hlavacek/redix_pubsub

Elixir library for using Redis Pub/Sub features (built on top of Redix)

DO NOT USE

This is an attempt to modify the original pub_sub library to work with redis streams instead of redis pub sub.

What works now:

{:ok, pubsub} = Redix.PubSub.start_link()
{:ok, client} = Redix.start_link()

{:ok, ref} = Redix.PubSub.subscribe(pubsub, "my_channel", self())
#=> {:ok, ref}

# We wait for the subscription confirmation
receive do
  {:redix_pubsub, ^pubsub, ^ref, :subscribed, %{channel: "my_channel"}} -> :ok
end

Redix.command!(client, ~w(XADD my_channel * sensor-id 1234 temperature 19.8))

receive do
  {:redix_pubsub, ^pubsub, ^ref, :message, %{channel: "my_channel"} = properties} ->
  properties.payload
end
#=> [["1541027511486-0", ["sensor-id", "1234", "temperature", "19.8"]]]

TODO:

• use redis streams consumer groups
• work with unsuscribe (does not work at all at the moment)
• no tests for xread at the moment

Redix PubSub

Elixir library for Redis Pub/Sub (based on Redix).

For basic Redis-related functionality, use Redix.

Installation

Add the :redix_pubsub dependency to your mix.exs file:

defp deps() do
  [{:redix_pubsub, ">= 0.0.0"}]
end

Use mix hex.info redix_pubsub to find out what the latest version is. Then, run mix deps.get in your shell to fetch the new dependency. Note that this library requires Erlang 20+.

Usage

A Redix.PubSub process holds a connection to Redis and acts as a pub/sub intermediary between the Redis server and Elixir processes. The architecture looks like this:

Each Redix.PubSub process is able to subcribe to or unsubscribe from multiple Redis channels. One Redix.PubSub connection can handle multiple Elixir processes subscribing each to different channels.

A Redix.PubSub process can be started via Redix.PubSub.start_link/2:

{:ok, pubsub} = Redix.PubSub.start_link()

Most communication with the Redix.PubSub process happens via Elixir messages (that simulate a Pub/Sub interaction with the pub/sub server).

{:ok, pubsub} = Redix.PubSub.start_link()

Redix.PubSub.subscribe(pubsub, "my_channel", self())
#=> {:ok, ref}

Confirmation of subscriptions is delivered as an Elixir message:

receive do
  {:redix_pubsub, ^pubsub, ^ref, :subscribed, %{channel: "my_channel"}} -> :ok
end

If someone publishes a message on a channel we're subscribed to:

receive do
  {:redix_pubsub, ^pubsub, ^ref, :message, %{channel: "my_channel", payload: "hello"}} ->
    IO.puts("Received a message!")
end

More information on usage of this library can be found in the documentation.

License

ISC 2016, Andrea Leopardi (see LICENSE.txt)