# Functions
New 创建ConcurrentMap，线程安全map.
# Structs
ConcurrentMapShared 线程安全的共享map.
Tuple Used by the Iter & IterBuffered functions to wrap two variables together over a channel,.
# Type aliases
ConcurrentMap 线程安全的MAP，创建SHARD_COUNT个共享map(ConcurrentMapShared), 防止单个锁的瓶颈引用的性能问题.
IterCb Iterator callback,called for every key,value found in maps.
RemoveCb Iterator callback,返回true从列表中移除key.
SetCb 设置回调函数.
UpsertCb Callback to return new element to be inserted into the map It is called while lock is held, therefore it MUST NOT try to access other keys in same map, as it can lead to deadlock since Go sync.RWLock is not reentrant.