MemoryCache

Defined in: packages/core/src/data/memory-cache.ts:104

TTL-based in-memory cache with LRU eviction.

Remarks

Features:

• LRU (Least Recently Used) eviction when at capacity
• Respects HTTP cache headers (ETag, Last-Modified)
• Configurable per-entry TTL
• Support for conditional requests (If-None-Match, If-Modified-Since)
• Automatic expiration checking on get operations

Example

const cache = new MemoryCache<GeoJSON.FeatureCollection>({
  maxSize: 100,
  defaultTTL: 300000, // 5 minutes
});

// Store data with ETag
cache.set('https://example.com/data.json', {
  data: geojsonData,
  timestamp: Date.now(),
  etag: '"abc123"',
});

// Retrieve (returns null if expired or missing)
const entry = cache.get('https://example.com/data.json');
if (entry) {
  console.log('Cache hit:', entry.data);
}

// Get conditional headers for HTTP request
const headers = cache.getConditionalHeaders('https://example.com/data.json');
// headers = { 'If-None-Match': '"abc123"' }

Type Parameters

Type Parameter	Default type	Description
T	unknown	Type of cached data

Constructors

Constructor

new MemoryCache<T>(config?): MemoryCache<T>

Defined in: packages/core/src/data/memory-cache.ts:121

Create a new MemoryCache instance

Parameters

Parameter	Type	Description
config?	Partial<CacheConfig>	Cache configuration options

Returns

MemoryCache<T>

Methods

clear()

clear(): void

Defined in: packages/core/src/data/memory-cache.ts:210

Clear all cache entries and reset statistics

Returns

void

---

delete()

delete(key): boolean

Defined in: packages/core/src/data/memory-cache.ts:199

Delete a cache entry

Parameters

Parameter	Type	Description
key	string	Cache key

Returns

boolean

True if entry was deleted, false if it didn’t exist

---

get()

get(key): CacheEntry<T> | null

Defined in: packages/core/src/data/memory-cache.ts:137

Retrieve a cache entry

Parameters

Parameter	Type	Description
key	string	Cache key (typically a URL)

Returns

CacheEntry<T> | null

Cache entry or null if not found/expired

Remarks

• Returns null if key doesn’t exist
• Returns null if entry has expired (and removes it)
• Updates access order for LRU
• Updates cache statistics

---

getConditionalHeaders()

getConditionalHeaders(key): Record<string, string>

Defined in: packages/core/src/data/memory-cache.ts:282

Get conditional request headers for HTTP caching

Parameters

Parameter	Type	Description
key	string	Cache key

Returns

Record<string, string>

Object with conditional headers (may be empty)

Remarks

Returns appropriate If-None-Match and/or If-Modified-Since headers based on cached entry metadata. Returns empty object if:

• Key doesn’t exist in cache
• Entry has expired
• useConditionalRequests is false

Example

const headers = cache.getConditionalHeaders(url);
const response = await fetch(url, { headers });
if (response.status === 304) {
  // Use cached data
}

---

getStats()

getStats(): CacheStats

Defined in: packages/core/src/data/memory-cache.ts:248

Get cache statistics

Returns

CacheStats

Current cache statistics including hit rate

---

has()

has(key): boolean

Defined in: packages/core/src/data/memory-cache.ts:166

Check if a key exists in cache (without checking expiration)

Parameters

Parameter	Type	Description
key	string	Cache key

Returns

boolean

True if key exists in cache

---

prune()

prune(): number

Defined in: packages/core/src/data/memory-cache.ts:225

Remove expired entries from cache

Returns

number

Number of entries removed

Remarks

Iterates through all entries and removes those that have exceeded their TTL. This is useful for periodic cleanup.

---

set()

set(key, entry): void

Defined in: packages/core/src/data/memory-cache.ts:180

Store a cache entry

Parameters

Parameter	Type	Description
key	string	Cache key (typically a URL)
entry	CacheEntry<T>	Cache entry to store

Returns

void

Remarks

• Evicts least recently used entries if at capacity
• Updates access order

---

touch()

touch(key): void

Defined in: packages/core/src/data/memory-cache.ts:314

Update the last access time for an entry

Parameters

Parameter	Type	Description
key	string	Cache key

Returns

void

Remarks

Useful for keeping an entry “fresh” without modifying its data. Updates the access order for LRU.