Class: FaradayThrottler::Middleware

Inherits:
Faraday::Middleware
  • Object
show all
Defined in:
lib/faraday_throttler/middleware.rb

Instance Method Summary collapse

Constructor Details

#initialize(app, enabled: true, cache: Cache.new, cache_key_resolver: KeyResolver.new, rate: 10, wait: 1, timeout: 0, rate_limit_response_checker: RateLimitResponseChecker.new, logger: Logger.new(STDOUT)) ⇒ Middleware

Returns a new instance of Middleware.



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# File 'lib/faraday_throttler/middleware.rb', line 10

def initialize(
    # The base Faraday adapter.
    app,

    # enable the throller
    enabled: true,

    # Sticks cache.
    cache: Cache.new,

    # Resolves response unique key to use as cache key
    # Interface:
    #   #call(response_env Hash) String
    cache_key_resolver: KeyResolver.new,

    # Maximum requests to sent to the backend api simultanous
    rate: 10,

    # Queued requests will wait for up to 1 seconds for current in-flight request
    # to the same path.
    # If in-flight request hasn't finished after that time, return a default placeholder response.
    wait: 1,

    # Wraps requests to backend service in a timeout block, in seconds.
    # timeout: 0 disables this behaviour.
    timeout: 0,

    # Use to check if backend api response is a rate limit
    rate_limit_response_checker: RateLimitResponseChecker.new,

    # Pass your own Logger instance (for example Rails.logger in a Rails app).
    # Defaults to STDOUT.
    # http://ruby-doc.org/stdlib-2.1.0/libdoc/logger/rdoc/Logger.html
    # Interface:
    #   #debug(msg String, &block)
    #   #warn(msg String, &block)
    #   #error(msg String, &block)
    #   #info(msg String, &block)
    #   #fatal(msg String, &block)
    logger: Logger.new(STDOUT)
)

  validate_dep! cache, :cache, :get, :set
  validate_dep! cache_key_resolver, :cache_key_resolver, :call
  validate_dep! rate_limit_response_checker, :rate_limit_response_checker, :call
  validate_dep! logger, :info, :error, :warn, :debug

  @enabled = enabled
  @cache = cache
  @cache_key_resolver = cache_key_resolver
  @rate = rate.to_i
  @wait = wait.to_i
  @timeout = timeout.to_i
  @rate_limit_response_checker = rate_limit_response_checker
  @logger = logger

  super app
end

Instance Method Details

#call(request_env) ⇒ Object 



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# File 'lib/faraday_throttler/middleware.rb', line 69

def call(request_env)
  return app.call(request_env) if skip?(request_env)

  start = Time.now

  cache_key = cache_key_resolver.call(request_env)

  # Wait stick to be available
  until request_stick?(cache_key)
    logger.debug logline(cache_key, "A.1. No stick available. Wait for new one.")
    sleep(wait)
  end

  logger.debug logline(cache_key, "A.2. start backend request.")
  handle_request(request_env, cache_key, start)
end