Event feed API endpoint may return duplicate entries

[johnbrvc]

Describe the issue:
When requesting the event feed using the contest/event-feed API endpoint, duplicate events may be sent in the returned stream.

To Reproduce:
To duplicate this issue, there are several prerequisites (we will use the "submissions" data records for this example):

1. Using a completed contest, or one in which there are already many submissions
2. Multiple (more than 1) consumers of the event feed had to be active (connected) when submissions were made.

Assuming both 1 and 2 are satisfied, a new connection on the event-feed endpoint will see every submission that was made duplicated N times where N = NC-1, where NC = number of event-feed consumers that were connected when the submissions were made.

Expected behavior:
Events should not be duplicated on the event-feed when a new consumer connects.

Actual behavior:
Duplicate events may be returned when a new consumer requests the event-feed API endpoint.

Environment:
All.

Log Info:

Screenshots:
N/A

Additional context:
Basically, for every client consuming the event feed, an entry is added to the EventfeedLog_Default--XXXXXXXXXX.log file for each event that is generated while said consumers are connected. This causes multiple copies of the same event to be put into the saved event feed log file: EventfeedLog_Default--XXXXXXXXXX.log When a new event-feed consumer connects, PC2 reads the EventfeedLog_Default--XXXXXXXXXX.log file and sends that to the new consumer. The file contains the duplicate entries. (See attached file). It seems, in EventFeedSTreamer.sendJSON(), the eventFeedLog.writeEvent(string) is called for each instance of the streamer.
sendJSON() is called (for each RunListener, and there is a RunLIstener for each connected consumer).

To obtain a correct event feed, use the report generator from an Admin or the Server GUI. The Event Feed client's View Event Feed button uses the EventFeedLog, and, as a result, will have duplicate entries as described above, whereas the report generator completely regenerates the event feed based on internal data structures.

EventfeedLog_Default-Excerpt.log