NODEJS(12)Platform - strict mode - underscore-generic pool

NODEJS(12)Platform - strict mode - underscore-generic pool

1. strict mode
“use strict”;

If we put it in the first line of the file, that means it will take effect for global. 
Some special environment
<script>
     “use strict”;
     console.log(“This is strict mode.”);
</script>

<script>
     console.log(“This is the normal mode.”);
</script>

We can also put this “use strict” in side one function.
function strict(){
     “use strict”;
     return “this is strict mode”;
}

Once we use strict mode, what need us to pay attention.
v = 1; // Error, we need to define the variable before we use it.
for( i = 0; i< 2; i++){} //Error, define i before we use it.

Not using with

eval Scope
scope: global and inside function
eval for example

“use strict”;
var x = 2;
console.info(eval(“var x=5;x”)); //5
console.info(x); //2

We need put new before we create an object.

2. underscore
http://sillycat.iteye.com/blog/1862248
http://underscorejs.org/#each

3. The way to Extends One Module
Here is the way to extends the underscore lib.

“use strict”;

var _ = require(“underscore”);

_.merge = function(dest) {
     ….snip...
}

module.exports = _;

That means we add one more method merge to the module underscore.

4. node-pool (generic-pool)
https://github.com/coopernurse/node-pool

Test Tool
http://visionmedia.github.io/expresso/

Check the Document
http://mongodb.github.io/node-mongodb-native/markdown-docs/insert.html#find-and-modify

Add some dependencies there>
{
     "name": "buglist",
     "version": "0.0.1",
     "private": true,
     "dependencies": {
          "express": "4.2.0",
          "body-parser": "1.2.0",
          "generic-pool": "2.0.4",
          "mongodb": "1.4.5"
     }
}

Most of the changes will happen in action.js. We are using the generic pool and we are not based on monk, instead of that, we are using native mongo nodeJS driver I think.
var config = require('../config.json');
var mongodb = require('mongodb');
var poolModule = require('generic-pool');

var pool = poolModule.Pool({
     name: 'mongo1',
     create: function(callback){
          var mongoClient = new mongodb.MongoClient(new mongodb.Server(config.host, config.port));
          mongoClient.open(function(err, mongoClient) {
                 var db = mongoClient.db(config.dbname);
               callback(err, db);
          });
     },
     destroy: function(db) { db.close(); },
     max: 10,
     min: 2,
     idleTimeoutMillis: 30000,
     log: false
});

// Returns all the bugs
exports.getAll = function(req, res) {
     pool.acquire(function(err, db){
          if (err) {
            res.json(500,err);
        } else {
               db.collection('bugs').find({}).toArray(function(err, bugs){
                    if (err) res.json(500, err);
                    else res.json(bugs);

                    pool.release(db);
               });
        }
     });
};

// Creates a bug
exports.create = function(req, res) {
     var body = req.body;
     console.log("post body  = " + body);
     console.log("create title = " + body.title);
     console.log("create creation = " + body.creation);
     console.log("create status = " + body.status);
     console.log("create assignee = " + body.assignee);

     pool.acquire(function(err, db){
          if (err) {
            res.json(500,err);
        } else {
               db.collection('bugs').insert(body, function(err, bug){
                    if (err) res.json(500, err);
                    else res.json(201, bug);

                    pool.release(db);
               });
        }
     });

};

// Get a bug
exports.get = function(req, res) {
     var id = req.params.id;

     pool.acquire(function(err, db){
          if (err) {
            res.json(500,err);
        } else {
               db.collection('bugs').findOne({_id: new mongodb.ObjectID(id) }, function(err, bug){
                    if (err) res.json(500, err);
                    else if (bug) res.json(bug);
                    else res.send(404);

                    pool.release(db);
               });
        }
     });

};

// Updates a bug
exports.update = function(req, res) {
     var id = req.params.id;
     var body = req.body;
     delete body._id;

     pool.acquire(function(err, db){
          if (err) {
            res.json(500,err);
        } else {
               db.collection('bugs').findAndModify({_id: new mongodb.ObjectID(id)}, [['_id','asc']], {$set: body}, {multi:false, new:true}, function(err, bug){
                    if (err) res.json(500, err);
                    else if (bug) res.json(bug);
                    else res.send(404);

                    pool.release(db);
               });
        }
     });
};

// Deletes a bug
exports.del = function(req, res) {
     var id = req.params.id;

     pool.acquire(function(err, db){
          if (err) {
            res.json(500,err);
        } else {
               db.collection('bugs').remove({_id: new mongodb.ObjectID(id) }, function(err){
                    if (err) res.json(500, err);
                    else res.send(204);

                    pool.release(db);
               });
        }
     });

};

Debug Information
VERBOSE pool mongo1 - availableObjects.length=2 VERBOSE pool mongo1 - availableObjects.length=2 VERBOSE pool mongo1 - availableObjects.length=2

Solution:
Change the log configuration to false
var pool = poolModule.Pool({
     name: 'mongo1',
     create: function(callback){
          var mongoClient = new mongodb.MongoClient(new mongodb.Server(config.host, config.port));
          mongoClient.open(function(err, mongoClient) {
                 var db = mongoClient.db(config.dbname);
               callback(err, db);
          });
     },
     destroy: function(db) { db.close(); },
     max: 10,
     min: 2,
     idleTimeoutMillis: 30000,
     log: false
});


References:
http://www.ruanyifeng.com/blog/2013/01/javascript_strict_mode.html
http://sillycat.iteye.com/blog/1862248

http://underscorejs.org/

generic connection pool
https://github.com/zs1621/NodejsStudy/wiki/connect-mongodb
http://blog.youkuaiyun.com/zenghuaidong/article/details/7428808
http://www.cnblogs.com/enix/p/3654894.html
https://github.com/zs1621/NodejsStudy/blob/master/mongodb-connect/connect_mongodb_pool.js