If some users need the message content to do user-defined actions, we need
to ensure the user can't use the `peekMessage` to do things like ack
because the message are still in the blockingQueue, return just a
content-copy?
introduced `localBuffer` might be good ? `hasMessagesInLocalBuffer`
JiangHaiting <jianghait...@foxmail.com> 于2021年10月26日周二 下午2:20写道：
> I'm totally +1 for the feature to check if we can get
> message immediately from consumer, this is to say we have message
> locally.
>
>
> In my understanding, it's useful to implement some user-defined order to
> consume messages among different topics, in your case, the "distributed
> flow control ability".
> But in the past few years, I've met some users have defined the consume
> order of different topics by part of the message content, like
> some critical property value.
> In these situations, a `peek` method is more suitable.
>
>
> Further more, peek is not effectively equals to `consumer.receive(0,
> TimeUnit.SECONDS)`. As you will have to store the message somewhere else if
> you find that it's not the most priority message to process.
>
>
> One last thing, put the concept of "receiverQueue" in the api of consumer,
> seems a little bit strange, IMHO.
>
>
>
>
> ------------------ Original ------------------
> From:
> "dev"
> <
> shoot...@gmail.com>;
> Date: Tue, Oct 26, 2021 12:54 PM
> To: "dev"<dev@pulsar.apache.org>;
>
> Subject: Re: [DISCUSSION] PIP-108: Add method to help user judge if
> consumer queue has message
>
>
>
> 3. Our solution implements the distributed flow control ability at client
> side, so we don't use the listener way.
> 2. Per customer per consumer in different tenants and namespace, and the
> `flow-control` need(Some of our customer's machines can't work on high
> traffic), So `Multi-topic` can't use.
> 1. We want to use this api to judge if there's messages to receive, like
> that pseudo code
> if (consumer.hasMessage()) {
> .submit(() -> {
> consumer.pollMessagesAccordingToTheDistributedFlowControl()
> })
> }
>
> Matteo Merli <matteo.me...@gmail.com> 于2021年10月26日周二 下午12:15写道：
>
> > I'm a bit hesitant about this because I think there are already at
> > least 3 different ways to handle similar scenarios.
> >
> > 1. Using listener and avoid calling receive directly
> > 2. Use multi-topic consumer, so there's a single `Consumer`
> instance
> > exposed
> > 3. Use `consumer.receive(0, TimeUnit.SECONDS)` to probe for
> message
> >
> >
> > --
> > Matteo Merli
> > <matteo.me...@gmail.com>
> >
> > On Mon, Oct 25, 2021 at 7:34 PM ZhangJian He <shoot...@gmail.com>
> wrote:
> > >
> > > I think it's better to add the method to Consumer interface
> instead of
> > let
> > > user casting it to `ConsumerBase`.
> > > `peek` is most complexly, for the reason, I can use the
> `peek` object to
> > > ack、negative ack, but when to remove from the `BlockingQueue`?
> > > IMHO, people use this api are just to judge if has the message,
> > otherwise,
> > > they can just use `receive(0,TimeUnit)
> > >
> > > JiangHaiting <jianghait...@foxmail.com> 于2021年10月26日周二
> 上午10:19写道：
> > >
> > > > Can this method
> > > >
> "org.apache.pulsar.client.impl.ConsumerBase#getTotalIncomingMessages"
> > do
> > > > the trick? Though you have to change the type to
> ConsumerBase.
> > > >
> > > >
> > > > And maybe `peek` is more suitable and useful to add to the
> Consumer
> > > > interface？
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> > > >
> ------------------&nbsp;Original&nbsp;------------------
> > > > From:
> > >
> >
> "dev"
> > >
> >
> <
> > > > shoot...@gmail.com&gt;;
> > > > Date:&nbsp;Mon, Oct 25, 2021 07:24 PM
> > > > To:&nbsp;"dev"<dev@pulsar.apache.org&gt;;
> > > >
> > > > Subject:&nbsp;[DISCUSSION] PIP-108: Add method to help
> user judge if
> > > > consumer queue has message
> > > >
> > > >
> > > >
> > > > https://github.com/apache/pulsar/issues/12479
> > > >
> > > > --- Pasted here for quoting convenience ---
> > > >
> > > > ## Motivation
> > > > Currently, I have an application that manages ten thousand
> of
> > consumers,
> > > > and a logic to schedule consumers's receive. It would be
> helpful to
> > know if
> > > > one of the consumers have message to recive.
> > > >
> > > > ## Goal
> > > > To make `Consumer` can judge if there are unreceiving
> messages
> > > >
> > > > ## API Changes
> > > >
> > > > Add `hasMessageInReceiverQueue` on the `Consumer` interface.
> > > >
> > > > ## Implementation
> > > >
> > > > For `ZeroQueueConsumerImpl` return false, Others, judge the
> > > > `receiveQueueSize` greater than zero.
> > > >
> > > >
> > > > ## Reject Alternatives
> > > >
> > > > No alternatives yet.
> > > >
> > > >
> > > >
> > > >
> > > > ---
> > > > Thanks,
> > > > Haiting Jiang (Github: Jason918)
> >
>
>
>
>
> ---
> Thanks,
> Haiting Jiang (Github: Jason918)
