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@mcsb/api / Exports / InMemoryCache

Class: InMemoryCache<T>

In-memory implementation of Cache. This is likely sufficient for most Cache implementations, however larger applications may benefit from an external or more complex caching system.

Type parameters

NameDescription
TType of the values stored in the Cache.

Hierarchy

  • Cache<T>

    InMemoryCache

Table of contents

Constructors

Properties

Methods

Constructors

constructor

new InMemoryCache<T>(options)

Constructor for the Cache class.

Type parameters

NameDescription
TThe type of the values stored in the cache.

Parameters

NameTypeDescription
optionsCacheOptions<T>The custom options for the Cache, type CacheOptions.

See

CacheOptions

Inherited from

Cache.constructor

Defined in

packages/api/src/cache/Cache.ts:67

Properties

policy

Readonly policy: CachePolicy<T>

The CachePolicy that this Cache is using.

Inherited from

Cache.policy

Defined in

packages/api/src/cache/Cache.ts:57

Methods

access

access(key): undefined | CacheItem<T>

Access a given key in the Cache directly, bypassing the CachePolicy. This is primarily used by the garbage collector to check if values are stale, but may be useful in other applications as well. Unlike get, this method returns the entire CacheItem. If you just want the value, use get instead.

Parameters

NameTypeDescription
keystringThe key to access in the Cache.

Returns

undefined | CacheItem<T>

The CacheItem stored at the given key, if it exists, or undefined if it does not. May also return a Promise that resolves to the CacheItem, or undefined if it does not exist.

Overrides

Cache.access

Defined in

packages/api/src/cache/InMemoryCache.ts:40


delete

delete(key): void

Delete the value at a given key from the Cache, such that a subsequent call to get or access would not return the value.

Parameters

NameTypeDescription
keystringThe key of the value to delete from the Cache.

Returns

void

Either void or a Promise of void that resolves when the key has successfully been deleted from the cache.

Overrides

Cache.delete

Defined in

packages/api/src/cache/InMemoryCache.ts:52


destroy

destroy(): void

Destroy this Cache instance, primarily by shutting down the garbage collector. Failure to do so may leave your program hanging if you do not explicitly interrupt it.

Returns

void

Inherited from

Cache.destroy

Defined in

packages/api/src/cache/Cache.ts:148


garbageCollect

Protected garbageCollect(): Promise<void>

A function responsible for cleaning up dead Cache values, usually with the help of policy. By default, this entails iterating all values in the cache and checking if they are still valid according to the CachePolicy. If not, they are deleted from the cache using delete.

Returns

Promise<void>

a Promise that resolves after all dead values have been deleted from the cache, i.e. get, and access, and keys will no longer return them unless they're added again.

Inherited from

Cache.garbageCollect

Defined in

packages/api/src/cache/Cache.ts:133


get

get(key): Promise<null | T>

Get the value of a given key from the cache, if it still exists.

Parameters

NameTypeDescription
keystringKey that was used in the call to write instructing the Cache on where to store the value.

Returns

Promise<null | T>

A Promise that resolves to the value of type T stored in the cache at the given key, if it still exists and is valid according to the CachePolicy. If the value does not exist, null will be returned.

See

CachePolicy

Inherited from

Cache.get

Defined in

packages/api/src/cache/Cache.ts:96

get(key, fn): Promise<T>

Get the value of a given key from the cache, if it exists, or call the passed generator function if not.

Parameters

NameTypeDescription
keystringKey that was used in the call to write instructing the Cache on where to store the value.
fn() => T | Promise<T>If the value does not exist in the cache, this function will be called to generate the value to store in the cache. This function can return the value directly or via a Promise.

Returns

Promise<T>

A Promise that resolves to the value of type T stored in the cache at the given key if it exists. If it does not exist, the value returned from fn is returned.

Inherited from

Cache.get

Defined in

packages/api/src/cache/Cache.ts:105


keys

keys(): string[]

Retrieve a list of all currently-stored keys stored in the Cache. These keys do not necessarily have to be associated with a still-valid value. In fact, this method is used by garbageCollect to iterate over the Cache and find stale values.

Returns

string[]

An Array of strings where each value corresponds to a key in the Cache. If the Cache is empty, an empty Array will be returned. May also return a Promise that resolves to an Array of strings.

Overrides

Cache.keys

Defined in

packages/api/src/cache/InMemoryCache.ts:64


write

write(key, value): void

Write a value to the cache. This inserts a CacheItem value into the Cache with the created value being set to the time of calling this method.

Parameters

NameTypeDescription
keystringThe key to write the value to in the cache. This key can later be used to retrieve the value from the cache, if it's still valid according to the CachePolicy. Generally these keys should be unique for each value stored in the cache.
valueTValue to write to the cache at the given key. Must be of type T.

Returns

void

Either void or a Promise of void that resolves when the value has successfully been added to the cache.

See

CachePolicy

Overrides

Cache.write

Defined in

packages/api/src/cache/InMemoryCache.ts:23

Released under the MIT License.