Invoked to handle synchronous call/3 messages.

call/3 will block until a reply is received (unless the call times out or nodes are disconnected).

request is the request message sent by a call/3, from is a two-element tuple containing the caller’s PID and a term that uniquely identifies the call, and state is the current state of the GenStage.

Returning {:reply, reply, [events], new_state} sends the response reply to the caller after events are dispatched (or buffered) and continues the loop with new state new_state. In case you want to deliver the reply before processing events, use reply/2 and return {:noreply, [event], state}.

Returning {:noreply, [event], new_state} does not send a response to the caller and processes the given events before continuing the loop with new state new_state. The response must be sent with reply/2.

Hibernating is also supported as an atom to be returned from either :reply and :noreply tuples.

Returning {:stop, reason, reply, new_state} stops the loop and terminate/2 is called with reason reason and state new_state. Then the reply is sent as the response to the call and the process exits with reason reason.

Returning {:stop, reason, new_state} is similar to {:stop, reason, reply, new_state} except that no reply is sent to the caller.

If this callback is not implemented, the default implementation by use GenStage will return {:stop, {:bad_call, request}, state}.

Callback implementation for GenStage.handle_call/3.

Invoked to handle asynchronous cast/2 messages.

request is the request message sent by a cast/2 and state is the current state of the GenStage.

Returning {:noreply, [event], new_state} dispatches the events and continues the loop with new state new_state.

Returning {:noreply, [event], new_state, :hibernate} is similar to {:noreply, new_state} except the process is hibernated before continuing the loop. See the return values for GenServer.handle_call/3 for more information on hibernation.

Returning {:stop, reason, new_state} stops the loop and terminate/2 is called with the reason reason and state new_state. The process exits with reason reason.

If this callback is not implemented, the default implementation by use GenStage will return {:stop, {:bad_cast, request}, state}.

Callback implementation for GenStage.handle_cast/2.

Invoked on :producer_consumer and :consumer stages to handle events.

Must always be explicitly implemented by such types.

Return values are the same as c:handle_cast/2.

Callback implementation for GenStage.handle_events/3.

Invoked to handle all other messages.

message is the message and state is the current state of the GenStage. When a timeout occurs the message is :timeout.

If this callback is not implemented, the default implementation by use GenStage will return {:noreply, [], state}.

Return values are the same as c:handle_cast/2.

Callback implementation for GenStage.handle_info/2.

Start Stage