(feat) Impl SegmentList to replace ArrayDequeue in LogManagerImpl, #335

[killme2008]

Motivation:

See #335

Modification:

• Introduce a new data structure SegmentList that is a list of segment, every segment is an array contains 128 elements, and only supports removing elements from start or end:

                            segments
       /                        |                       \
segment                      segment                      segment 
[0, 1 ...  127]             [128, 129 ... 255]          [256, 1 ... 383] 

The removeFromFirstWhen and removeFromLastWhen methods accept a predicate and delete the elements from start or end until the predicate returns false. The remove operation only set the elements to be null and remeber the deleted poistion,do not have any array elements movement at all. If a segment is empty after remove, it will be removed from segment list too.
Also, I use the Recyclable to reuse the Segment instances.

The SegmentList performance in benchmark is alaways better than ArrayDequeue in SegmentListTest#simpleBenchmark, at most 10% improvement(The benchmark has some random factor).

• Replace ArrayDeque in LogManagerImpl with SegmentList
• Fixed deadlock in RepeatedTimer#destroy and RepeatedTimer#run

Result:

Fixes #335

[OpenOpened]

every segment contains at most 128 elements, but SEGMENT_SIZE 2 << 7 equals 256.

[killme2008]

Fixed. 128 is a balance between time and space.

[fengjiachun]

入参为 Collection 类型更通用，原有 ArrayDeque 的设计也没有避免一次 toArray 的多余 memcopy

但我还是建议这里针对 ArrayList 做一个 fast path 优化，在入参 coll 为 ArrayList 类型且 UnsafeUtil.hasUnsafe() == true 的情况下通过 UnsafeReferenceFieldUpdater 直接拿到 ArrayList 中的 object[]，用于后面的 copy，这样节省了一次 memcopy；

AppendEntries() 是 jraft 中的热点执行路径，会调用 addAll () 来 append log，所以我认为即使代码丑一点，但是优化是值得的，理论上会减少大量的 toArray 带来的临时 'object[]' 的创建和 memcopy

[killme2008]

嗯，搞了下，测试下来，稳定提升在 15% 以上 👍 ，不过需要将 UnsafeReferenceFieldUpdater 从 rheakv 拷贝一份到 jraft-core 。不做 move，因为不确定外面有没有人依赖了。

[fengjiachun]

                            segments
       /                        |                       \
segment                      segment                      segment 
[0, 1 ...  127]             [128, 129 ... 255]          [256, 1 ... 383] 

这个图是不是可以加到 SegmentList 的类注释里面

[killme2008]

Updated:

1. SegmentList constructor accepts boolean recycleSegment to choose whether to enable recycling segment.
2. SegmentList#addAll adds a fast path for ArrayList, suggested by @fengjiachun
3. Replace pendingMetaQueue in BallotBox with SegmentList too.
4. Move some utilities from rheakv-core to jraft-core, such as ReferenceFieldUpdater etc.