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phoenix
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Productive. Reliable. Fast. A productive web framework that does not compromise speed or maintainability.
Security advisory:
This version has known vulnerabilities.
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Files
lib/phoenix/debug.ex
defmodule Phoenix.Debug do
@moduledoc """
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:
* List all currently connected `Phoenix.Socket` transport processes.
* List all channels for a given `Phoenix.Socket` process.
* Get the socket of a channel process.
* Check if a process is a `Phoenix.Socket` or `Phoenix.Channel`.
"""
@doc """
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}]
"""
def list_sockets do
for pid <- Process.list(), dict = socket_process_dict(pid), not is_nil(dict) do
{Phoenix.Socket, mod, id} = keyfind(dict, :"$process_label")
%{pid: pid, module: mod, id: id}
end
end
defp keyfind(list, key) do
case List.keyfind(list, key, 0) do
{^key, value} -> value
_ -> nil
end
end
defp socket_process_dict(pid) do
# Phoenix.Socket sets the "$process_label" to {Phoenix.Socket, handler_module, id}
with info when is_list(info) <- Process.info(pid, [:dictionary]),
dictionary when not is_nil(dictionary) <- keyfind(info, :dictionary),
label when not is_nil(label) <- keyfind(dictionary, :"$process_label"),
{Phoenix.Socket, mod, id} when is_atom(mod) and (is_binary(id) or is_nil(id)) <- label do
dictionary
else
_ -> nil
end
end
@doc """
Returns true if the given pid is a `Phoenix.Socket` transport process.
It returns `false` for custom sockets implementing the `Phoenix.Socket.Transport` behaviour.
## Examples
iex> Phoenix.Debug.list_sockets() |> Enum.at(0) |> Map.fetch!(:pid) |> socket_process?()
true
iex> socket_process?(pid(0,456,0))
false
"""
def socket_process?(pid) do
not is_nil(socket_process_dict(pid))
end
@doc """
Checks if the given pid is a `Phoenix.Channel` process.
Note: this function returns false for [custom channels](https://hexdocs.pm/phoenix/Phoenix.Socket.html#module-custom-channels).
"""
def channel_process?(pid) do
# Phoenix.Channel sets the "$process_label" to {Phoenix.Socket, handler_module, id}
with info when is_list(info) <- Process.info(pid, [:dictionary]),
dictionary when not is_nil(dictionary) <- keyfind(info, :dictionary),
label when not is_nil(label) <- keyfind(dictionary, :"$process_label"),
{Phoenix.Channel, mod, topic} when is_atom(mod) and is_binary(topic) <- label do
true
else
_ -> false
end
end
@doc """
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](https://hexdocs.pm/phoenix/Phoenix.Socket.html#module-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}
"""
def list_channels(socket_pid) do
ref = make_ref()
if Process.alive?(socket_pid) and socket_process?(socket_pid) do
send(socket_pid, {:debug_channels, ref, self()})
receive do
{:debug_channels, ^ref, channels} ->
{:ok, channels}
after
5_000 -> {:error, :timeout}
end
else
{:error, :not_alive}
end
end
@doc """
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}
"""
def socket(channel_pid) do
if channel_process?(channel_pid) do
{:ok, Phoenix.Channel.Server.socket(channel_pid)}
else
{:error, :not_alive_or_not_a_channel}
end
catch
:exit, _ -> {:error, :not_alive_or_not_a_channel}
end
end