AMQP connector has no way to adjust initial credits for incoming channel.

[ylepikhov]

Hi. Vertx AmqpReceiverImpl has default value of 1000 for initial credits. It can be changed via AmqpReceiverOptions.maxBufferedMessages, but smallrye AMQP Connector never use it.

1000 initial credits is too much for slow consumers and large messages.

It will be nice, if AmqpReceiverOptions.maxBufferedMessages could be configured via channel configuration.

It might be something like:

• smallrye-reactive-messaging-amqp/src/main/java/io/smallrye/reactive/messaging/amqp/AmqpConnector.java:
  @ConnectorAttribute(name = "initial-credits", type = "int", direction = INCOMING, description = "Initial credits for receiver.")
• smallrye-reactive-messaging-amqp/src/main/java/io/smallrye/reactive/messaging/amqp/IncomingAmqpChannel.java:

        AmqpReceiverOptions options = new AmqpReceiverOptions()
                .setAutoAcknowledgement(ic.getAutoAcknowledgement())
                .setDurable(ic.getDurable())
                .setLinkName(link)
                .setCapabilities(getClientCapabilities(ic))
                .setSelector(ic.getSelector().orElse(null))
                .setMaxBufferedMessages(ic.getInitialCredits().orElse(1000));

[ozangunalp]

This looks reasonable. I think we do keep the sender credits up-to-date, but we don't do anything for receiver credits.

@ylepikhov would you like to create a PR ?

[ylepikhov]

Why not. New option should be documented. Not sure if any tests are needed.