PersistentHttpClient

persistent_http_client.rb

class PersistentHttpClient
  def self.get(url)
    uri = url.is_a?(URI) ? url : URI(url)
    connection_manager.get_connection(uri)
  end

  def self.connection_manager
    Thread.current[:persistent_http_connection_manager] ||= new_manager
  end

  def self.connection_managers
    @connection_managers ||= []
  end

  def self.new_manager
    remove_old_managers
    mutex.synchronize do
      manager = ConnectionManager.new
      connection_managers << manager
      manager
    end
  end

  def self.remove_old_managers
    mutex.synchronize do
      removed = connection_managers.reject!(&:stale?)
      (removed || []).each(&:close_connections!)
    end
  end

  def self.mutex
    @mutex ||= Mutex.new
  end

  class ConnectionManager
    attr_accessor :connections, :last_used

    def initialize
      self.connections = {}
      self.last_used = Time.now
    end

    def get_connection(uri)
      mutex.synchronize do
        self.last_used = Time.now

        params = [uri.host, uri.port]
        connection = connections[params]
        if connection
          return connection
        end
        # https://github.com/stripe/stripe-ruby/blob/f3b83f132ec83646fd1fe74a648954db3f681b12/lib/stripe/connection_manager.rb#L103
        connection = Net::HTTP.new(uri.host, uri.port)
        connection.keep_alive_timeout = 30
        connection.use_ssl = uri.scheme == "https"
        connection.open_timeout = 30
        connection.read_timeout = 80
        connection.start
        connections[params] = connection

        connection
      end
    end

    def close_connections!
      mutex.synchronize do
        connections.values.each(&:finish)
        self.connections = {}
      end
    end

    def stale?
      Time.now - last_used > 5.minutes
    end

    def mutex
      @mutex ||= Mutex.new
    end
  end
end

usage.rb

uri = URI("https://example.com/api")
http = PersistentHttpClient.get(uri)
request = Net::HTTP::Post.new(uri.request_uri)
response = http.request(request)