pongo/index.js

Connection pooling for node-mongodb-native

var mongo = require("mongodb");
var DEFAULT_HOST = "127.0.0.1";
var DEFAULT_PORT = 27017;
var DEFAULT_BUFFERSIZE = 100;

/**
 * Pongo constructor.
 *
 * ####Example:
 *
 *      var pongo = new Pongo({
 *          server: {poolSize: 3},
 *          db: {w: 1}
 *      });
 *
 * ####Options:
 *
 * - [host]: string - defaults to '127.0.0.1'
 * - [port]: number - defaults to 27017
 * - [bufferSize]: number - defaults to 100
 * - [server]: object - defaults from http://mongodb.github.com/node-mongodb-native/api-generated/server.html?highlight=server#server
 * - [db]: object - defaults from http://mongodb.github.com/node-mongodb-native/api-generated/db.html?highlight=db#db
 *
 * @param {Object} options
 * @api public
 */
function Pongo (options) {
    
    options = options || {};
    
    this.host = options.host || DEFAULT_HOST;
    this.port = options.port || DEFAULT_PORT;
    
    this.pool = {};
    this.buffer = {};
    this.MAX_CALLBACKS_IN_BUFFER = options.bufferSize || DEFAULT_BUFFERSIZE;
    
    if (options.server) {
        this.serverOptions = options.server;
    }
    
    if (options.db) {
        this.dbOptions = options.db;
    }
}

function callbacks (err) {
    
    for (var dbName in this.buffer) {
        
        if (!this.pool[dbName] && this._Db) {
            
            //cache db instance
            this.pool[dbName] = this._Db.db(dbName);
        }
        
        var length = this.buffer[dbName].length;
        
        //execute callbacks in buffer
        if (length > 0) {
            
            for (var i = 0; i < length; ++i) {
                this.buffer[dbName][i](err, this.pool[dbName]);
            }
        }
        
        this.buffer[dbName] = [];
    }
}

function bufferCallback (dbName, callback) {

    if (!this.buffer[dbName]) {
        
        this.buffer[dbName] = [];
    }
    
    if (this.buffer[dbName].length < this.MAX_CALLBACKS_IN_BUFFER) {
        
        this.buffer[dbName].push(callback);
    }
    else {
        
        callback(new Error("Number of callbacks in buffer exceeded."));
    }
}

Pongo.prototype = mongo;

/**
 * Pongo connect.
 *
 * ####Example:
 *      
 *      pongo.connect('myMongoDb', function (err, db) {
 *          // use the db instance as you would with the https://github.com/mongodb/node-mongodb-native driver.
 *      });
 *      
 *      pongo.connect('myOtherMongoDb', function (err, db) {
 *          // use the db instance as you would with the https://github.com/mongodb/node-mongodb-native driver.
 *      });
 *
 * ####Options:
 *
 * - [dbName]: string - no default
 * - [callback]: function - no default\
 *
 * ####Note:
 *
 * No more sockets are opened, as defined in the server.poolSize option.
 *
 * @param {Object} options
 * @api public
 */
Pongo.prototype.connect = function (dbName, callback) {
    
    // return Db instance, if allready in pool
    if (this.pool[dbName]) {
        return callback(null, this.pool[dbName]);
    }
    
    // buffer callbacks when db is connecting
    if (this.pool[dbName] === null) {
        return bufferCallback.call(this, dbName, callback);
    }
    
    this.pool[dbName] = null;
    
    // buffer the callback
    bufferCallback.call(this, dbName, callback);
    
    // return if Db is opening
    if (this._Db === null) {
        return;
    }
    
    // create connection
    if (!this._Db) {
    
        this._Db = null;
        
        var self = this;
        
        new mongo.Db(
            dbName,
            new mongo.Server(
                this.host,
                this.port,
                this.serverOptions
            ),
            this.dbOptions
        ).open(function (err, db) {
    
            if (err) {
                return callbacks.call(self, err);
            }
            
            // save db ref
            self._Db = db;
            
            //cache db
            self.pool[dbName] = db;
            
            //retrun collection
            callbacks.call(self, null);
        });
    
    // Create a new Db instance sharing the current socket connections.
    // http://mongodb.github.com/node-mongodb-native/api-generated/db.html?highlight=db#id1 
    } else {
        
        this.pool[dbName] = this._Db.db(dbName);
        callbacks.call(this, null);
    }
};

// export object id class
Pongo.ObjectId = mongo.ObjectID;

module.exports = Pongo;