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如果我GenStage的handle_demand/2
方法是这样的:GenStage:重试handle_demand时GenServer更新
def handle_demand(demand, _state) when demand > 0 do
case Queue.dequeue do
nil ->
Logger.debug("Queue empty.")
{:noreply, [], []}
{job, updated_queue} -> {:noreply, job, updated_queue}
end
end
我如何得到它“重新运行”当我Queue
(一GenServer)改变/更新?
我的队列模块看起来就像这样:
defmodule Queue do
use GenServer
### client
def start_link(state \\ []) do
GenServer.start_link(__MODULE__, state, name: __MODULE__)
end
def queue, do: GenServer.call(__MODULE__, :queue)
def enqueue(value), do: GenServer.cast(__MODULE__, {:enqueue, value})
def dequeue, do: GenServer.call(__MODULE__, :dequeue)
### server
def init(state), do: {:ok, state}
def handle_call(:dequeue, _from, [value | state]) do
{:reply, value, state}
end
def handle_call(:dequeue, _from, []), do: {:reply, nil, []}
def handle_call(:queue, _from, state), do: {:reply, state, state}
def handle_cast({:enqueue, value}, state) do
{:noreply, state ++ [value]}
end
end