DownloadProgress event always sends zeroes in copiedFromOrigin and copiedFromElsewhere fields

[mackinleysmith]

Hey there, quick followup after syncthing/docs#830. My team has noticed that the copiedFromOrigin and copiedFromElsewhere fields always seem to be 0 when DownloadProgress events fire. This appears to have been noted back in 2019 here: #5867 (comment) but no response was given back then.

Perhaps there is a better way to do what I'm after. I would really like to measure the exchange of data between peers in the network. Maybe this information is available somewhere in the database?

[calmh]

You probably want to use the new metrics endpoint, which will give you want you want in a reliable manner. The download progress event is not that, for reasons discussed in the previous issues. That said, it works as designed for me:

{
    "id": 75,
    "type": "DownloadProgress",
    "time": "2023-10-12T18:22:28.962668+02:00",
    "data": {
        "default": {
            "s2": {
                "bytesDone": 56161635,
                "bytesTotal": 65980102,
                "copiedFromElsewhere": 388,
                "copiedFromOrigin": 0,
                "copiedFromOriginShifted": 0,
                "pulled": 41,
                "pulling": 75,
                "reused": 0,
                "total": 504
            }
        }
    }
}

I think you're just not getting data for the expected reason -- files that are mostly "copied from origin" or "copied from elsewhere" are handled very quickly since they are just local I/O and less download, hence you are unlikely to see download events for them.