Multiple requests for the same tile ???

[nlneilson]

Good you are taking an interest in this, the download code is one of the main things hanging up the next release. That code has been hacked pretty good, needs to be cleaned up.

You know much more than I do and some of your post is above me. Let me point this out again.
"Don't confuse this with the download queue, that has been hard coded to 2 and the multiple requests need to be blocked before it gets to that queue."
Assume there is only one thread for download, download queue of 1, no problem on the server or client. The multiple requests for the same tile still exists, nothing has been done between GetClosestDownloadRequest() and actually requesting that tile for download to see if it has been requested before. Just a comma delimited list to check if the closest request has been requested before, if it has it will not be sent for download.

I have not looked into how the tiles are determined that are needed. The request probably checks the cache first, if not there then it is sent for download, if there is no tile to be downloaded then the same tile is calculated as being needed, check the cache then requested to be downloaded again, and again, and again, etc. This is like an endless loop, it needs to be stopped.

After the cache is checked that tile can be added to the list so only one attempt will be made for that tile. After the list is filled, whatever length it is set at, the oldest will be bumped. If the image is panned and then returned to the same area again later after the list has been completely changed then the tile will be requested again but you will not have the same tile attempt to download consecutively 20, 50, ??? times.

edit: see the attached .jpg images on posts #1 and #4.