Ticruz
110 lines
2.2 KiB
Markdown
110 lines
2.2 KiB
Markdown
# LRU Cache
|
|
|
|
The LRU (Least Recently Used) Cache implementation provides efficient caching with automatic eviction of least recently used items when the cache reaches its maximum size.
|
|
|
|
## Basic Usage
|
|
|
|
```typescript
|
|
// Create cache with max size
|
|
const cache = new LRUCache<string, number>(3)
|
|
|
|
// Add items
|
|
cache.set('a', 1)
|
|
cache.set('b', 2)
|
|
cache.set('c', 3)
|
|
|
|
// Access items
|
|
cache.get('a') // => 1
|
|
|
|
// Check if key exists
|
|
cache.has('b') // => true
|
|
|
|
// Adding beyond max size evicts least recently used
|
|
cache.set('d', 4) // Evicts oldest item
|
|
```
|
|
|
|
## API Reference
|
|
|
|
### Constructor
|
|
|
|
```typescript
|
|
constructor(maxSize: number = Infinity)
|
|
```
|
|
|
|
Creates a new LRU cache with specified maximum size.
|
|
|
|
### Methods
|
|
|
|
#### set(key: T, value: U)
|
|
```typescript
|
|
set(key: T, value: U): void
|
|
```
|
|
Adds or updates an item in the cache. If cache is at maximum size, evicts least recently used item.
|
|
|
|
#### get(key: T)
|
|
```typescript
|
|
get(key: T): U | undefined
|
|
```
|
|
Retrieves item from cache. Also marks item as recently used.
|
|
|
|
#### has(key: T)
|
|
```typescript
|
|
has(key: T): boolean
|
|
```
|
|
Checks if key exists in cache without affecting usage tracking.
|
|
|
|
## Cache Decorator
|
|
|
|
The package also provides a convenient decorator function for creating memoized functions with LRU caching:
|
|
|
|
```typescript
|
|
function cached<T, V, Args extends any[]>({
|
|
maxSize,
|
|
getKey,
|
|
getValue,
|
|
}: {
|
|
maxSize: number
|
|
getKey: (args: Args) => T
|
|
getValue: (args: Args) => V
|
|
}): (...args: Args) => V
|
|
```
|
|
|
|
### Usage Example
|
|
|
|
```typescript
|
|
// Create cached function
|
|
const getUser = cached({
|
|
maxSize: 1000,
|
|
getKey: (args) => args[0], // Use first argument as cache key
|
|
getValue: async (args) => {
|
|
const [id] = args
|
|
return await fetchUser(id)
|
|
}
|
|
})
|
|
|
|
// Use cached function
|
|
const user1 = await getUser(123)
|
|
const user2 = await getUser(123) // Returns cached result
|
|
```
|
|
|
|
### Simple Cache Helper
|
|
|
|
For basic caching needs, there's also a simplified cache creator:
|
|
|
|
```typescript
|
|
function simpleCache<V, Args extends any[]>(
|
|
getValue: (args: Args) => V
|
|
) {
|
|
return cached({
|
|
maxSize: 100000,
|
|
getKey: xs => xs.join(':'),
|
|
getValue
|
|
})
|
|
}
|
|
|
|
// Usage
|
|
const cachedFn = simpleCache(async (id: string) => {
|
|
return await expensiveOperation(id)
|
|
})
|
|
```
|