chaingate/dist/esm/InternalUtils/TtlCache.js

A complete TypeScript library for connecting to and making transactions on different blockchains

const NOT_CACHED = Symbol('not-cached');
export class TtlCache {
    fetcher;
    ttlMs;
    cachedValue = NOT_CACHED;
    expiresAt = 0;
    pendingPromise = null;
    constructor(fetcher, ttlSeconds) {
        this.fetcher = fetcher;
        this.ttlMs = ttlSeconds * 1000;
    }
    /**
     * Fetches a value, optionally using the cache.
     *
     * @param useCache – if true, return the cached value when still fresh;
     *                   if false, always re-fetch, cache & return the new value.
     */
    async get(useCache) {
        const now = Date.now();
        // 1) If we’re allowed to use cache, and it’s still valid, just return it.
        if (useCache && this.cachedValue !== NOT_CACHED && now < this.expiresAt) {
            return this.cachedValue;
        }
        // 2) If there’s already a fetch in flight, join it (no double-fetch).
        if (this.pendingPromise) {
            return this.pendingPromise;
        }
        // 3) Kick off a (new or forced) fetch, cache the result & reset TTL.
        this.pendingPromise = (async () => {
            try {
                const result = await this.fetcher();
                this.cachedValue = result;
                this.expiresAt = Date.now() + this.ttlMs;
                return result;
            }
            finally {
                this.pendingPromise = null;
            }
        })();
        return this.pendingPromise;
    }
    /** Clear both the cached value and any in-flight fetch. */
    clear() {
        this.cachedValue = NOT_CACHED;
        this.expiresAt = 0;
        this.pendingPromise = null;
    }
}
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