use BlockingQueue in LazyMemorySegmentPool

[0rrange]

Purpose

Linked issue: close #90 #136

use BlockingQueue instead of List with lock in LazyMemorySegmentPool

Tests

API and Format

com.alibaba.fluss.memory.LazyMemorySegmentPool#nextSegment
com.alibaba.fluss.memory.LazyMemorySegmentPool#waitForSegment
com.alibaba.fluss.memory.LazyMemorySegmentPool#getAllCachePages

Documentation

[CLAassistant]

All committers have signed the CLA.

[loserwang1024]

Could you please give more explaination why use use BlockingQueue instead of List with lock in LazyMemorySegmentPool?

It's thread safe If one thread only produces into BlockingQueue while another thread only consumes. However, in many places, use multiple operations on cachePages happens. for example in com.alibaba.fluss.memory.LazyMemorySegmentPool#nextSegment includes cachePages.isEmpty(), cachePages.add(） and cachePages.remove. Can these operations be thread safe?

[0rrange]

Could you please give more explaination why use use BlockingQueue instead of List with lock in LazyMemorySegmentPool?

It's thread safe If one thread only produces into BlockingQueue while another thread only consumes. However, in many places, use multiple operations on cachePages happens. for example in com.alibaba.fluss.memory.LazyMemorySegmentPool#nextSegment includes cachePages.isEmpty(), cachePages.add(） and cachePages.remove. Can these operations be thread safe?

Blocking queues are thread-safe, which can be used directly without additional synchronisation mechanisms, and then it comes with a blocking operation that doesn't require the wait logic to be implemented via Condition.
I used BlockingQueue's poll instead of cachePages.remove() and condition.await(). cachePages.isEmpty() and cachePages.add() I didn't change, and I think that locking control is still needed in a concurrent environment.

[0rrange]

@swuferhong I've submitted the code, please review, thx