Created
May 25, 2016 13:24
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| defmodule Rumbl.InfoSys do | |
| @backends [Rumbl.InfoSys.Wolfram] | |
| defmodule Result do | |
| defstruct score: 0, text: nil, url: nil, backend: nil | |
| end | |
| def start_link(backend, query, query_ref, owner, limit) do | |
| backend.start_link(query, query_ref, owner, limit) | |
| end | |
| def compute(query, opts \\ []) do | |
| limit = opts[:limit] || 10 | |
| backends = opts[:backends] || @backends | |
| backends | |
| |> Enum.map(&spawn_query(&1, query, limit)) | |
| |> await_results(opts) | |
| |> Enum.sort(&(&1.score >= &2.score)) | |
| |> Enum.take(limit) | |
| end | |
| defp spawn_query(backend, query, limit) do | |
| query_ref = make_ref() | |
| opts = [backend, query, query_ref, self(), limit] | |
| {:ok, pid} = Supervisor.start_child(Rumbl.InfoSys.Supervisor, opts) | |
| monitor_ref = Process.monitor(pid) | |
| {pid, monitor_ref, query_ref} | |
| end | |
| defp await_results(children, opts) do | |
| timeout = opts[:timeout] || 5000 | |
| timer = Process.send_after(self(), :timedout, timeout) | |
| results = await_result(children, [], :infinity) | |
| cleanup(timer) | |
| results | |
| end | |
| defp await_result([head|tail], acc, timeout) do | |
| {pid, monitor_ref, query_ref} = head | |
| receive do | |
| {:results, ^query_ref, results} -> | |
| Process.demonitor(monitor_ref, [:flush]) | |
| await_result(tail, results ++ acc, timeout) | |
| {:DOWN, ^monitor_ref, :process, ^pid, _reason} -> | |
| await_result(tail, acc, timeout) | |
| :timedout -> | |
| kill(pid, monitor_ref) | |
| await_result(tail, acc, 0) | |
| after | |
| timeout -> | |
| kill(pid, monitor_ref) | |
| await_result(tail, acc, 0) | |
| end | |
| end | |
| defp await_result([], acc, _) do | |
| acc | |
| end | |
| defp kill(pid, ref) do | |
| Process.demonitor(ref, [:flush]) | |
| Process.exit(pid, :kill) | |
| end | |
| defp cleanup(timer) do | |
| :erlang.cancel_timer(timer) | |
| receive do | |
| :timedout -> :ok | |
| after | |
| 0 -> :ok | |
| end | |
| end | |
| end |
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