Class: FaradayMiddleware::Reddit::RateLimit

Inherits:
Faraday::Middleware
  • Object
show all
Defined in:
lib/faraday_middleware/reddit/use/rate_limit.rb

Overview

Middleware for automatic rate limiting.

Logs reddit’s ratelimit HTTP headers and applies a caching strategy based on them. The default strategy is to block for x-ratelimit-reset / x-ratelimit-remaining.

Instance Method Summary collapse

Constructor Details

#initialize(app, options = nil) ⇒ RateLimit

Returns a new instance of RateLimit.



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# File 'lib/faraday_middleware/reddit/use/rate_limit.rb', line 13

def initialize(app, options = nil)
  super(app)
  @options = options || {}
  @strategy = @options[:strategy] || -> { burst_strategy }

  # Default rate limit settings.
  @ratelimit_remaining = 30
  @ratelimit_used      = 0
  @ratelimit_reset     = 60
  @ratelimit_cap       = 30
end

Instance Method Details

#burst_strategy(threshold = 0.5) ⇒ Object 



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# File 'lib/faraday_middleware/reddit/use/rate_limit.rb', line 43

def burst_strategy(threshold = 0.5)
  linear_strategy if (@ratelimit_used / @ratelimit_cap.to_f) > threshold
end

#call(env) ⇒ Object 



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# File 'lib/faraday_middleware/reddit/use/rate_limit.rb', line 25

def call(env)
  @strategy.call
  @app.call(env).on_complete { |response_env| on_complete_callback(response_env) }
end

#linear_strategy ⇒ Object 



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# File 'lib/faraday_middleware/reddit/use/rate_limit.rb', line 39

def linear_strategy
  sleep @ratelimit_reset.to_f / [1, @ratelimit_remaining].max
end

#on_complete_callback(env) ⇒ Object 



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# File 'lib/faraday_middleware/reddit/use/rate_limit.rb', line 30

def on_complete_callback(env)
  @ratelimit_remaining = env[:response_headers]['x-ratelimit-remaining'].to_i
  @ratelimit_used      = env[:response_headers]['x-ratelimit-used'].to_i
  @ratelimit_reset     = env[:response_headers]['x-ratelimit-reset'].to_i
  @ratelimit_cap       = @ratelimit_remaining + @ratelimit_used

  sleep(@ratelimit_reset) if @ratelimit_remaining == 0 || env[:status] == 429
end