level-lru-cache

library1.0.0jsnpmunverified

Simple LRU (Least Recently Used) cache implementation on top of LevelUP. Version 1.0.0 is the current stable release with no active development. It uses timestamps for eviction ordering, trading off worst-case consistency for simplicity. Unlike other caches, it avoids race conditions by performing all operations atomically within LevelUP batches, making it suitable for single-machine concurrent usage but not recommended for distributed systems. The cache stores multiple records per key with timestamps, cleaning up old records on each put and get. It requires a LevelUP instance with any LevelDOWN backend and sets a loose limit for key count.

storage

npm install level-lru-cache

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · LEVEL-LRU-CACHE

level-lru-cache

storagejavascriptv1.0.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

Cache

✓ const Cache = require('level-lru-cache')

✗ import Cache from 'level-lru-cache'

This package uses CommonJS and does not support ESM imports directly. Use require().

Cache

✓ const { default: Cache } = await import('level-lru-cache')

In Node.js with ESM, use dynamic import with .default.

levelup

✓ const levelup = require('levelup')

✗ import levelup from 'levelup'

levelup also uses CommonJS; import may not work depending on module system.

memdown

✓ const memdown = require('memdown')

✗ import memdown from 'memdown'

For testing, memdown is a common LevelDOWN choice.

Create a LevelUP instance with memdown, initialize a level-lru-cache with limit 100, then put and get a value asynchronously.

Debug

Known issues

gotchaTimestamps are used for eviction ordering, but if multiple operations occur quickly on the same machine, timestamps may be equal, causing incorrect eviction.

fix

Consider using monotonic clock sources or add microsecond precision to avoid ties.

affects: >=1.0.0

gotchaThe cache does not support TTL (time-to-live) expiration; it only evicts based on count limit.

fix

Implement your own expiration layer on top, or use a different caching library like lru-cache with TTL support.

affects: >=1.0.0

gotchaThe cache stores multiple records per key (old and new versions). On get, all old records are deleted and a new record is written. This could degrade performance under heavy write load.

fix

If write-heavy, consider tuning the limit or using a different cache.

affects: >=1.0.0

gotchaThe limit parameter is a 'loose limit'; the cache may temporarily store more keys than the limit due to asynchronous batch operations.

fix

Set a slightly smaller limit than desired if exactness is needed.

affects: >=1.0.0

Errors

Common errors & fixes

Error: The "db" keyword must be a LevelUP instance

First argument to Cache constructor is not a LevelUP instance.

fix

const db = levelup(memdown()); const cache = new Cache(db, 100);

TypeError: cache.put is not a function

Cache was not instantiated with 'new'.

fix

const cache = new Cache(db, 100);

Error: LevelUP instance not provided

Missing LevelUP instance as first argument.

fix

Pass a valid LevelUP instance. Example: const db = levelup(memdown()); const cache = new Cache(db, 100);

Upgrade

Version history

1.0.0latest on npm

Audit

Dependencies

leveluprequiredlevel-lru-cache wraps a LevelUP database instance; LevelUP is a peer dependency.

leveldownrequiredLevelUP requires a LevelDOWN backend (like leveldown, memdown, level-js) to operate.

Agent activity

11 hits · last 30 days

node

Amazon

Resources

githubhttps://github.com/kemitchell/level-lru-cache.js ↗

packagelevel-lru-cache ↗

homepagehttps://github.com/kemitchell/level-lru-cache.js#readme ↗