Small FlatMap optimization with default initialization #2620
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What problem does this PR solve?
Issue Number:
Problem Summary:
目前FlatMap是两阶段初始化:构造函数+init函数。这种初始化方式很容易用错,甚至出core,所以使用上必须小心翼翼,体验不好。
What is changed and the side effects?
Changed:
FlatMap构造完成即完成初始化。使用sso、IOBuf::SmallView的策略,初始化_buckets和_thumbnail使用类内的内存块,没有init函数中Alloc失败的顾虑。
Side effects:
Performance effects(性能影响):
Breaking backward compatibility(向后兼容性):
Check List: