Thread-Safe LRU Cache with TTL

HardPython

Problem

Implement a class-based cache that supports get(key, now) and put(key, value, ttl, now) with capacity-limited LRU eviction and expiration. Each entry expires at time now + ttl; expired entries must behave as missing, and when capacity is full, the least recently used non-expired entry should be evicted. Design the cache so operations are thread-safe while keeping lock contention low.

Constraints

1 <= capacity <= 10^5
At most 10^5 operations
key is hashable
0 <= now, ttl <= 10^9
Expired entries must behave as absent
Average-case target per operation is O(1)

Function Signature

def run_lru_ttl_cache(capacity, operations):

CodePython 3

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