Class: RateLimit::Limiter

Inherits:
Object
  • Object
show all
Defined in:
lib/ratelimit-ruby.rb

Instance Method Summary collapse

Constructor Details

#initialize(apikey:, on_error: :log_and_pass, logger: nil, debug: false, stats: nil, shared_cache: nil, in_process_cache: nil, use_expiry_cache: true, local: false) ⇒ Limiter

Returns a new instance of Limiter.



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# File 'lib/ratelimit-ruby.rb', line 10

def initialize(apikey:,
               on_error: :log_and_pass,
               logger: nil,
               debug: false,
               stats: nil, # receives increment("it.ratelim.limitcheck", {:tags=>["policy_group:page_view", "pass:true"]})
               shared_cache: nil, # Something that quacks like Rails.cache ideally memcached
               in_process_cache: nil, # ideally ActiveSupport::Cache::MemoryStore.new(size: 2.megabytes)
               use_expiry_cache: true, # must have shared_cache defined
               local: false # local development
)
  @on_error = on_error
  @logger = (logger || Logger.new($stdout)).tap do |log|
    log.progname = "RateLimit"
  end
  @stats = (stats || NoopStats.new)
  @shared_cache = (shared_cache || NoopCache.new)
  @in_process_cache = (in_process_cache || NoopCache.new)
  @use_expiry_cache = use_expiry_cache
  @conn = Faraday.new(:url => self.base_url(local)) do |faraday|
    faraday.request :json # form-encode POST params
    faraday.headers["accept"] = "application/json"
    faraday.response :logger if debug
    faraday.options[:open_timeout] = 2
    faraday.options[:timeout] = 5
    faraday.adapter Faraday.default_adapter # make requests with Net::HTTP
  end
  (@account_id, pass) = apikey.split("|")
  @conn.basic_auth(@account_id, pass)
end

Instance Method Details

#acquire(group, acquire_amount, allow_partial_response: false) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 85

def acquire(group, acquire_amount, allow_partial_response: false)

  expiry_cache_key = "it.ratelim.expiry:#{group}"
  if @use_expiry_cache
    expiry = @shared_cache.read(expiry_cache_key)
    if !expiry.nil? && Integer(expiry) > Time.now.utc.to_f * 1000
      @stats.increment("it.ratelim.limitcheck.expirycache.hit", tags: [])
      return OpenStruct.new(passed: false, amount: 0)
    end
  end

  result = @conn.post '/api/v1/limitcheck', { acquireAmount: acquire_amount,
                                              groups: [group],
                                              allowPartialResponse: allow_partial_response }.to_json
  handle_failure(result) unless result.success?
  res =JSON.parse(result.body, object_class: OpenStruct)
  res.amount ||= 0

  @stats.increment("it.ratelim.limitcheck", tags: ["policy_group:#{res.policyGroup}", "pass:#{res.passed}"])
  if @use_expiry_cache
    reset = result.headers['X-Rate-Limit-Reset']
    @shared_cache.write(expiry_cache_key, reset) unless reset.nil?
  end
  return res
rescue => e
  handle_error(e)
end

#acquire_or_wait(key:, acquire_amount:, max_wait_secs:, init_backoff: 0) ⇒ Object

Raises:



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# File 'lib/ratelimit-ruby.rb', line 113

def acquire_or_wait(key:, acquire_amount:, max_wait_secs:, init_backoff: 0)
  start = Time.now
  sleep = init_backoff
  while Time.now - start < max_wait_secs
    sleep(sleep)
    res = acquire(key, acquire_amount)
    if res.passed
      return res
    end
    sleep += rand * WAIT_INCR_MAX
  end
  raise RateLimit::WaitExceeded
end

#base_url(local) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 166

def base_url(local)
  local ? 'http://localhost:8080' : 'http://www.ratelim.it'
end

#create_limit(group, limit, policy, burst: nil) ⇒ Object

create only. does not overwrite if it already exists



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# File 'lib/ratelimit-ruby.rb', line 52

def create_limit(group, limit, policy, burst: nil)
  upsert(LimitDefinition.new(group, limit, policy, false, burst || limit), :post)
end

#create_returnable_limit(group, total_tokens, seconds_to_refill_one_token) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 41

def create_returnable_limit(group, total_tokens, seconds_to_refill_one_token)
  upsert_returnable_limit(group, total_tokens, seconds_to_refill_one_token, method: :post)
end

#feature_is_on?(feature) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ratelimit-ruby.rb', line 137

def feature_is_on?(feature)
  feature_is_on_for?(feature, nil)
end

#feature_is_on_for?(feature, lookup_key, attributes: []) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ratelimit-ruby.rb', line 141

def feature_is_on_for?(feature, lookup_key, attributes: [])
  @stats.increment("it.ratelim.featureflag.on", tags: ["feature:#{feature}"])

  cache_key = "it.ratelim.ff:#{feature}.#{lookup_key}.#{attributes}"
  @in_process_cache.fetch(cache_key, expires_in: 60) do
    next uncached_feature_is_on_for?(feature, lookup_key, attributes) if @shared_cache.class == NoopCache

    feature_obj = get_feature(feature)
    if feature_obj.nil?
      next false
    end

    attributes << lookup_key if lookup_key
    if (attributes & feature_obj.whitelisted).size > 0
      next true
    end

    if lookup_key
      next get_user_pct(feature, lookup_key) < feature_obj.pct
    end

    next feature_obj.pct > 0.999
  end
end

#pass?(group) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/ratelimit-ruby.rb', line 80

def pass?(group)
  result = acquire(group, 1)
  return result.passed
end

#return(limit_result) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 127

def return(limit_result)
  result = @conn.post '/api/v1/limitreturn',
                      { enforcedGroup: limit_result.enforcedGroup,
                        expiresAt: limit_result.expiresAt,
                        amount: limit_result.amount }.to_json
  handle_failure(result) unless result.success?
rescue => e
  handle_error(e)
end

#upsert(limit_definition, method) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 61

def upsert(limit_definition, method)
  to_send = { limit: limit_definition.limit,
              group: limit_definition.group,
              burst: limit_definition.burst,
              policyName: limit_definition.policy,
              safetyLevel: limit_definition.safety_level,
              returnable: limit_definition.returnable }.to_json
  result= @conn.send(method, '/api/v1/limits', to_send)
  if !result.success?
    if method == :put
      handle_failure(result)
    elsif result.status != 409 # conflicts routinely expected on create
      handle_failure(result)
    end
  end
rescue => e
  handle_error(e)
end

#upsert_limit(group, limit, policy, burst: nil) ⇒ Object

upsert. overwrite whatever is there



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# File 'lib/ratelimit-ruby.rb', line 57

def upsert_limit(group, limit, policy, burst: nil)
  upsert(LimitDefinition.new(group, limit, policy, false, burst || limit), :put)
end

#upsert_returnable_limit(group, total_tokens, seconds_to_refill_one_token, method: :put) ⇒ Object 



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# File 'lib/ratelimit-ruby.rb', line 45

def upsert_returnable_limit(group, total_tokens, seconds_to_refill_one_token, method: :put)
  recharge_rate = (24*60*60)/seconds_to_refill_one_token
  recharge_policy = DAILY_ROLLING
  upsert(LimitDefinition.new(group, recharge_rate, recharge_policy, true, total_tokens), method)
end