Class: RedisRateLimiter

Inherits:
Object
  • Object
show all
Defined in:
lib/redis_rate_limiter.rb,
lib/redis_rate_limiter/version.rb

Constant Summary collapse

VERSION = 
'0.2.0'.freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(key, redis, options = {}) ⇒ RedisRateLimiter

Initializes a new RedisRateLimiter object

Parameters:

  • key (String) —

    A name to uniquely identify this rate limiter

  • redis (Redis) —

    Redis client associated with rate limiter

  • options (Integer) (defaults to: {}) —

    :interval Time span to track in seconds

  • options (Integer) (defaults to: {}) —

    :limit Max count allowed in interval



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# File 'lib/redis_rate_limiter.rb', line 22

def initialize key, redis, options = {}
  @key      = key
  @redis    = redis
  @limit    = options[:limit] || 50
  @interval = options[:interval] || 60
end

Instance Attribute Details

#interval ⇒ Integer

Returns Time span this rate limiter tracks in seconds.

Returns:

  • (Integer) —

    Time span this rate limiter tracks in seconds



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# File 'lib/redis_rate_limiter.rb', line 13

attr_accessor :key, :redis, :limit, :interval

#key ⇒ String

Returns Name which uniquely identifies this rate limiter.

Returns:

  • (String) —

    Name which uniquely identifies this rate limiter



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# File 'lib/redis_rate_limiter.rb', line 13

def key
  @key
end

#limit ⇒ Integer

Returns Max count allowed by rate limiter in interval.

Returns:

  • (Integer) —

    Max count allowed by rate limiter in interval



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# File 'lib/redis_rate_limiter.rb', line 13

attr_accessor :key, :redis, :limit, :interval

#redis ⇒ Redis

Returns Redis client associated with this rate limiter.

Returns:

  • (Redis) —

    Redis client associated with this rate limiter



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# File 'lib/redis_rate_limiter.rb', line 13

attr_accessor :key, :redis, :limit, :interval

Instance Method Details

#add(subject, time = Time.now.to_f) ⇒ Object

Add to subject’s count

Parameters:

  • subject (String) —

    A name to uniquely identify subject

  • time (time) (defaults to: Time.now.to_f) —

    UNIX timestamp of event



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# File 'lib/redis_rate_limiter.rb', line 33

def add subject, time = Time.now.to_f
  subject_key = "#{@key}:#{subject}"
  @redis.multi do |pipeline|
    pipeline.lpush(subject_key, time)
    pipeline.ltrim(subject_key, 0, @limit - 1)
    pipeline.expire(subject_key, @interval)
  end
end

#count(subject) ⇒ Integer

Get number of events currently recorded for subject

Parameters:

  • subject (String) —

    Name which uniquely identifies subject

Returns:

  • (Integer) —

    Returns number of events currently recorded for subject



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# File 'lib/redis_rate_limiter.rb', line 67

def count subject
  @redis.llen("#{@key}:#{subject}")
end

#exceeded?(subject) ⇒ Boolean

Check if subject has exceeded count

Parameters:

  • subject (String) —

    Name which uniquely identifies subject

Returns:

  • (Boolean) —

    Returns true if subject has exceeded count



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# File 'lib/redis_rate_limiter.rb', line 46

def exceeded? subject
  subject_key = "#{@key}:#{subject}"
  return false if @redis.llen(subject_key) < @limit
  time_since_oldest(subject_key) < @interval
end

#retry_in?(subject) ⇒ Float

Get time in seconds until subject is not rate limited

Parameters:

  • subject (String) —

    Name which uniquely identifies subject

Returns:

  • (Float) —

    Returns time in seconds until subject is not rate limited



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# File 'lib/redis_rate_limiter.rb', line 56

def retry_in? subject
  subject_key = "#{@key}:#{subject}"
  return 0.0 if @redis.llen(subject_key) < @limit
  elapsed = time_since_oldest(subject_key)
  elapsed > @interval ? 0.0 : @interval - elapsed
end