Revert minor part of #16968 to fix message redelivery

[michaeljmarshall]

Fixes #17028 #16830

Motivation

In #16968, there was a change to remove some logic that appears necessary for certain message delivery guarantees. This PR fixes the minor regression introduced in that PR.

Modifications

• Set sendInProgress = true before dispatching the read request.
• Remove volatile keyword from sendInProgress. It is only updated within synchronized blocks.

Verifying this change

I verified that both testDelayedDeliveryWithMultipleConcurrentReadEntries and testMessageRedelivery pass consistently. Both were failing on my machine and stopped failing when I set sendInProgress = true.

Documentation

• doc-not-needed

[michaeljmarshall]

I removed the synchronized block because the two method calls are independent and do not need to happen with in the same lock (as far as I can tell).

[mattisonchao]

Hi, this problem has already reverted at PR #17018

[michaeljmarshall]

Thanks for pointing that out @mattisonchao. Closing this as it is superseded by #17018