Cache

Class | Source Code

Facilitates caching generic data. Generic arguments allow setting the type of the value stored in cache entries as well as the expected names (defaults to any string) for cache entries.

Entries are added to the cache via set. Entries can later be retrieved from the cache by calling get with the name originally provided to set.

Once an entry expires, attempts to get it will report a miss and the expired entry will be removed from the cache.

Note: If an entryLifetimeMs is not configured on the cache instance during construction, you must set a lifetime on every call to set. If you exclude a lifetime both at construction and when calling set, your entries will expire immediately.

Constructors

new Cache(options: CacheOptions)

Accessors

hasUnexpiredEntries: boolean

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isEmpty: boolean

Methods

get(name: TCacheEntryName): undefined | TCacheValue

Returns

The value that was last cached under the specified name, or undefined if the entry is absent or expired.

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purge(): void

Removes all expired entries from the cache.

Keep in mind that expired entries are automatically cleaned up as they’re requested via get. You should only be calling this if your use case satisfies all of the following:

1. The cache itself has a long lifetime, high volume, and/or high memory usage.
2. Invoking get on the potentially expired entries is infrequent.
3. You want to free the memory being used by expired entries.

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remove(name: TCacheEntryName): void

Removes the specified entry from the cache.

If an entry with the name doesn’t exist, this is a no-op.

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set(name: TCacheEntryName, value: TCacheValue, lifetimeMs: number): void

Sets the specified cache entry to the value. After lifetimeMs, the entry will be invalid and attempts to get it will result in a miss. Setting an entry that already exists will overwrite the existing entry and update its lifetime.

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toArray(): [TCacheEntryName, TCacheValue][]

Returns

The cache as an array of unexpired entries.

Example

const cache = new Cache<number>();

const cacheEntries = cache.toArray();

cacheEntries.forEach(([entryName, entryValue]) => console.log(`${entryName}: ${entryValue}`));

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wipe(): void

Removes all entries from the cache, including unexpired ones that are still valid.