', format_type=None)
    print(traceReader.message_offsets)

if __name__ == "__main__":
    main()

[vkresch]

You are right thanks for reporting! message_offsets should contain offsets and not the actual deserialzed messages. But this does not effect txt2osi and osi2read since only the length of the list is currently important. I will create a PR to fix it. For a quick fix just replace message with the iterator i.