Claudio Ortolina
72 lines
2.3 KiB
Elixir
72 lines
2.3 KiB
Elixir
defmodule MusicBrainz.API.ErrorResponse do
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@moduledoc """
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Structured error response for MusicBrainz API calls.
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MusicBrainz uses classic HTTP status codes as the error channel. The body is a
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flat JSON `{"error": "message"}` with no numeric application codes.
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## Rate limiting
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MusicBrainz signals rate limiting with **HTTP 503**, not 429. The service does
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not use 429 at all — a 503 response with a `Retry-After` header is the rate
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limit signal. `from_response/1` therefore maps 503 to `:rate_limit` (not the
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generic `:server_error` classification from `MusicLibrary.HttpError`).
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"""
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@behaviour MusicLibrary.ErrorResponse
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alias MusicLibrary.HttpError
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alias MusicLibrary.RetryDelay
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@type t :: %__MODULE__{
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status: integer() | nil,
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message: String.t() | nil,
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kind: HttpError.kind(),
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body: term(),
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retry_delay_seconds: pos_integer() | nil
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}
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defstruct [:status, :message, :kind, :body, :retry_delay_seconds]
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@spec from_response(Req.Response.t() | map()) :: t()
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def from_response(%{status: 503, body: body} = response) do
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%__MODULE__{
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status: 503,
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message: extract_message(body),
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kind: :rate_limit,
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body: body,
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retry_delay_seconds: RetryDelay.retry_after_seconds(response)
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}
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end
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def from_response(%{status: status, body: body} = response) do
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%__MODULE__{
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status: status,
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message: extract_message(body),
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kind: HttpError.default_kind(status),
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body: body,
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retry_delay_seconds: RetryDelay.retry_after_seconds(response)
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}
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end
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@impl MusicLibrary.ErrorResponse
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@spec retryable?(t()) :: boolean()
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def retryable?(%__MODULE__{kind: kind}) when kind in [:rate_limit, :server_error, :timeout],
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do: true
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def retryable?(%__MODULE__{}), do: false
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@impl MusicLibrary.ErrorResponse
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@spec retry_delay_seconds(t()) :: pos_integer()
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def retry_delay_seconds(%__MODULE__{retry_delay_seconds: seconds}) when is_integer(seconds),
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do: seconds
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def retry_delay_seconds(%__MODULE__{kind: :rate_limit}), do: 60
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def retry_delay_seconds(%__MODULE__{kind: :server_error}), do: 30
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def retry_delay_seconds(%__MODULE__{kind: :timeout}), do: 10
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def retry_delay_seconds(%__MODULE__{}), do: 30
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defp extract_message(%{"error" => message}) when is_binary(message), do: message
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defp extract_message(_), do: nil
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end
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