NodeBB/NodeBB

'use strict';

module.exports = function (opts) {
    const TTLCache = require('@isaacs/ttlcache');
    const pubsub = require('../pubsub');

    const ttlCache = new TTLCache(opts);

    const cache = {};
    cache.name = opts.name;
    cache.hits = 0;
    cache.misses = 0;
    cache.enabled = opts.hasOwnProperty('enabled') ? opts.enabled : true;
    const cacheSet = ttlCache.set;

    // expose properties
    const propertyMap = new Map([
        ['max', 'max'],
        ['itemCount', 'size'],
        ['size', 'size'],
        ['ttl', 'ttl'],
    ]);
    propertyMap.forEach((ttlProp, cacheProp) => {
        Object.defineProperty(cache, cacheProp, {
            get: function () {
                return ttlCache[ttlProp];
            },
            configurable: true,
            enumerable: true,
        });
    });

    cache.has = (key) => {
        if (!cache.enabled) {
            return false;
        }

        return ttlCache.has(key);
    };

    cache.set = function (key, value, ttl) {
        if (!cache.enabled) {
            return;
        }
        const opts = {};
        if (ttl) {
            opts.ttl = ttl;
        }
        cacheSet.apply(ttlCache, [key, value, opts]);
    };

    cache.get = function (key) {
        if (!cache.enabled) {
            return undefined;
        }
        const data = ttlCache.get(key);
        if (data === undefined) {
            cache.misses += 1;
        } else {
            cache.hits += 1;
        }
        return data;
    };

    cache.del = function (keys) {
        if (!Array.isArray(keys)) {
            keys = [keys];
        }
        pubsub.publish(`${cache.name}:ttlCache:del`, keys);
        keys.forEach(key => ttlCache.delete(key));
    };
    cache.delete = cache.del;

    cache.reset = function () {
        pubsub.publish(`${cache.name}:ttlCache:reset`);
        localReset();
    };
    cache.clear = cache.reset;

    function localReset() {
        ttlCache.clear();
        cache.hits = 0;
        cache.misses = 0;
    }

    pubsub.on(`${cache.name}:ttlCache:reset`, () => {
        localReset();
    });

    pubsub.on(`${cache.name}:ttlCache:del`, (keys) => {
        if (Array.isArray(keys)) {
            keys.forEach(key => ttlCache.delete(key));
        }
    });

    cache.getUnCachedKeys = function (keys, cachedData) {
        if (!cache.enabled) {
            return keys;
        }
        let data;
        let isCached;
        const unCachedKeys = keys.filter((key) => {
            data = cache.get(key);
            isCached = data !== undefined;
            if (isCached) {
                cachedData[key] = data;
            }
            return !isCached;
        });

        const hits = keys.length - unCachedKeys.length;
        const misses = keys.length - hits;
        cache.hits += hits;
        cache.misses += misses;
        return unCachedKeys;
    };

    cache.dump = function () {
        return Array.from(ttlCache.entries());
    };

    cache.peek = function (key) {
        return ttlCache.get(key, { updateAgeOnGet: false });
    };

    return cache;
};