simple-node-memory-cache/dist/strategies/SimpleLFU.js

In-memory object cache written in typescript for Node that supports multiple eviction strategies.

"use strict";
var __extends = (this && this.__extends) || (function () {
    var extendStatics = function (d, b) {
        extendStatics = Object.setPrototypeOf ||
            ({ __proto__: [] } instanceof Array && function (d, b) { d.__proto__ = b; }) ||
            function (d, b) { for (var p in b) if (b.hasOwnProperty(p)) d[p] = b[p]; };
        return extendStatics(d, b);
    };
    return function (d, b) {
        extendStatics(d, b);
        function __() { this.constructor = d; }
        d.prototype = b === null ? Object.create(b) : (__.prototype = b.prototype, new __());
    };
})();
var __values = (this && this.__values) || function (o) {
    var m = typeof Symbol === "function" && o[Symbol.iterator], i = 0;
    if (m) return m.call(o);
    return {
        next: function () {
            if (o && i >= o.length) o = void 0;
            return { value: o && o[i++], done: !o };
        }
    };
};
var __read = (this && this.__read) || function (o, n) {
    var m = typeof Symbol === "function" && o[Symbol.iterator];
    if (!m) return o;
    var i = m.call(o), r, ar = [], e;
    try {
        while ((n === void 0 || n-- > 0) && !(r = i.next()).done) ar.push(r.value);
    }
    catch (error) { e = { error: error }; }
    finally {
        try {
            if (r && !r.done && (m = i["return"])) m.call(i);
        }
        finally { if (e) throw e.error; }
    }
    return ar;
};
Object.defineProperty(exports, "__esModule", { value: true });
var Cache_1 = require("../cacheBase/Cache");
var SimpleLFU = /** @class */ (function (_super) {
    __extends(SimpleLFU, _super);
    function SimpleLFU() {
        return _super !== null && _super.apply(this, arguments) || this;
    }
    SimpleLFU.prototype.get = function (key) {
        return this.update(key, this.cache.get(key));
    };
    SimpleLFU.prototype.set = function (key, value) {
        var e_1, _a;
        if (this.cache.size >= this._maxObjectsInCache && !this.cache.has(key)) {
            // Find the least recently used.
            var leastFrequentlyUsedKey = undefined;
            var lowestEntry = undefined;
            try {
                for (var _b = __values(this.cache.entries()), _c = _b.next(); !_c.done; _c = _b.next()) {
                    var _d = __read(_c.value, 2), key_1 = _d[0], value_1 = _d[1];
                    if (value_1[2] < lowestEntry || lowestEntry === undefined) {
                        lowestEntry = value_1[2];
                        leastFrequentlyUsedKey = key_1;
                    }
                    // If 0 then break as lower is not possible.
                    if (lowestEntry === 0) {
                        break;
                    }
                }
            }
            catch (e_1_1) { e_1 = { error: e_1_1 }; }
            finally {
                try {
                    if (_c && !_c.done && (_a = _b.return)) _a.call(_b);
                }
                finally { if (e_1) throw e_1.error; }
            }
            // And delete it.
            this.cache.delete(leastFrequentlyUsedKey);
        }
        return this.cache.set(key, [value, 0, 0]);
    };
    SimpleLFU.prototype.update = function (key, value) {
        this.cache.set(key, [value[0], 0, value[2] + 1]);
        return [value[0], 0, value[2] + 1];
    };
    return SimpleLFU;
}(Cache_1.SimpleCache));
exports.SimpleLFU = SimpleLFU;