count events within last XX minutes - Erlang Programming

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From: Max Bourinov <bouri...@gmail.com>
Date: Sun, 26 Aug 2012 11:54:48 +0400
Message-ID: <CANsaZAhO6jJc=ccmkMOhdYTU3nQ-OMN1bDa+ZJUrO8R7DFX...@mail.gmail.com>
To: Max Lapshin <max.laps...@gmail.com>
Cc: erlang-questions <erlang-questi...@erlang.org>
Subject: Re: [erlang-questions] count events within last XX minutes
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Hi Max,

Thank you for you comments and explanation.

Did you saw that I need only 120 minutes? So it will be a list with 121
element at most. In this case memory won't grow at all and size of the
state will be the same.

I agree about coping but I don't understand why state will grow. Could you
please explain it?

Best regards,
Max




On Sun, Aug 26, 2012 at 11:22 AM, Max Lapshin <max.laps...@gmail.com> wrote:

> On Sun, Aug 26, 2012 at 10:33 AM, Max Bourinov <bouri...@gmail.com> wrote:
> > 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?
>
> because ets have update_counter API
>
>
> > Why keeping data in the state is not ok?
>
> because you will have giant state with all problems
>
> >  I think on heavy load the state approach will perform
> > better than ETS. Moreover, I think ETS is overkill for this task.
>
> "overkill" here is an emotion without any exact results.
> Keeping this info in state will lead to copy of growing amount of memory.
>
>
> > p.s. In my case XX minutes wont exceed 120.
> >
> > Best regards,
> > Max
> >
> >
> >
> >
> > On Sat, Aug 25, 2012 at 12:05 AM, Mike Oxford <moxf...@gmail.com> 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.nyg...@gmail.com
> >
> >> 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 <bouri...@gmail.com>
> 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
> >>> >
> >>> >
> >>> >
> >>> > _______________________________________________
> >>> > erlang-questions mailing list
> >>> > erlang-questi...@erlang.org
> >>> > http://erlang.org/mailman/listinfo/erlang-questions
> >>> >
> >>> _______________________________________________
> >>> erlang-questions mailing list
> >>> erlang-questi...@erlang.org
> >>> http://erlang.org/mailman/listinfo/erlang-questions
> >>
> >>
> >
> >
> > _______________________________________________
> > erlang-questions mailing list
> > erlang-questi...@erlang.org
> > http://erlang.org/mailman/listinfo/erlang-questions
> >
>

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Hi Max,<div><br></div><div>Thank you for you comments and explanation.<br><=
div><br></div><div>Did you saw that I need only 120 minutes? So it will be =
a list with 121 element at most. In this case memory won&#39;t grow at all =
and size of the state will be the same.</div>

<div><br></div><div>I agree about coping but I don&#39;t understand why sta=
te will grow. Could you please explain it?</div>
<div><br clear=3D"all"><div>Best regards,</div><div>Max</div><br><br>
<br><br><div class=3D"gmail_quote">On Sun, Aug 26, 2012 at 11:22 AM, Max La=
pshin <span dir=3D"ltr">&lt;<a href=3D"mailto:max.laps...@gmail.com" target=
=3D"_blank">max.laps...@gmail.com</a>&gt;</span> wrote:<br><blockquote clas=
s=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;pad=
ding-left:1ex">


<div>On Sun, Aug 26, 2012 at 10:33 AM, Max Bourinov &lt;<a href=3D"mailto:b=
ouri...@gmail.com" target=3D"_blank">bouri...@gmail.com</a>&gt; wrote:<br>
&gt; Hi guys,<br>
&gt;<br>
&gt; Thank you guys for all your replies.<br>
&gt;<br>
&gt; I think I will go with my own implementation. The only thing I cannot<=
br>
&gt; understand, why you suggest using ETS for this?<br>
<br>
</div>because ets have update_counter API<br>
<div><br>
<br>
&gt; Why keeping data in the state is not ok?<br>
<br>
</div>because you will have giant state with all problems<br>
<div><br>
&gt; =A0I think on heavy load the state approach will perform<br>
&gt; better than ETS. Moreover, I think ETS is overkill for this task.<br>
<br>
</div>&quot;overkill&quot; here is an emotion without any exact results.<br=
>
Keeping this info in state will lead to copy of growing amount of memory.<b=
r>
<div><div><br>
<br>
&gt; p.s. In my case XX minutes wont exceed 120.<br>
&gt;<br>
&gt; Best regards,<br>
&gt; Max<br>
&gt;<br>
&gt;<br>
&gt;<br>
&gt;<br>
&gt; On Sat, Aug 25, 2012 at 12:05 AM, Mike Oxford &lt;<a href=3D"mailto:mo=
xf...@gmail.com" target=3D"_blank">moxf...@gmail.com</a>&gt; wrote:<br>
&gt;&gt;<br>
&gt;&gt; If you care about, as you say, &quot;certain minute&quot; you can =
use Ulf&#39;s gproc.<br>
&gt;&gt; If you want &quot;last minute&quot; then the ETS solution below wi=
ll work well, with<br>
&gt;&gt; the modification on the Counter to use a ms/us timer like erlang:n=
ow().<br>
&gt;&gt;<br>
&gt;&gt; -mox<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;&gt; On Fri, Aug 24, 2012 at 8:14 AM, Anders Nygren &lt;<a href=3D"mail=
to:anders.nyg...@gmail.com" target=3D"_blank">anders.nyg...@gmail.com</a>&g=
t;<br>
&gt;&gt; wrote:<br>
&gt;&gt;&gt;<br>
&gt;&gt;&gt; Use an ETS table with {Counter,{YYYY,MM,DD,HH,MM}} as key, and=
<br>
&gt;&gt;&gt; ets:update_counter/2,3.<br>
&gt;&gt;&gt; update_counter returns the new counter value, so if it is 1, (=
or the<br>
&gt;&gt;&gt; increment used) You know that a new minute has been entered so=
 You can<br>
&gt;&gt;&gt; delete the oldest.<br>
&gt;&gt;&gt;<br>
&gt;&gt;&gt; /Anders<br>
&gt;&gt;&gt;<br>
&gt;&gt;&gt; On Fri, Aug 24, 2012 at 9:16 AM, Max Bourinov &lt;<a href=3D"m=
ailto:bouri...@gmail.com" target=3D"_blank">bouri...@gmail.com</a>&gt; wrot=
e:<br>
&gt;&gt;&gt; &gt; Dear Erlangers,<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; Does anybody know best memory efficient way to count even=
ts within last<br>
&gt;&gt;&gt; &gt; XX<br>
&gt;&gt;&gt; &gt; minutes?<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; So far I have the following idea: For each counter I have=
 a process.<br>
&gt;&gt;&gt; &gt; The<br>
&gt;&gt;&gt; &gt; counter process has a list of XX items. Each item represe=
nts a certain<br>
&gt;&gt;&gt; &gt; minute, so I always know where is my current counter. The=
re is also<br>
&gt;&gt;&gt; &gt; must be<br>
&gt;&gt;&gt; &gt; a mechanism to remove last item from the list and add a n=
ew one.<br>
&gt;&gt;&gt; &gt; Summing<br>
&gt;&gt;&gt; &gt; values from all items is a number of events within last X=
X minutes.<br>
&gt;&gt;&gt; &gt; This is<br>
&gt;&gt;&gt; &gt; it.<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; Maybe there is a ready lib that does the same in a better=
 way?<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; Any suggestions are welcome!<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; Best regards,<br>
&gt;&gt;&gt; &gt; Max<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; &gt; _______________________________________________<br>
&gt;&gt;&gt; &gt; erlang-questions mailing list<br>
&gt;&gt;&gt; &gt; <a href=3D"mailto:erlang-questi...@erlang.org" target=3D"=
_blank">erlang-questi...@erlang.org</a><br>
&gt;&gt;&gt; &gt; <a href=3D"http://erlang.org/mailman/listinfo/erlang-ques=
tions" target=3D"_blank">http://erlang.org/mailman/listinfo/erlang-question=
s</a><br>
&gt;&gt;&gt; &gt;<br>
&gt;&gt;&gt; _______________________________________________<br>
&gt;&gt;&gt; erlang-questions mailing list<br>
&gt;&gt;&gt; <a href=3D"mailto:erlang-questi...@erlang.org" target=3D"_blan=
k">erlang-questi...@erlang.org</a><br>
&gt;&gt;&gt; <a href=3D"http://erlang.org/mailman/listinfo/erlang-questions=
" target=3D"_blank">http://erlang.org/mailman/listinfo/erlang-questions</a>=
<br>
&gt;&gt;<br>
&gt;&gt;<br>
&gt;<br>
&gt;<br>
&gt; _______________________________________________<br>
&gt; erlang-questions mailing list<br>
&gt; <a href=3D"mailto:erlang-questi...@erlang.org" target=3D"_blank">erlan=
g-questi...@erlang.org</a><br>
&gt; <a href=3D"http://erlang.org/mailman/listinfo/erlang-questions" target=
=3D"_blank">http://erlang.org/mailman/listinfo/erlang-questions</a><br>
&gt;<br>
</div></div></blockquote></div><br></div></div>

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