DNS resolver LRU cache used []string slice for access ordering:
- moveToFrontLocked: O(n) linear scan + slice重组 per cache update
- storeCache held exclusive write lock during entire O(n) operation,
blocking all concurrent reads
Replace with container/list + map[string]*list.Element:
- storeCache: O(1) MoveToFront via list.Element pointer
- evictLRULocked: O(1) Back() + Remove()
- DeleteCacheEntry: O(1) instead of O(n) scan
This matches the LRU pattern already used by FileCache and
FileInfoCache. Write lock duration reduced from O(n) to O(1),
significantly reducing read contention under mixed workloads.
xfy
12caed5d4e