Claudio Ortolina
127 lines
3.0 KiB
Elixir
127 lines
3.0 KiB
Elixir
defmodule MusicLibraryWeb.Telemetry.Storage do
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use GenServer
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@buffer_size Application.compile_env(
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:music_library,
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[__MODULE__, :buffer_size],
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50
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)
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def metrics_history(metric) do
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GenServer.call(__MODULE__, {:data, metric})
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end
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def start_link(args) do
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GenServer.start_link(__MODULE__, args, name: __MODULE__)
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end
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@impl true
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def init(metrics) do
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Process.flag(:trap_exit, true)
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for metric <- metrics do
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attach_handler(metric)
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end
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{:ok, metrics}
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end
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@impl true
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def terminate(_, metrics) do
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for metric <- metrics do
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:telemetry.detach({__MODULE__, metric, self()})
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end
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:ok
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end
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defp attach_handler(%{event_name: name_list} = metric) do
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:telemetry.attach(
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{__MODULE__, metric, self()},
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name_list,
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&__MODULE__.handle_event/4,
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metric
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)
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end
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def handle_event(_event_name, data, metadata, metric) do
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if data = Phoenix.LiveDashboard.extract_datapoint_for_metric(metric, data, metadata) do
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GenServer.cast(__MODULE__, {:telemetry_metric, data, metric})
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end
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end
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@impl true
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def handle_cast({:telemetry_metric, data, metric}, state) do
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key = metric_key(metric)
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label = if is_map(data), do: Map.get(data, :label)
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measurement = if is_map(data), do: Map.get(data, :measurement, 0), else: 0
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time =
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if is_map(data),
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do: Map.get(data, :time, System.system_time(:microsecond)),
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else: System.system_time(:microsecond)
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insert_and_prune(key, label, measurement, time)
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{:noreply, state}
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end
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@impl true
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def handle_call({:data, metric}, _from, state) do
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key = metric_key(metric)
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datapoints = fetch_datapoints(key)
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{:reply, datapoints, state}
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end
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defp metric_key(metric) do
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Enum.join(
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[
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inspect(metric.__struct__),
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Enum.join(metric.name, "."),
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Enum.join(metric.tags, ".")
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],
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":"
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)
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end
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defp insert_and_prune(key, label, measurement, time) do
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MusicLibrary.TelemetryRepo.query(
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"INSERT INTO telemetry_datapoints (metric_key, label, measurement, time) VALUES (?1, ?2, ?3, ?4)",
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[key, label, measurement, time]
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)
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MusicLibrary.TelemetryRepo.query(
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"""
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DELETE FROM telemetry_datapoints
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WHERE metric_key = ?1
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AND id NOT IN (
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SELECT id FROM telemetry_datapoints
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WHERE metric_key = ?1
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ORDER BY id DESC
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LIMIT ?2
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)
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""",
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[key, @buffer_size]
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)
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catch
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_, _ -> :ok
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end
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defp fetch_datapoints(key) do
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case MusicLibrary.TelemetryRepo.query(
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"SELECT label, measurement, time FROM telemetry_datapoints WHERE metric_key = ?1 ORDER BY time ASC",
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[key]
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) do
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{:ok, %{rows: rows}} ->
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Enum.map(rows, fn [label, measurement, time] ->
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%{label: label, measurement: measurement, time: time}
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end)
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_ ->
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[]
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end
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catch
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_, _ -> []
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end
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end
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