defmodule Kino.Process do
@moduledoc """
This module contains kinos for generating visualizations to help
introspect your running processes.
"""
alias Kino.Mermaid
alias Kino.Process.Tracer
@mermaid_classdefs """
classDef root fill:#c4b5fd, stroke:#374151, stroke-width:4px;
classDef supervisor fill:#c4b5fd, stroke:#374151, stroke-width:1px;
classDef worker fill:#93c5fd, stroke:#374151, stroke-width:1px;
classDef notstarted color:#777, fill:#d9d9d9, stroke:#777, stroke-width:1px;
"""
@type supervisor :: pid() | atom()
@type trace_target :: :all | pid() | [pid()]
@doc """
Generates a visualization of an application tree.
Given the name of an application as an atom, this function will render the
application tree. It is displayed with solid lines denoting supervisor-worker
relationships and dotted lines denoting links between processes. The graph
rendering supports the following options:
## Options
* `:direction` - defines the direction of the graph visual. The
value can either be `:top_down` or `:left_right`. Defaults to `:top_down`.
## Examples
To view the applications running in your instance run:
:application_controller.which_applications()
You can then call `Kino.Process.app_tree/1` to render
the application tree using using the atom of the application.
Kino.Process.app_tree(:logger)
You can also change the direction of the rendering by calling
`Kino.Process.app_tree/2` with the `:direction` option.
Kino.Process.app_tree(:logger, direction: :left_right)
"""
@spec app_tree(atom(), keyword()) :: Mermaid.t()
def app_tree(application, opts \\ []) when is_atom(application) do
{master, root_supervisor} =
case :application_controller.get_master(application) do
:undefined ->
if Application.spec(application, :vsn) do
raise ArgumentError,
"the provided application #{inspect(application)} does not have a supervision tree"
else
raise ArgumentError, "there is no application named #{inspect(application)}"
end
master ->
case :application_master.get_child(master) do
{root, _application} when is_pid(root) ->
{master, root}
_ ->
raise ArgumentError,
"the provided application #{inspect(application)} does not have a root supervisor"
end
end
direction = direction_from_opts(opts)
edges = traverse_supervisor(root_supervisor)
{:dictionary, dictionary} = Process.info(root_supervisor, :dictionary)
[ancestor] = dictionary[:"$ancestors"]
Mermaid.new("""
graph #{direction};
application_master(#{inspect(master)}):::supervisor ---> supervisor_ancestor;
supervisor_ancestor(#{inspect(ancestor)}):::supervisor ---> 0;
#{edges}
#{@mermaid_classdefs}
""")
end
@doc """
Generates a visualization of a supervision tree.
The provided supervisor can be either a named process or a PID. The supervision tree
is displayed with solid lines denoting supervisor-worker relationships and dotted
lines denoting links between processes. The graph rendering supports the following
options:
## Options
* `:direction` - defines the direction of the graph visual. The
value can either be `:top_down` or `:left_right`. Defaults to `:top_down`.
## Examples
With a supervisor definition like so:
{:ok, supervisor_pid} =
Supervisor.start_link(
[
{DynamicSupervisor, strategy: :one_for_one, name: MyApp.DynamicSupervisor},
{Agent, fn -> [] end}
],
strategy: :one_for_one,
name: MyApp.Supervisor
)
Enum.each(1..3, fn _ ->
DynamicSupervisor.start_child(MyApp.DynamicSupervisor, {Agent, fn -> %{} end})
end)
You can then call `Kino.Process.sup_tree/1` to render
the supervision tree using using the PID of the supervisor.
Kino.Process.sup_tree(supervisor_pid)
You can also render the supervisor by passing the name of the supervisor
if the supervisor was started with a name.
Kino.Process.sup_tree(MyApp.Supervisor)
You can also change the direction of the rendering by calling
`Kino.Process.sup_tree/2` with the `:direction` option.
Kino.Process.sup_tree(MyApp.Supervisor, direction: :left_right)
"""
@spec sup_tree(supervisor(), keyword()) :: Mermaid.t()
def sup_tree(supervisor, opts \\ []) do
direction = direction_from_opts(opts)
edges = traverse_supervisor(supervisor)
Mermaid.new("""
graph #{direction};
#{edges}
#{@mermaid_classdefs}
""")
end
@doc """
Renders a visual of the provided application tree.
This function renders an application tree much like `app_tree/2` with the difference
being that this function can be called anywhere within the Livebook code block
whereas `app_tree/2` must have its result be the last thing returned from the code
block in order to render the visual. It supports the same options as `app_tree/2` as
it delegates to that function to generate the visual.
"""
@spec render_app_tree(atom(), keyword()) :: Kino.nothing()
def render_app_tree(application, opts \\ []) do
application
|> app_tree(opts)
|> Kino.render()
Kino.nothing()
end
@doc """
Renders a sequence diagram of process messages and returns the function result.
This function renders a sequence diagram much like `seq_trace/2` with the difference
being that this function can be called anywhere within the Livebook code block
whereas `seq_trace/2` must have its result be the last thing returned from the code
block in order to render the visual. In addition, this function returns the result
from the provided trace function.
"""
@spec render_seq_trace(trace_target(), (() -> any())) :: any()
def render_seq_trace(trace_target \\ :all, trace_function) do
{func_result, sequence_diagram} = seq_trace(trace_target, trace_function)
Kino.render(sequence_diagram)
func_result
end
@doc """
Renders a visual of the provided supervision tree.
This function renders a supervision tree much like `sup_tree/2` with the difference
being that this function can be called anywhere within the Livebook code block
whereas `sup_tree/2` must have its result be the last thing returned from the code
block in order to render the visual. It supports the same options as `sup_tree/2` as
it delegates to that function to generate the visual.
"""
@spec render_sup_tree(supervisor(), keyword()) :: Kino.nothing()
def render_sup_tree(supervisor, opts \\ []) do
supervisor
|> sup_tree(opts)
|> Kino.render()
Kino.nothing()
end
@doc """
Generate a sequence diagram of process messages starting from `self()`.
The provided function is executed and traced, with all the events sent to and
received by the trace target processes rendered in a sequence diagram. The trace
target argument can either be a single PID, a list of PIDs, or the atom `:all`
depending on what messages you would like to retain in your trace.
## Examples
To generate a trace of all the messages occurring during the execution of the
provided function, you can do the following:
Kino.Process.seq_trace(fn ->
{:ok, agent_pid} = Agent.start_link(fn -> [] end)
Process.monitor(agent_pid)
1..2
|> Task.async_stream(
fn value ->
Agent.get(agent_pid, fn value -> value end)
100 * value
end,
max_concurrency: 3
)
|> Stream.run()
Agent.stop(agent_pid)
end)
If you are only interested in messages being sent to or received by certain PIDs,
you can filter the sequence diagram by specifying the PIDs that you are interested
in:
{:ok, agent_pid} = Agent.start_link(fn -> [] end)
Process.monitor(agent_pid)
Kino.Process.seq_trace(agent_pid, fn ->
1..2
|> Task.async_stream(
fn value ->
Agent.get(agent_pid, fn value -> value end)
100 * value
end,
max_concurrency: 3
)
|> Stream.run()
Agent.stop(agent_pid)
end)
"""
@spec seq_trace(trace_target(), (() -> any())) :: {any(), Mermaid.t()}
def seq_trace(trace_target \\ :all, trace_function)
def seq_trace(pid, trace_function) when is_pid(pid) do
seq_trace([pid], trace_function)
end
def seq_trace(trace_pids, trace_function) when is_list(trace_pids) or trace_pids == :all do
# Set up the process message tracer and the Erlang seq_trace_module
calling_pid = self()
{:ok, tracer_pid} = Tracer.start_link()
:seq_trace.set_token(:send, true)
:seq_trace.set_token(:receive, true)
:seq_trace.set_token(:monotonic_timestamp, true)
previous_tracer = :seq_trace.set_system_tracer(tracer_pid)
# Run the user supplied function and capture the events if no errors were encountered
{raw_trace_events, func_result} =
try do
func_result =
try do
# Run the user provided function
trace_function.()
after
# Reset all of the seq_trace options
:seq_trace.set_system_tracer(previous_tracer)
:seq_trace.reset_trace()
end
{Tracer.get_trace_events(tracer_pid), func_result}
after
# The Tracer GenServer is no longer needed, shut it down
GenServer.stop(tracer_pid)
end
# Get all of the events from the Tracer GenServer
trace_events =
raw_trace_events
|> Enum.filter(fn
# Skip :spawn_reply messages
%{message: {:spawn_reply, _, _, _}} ->
false
# Skip loopback messages
%{from: pid, to: pid} ->
false
# Filter out messages based on the trace target
%{from: from_pid, to: to_pid} ->
trace_pids == :all or from_pid in trace_pids or to_pid in trace_pids
# Reject the rest
_ ->
false
end)
|> Enum.sort_by(fn %{timestamp: timestamp} ->
timestamp
end)
# Get all the participating actors in the trace along with their sequence diagram IDs
{participants_lookup, _idx} =
Enum.reduce(trace_events, {%{}, 0}, fn %{from: from, to: to}, acc ->
acc
|> maybe_add_participant(from)
|> maybe_add_participant(to)
end)
# Generate the Mermaid formatted list of participants
participants =
Enum.map_join(participants_lookup, "\n", fn {pid, idx} ->
if pid == calling_pid do
"participant #{idx} AS self();"
else
generate_participant_entry(pid, idx)
end
end)
# Generate the mermaid formatted list of message events
{formatted_messages, _} =
trace_events
|> Enum.reduce({[], MapSet.new()}, fn %{from: from, to: to, message: message},
{events, started_processes} ->
events = [normalize_message(from, to, message, participants_lookup) | events]
from_idx = Map.get(participants_lookup, from, :not_found)
to_idx = Map.get(participants_lookup, to, :not_found)
cond do
activate?(to_idx, message) ->
{["activate #{to_idx}" | events], MapSet.put(started_processes, to_idx)}
deactivate?(from_idx, message) and MapSet.member?(started_processes, from_idx) ->
{["deactivate #{from_idx}" | events], MapSet.delete(started_processes, from_idx)}
true ->
{events, started_processes}
end
end)
messages =
formatted_messages
|> Enum.reverse()
|> Enum.join("\n")
sequence_diagram =
Mermaid.new("""
sequenceDiagram
#{participants}
#{messages}
""")
{func_result, sequence_diagram}
end
defp generate_participant_entry(pid, idx) do
try do
{:registered_name, name} = Process.info(pid, :registered_name)
"participant #{idx} AS #{module_or_atom_to_string(name)};"
rescue
_ -> "participant #{idx} AS #35;PID#{:erlang.pid_to_list(pid)};"
end
end
defp maybe_add_participant({participants, idx}, pid) when is_pid(pid) do
if Map.has_key?(participants, pid) do
{participants, idx}
else
{Map.put(participants, pid, idx), idx + 1}
end
end
defp maybe_add_participant(acc, _) do
acc
end
defp activate?(idx, {:spawn_request, _, _, _, _, _, _, _}) when idx != :not_found, do: true
defp activate?(_idx, _), do: false
defp deactivate?(idx, {:EXIT, _, _}) when idx != :not_found, do: true
defp deactivate?(_idx, _), do: false
defp normalize_message(from, to, message, participants_lookup)
when is_map_key(participants_lookup, from) and is_map_key(participants_lookup, to) do
formatted_message = label_from_message(message)
from_idx = participants_lookup[from]
to_idx = participants_lookup[to]
"#{from_idx}->>#{to_idx}: #{formatted_message}"
end
defp normalize_message(_, _, _, _), do: ""
defp label_from_message(message) do
case message do
{:EXIT, _, reason} -> "EXIT: #{label_from_reason(reason)}"
{:spawn_request, _, _, _, _, _, _, _} -> "SPAWN"
{:DOWN, _, :process, _, reason} -> "DOWN: #{label_from_reason(reason)}"
{:"$gen_call", _ref, value} -> "CALL: #{label_from_value(value)}"
{:"$gen_cast", value} -> "CAST: #{label_from_value(value)}"
value -> "INFO: #{label_from_value(value)}"
end
end
defp label_from_reason(:normal), do: "normal"
defp label_from_reason(:shutdown), do: "shutdown"
defp label_from_reason({:shutdown, _}), do: "shutdown"
defp label_from_reason(_), do: "abnormal"
defp label_from_value(tuple)
when is_tuple(tuple) and is_atom(elem(tuple, 0)),
do: elem(tuple, 0)
defp label_from_value(atom) when is_atom(atom), do: atom
defp label_from_value(ref) when is_reference(ref), do: inspect(ref)
defp label_from_value(tuple) when is_tuple(tuple), do: "tuple"
defp label_from_value(_), do: "term"
defp direction_from_opts(opts) do
opts
|> Keyword.get(:direction, :top_down)
|> convert_direction()
end
defp traverse_supervisor(supervisor) do
supervisor =
case GenServer.whereis(supervisor) do
supervisor_pid when is_pid(supervisor_pid) ->
supervisor_pid
_ ->
raise ArgumentError,
"the provided identifier #{inspect(supervisor)} does not reference a running process"
end
supervisor_children =
try do
Supervisor.which_children(supervisor)
catch
_, _ ->
raise ArgumentError, "the provided process #{inspect(supervisor)} is not a supervisor"
end
root_node = graph_node(0, :root, supervisor, :supervisor)
supervisor_children
|> traverse_processes(root_node, {%{}, 1, %{root_node.pid => root_node}})
|> traverse_links()
|> Enum.map_join("\n", fn {_pid_pair, edge} ->
generate_mermaid_entry(edge)
end)
end
defp convert_direction(:top_down), do: "TD"
defp convert_direction(:left_right), do: "LR"
defp convert_direction(invalid_direction),
do: raise(ArgumentError, "expected a valid direction, got: #{inspect(invalid_direction)}")
defp traverse_processes(
[{id, :undefined, type, _} | rest],
parent_node,
{rels, idx, pid_keys}
) do
child_node = graph_node(idx, id, :undefined, type)
connection = graph_edge(parent_node, child_node, :supervisor)
traverse_processes(rest, parent_node, {add_rel(rels, connection), idx + 1, pid_keys})
end
defp traverse_processes(
[{id, pid, :supervisor, _} | rest],
parent_node,
{rels, idx, pid_keys}
) do
child_node = graph_node(idx, id, pid, :supervisor)
connection = graph_edge(parent_node, child_node, :supervisor)
pid_keys = Map.put(pid_keys, pid, child_node)
children = Supervisor.which_children(pid)
{subtree_rels, idx, pid_keys} =
traverse_processes(children, child_node, {%{}, idx + 1, pid_keys})
updated_rels =
rels
|> add_rels(subtree_rels)
|> add_rel(connection)
traverse_processes(rest, parent_node, {updated_rels, idx, pid_keys})
end
defp traverse_processes(
[{id, pid, :worker, _} | rest],
parent_node,
{rels, idx, pid_keys}
) do
child_node = graph_node(idx, id, pid, :worker)
connection = graph_edge(parent_node, child_node, :supervisor)
pid_keys = Map.put(pid_keys, pid, child_node)
traverse_processes(rest, parent_node, {add_rel(rels, connection), idx + 1, pid_keys})
end
defp traverse_processes([], _, acc) do
acc
end
defp add_rels(rels, additional_rels) do
Map.merge(rels, additional_rels, fn _key, edge_1, _edge_2 -> edge_1 end)
end
defp add_rel(rels, edge) do
lookup = Enum.sort([edge.node_1.idx, edge.node_2.idx])
Map.put_new(rels, lookup, edge)
end
defp traverse_links({rels, _idx, pid_keys}) do
rels_with_links =
Enum.reduce(pid_keys, rels, fn {pid, _idx}, rels_with_links ->
{:links, links} = Process.info(pid, :links)
Enum.reduce(links, rels_with_links, fn link_pid, acc ->
add_new_links_to_acc(pid_keys, pid, link_pid, acc)
end)
end)
rels_with_links
end
defp add_new_links_to_acc(pid_keys, pid, link_pid, acc) do
case pid_keys do
%{^pid => node_1, ^link_pid => node_2} ->
add_rel(acc, graph_edge(node_1, node_2, :link))
_ ->
acc
end
end
# Mermaid rendering helper functions
defp graph_edge(node_1, node_2, relationship) do
%{
node_1: node_1,
node_2: node_2,
relationship: relationship
}
end
defp graph_node(idx, id, pid, type) do
%{
idx: idx,
id: id,
pid: pid,
type: type
}
end
defp generate_mermaid_entry(%{node_1: node_1, node_2: node_2, relationship: :link}) do
"#{graph_node(node_1)} -..- #{graph_node(node_2)}"
end
defp generate_mermaid_entry(%{node_1: node_1, node_2: node_2, relationship: :supervisor}) do
"#{graph_node(node_1)} ---> #{graph_node(node_2)}"
end
defp graph_node(%{pid: :undefined, id: id, idx: idx}) do
"#{idx}(id: #{inspect(id)}):::notstarted"
end
defp graph_node(%{idx: idx, pid: pid, type: type}) do
type =
if idx == 0 do
:root
else
type
end
display =
case Process.info(pid, :registered_name) do
{:registered_name, []} -> inspect(pid)
{:registered_name, name} -> module_or_atom_to_string(name)
end
"#{idx}(#{display}):::#{type}"
end
defp module_or_atom_to_string(atom) do
case Atom.to_string(atom) do
"Elixir." <> rest -> rest
rest -> rest
end
end
end
