Question

I am using the queue api and have encountered to errors which crash my program.

First off I fetch the queue from the dictionary which returns this in a printout

The fetched queue is [{[],[]}]

Is this normal? Is the queue created correctly?

Then either when I try add to the queue or get its length I get an error badargs on both.

TorrentDownloadQueue = dict:fetch(torrentDownloadQueue, State),
io:format("The fetched queue is  ~p~n", [dict:fetch(torrentDownloadQueue, State)]),
% Add the item to the front of the queue (main torrent upload queue)
TorrentDownloadQueue2 = queue:in_r(Time, TorrentDownloadQueue),
% Get the lenght of the downloadQueue
TorrentDownloadQueueLength = queue:len(TorrentDownloadQueue2),

When I try to insert the value 10 the error is

** Reason for termination ==
** {badarg,[{queue,in_r,[10,[{[],[]}]]},
{ph_speed_calculator,handle_cast,2},
{gen_server,handle_msg,5},
{proc_lib,init_p_do_apply,3}]}
** exception exit: badarg
in function queue:in_r/2
called as queue:in_r(10,[{[],[]}])
in call from ph_speed_calculator:handle_cast/2
in call from gen_server:handle_msg/5
in call from proc_lib:init_p_do_apply/3
13>

This is the error for the in_r, but I get a badargs error for the len call too.

What is wrong with the way I call these or is the inital Queue incorrect?
I create the queue as follows and add it to the dictionary

TorrentDownloadQueue = queue:new(),
TorrentUploadQueue = queue:new(),
D4 = dict:store(torrentDownloadQueue, [TorrentDownloadQueue], D3),
D5 = dict:store(torrentUploadQueue, [TorrentUploadQueue], D4),

I have no idea what I am doing wrong.

Answer 1

What you have ([{[],[]}]) is a queue in a list. A standard queue looks like {list(), list()}. Obviously, because of this, every subsequent call to queues will fail.

My guess is that you either carry your queue wrong or extract it in the wrong manner.