86 lines
2.6 KiB
Elixir
86 lines
2.6 KiB
Elixir
defmodule Phoenix.Tracker.Replica do
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@moduledoc false
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alias Phoenix.Tracker.Replica
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@type name :: String.t
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@type vsn :: integer
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@type replica_ref :: {name, vsn}
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@type t :: %Replica{
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name: name,
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vsn: vsn,
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last_heartbeat_at: pos_integer | nil,
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status: :up | :down | :permdown
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}
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defstruct name: nil,
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vsn: nil,
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last_heartbeat_at: nil,
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status: :up
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@type op_result :: {%{name => Replica.t}, previous_node :: Replica.t | nil, updated_node :: Replica.t}
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@doc """
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Returns a new Replica with a unique vsn.
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"""
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@spec new(name) :: Replica.t
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def new(name) do
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%Replica{name: name, vsn: unique_vsn()}
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end
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@spec ref(Replica.t) :: replica_ref
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def ref(%Replica{name: name, vsn: vsn}), do: {name, vsn}
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@spec put_heartbeat(%{name => Replica.t}, replica_ref) :: op_result
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def put_heartbeat(replicas, {name, vsn}) do
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case Map.fetch(replicas, name) do
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:error ->
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new_replica = touch_last_heartbeat(%Replica{name: name, vsn: vsn, status: :up})
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{Map.put(replicas, name, new_replica), nil, new_replica}
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{:ok, %Replica{} = prev_replica} ->
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updated_replica = touch_last_heartbeat(%Replica{prev_replica | vsn: vsn, status: :up})
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{Map.put(replicas, name, updated_replica), prev_replica, updated_replica}
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end
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end
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@spec detect_down(%{name => Replica.t}, Replica.t, pos_integer, pos_integer) :: op_result
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def detect_down(replicas, replica, temp_interval, perm_interval, now \\ now_ms()) do
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downtime = now - replica.last_heartbeat_at
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cond do
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downtime > perm_interval -> {Map.delete(replicas, replica.name), replica, permdown(replica)}
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downtime > temp_interval ->
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updated_replica = down(replica)
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{Map.put(replicas, replica.name, updated_replica), replica, updated_replica}
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true -> {replicas, replica, replica}
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end
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end
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@doc """
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Fetches a replica from the map with matching name and version from the ref.
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"""
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@spec fetch_by_ref(%{name => Replica.t}, replica_ref) :: {:ok, Replica.t} | :error
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def fetch_by_ref(replicas, {name, vsn}) do
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case Map.fetch(replicas, name) do
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{:ok, %Replica{vsn: ^vsn} = replica} -> {:ok, replica}
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{:ok, %Replica{vsn: _vsn}} -> :error
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:error -> :error
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end
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end
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defp permdown(replica), do: %Replica{replica | status: :permdown}
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defp down(replica), do: %Replica{replica | status: :down}
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defp touch_last_heartbeat(replica) do
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%Replica{replica | last_heartbeat_at: now_ms()}
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end
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defp now_ms, do: System.system_time(:millisecond)
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defp unique_vsn do
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System.system_time(:microsecond) + System.unique_integer([:positive])
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end
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end
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