Beefy Boxes and Bandwidth Generously Provided by pair Networks
more useful options

comment on

( #3333=superdoc: print w/replies, xml ) Need Help??

I figured it out, using one of my own CPAN distributions no less. I updated my Async::Event::Interval software to accept an "interval" of zero, which instead of looping every N seconds, simply runs a single time. So when the Dancer2 route is called, it'll spin off an external event to fetch and update the data, and then I can return existing data if it exists immediately while the background task is still working.

The software also already has a built-in check to see if the event is still running or not. Here's a minimal demo:

use warnings; use strict; use Async::Event::Interval; use IPC::Shareable; my $data; tie $data, 'IPC::Shareable', 'TSLA', {create => 1, destroy => 1}; $data = '{"charge": 85}'; my $event = Async::Event::Interval->new(0, sub {$data = '{"charge": 10 +0}'}); print "$data\n"; $event->start; print "Main program continues...\n"; print "Background event still running...\n" if $event->status; sleep 1; print $event->status == -1 ? "Event stopped\n" : "Event running\n"; print "$data\n";


{"charge": 85} Main program continues... Background event still running... Event stopped {"charge": 100}

Since the Dancer2 app is always running, I just make the event itself along with the data string (JSON) global, and use IPC::Shareable (which I have CO-MAINT to) to share the data between the processes. The Dancer2 route just calls $event->start if $event->status != -1;, and can then return back to the calling microcontroller immediately while the updater event runs as a separate proc.

In reply to Re: Dancer2: respond to client while making its own async call by stevieb
in thread Dancer2: respond to client while making its own async call by stevieb

Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":

  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or or How to display code and escape characters are good places to start.
Log In?

What's my password?
Create A New User
Domain Nodelet?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (2)
As of 2022-07-07 11:00 GMT
Find Nodes?
    Voting Booth?

    No recent polls found