【NoSQL】mongo_detail.py中均衡器信息的处

【ToolsForMongo】mongo_detail.py中均衡器信息的处理思路

先看下几种典型状况下的db.settings.find({'_id':'balancer'})输出:

1.创建mongos之后，从未设置balancer时：

mongos> var x = db.settings.findOne({'_id':'balancer'})mongos> x == nulltruemongos> sh.getBalancerState()true

2.创建了mongos之后，因故手动关闭了balancer

mongos> db.settings.findOne({'_id':'balancer'}){ "_id" : "balancer", "mode" : "off", "stopped" : true }mongos> sh.getBalancerState()false

3.设置了balancer的运行时间段，但当前时间不在其中

mongos>  var x = db.settings.findOne({'_id':'balancer'})mongos> x{    "_id" : "balancer",    "stopped" : true,    "activeWindow" : {        "start" : "00:00",        "stop" : "06:00"    }}mongos> sh.getBalancerState()false

4.设置了balancer的运行时间段，当前时间在其中

mongos> var x = db.settings.findOne({'_id':'balancer'})mongos> x{    "_id" : "balancer",    "stopped" : false,    "activeWindow" : {        "start" : "00:00",        "stop" : "22:00"    }}mongos> sh.getBalancerState()true

再看下官方mongo shell中的js代码

mongos> sh.getBalancerStatefunction (configDB) {    if (configDB === undefined)        configDB = sh._getConfigDB();    var x = configDB.settings.findOne({_id: "balancer"});    if (x == null)        return true;    return !x.stopped;}

1.先处理了configDB不是默认的config库的情况

2.x == null代表了上面的从未设置balancer，默认开启的状况

3.对返回值中的.stopped项进行取反，得到是否正在运行

mongos> sh.isBalancerRunningfunction (configDB) {    if (configDB === undefined)        configDB = sh._getConfigDB();    var x = configDB.locks.findOne({_id: "balancer"});    if (x == null) {        print("config.locks collection empty or missing. be sure you are connected to a mongos");        return false;    }    return x.state > 0;}