[improve][cpp] Support acknowledging a list of messages

[shibd]

Motivation

apache/pulsar-client-cpp#90

Modifications

• Add acknowledge message id list API.

Documentation

• doc-required
  (Your PR needs to update docs and you will update later)

• doc-not-needed
  (Please explain why)

• doc
  (Your PR contains doc changes)

• doc-complete
  (Docs have been already added)

Matching PR in forked repository

shibd#13

[BewareMyPower]

Could you rebase to master? I saw some strange errors in CI.

[shibd]

Could you rebase to master? I saw some strange errors in CI.

I rebased master, PTAL.

[BewareMyPower]

We should add thread safe remove and deleteAckedMessage methods that accept MessageIdList to make these calls thread safe. You can see both UnAckedMessageTrackerEnabled::remove and BatchAcknowledgementTracker::deleteAckedMessage are thread safe so the acknowledgeAsync method for a single message won't lead to a race condition for each component (unAckedMessageTrackerPtr_ and unAckedMessageTrackerPtr_)

[shibd]

Yes, It is better to provide an accept MessageIdList method. I will provide it.

But I want to know what is the race condition for the actual scenario. For UnAckedMessageTracker, Will there be the following scenario?

have a MessageIdList: {1, 2, 3, 4}

on acknowledge thread:

for MessageIdList{
     this->unAckedMessageTrackerPtr_->remove(msgId);
}

and another thread to call: this->unAckedMessageTrackerPtr_->add(msgId);

[shibd]

I add new remove(MessageIdList) method on UnAckedMessageTracker, Since BatchAcknowledgementTracker not support Individual ack, so, I remove invoke this->batchAcknowledgementTracker_.deleteAckedMessage code. PTAL. Thanks.

[shibd]

Resubmit the PR in pulsar-client-cpp repository: apache/pulsar-client-cpp#23