Daisuke Maki > Data-Valve > Data::Valve

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Module Version: 0.00010   Source  

NAME ^

Data::Valve - Throttle Your Data

SYNOPSIS ^

  use Data::Valve;

  my $valve = Data::Valve->new(
    max_items => 10,
    interval  => 30
  );

  if ($valve->try_push()) {
    print "ok\n";
  } else {
    print "throttled\n";
  }

  if ($valve->try_push(key => "foo")) {
    print "ok\n";
  } else {
    print "throttled\n";
  }

DESCRIPTION ^

Data::Valve is a throttler based on Data::Throttler. The underlying throttling mechanism is much simpler than Data::Throttler, and so is faster.

It also comes with Memcached support for a distributed throttling via memcached + keyedmutexd. This means that you can have multiple hosts throttling on the same "key". For example, multiple crawler instances can throttle requests against a single host safely. To enable distributed throttling, you simply need to specify a Data::Valve::BucketStore instance that supports distribution (i.e. Data::Valve::BucketStore::Memcached) or create your own instance, and pass it to the constructor:

  Data::Valve->new(
    ...,
    bucket_store => {
      module => "Memcached", # to use Data::Valve::BucketStore::Memcached
      args   => {
        servers => [ '127.0.0.1:11211' ]
      }
    }
  );

Please note that for distributed throttling to work, you must specify the correct values in max_items, interval, and so forth, for each Data::Valve instance. Data::Valve will not try to automatically adjust this for you. You must coordinate it in the client side (i.e., whatever that's using Data::Valve)

Since version 0.00006, Data::Valve supports "strict_interval" mode, where instead of counting the number of items over a range of time, it simply calculates the amount of time elapsed since the last logged request.

To enable, specify it in the constrctor:

  # This specifies that at least 5 seconds should have passed before
  # the next item can go
  Data::Valve->new(
    interval        => 5,
    strict_interval => 1, 
  );

METHODS ^

new(%args)

max_items

In strict interval mode, does not mean anything. If NOT in strict interval mode, specifies the max number of items that can go through this throttler in the given interval.

interval

In strict interval mode, this specifies the number of seconds to wait between each request. If NOT in strict interval mode, specifies the number of seconds to span the requests, up to the value specified in max_items

interval may be a fractional number, denoting fractional seconds.

strict_interval

Boolean. Enable/Disable strict interval mode. Default is off.

fill([key => $key_name])

Fills up the specified bucket until it starts throttling

reset([key => $key_name])

Clears the specified bucket so the next request will succeed for sure

try_push([key => $key_name])

AUTHOR ^

Daisuke Maki <daisuke@endeworks.jp>

LICENSE ^

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

See http://www.perl.com/perl/misc/Artistic.html

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