I have a another stupid question:
How is this a race-condition / a source of problem given that:
* all I want to do is to read, I'm not writing / modifying
In particular, the sole goal of this read is to show a counter saying
"there are XYZ people ahead of you in line."
It seems that to have a race conditions, one needs to :
(1) thread-1 reads x
(2) thread-2 modifies x
(3) thread-1 writes some state depending on old value of x
On Sat, Jan 11, 2014 at 5:47 PM, Brandon Bloom <[email protected]>wrote:
> Any API that lets you peek at the "state" of a channel is a surefire
> source of race conditions. So no, public API-wise, there isn't any way to
> do what you want. In theory, you can peek at the internals using reflection
> to get that information, but don't do that!
>
> Instead, you can simply *count* yourself. Stick an extra go-loop on either
> end that swaps an atom with inc or dec.
>
> On Saturday, January 11, 2014 12:19:51 PM UTC-5, t x wrote:
>>
>> Hi,
>>
>> I have a clojure.core.async.chan
>>
>> Is there a way to figure out the # of elements currently queued on the
>> channel? (preferably in O(1) time)
>>
>> I don't want to actually take any item off the channel, I just want a
>> progress bar, something like "there are 20 transactions ahead of you in
>> life to be processed"
>>
>> Thanks!
>>
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