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eris/utils/kvMemoize.ts

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export interface KvMemoizeOptions<A extends Deno.KvKey, R> {
/**
* The time in milliseconds until the cached result expires.
*/
expireIn?: ((result: R, ...args: A) => number) | number | undefined;
/**
* Whether to recalculate the result if it was already cached.
*
* Runs whenever the result is retrieved from the cache.
*/
shouldRecalculate?: ((result: R, ...args: A) => boolean) | undefined;
/**
* Whether to cache the result after computing it.
*
* Runs whenever a new result is computed.
*/
shouldCache?: ((result: R, ...args: A) => boolean) | undefined;
/**
* Override the default KV store functions.
*/
override?: {
set: (
key: Deno.KvKey,
args: A,
value: R,
options: { expireIn?: number },
) => Promise<void>;
get: (key: Deno.KvKey, args: A) => Promise<R | undefined>;
};
}
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/**
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* Memoizes the function result in KV store.
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*/
export function kvMemoize<A extends Deno.KvKey, R>(
db: Deno.Kv,
key: Deno.KvKey,
fn: (...args: A) => Promise<R>,
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options?: KvMemoizeOptions<A, R>,
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): (...args: A) => Promise<R> {
return async (...args) => {
const cachedResult = options?.override?.get
? await options.override.get(key, args)
: (await db.get<R>([...key, ...args])).value;
if (cachedResult != null) {
if (!options?.shouldRecalculate?.(cachedResult, ...args)) {
return cachedResult;
}
}
const result = await fn(...args);
const expireIn = typeof options?.expireIn === "function"
? options.expireIn(result, ...args)
: options?.expireIn;
if (options?.shouldCache?.(result, ...args) ?? (result != null)) {
if (options?.override?.set) {
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await options.override.set(key, args, result, expireIn != null ? { expireIn } : {});
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} else {
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await db.set([...key, ...args], result, expireIn != null ? { expireIn } : {});
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}
}
return result;
};
}