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lib/credo/check/worker.ex

defmodule Credo.Check.Worker do
@moduledoc false
@doc """
Runs all members of `workloads` using ``.
"""
def run(workloads, max_concurrency, work_fn) do
{:ok, server_pid} = GenServer.start_link(__MODULE__.Server, workloads)
worker_context = %{
runner_pid: self(),
server_pid: server_pid,
max_concurrency: max_concurrency,
work_fn: work_fn,
results: []
}
outer_loop(worker_context, 0)
end
@doc """
Called when a workload has finished.
"""
def send_workload_finished_to_runner(worker_context, _workload, result) do
send(worker_context.runner_pid, {self(), {:workload_finished, result}})
end
defp outer_loop(worker_context, taken) do
available = worker_context.max_concurrency - taken
cond do
available <= 0 ->
wait_for_workload_finished(worker_context, taken)
taken_workloads = __MODULE__.Server.take_workloads(worker_context.server_pid, available) ->
inner_loop(worker_context, taken_workloads, taken)
# we fall thru here if there are no checks left
# there are two options: we are done ...
taken == 0 ->
{:ok, worker_context.results}
# ... or we need for the very last batch to finish up
true ->
wait_for_workload_finished(worker_context, taken)
end
end
defp wait_for_workload_finished(worker_context, taken) do
receive do
{_spawned_pid, {:workload_finished, result}} ->
# IO.puts("Finished #{workload}")
new_worker_context = %{worker_context | results: [result | worker_context.results]}
outer_loop(new_worker_context, taken - 1)
end
end
defp inner_loop(worker_context, [], taken) do
outer_loop(worker_context, taken)
end
defp inner_loop(worker_context, [workload | rest], taken) do
spawn_fn = fn ->
result = worker_context.work_fn.(workload)
send_workload_finished_to_runner(worker_context, workload, result)
end
spawn_link(spawn_fn)
inner_loop(worker_context, rest, taken + 1)
end
defmodule Server do
@moduledoc false
@timeout :infinity
use GenServer
def take_workloads(pid, count) do
GenServer.call(pid, {:take_workloads, count}, @timeout)
end
#
# Server
#
@impl true
def init(workloads) do
state = %{
waiting: nil,
workloads: workloads
}
{:ok, state}
end
@impl true
def handle_call({:take_workloads, count}, from, %{waiting: nil} = state) do
{:noreply, take_workloads(%{state | waiting: {from, count}})}
end
defp take_workloads(%{waiting: nil} = state) do
state
end
defp take_workloads(%{waiting: {from, _count}, workloads: []} = state) do
GenServer.reply(from, nil)
%{state | waiting: nil}
end
defp take_workloads(%{workloads: []} = state) do
state
end
defp take_workloads(%{waiting: {from, count}, workloads: workloads} = state) do
{reply, workloads} = Enum.split(workloads, count)
GenServer.reply(from, reply)
%{state | workloads: workloads, waiting: nil}
end
end
end