PromiseCache Class

A specialized cache for async work, allowing you to safely cache the promised result of some async work without fear of running it multiple times or losing track of errors.

This API is provided for existing users, but is not recommended for new users.

To use, import via @fluidframework/core-utils/legacy.

For more information about our API support guarantees, see here.

Signature

export declare class PromiseCache<TKey, TResult>

Type Parameters

Parameter	Description
TKey
TResult

Constructors

Constructor	Alerts	Description
(constructor)({ expiry, removeOnError, })	Beta	Create the PromiseCache with the given options, with the following defaults: expiry: indefinite, removeOnError: true for all errors

Methods

Method	Alerts	Return Type	Description
add(key, asyncFn)	Beta	boolean	Try to add the result of the given asyncFn, without overwriting an existing cache entry at that key. Returns false if the cache already contained an entry at that key, and true otherwise.
addOrGet(key, asyncFn)	Beta	Promise<TResult>	Try to add the result of the given asyncFn, without overwriting an existing cache entry at that key. Returns a Promise for the added or existing async work being done at that key.
addValue(key, value)	Beta	boolean	Try to add the given value, without overwriting an existing cache entry at that key. Returns false if the cache already contained an entry at that key, and true otherwise.
addValueOrGet(key, value)	Beta	Promise<TResult>	Try to add the given value, without overwriting an existing cache entry at that key. Returns a Promise for the added or existing async work being done at that key.
get(key)	Beta	Promise<TResult> | undefined	Get the Promise for the given key, or undefined if it's not found. Extend expiry if applicable.
has(key)	Beta	boolean	Check if there's anything cached at the given key
remove(key)	Beta	boolean	Remove the Promise for the given key, returning true if it was found and removed

Constructor Details

(constructor)

Create the PromiseCache with the given options, with the following defaults:

expiry: indefinite, removeOnError: true for all errors

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

constructor({ expiry, removeOnError, }?: PromiseCacheOptions);

Parameters

Parameter	Modifiers	Type	Description
{ expiry, removeOnError, }	optional	PromiseCacheOptions

Method Details

add

Try to add the result of the given asyncFn, without overwriting an existing cache entry at that key. Returns false if the cache already contained an entry at that key, and true otherwise.

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

add(key: TKey, asyncFn: () => Promise<TResult>): boolean;

Parameters

Parameter	Type	Description
key	TKey	key name where to store the async work
asyncFn	() => Promise<TResult>	the async work to do and store, if not already in progress under the given key

Returns

Return type: boolean

addOrGet

Try to add the result of the given asyncFn, without overwriting an existing cache entry at that key. Returns a Promise for the added or existing async work being done at that key.

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

addOrGet(key: TKey, asyncFn: () => Promise<TResult>): Promise<TResult>;

Parameters

Parameter	Type	Description
key	TKey	key name where to store the async work
asyncFn	() => Promise<TResult>	the async work to do and store, if not already in progress under the given key

Returns

Return type: Promise<TResult>

addValue

Try to add the given value, without overwriting an existing cache entry at that key. Returns false if the cache already contained an entry at that key, and true otherwise.

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

addValue(key: TKey, value: TResult): boolean;

Parameters

Parameter	Type	Description
key	TKey	key name where to store the value
value	TResult	value to store

Returns

Return type: boolean

addValueOrGet

Try to add the given value, without overwriting an existing cache entry at that key. Returns a Promise for the added or existing async work being done at that key.

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

addValueOrGet(key: TKey, value: TResult): Promise<TResult>;

Parameters

Parameter	Type	Description
key	TKey	key name where to store the async work
value	TResult	value to store

Returns

Return type: Promise<TResult>

get

Get the Promise for the given key, or undefined if it's not found. Extend expiry if applicable.

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

get(key: TKey): Promise<TResult> | undefined;

Parameters

Parameter	Type	Description
key	TKey

Returns

Return type: Promise<TResult> | undefined

has

Check if there's anything cached at the given key

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

has(key: TKey): boolean;

Parameters

Parameter	Type	Description
key	TKey

Returns

Return type: boolean

remove

Remove the Promise for the given key, returning true if it was found and removed

This API is provided for existing users, but is not recommended for new users.

For more information about our API support guarantees, see here.

Signature

remove(key: TKey): boolean;

Parameters

Parameter	Type	Description
key	TKey

Returns

Return type: boolean