sharedmemory/lib/lru.js

Cluster Shared Memory

var LinkedList = require('./linkedlist');

var CacheLRU = function(max) {

    var self = this;

    LinkedList.call(self);

    // 记录数上限
    self.__max__ = max || 10000;

    // 统计
    self.__total__ = 0;
    self.__miss__ = 0;
    self.__hit__ = 0;

};

CacheLRU.prototype = new LinkedList;

CacheLRU.prototype.set = function(key, value) {

    if (typeof value == 'undefined') {
        this.remove(key);
    }

    var self = this;
    var __list__ = self.__list__;
    var record = __list__[key];

    if (!record) {

        record = {
            key: key,
            value: value
        };

    } else {

        record.value = value;
        this.remove(key);

    }

    this.unshift(record);

    if (this.__length__ > this.__max__) {
        this.pop();
    }

};

CacheLRU.prototype.get = function(key) {

    var value;
    var record = this.__list__[key];

    this.__total__++;

    if (record) {

        value = record.value;
        this.remove(key);
        this.__list__[key] = record;
        this.unshift(record);
        this.__hit__++;

    } else {

        this.__miss__++;

    }

    return value;

};

exports.init = function(max) {
    return new CacheLRU(max);
};