Phoenix.Debug (Phoenix v1.8.0-rc.4)

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Functions for runtime introspection and debugging of Phoenix applications.

This module provides utilities for inspecting and debugging Phoenix applications. At the moment, it only includes functions related to Phoenix.Socket and Phoenix.Channel processes.

It allows you to:

Summary

Functions

Checks if the given pid is a Phoenix.Channel process.

Returns a list of all currently connected channels for the given Phoenix.Socket pid.

Returns a list of all currently connected Phoenix.Socket transport processes.

Returns the socket of the channel process.

Returns true if the given pid is a Phoenix.Socket transport process.

Functions

channel_process?(pid)

Checks if the given pid is a Phoenix.Channel process.

Note: this function returns false for custom channels.

list_channels(socket_pid)

Returns a list of all currently connected channels for the given Phoenix.Socket pid.

Each channel is represented as a map with the following keys:

  • :pid - the pid of the channel process
  • :status - the status of the channel
  • :topic - the topic of the channel

Note that this list also contains custom channels like LiveViews. You can check if a channel is a custom channel by using the channel?/1 function, which returns false for custom channels.

Examples

iex> pid = Phoenix.Debug.list_sockets() |> Enum.at(0) |> Map.fetch!(:pid)
iex> Phoenix.Debug.list_channels(pid)
{:ok,
 [
   %{pid: #PID<0.1702.0>, status: :joined, topic: "lv:phx-GDp9a9UZPiTxcgnE"},
   %{pid: #PID<0.1727.0>, status: :joined, topic: "lv:sidebar"}
 ]}

iex> Phoenix.Debug.list_channels(pid(0,456,0))
{:error, :not_alive}

list_sockets()

Returns a list of all currently connected Phoenix.Socket transport processes.

Note that custom sockets implementing the Phoenix.Socket.Transport behaviour are not listed.

Each process corresponds to one connection that can have multiple channels.

For example, when using Phoenix LiveView, the browser establishes a socket connection when initially navigating to the page, and each live navigation retains the same socket connection. Nested LiveViews also share the same connection, each being a different channel. See Phoenix.Debug.channels/1.

Examples

iex> Phoenix.Debug.list_sockets()
[%{pid: #PID<0.123.0>, module: Phoenix.LiveView.Socket, id: nil}]

socket(channel_pid)

Returns the socket of the channel process.

Note: this only works for channels defined with use Phoenix.Channel. For LiveViews, use the functions defined in Phoenix.LiveView.Debug instead.

Examples

iex> pid = Phoenix.Debug.list_sockets() |> Enum.at(0) |> Map.fetch!(:pid)
iex> {:ok, channels} = Phoenix.Debug.list_channels(pid)
iex> channels |> Enum.at(0) |> Map.fetch!(:pid) |> socket()
{:ok, %Phoenix.Socket{...}}

iex> socket(pid(0,456,0))
{:error, :not_alive_or_not_a_channel}

socket_process?(pid)

Returns true if the given pid is a Phoenix.Socket transport process.

It returns false for custom sockets implementing the Phoenix.Socket.Transport behaviour.

Examples

iex> Phoenix.Debug.list_sockets() |> Enum.at(0) |> Map.fetch!(:pid) |> socket_process?()
true

iex> socket_process?(pid(0,456,0))
false