Class: LWS::Middleware::Caching

Inherits:
Faraday::Middleware
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/lws/middleware/caching.rb

Overview

Public: Caches GET responses and pulls subsequent ones from the cache.

Constant Summary collapse

CACHEABLE_STATUS_CODES =

Internal: List of status codes that can be cached:

  • 200 - ‘OK’

  • 203 - ‘Non-Authoritative Information’

  • 300 - ‘Multiple Choices’

  • 301 - ‘Moved Permanently’

  • 302 - ‘Found’

  • 404 - ‘Not Found’

  • 410 - ‘Gone’

[200, 203, 300, 301, 302, 404, 410].freeze

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(app, cache = nil, options = {}) ⇒ Caching

Public: initialize the middleware.

cache - An object that responds to read and write (default: nil). options - An options Hash (default: {}):

:ignore_params - String name or Array names of query
                         params that should be ignored when forming
                         the cache key (default: []).
:write_options - Hash of settings that should be passed as the
                         third options parameter to the cache's #write
                         method. If not specified, no options parameter
                         will be passed.
:full_key      - Boolean - use full URL as cache key:
                         (url.host + url.request_uri)
:status_codes  - Array of http status code to be cache
                         (default: CACHEABLE_STATUS_CODE)

Yields if no cache is given. The block should return a cache object.



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# File 'lib/lws/middleware/caching.rb', line 66

def initialize(app, cache = nil, options = {})
  super(app)
  if cache.is_a?(Hash) && block_given?
    options = cache
    cache = nil
  end
  @cache = cache || yield
  @options = options
end

Instance Attribute Details

#cache ⇒ Object (readonly)

Returns the value of attribute cache.



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# File 'lib/lws/middleware/caching.rb', line 34

def cache
  @cache
end

Instance Method Details

#cache_key(env) ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 95

def cache_key(env)
  url = env[:url].dup
  if url.query && params_to_ignore.any?
    params = parse_query url.query
    params.reject! { |k,| params_to_ignore.include? k }
    url.query = params.any? ? build_query(params) : nil
  end
  url.normalize!
  digest = full_key? ? url.host + url.request_uri : url.request_uri
  Digest::SHA1.hexdigest(digest)
end

#cache_on_complete(env) ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 122

def cache_on_complete(env)
  key = cache_key(env)
  if (cached_response = cache.read(key))
    finalize_response(cached_response, env)
  else
    # response.status is nil at this point
    # any checks need to be done inside on_complete block
    @app.call(env).on_complete do |response_env|
      store_response_in_cache(key, response_env.response)
      response_env
    end
  end
end

#call(env) ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 76

def call(env)
  if env[:method] == :get
    if env[:parallel_manager]
      # callback mode
      cache_on_complete(env)
    else
      # synchronous mode
      key = cache_key(env)
      unless (response = cache.read(key)) && response
        response = @app.call(env)
        store_response_in_cache(key, response)
      end
      finalize_response(response, env)
    end
  else
    @app.call(env)
  end
end

#custom_status_codes ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 115

def custom_status_codes
  @custom_status_codes ||= begin
    codes = CACHEABLE_STATUS_CODES & Array(@options[:status_codes]).map(&:to_i)
    codes.any? ? codes : CACHEABLE_STATUS_CODES
  end
end

#finalize_response(response, env) ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 146

def finalize_response(response, env)
  response = response.dup if response.frozen?
  env[:response] = response
  unless env[:response_headers]
    env.update response.env
    # FIXME: omg hax
    response.instance_variable_set('@env', env)
  end
  response
end

#full_key? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/lws/middleware/caching.rb', line 111

def full_key?
  @full_key ||= @options[:full_key]
end

#params_to_ignore ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 107

def params_to_ignore
  @params_to_ignore ||= Array(@options[:ignore_params]).map(&:to_s)
end

#store_response_in_cache(key, response) ⇒ Object 



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# File 'lib/lws/middleware/caching.rb', line 136

def store_response_in_cache(key, response)
  return unless custom_status_codes.include?(response.status)

  if @options[:write_options]
    cache.write(key, response, @options[:write_options])
  else
    cache.write(key, response)
  end
end