FirstExpire

Firstexpire is a term encountered in software contexts rather than a formally standardized concept. It generally refers to the earliest expiration among a set of items or to a policy or function that prioritizes actions based on the soonest expiry. Because it is not a single defined standard, its exact meaning can vary between projects and domains.

In caching and data stores, firstexpire commonly describes a mechanism that focuses on items that will expire soonest. A function or process labeled FirstExpire may determine which entries to evict, refresh, or invalidate first in order to minimize stale reads and unnecessary storage use. This approach helps ensure that resources with imminent expiry are addressed promptly.

Implementation approaches to realize a firstexpire behavior include maintaining a data structure that tracks expiration times, such as a min-heap or priority queue, which allows quickly locating the earliest expiry. Another approach is scheduling a timer or heartbeat that triggers at the next expiry time, coupled with periodic checks to handle any updates. Trade-offs involve the cost of maintaining expiry data as items are added, updated, or removed, versus the benefit of timely expiration handling.

Alternate usages of the term may appear as function names, method identifiers, or feature descriptors within codebases, where firstexpire simply denotes the concept of processing in order of increasing expiration time. See also TTL, expiration policy, cache eviction, and priority queues.