[erlang-questions] count events within last XX minutes

[Max Bourinov]

Hi guys,

Thank you guys for all your replies.

I think I will go with my own implementation. The only thing I cannot
understand, why you suggest using ETS for this? Why keeping data in the
state is not ok? I think on heavy load the state approach will perform
better than ETS. Moreover, I think ETS is overkill for this task.

p.s. In my case XX minutes wont exceed 120.

Best regards,
Max




On Sat, Aug 25, 2012 at 12:05 AM, Mike Oxford <moxford@REDACTED> wrote:

> If you care about, as you say, "certain minute" you can use Ulf's gproc.
>  If you want "last minute" then the ETS solution below will work well, with
> the modification on the Counter to use a ms/us timer like erlang:now().
>
> -mox
>
>
> On Fri, Aug 24, 2012 at 8:14 AM, Anders Nygren <anders.nygren@REDACTED>wrote:
>
>> Use an ETS table with {Counter,{YYYY,MM,DD,HH,MM}} as key, and
>> ets:update_counter/2,3.
>> update_counter returns the new counter value, so if it is 1, (or the
>> increment used) You know that a new minute has been entered so You can
>> delete the oldest.
>>
>> /Anders
>>
>> On Fri, Aug 24, 2012 at 9:16 AM, Max Bourinov <bourinov@REDACTED> wrote:
>> > Dear Erlangers,
>> >
>> > Does anybody know best memory efficient way to count events within last
>> XX
>> > minutes?
>> >
>> > So far I have the following idea: For each counter I have a process. The
>> > counter process has a list of XX items. Each item represents a certain
>> > minute, so I always know where is my current counter. There is also
>> must be
>> > a mechanism to remove last item from the list and add a new one. Summing
>> > values from all items is a number of events within last XX minutes.
>> This is
>> > it.
>> >
>> > Maybe there is a ready lib that does the same in a better way?
>> >
>> > Any suggestions are welcome!
>> >
>> > Best regards,
>> > Max
>> >
>> >
>> >
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