@botonic/plugin-contentful/lib/esm/util/cache.js

Botonic Plugin Contentful is one of the **[available](https://github.com/hubtype/botonic/tree/master/packages)** plugins for Botonic. **[Contentful](http://www.contentful.com)** is a CMS (Content Management System) which manages contents of a great variet

import { roughSizeOfObject } from './objects';
export const NOT_FOUND_IN_CACHE = Symbol('NOT_FOUND');
export class InMemoryCache {
    constructor() {
        this.cache = {};
        this.sizeBytes = 0;
    }
    set(id, val) {
        this.del(id);
        this.sizeBytes += roughSizeOfObject(id) + roughSizeOfObject(val);
        this.cache[id] = val;
    }
    del(id) {
        const val = this.get(id);
        if (val == NOT_FOUND_IN_CACHE) {
            return;
        }
        delete this.cache[id];
        this.sizeBytes -= roughSizeOfObject(id) + roughSizeOfObject(val);
    }
    get(id) {
        // Cache.has is only checked when undefined to avoid always searching twice in the object
        const val = this.cache[id];
        if (val === undefined && !this.has(id)) {
            return NOT_FOUND_IN_CACHE;
        }
        return val;
    }
    has(id) {
        return id in this.cache;
    }
    size() {
        return this.sizeBytes / 1024;
    }
    len() {
        return Object.keys(this.cache).length;
    }
    *keys() {
        for (const k of Object.keys(this.cache)) {
            yield k;
        }
    }
}
/**
 * Decorates a cache by limiting its size.
 *
 * TODO Use an external library to have a LRU cache. However, it's not critical
 * because typically data in CMS is small (we're not caching media, only their
 * URLs)
 */
export class LimitedCacheDecorator {
    constructor(cache, limitKB, logger = console.error, sizeWarningsRatio = [0.5, 0.75, 0.9]) {
        this.cache = cache;
        this.limitKB = limitKB;
        this.logger = logger;
        this.sizeWarningsRatio = sizeWarningsRatio;
    }
    set(id, val) {
        const incBytes = roughSizeOfObject(id) + roughSizeOfObject(val);
        const checkFit = () => this.cache.size() * 1024 + incBytes <= this.limitKB * 1024;
        let itFits = checkFit();
        if (!itFits) {
            for (const k of this.cache.keys()) {
                if (itFits) {
                    break;
                }
                this.cache.del(k);
                itFits = checkFit();
            }
            if (!itFits) {
                this.logger(`Cannot add entry in cache because IT ALONE is larger than max capacity(${this.limitKB})`);
                return;
            }
        }
        this.cache.set(id, val);
        this.warnSizeRatio(incBytes / 1024);
    }
    warnSizeRatio(incKB) {
        const sizeKB = this.size();
        for (const warnRatio of this.sizeWarningsRatio.sort((a, b) => b - a)) {
            if (sizeKB / this.limitKB >= warnRatio && sizeKB - incKB < warnRatio) {
                this.logger(`Cache is now more than ${warnRatio * 100}% full`);
                return;
            }
        }
    }
    get(id) {
        return this.cache.get(id);
    }
    has(id) {
        return this.cache.has(id);
    }
    del(id) {
        return this.cache.del(id);
    }
    keys() {
        return this.cache.keys();
    }
    size() {
        return this.cache.size();
    }
}
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