Class: ContentGateway::Cache

Inherits:
Object
  • Object
show all
Defined in:
lib/content_gateway/cache.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(config, url, method, params = {}) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/content_gateway/cache.rb', line 5

def initialize(config, url, method, params = {})
  @config = config
  @url = url
  @method = method.to_sym
  @skip_cache = params[:skip_cache] || false
end

Instance Attribute Details

#status ⇒ Object (readonly)

Returns the value of attribute status.



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# File 'lib/content_gateway/cache.rb', line 3

def status
  @status
end

Instance Method Details

#fetch(request, params = {}) ⇒ Object 



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# File 'lib/content_gateway/cache.rb', line 16

def fetch(request, params = {})
  timeout = params[:timeout] || @config.timeout
  expires_in = params[:expires_in] || @config.cache_expires_in
  stale_expires_in = params[:stale_expires_in] || @config.cache_stale_expires_in
  stale_on_error = config_stale_on_error params, @config

  begin
    Timeout.timeout(timeout) do
      @config.cache.fetch(@url, expires_in: expires_in) do
        @status = "MISS"
        response = request.execute
        response = String.new(response) if response

        @config.cache.write(stale_key, response, expires_in: stale_expires_in)
        response
      end
    end

  rescue Timeout::Error => e
    begin
      serve_stale
    rescue ContentGateway::StaleCacheNotAvailableError
      raise ContentGateway::TimeoutError.new(@url, e, timeout)
    end

  rescue ContentGateway::ServerError => e
    begin
      raise e unless stale_on_error
      serve_stale
    rescue ContentGateway::StaleCacheNotAvailableError
      raise e
    end
  end
end

#serve_stale ⇒ Object 



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# File 'lib/content_gateway/cache.rb', line 51

def serve_stale
  @config.cache.read(stale_key).tap do |cached|
    raise ContentGateway::StaleCacheNotAvailableError.new unless cached
    @status = "STALE"
  end
end

#stale_key ⇒ Object 



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# File 'lib/content_gateway/cache.rb', line 58

def stale_key
  @stale_key ||= "stale:#{@url}"
end

#use? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/content_gateway/cache.rb', line 12

def use?
  !@skip_cache && [:get, :head].include?(@method)
end