View Source Slipstream.Socket (Slipstream v1.1.3)

A data structure representing a potential websocket client connection

This structure closely resembles Phoenix.Socket.t/0, but is not compatible with its functions. All documented functions from this module are imported by use Slipstream.

Summary

Types

t()

A socket data structure representing a potential websocket client connection

Functions

assign(socket, attrs)

assign(socket, key, value)

Adds key-value pairs to socket assigns

channel_pid(socket)

Gets the process ID of the connection

connected?(socket)

Checks if a socket is connected to a remote websocket host

join_status(socket, topic)

Checks the status of a join request

joined?(socket, topic)

Checks if a channel is currently joined

update(socket, key, func)

Updates an existing key in the socket assigns

Types

t()

(since 0.1.0)

@type t() :: %Slipstream.Socket{
  assigns: map(),
  channel_config: Slipstream.Configuration.t() | nil,
  channel_pid: nil | pid(),
  joins: %{
    required(String.t()) => %Slipstream.Socket.Join{
      params: term(),
      rejoin_counter: term(),
      status: term(),
      topic: term()
    }
  },
  metadata: %{
    required(atom()) => String.t() | %{required(String.t()) => String.t()}
  },
  reconnect_counter: non_neg_integer(),
  response_headers: term(),
  socket_pid: pid()
}

A socket data structure representing a potential websocket client connection

Functions

assign(socket, attrs)

@spec assign(t(), Keyword.t()) :: t()

assign(socket, key, value)

(since 0.1.0)

@spec assign(t(), key :: atom(), value :: any()) :: t()

Adds key-value pairs to socket assigns

Behaves the same as Phoenix.Socket.assign/3

Examples

iex> assign(socket, :key, :value)
iex> assign(socket, key: :value)

channel_pid(socket)

(since 0.1.0)

@spec channel_pid(t()) :: pid() | nil

Gets the process ID of the connection

The slipstream implementor module is not the same process as the GenServer which interfaces with the remote server for websocket communication. This other process, the Slipstream.Connection process, interfaces with the low-level WebSocket connection and communicates with the implementor module by puassing messages (mostly with Kernel.send/2).

It can be useful to have access to this pid for testing or debugging purposes, such as sending a fake disconnect message or for getting state with :sys.get_state/1.

Examples

iex> Slipstream.Socket.channel_pid(socket)
#PID<0.1.2>

connected?(socket)

(since 0.1.0)

@spec connected?(t()) :: boolean()

Checks if a socket is connected to a remote websocket host

Examples

iex> socket = connect(socket, uri: "ws://example.org")
iex> socket = await_connect!(socket)
iex> connected?(socket)
true

join_status(socket, topic)

(since 0.1.0)

@spec join_status(t(), topic :: String.t()) :: :requested | :joined | :closed | nil

Checks the status of a join request

When a join is requested with Slipstream.join/3, the join request is considered to be in the :requested state. Once the topic is successfully joined, it is considered :joined until closed. If there is a failure to join the topic, if the topic crashes, or if the topic is left after being joined, the status of the join is considered :closed. Finally, if a topic has not been requested in a join so far for a socket, the status is nil.

Notably, the status of a join will not automatically change to :joined once the remote server replies with successful join. Either the join must be awaited with Slipstream.await_join/2 or the status may be checked later in the Slipstream.handle_join/3 callback.

Examples

iex> socket = join(socket, "room:lobby")
iex> join_status(socket, "room:lobby")
:requested
iex> {:ok, socket, _join_response} = await_join(socket, "room:lobby")
iex> join_status(socket, "room:lobby")
:joined

joined?(socket, topic)

(since 0.1.0)

@spec joined?(t(), topic :: String.t()) :: boolean()

Checks if a channel is currently joined

Examples

iex> joined?(socket, "room:lobby")
true

update(socket, key, func)

(since 0.5.0)

@spec update(t(), key :: atom(), func :: (value :: any() -> value :: any())) :: t()

Updates an existing key in the socket assigns

Raises a KeyError if the key is not present in socket.assigns.

func should be an 1-arity function which takes the existing value at assign key and updates it to a new value. The new value will take the old value's place in socket.assigns[key].

This function is a useful alternative to assign/3 when the key is already present in assigns and is a list, map, or similarly malleable data structure.

Examples

@impl Slipstream
def handle_cast({:join, topic}, socket) do
  socket =
    socket
    |> update(:topics, &[topic | &1])
    |> join(topic)

  {:noreply, socket}
end

@impl Slipstream
def handle_call({:join, topic}, from, socket) do
  socket =
    socket
    |> update(:join_requests, &Map.put(&1, topic, from))
    |> join(topic)

  # note: not replying here so we can provide a synchronous call to a
  # topic being joined
  {:noreply, socket}
end

@impl Slipstream
def handle_join(topic, response, socket) do
  case Map.fetch(socket.assigns.join_requests, topic) do
    {:ok, from} -> GenServer.reply(from, {:ok, response})
    :error -> :ok
  end

  {:ok, socket}
end