if Code.ensure_loaded?(Phoenix.LiveView) do
defmodule PromEx.Plugins.PhoenixLiveView do
@moduledoc """
This plugin captures metrics emitted by PhoenixLiveView. Specifically, it captures events related to the
mount, handle_event, and handle_params callbacks for live views and live components.
This plugin supports the following options:
- `metric_prefix`: This option is OPTIONAL and is used to override the default metric prefix of
`[otp_app, :prom_ex, :phoenix_live_view]`. If this changes you will also want to set
`phoenix_live_view_metric_prefix` in your `dashboard_assigns` to the snakecase version of your
prefix, the default `phoenix_live_view_metric_prefix` is `{otp_app}_prom_ex_phoenix_live_view`.
- `duration_unit`: This is an OPTIONAL option and is a `Telemetry.Metrics.time_unit()`. It can be one of:
`:second | :millisecond | :microsecond | :nanosecond`. It is `:millisecond` by default.
This plugin exposes the following metric groups:
- `:phoenix_live_view_event_metrics`
- `:phoenix_live_view_component_event_metrics`
To use plugin in your application, add the following to your PromEx module:
```
defmodule WebApp.PromEx do
use PromEx, otp_app: :web_app
@impl true
def plugins do
[
...
PromEx.Plugins.PhoenixLiveView
]
end
@impl true
def dashboards do
[
...
{:prom_ex, "phoenix_live_view.json"}
]
end
end
```
"""
use PromEx.Plugin
alias Phoenix.LiveView.Socket
alias PromEx.Utils
@live_view_mount_stop [:phoenix, :live_view, :mount, :stop]
@live_view_mount_exception [:phoenix, :live_view, :mount, :exception]
@live_view_handle_event_stop [:phoenix, :live_view, :handle_event, :stop]
@live_view_handle_event_exception [:phoenix, :live_view, :handle_event, :exception]
# Coming soon
# @live_view_handle_params_stop [:phoenix, :live_view, :handle_params, :stop]
# @live_view_handle_params_exception [:phoenix, :live_view, :handle_params, :exception]
# Coming soon
# @live_component_handle_event_stop [:phoenix, :live_component, :handle_event, :stop]
# @live_component_handle_event_exception [:phoenix, :live_component, :handle_event, :exception]
@impl true
def event_metrics(opts) do
otp_app = Keyword.fetch!(opts, :otp_app)
metric_prefix = Keyword.get(opts, :metric_prefix, PromEx.metric_prefix(otp_app, :phoenix_live_view))
duration_unit = Keyword.get(opts, :duration_unit, :millisecond)
# Event metrics definitions
[
live_view_event_metrics(metric_prefix, duration_unit),
live_component_event_metrics(metric_prefix)
]
end
defp live_view_event_metrics(metric_prefix, duration_unit) do
bucket_intervals = [10, 100, 500, 1_000, 2_500, 5_000, 10_000]
duration_unit_plural = String.to_atom("#{duration_unit}s")
Event.build(
:phoenix_live_view_event_metrics,
[
distribution(
metric_prefix ++ [:mount, :duration, duration_unit_plural],
event_name: @live_view_mount_stop,
measurement: :duration,
description: "The time it takes for the live view to complete the mount callback.",
reporter_options: [
buckets: bucket_intervals
],
tag_values: &get_mount_socket_tags/1,
tags: [:action, :module],
unit: {:native, duration_unit}
),
distribution(
metric_prefix ++ [:mount, :exception, :duration, duration_unit_plural],
event_name: @live_view_mount_exception,
measurement: :duration,
description:
"The time it takes for the live view to complete the mount callback that resulted in an exception",
reporter_options: [
buckets: bucket_intervals
],
tag_values: &get_mount_exception_tags/1,
tags: [:action, :module, :kind, :reason],
unit: {:native, duration_unit}
),
distribution(
metric_prefix ++ [:handle_event, :duration, duration_unit_plural],
event_name: @live_view_handle_event_stop,
measurement: :duration,
description: "The time it takes for the live view to complete the handle_event callback.",
reporter_options: [
buckets: bucket_intervals
],
tag_values: &get_handle_event_socket_tags/1,
tags: [:event, :action, :module],
unit: {:native, duration_unit}
),
distribution(
metric_prefix ++ [:handle_event, :exception, :duration, duration_unit_plural],
event_name: @live_view_handle_event_exception,
measurement: :duration,
description:
"The time it takes for the live view to complete the handle_event callback that resulted in an exception.",
reporter_options: [
buckets: bucket_intervals
],
tag_values: &get_handle_event_exception_socket_tags/1,
tags: [:event, :action, :module, :kind, :reason],
unit: {:native, duration_unit}
)
]
)
end
defp live_component_event_metrics(_metric_prefix) do
Event.build(
:phoenix_live_view_component_event_metrics,
[]
)
end
defp get_handle_event_exception_socket_tags(%{socket: socket = %Socket{}} = metadata) do
%{
event: metadata.event,
action: get_live_view_action(socket),
module: get_live_view_module(socket),
kind: metadata.kind,
reason: Utils.normalize_exception(metadata.kind, metadata.reason, metadata.stacktrace)
}
end
defp get_handle_event_socket_tags(%{socket: socket = %Socket{}} = metadata) do
%{
event: metadata.event,
action: get_live_view_action(socket),
module: get_live_view_module(socket)
}
end
defp get_mount_socket_tags(%{socket: socket = %Socket{}}) do
%{
action: get_live_view_action(socket),
module: get_live_view_module(socket)
}
end
defp get_mount_exception_tags(%{socket: socket = %Socket{}} = metadata) do
%{
action: get_live_view_action(socket),
module: get_live_view_module(socket),
kind: metadata.kind,
reason: Utils.normalize_exception(metadata.kind, metadata.reason, metadata.stacktrace)
}
end
defp get_live_view_module(%Socket{} = socket) do
socket
|> Map.get(:view, :unknown)
|> normalize_module_name()
end
defp get_live_view_action(%Socket{} = socket) do
socket.assigns
|> Map.get(:live_action, :unknown)
end
defp normalize_module_name(name) when is_atom(name) do
name
|> Atom.to_string()
|> String.trim_leading("Elixir.")
end
defp normalize_module_name(name), do: name
end
else
defmodule PromEx.Plugins.PhoenixLiveView do
@moduledoc false
use PromEx.Plugin
@impl true
def event_metrics(_opts) do
PromEx.Plugin.no_dep_raise(__MODULE__, "PhoenixLiveView")
end
end
end
