55 lines
1.9 KiB
TypeScript
55 lines
1.9 KiB
TypeScript
/**
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* Use as a Decorator on async functions, it will prevent multiple 'active' calls as the same time
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*
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* If a promise was returned from a previous call to this function, that hasn't yet resolved it will
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* be returned, instead of calling the original function again
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*
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* Results are not cached, once the promise has returned, the next call will result in a fresh call
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*
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* Read more at https://github.com/bitwarden/jslib/pull/7
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*/
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export function sequentialize(cacheKey: (args: any[]) => string) {
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return (target: any, propertyKey: string | symbol, descriptor: PropertyDescriptor) => {
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const originalMethod: () => Promise<any> = descriptor.value;
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const caches = new Map<any, Map<string, Promise<any>>>();
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const getCache = (obj: any) => {
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let cache = caches.get(obj);
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if (cache != null) {
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return cache;
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}
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cache = new Map<string, Promise<any>>();
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caches.set(obj, cache);
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return cache;
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};
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return {
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value: function(...args: any[]) {
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const cache = getCache(this);
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const argsCacheKey = cacheKey(args);
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let response = cache.get(argsCacheKey);
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if (response != null) {
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return response;
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}
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const onFinally = () => {
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cache.delete(argsCacheKey);
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if (cache.size === 0) {
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caches.delete(this);
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}
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};
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response = originalMethod.apply(this, args).then((val: any) => {
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onFinally();
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return val;
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}).catch((err: any) => {
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onFinally();
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throw err;
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});
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cache.set(argsCacheKey, response);
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return response;
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},
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};
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};
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}
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