node-postgres/lib/native/index.js

//require the c++ bindings & export to javascript
var EventEmitter = require('events').EventEmitter;
var utils = require(__dirname + "/../utils");

var binding;

try{
  //v0.5.x
 binding = require(__dirname + '/../../build/Release/binding.node');
} catch(e) {
  //v0.4.x
 binding = require(__dirname + '/../../build/default/binding');
}

var Connection = binding.Connection;
var types = require(__dirname + "/../types");
var NativeQuery = require(__dirname + '/query');

var EventEmitter = require('events').EventEmitter;
var p = Connection.prototype;
for(var k in EventEmitter.prototype) {
  p[k] = EventEmitter.prototype[k];
}

var nativeConnect = p.connect;

p.connect = function(cb) {
  var self = this;
  utils.buildLibpqConnectionString(this._config, function(err, conString) {
    if(err) {
      return cb ? cb(err) : self.emit('error', err);
    }
    if(cb) {
      var errCallback;
      var connectCallback = function() {
        //remove single-fire connection error callback
        self.removeListener('error', errCallback);
        cb(null);
      }
      errCallback = function(err) {
        //remove singel-fire connection success callback
        self.removeListener('connect', connectCallback);
        cb(err);
      }
      self.once('connect', connectCallback);
      self.once('error', errCallback);
    }
    nativeConnect.call(self, conString);
  })
}

p.query = function(config, values, callback) {
  var q = new NativeQuery(config, values, callback);
  this._queryQueue.push(q);
  this._pulseQueryQueue();
  return q;
}

var nativeCancel = p.cancel;

p.cancel = function(client, query) {
	if (client._activeQuery == query)
		this.connect(nativeCancel.bind(client));
	else if (client._queryQueue.indexOf(query) != -1)
		client._queryQueue.splice(client._queryQueue.indexOf(query), 1);
};

p._pulseQueryQueue = function(initialConnection) {
  if(!this._connected) {
    return;
  }
  if(this._activeQuery) {
    return;
  }
  var query = this._queryQueue.shift();
  if(!query) {
    if(!initialConnection) {
      this._drainPaused ? this._drainPaused++ : this.emit('drain');
    }
    return;
  }
  this._activeQuery = query;
  if(query.name) {
    if(this._namedQueries[query.name]) {
      this._sendQueryPrepared(query.name, query.values||[]);
    } else {
      this._namedQuery = true;
      this._namedQueries[query.name] = true;
      this._sendPrepare(query.name, query.text, (query.values||[]).length);
    }
  }
  else if(query.values) {
    //call native function
    this._sendQueryWithParams(query.text, query.values)
  } else {
    //call native function
    this._sendQuery(query.text);
  }
}

p.pauseDrain = function() {
  this._drainPaused = 1;
};

p.resumeDrain = function() {
  if(this._drainPaused > 1) {
    this.emit('drain')
  };
  this._drainPaused = 0;
};

var clientBuilder = function(config) {
  config = config || {};
  var connection = new Connection();
  connection._queryQueue = [];
  connection._namedQueries = {};
  connection._activeQuery = null;
  connection._config = utils.normalizeConnectionInfo(config);
  //attach properties to normalize interface with pure js client
  connection.user = connection._config.user;
  connection.password = connection._config.password;
  connection.database = connection._config.database;
  connection.host = connection._config.host;
  connection.port = connection._config.port;
  connection.on('connect', function() {
    connection._connected = true;
    connection._pulseQueryQueue(true);
  });

  //proxy some events to active query
  connection.on('_row', function(row) {
    connection._activeQuery.handleRow(row);
  });

  connection.on('_cmdStatus', function(status) {
    //set this here so we can pass it to the query
    //when the query completes
    connection._lastMeta = status;
  });

  //TODO: emit more native error properties (make it match js error)
  connection.on('_error', function(err) {
    //create Error object from object literal
    var error = new Error(err.message || "Unknown native driver error");
    for(var key in err) {
      error[key] = err[key];
    }

    //give up on trying to wait for named query prepare
    this._namedQuery = false;
    if(connection._activeQuery) {
      connection._activeQuery.handleError(error);
    } else {
      connection.emit('error', error);
    }
  });

  connection.on('_readyForQuery', function() {
    var q = this._activeQuery;
    //a named query finished being prepared
    if(this._namedQuery) {
      this._namedQuery = false;
      this._sendQueryPrepared(q.name, q.values||[]);
    } else {
      connection._activeQuery.handleReadyForQuery(connection._lastMeta);
      connection._activeQuery = null;
      connection._pulseQueryQueue();
    }
  });

  return connection;
};

module.exports = clientBuilder;