On 1/27/06, Jeff Pang <[EMAIL PROTECTED]> wrote:
> Now I'm still confused on this work.Maybe I have not described the problem
> clearly.
> Fox example,there are some items coming in continuous time piece:
>
> 00:00:01 itemA 200
> 00:00:02 itemB 100
> 00:00:03 itemC 150
> 00:00:04 itemD 300
> 00:00:05 itemE 250
> ...
> (the item appear as 'name => vaule' style. And most of the items's name are
> different from others)
>
> In every 5 minutes, I'm doing it as following:
>
> {
> sleep 5*60;
> my %hash = calculate_from_the_items(); #for each item,I'll plus all
> the historical records to a hash value,and the hash key is this item's name.
> for (keys %hash){
> do_something() if $hash{$_} > LIMIT;
> }
> clear_the_items_to_null(); #clear all the items's records to null
> }
>
> But it's a very simple resolving method.I'm not satisfied with this way.
> I want to get this result when each one item is coming:
>
> {
> my $sock=shift;
> while(<$sock>)
> {
> my $isTrue = do_judgement();#judge if it reach some a limit in last
> 5 minutes relative the current time
> if ($isTrue){
> do_something();
> }
> clear(); #clear this item's historical record out of 5 minutes
> relative the current time
> }
> }
>
> How can I do it?Any suggestion is welcome.Thanks.
In your first example you are creating an aggregate based on a key.
In your second example you want a similar aggregate, but you don't
want to count items that are older than 5 minutes ago. This means you
will need to keep the items separate until the check and you will need
to store a timestamp (to know how old an item is). Assuming you
cannot change what is coming in from the socket, you will need to add
the timestamp that item was read (as opposed to when it was created).
The ideal pattern for this is an array of either arrays or hashes
depending on your preference. You will need to read in all available
records from the socket attaching the time the item was read. At the
end you should have a data structure that looks like this:
my @records = (
{
time => 1138374300,
key => 'joe',
amount => 20
},
{
time => 1138374362,
key => 'mary',
amount => 10
},
{
time => 1138374462,
key => 'joe',
amount => 5
},
{
time => 1138374500,
key => 'joe',
amount => 1
},
{
time => 1138374530,
key => 'mary',
amount => 20
},
);
Assuming it is now 1138374600 then the first record needs to be
expunged with delete(). This could be achieved by doing something
like this (warning untested code):
for (@records) {
delete $_ if $_->{time} < time() - 5*60;
}
You can then loop over the remaing records creating the aggregate like this
my %sum;
for my $rec (@records) {
$sum{$rec->{key}} += $rec->{amount};
}
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