MaxwellCache

Maxwell middleware to cache success response. Backend by Cachex.

Installation

Add maxwell_cache to your list of dependencies in mix.exs:

def deps do
  [
    {:maxwell_cache, ~> 0.1.0"},
  ]
end

Usage

More Maxwell usage could be seen here.

Short usage of this middleware here:

    #Set Maxwell Middleware.
    middleware Maxwell.Middleware.Cache, ttl: :timer.minutes(1), namespace: "httpbin"


    # Import middleware method.
    import Maxwell.Middleware.Cache, only: [from_cache: 1, from_source: 1, set_ttl: 2]

    # Middleware is doing nothing.
    def get_uuid do
      "/uuid"
      |> new()
      |> get!
      |> get_resp_body
    end

    # Set to requrest from real remote server and set cache if response success.
    def get_uuid_from_source do
      "/uuid"
      |> new()
      |> from_source()
      |> get!
      |> get_resp_body
    end

    # Set to get response from cache first and set ttl. Request real remote server if cache not found.
    def get_uuid_from_cache do
      "/uuid"
      |> new()
      |> from_cache()
      |> set_ttl(:timer.seconds(5))
      |> get!
      |> get_resp_body
    end

Options

Cache key relate to request

Cache key is consist of two parts, middleware namespace and information generated by hash_func/1.

Default hash_func/1 is below:

  def default_hash_func(%Maxwell.Conn{} = conn) do
    query_string = conn.query_string |> Maxwell.Query.encode
    headers      = conn.req_headers  |> Maxwell.Query.encode
    body         = conn.req_body     |> :erlang.phash2

    "#{conn.method}|#{conn.url}|#{conn.path}|#{query_string}|#{headers}|#{body}"
  end

Both of them could be set by middleware init/1.

    middleware Maxwell.Middleware.Cache, namespace: "yournamespace", hash_func: &your_hash_func/1

Cache limit

Default Cachex limit is %Cachex.Limit{limit: 2000, reclaim: 0.1}, could be change in config.exs:

config :maxwell_cache, limit: %Cachex.Limit{limit: 2000, reclaim: 0.1}

More information could be seen cachex doc.

Cache ttl

Default ttl is :timer.seconds(10), this could be change in config.exs:

config :maxwell_cache, default_ttl: :timer.seconds(10)

Client moudle could have their own ttl:

    middleware Maxwell.Middleware.Cache, ttl: :timer.seconds(10)

Request could set ttl by using set_ttl/1:

    def get_uuid_from_cache do
      "/uuid"
      |> new()
      |> from_cache()
      |> set_ttl(:timer.seconds(5))
      |> get!
      |> get_resp_body
    end