Class: Above::MiddleWare::Cache

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

Overview

Middleware for a naive cache that stores the last max_size worth of results in memory

Instance Method Summary collapse

Constructor Details

#initialize(app:) ⇒ Cache

Returns a new instance of Cache.



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# File 'lib/above/middleware/cache.rb', line 9

def initialize(app:)
  @app = app # who you gonna call
  @cache = {}
  @max_size = nil
end

Instance Method Details

#call(env:) ⇒ Object 



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# File 'lib/above/middleware/cache.rb', line 15

def call(env:)
  # env is {socket:, request:, config:, valid:}

  # can't cache an invalid url
  return @app&.call(env:) unless env[:valid]

  if @max_size.nil?
    config = env[:config]["Above::MiddleWare::Cache"]
    @max_size = config["max_size"]
  end

  request = env[:request].to_s.chomp("/")
  if @cache.key?(request)
    # use the cached result if we have it
    @cache[request][:result]
  else
    # otherwise go on to find & cache the result
    result = @app.call(env:) unless @app.nil?

    # only keep the most recent @max_size worth of results
    if @cache.size >= @max_size
      oldest = @cache.min_by { |key, val| val[:time] }[0]
      @cache.delete(oldest)
    end
    @cache[request] = {
      result: result,
      time: Time.now
    }

    result
  end
end