function(callback) {
      var t = this;
      async.waterfall([
        function readDb(callback) {
          fs.exists(t.__dbFilename, function(exists) {
            if (exists) {
              fs.readFile(t.__dbFilename, {
                encoding: "utf-8"
              }, callback);
            } else {
              callback(null, null); 
            }
          });
        },

        function parseDb(data, callback) {
          t.__db = data && data.trim().length ? jsonlint.parse(data) : {};
          callback(null, t.__db);
        }
      ], callback);
    }
function(callback) {
      var t = this;
      async.waterfall([
        function readDb(callback) {
          fs.exists(t.__dbFilename, function(exists) {
            if (exists) {
              fs.readFile(t.__dbFilename, {
                encoding: "utf-8"
              }, callback);
            } else {
              callback(null, null); 
            }
          });
        },

        function parseDb(data, callback) {
          t.__db = data && data.trim().length ? jsonlint.parse(data) : {};
          callback(null, t.__db);
        }
      ], callback);
    }
function ( callback ) { var t = this ; async . waterfall ( [ function readDb ( callback ) { fs . exists ( t . __dbFilename , function ( exists ) { if ( exists ) { fs . readFile ( t . __dbFilename , { encoding : "utf-8" } , callback ) ; } else { callback ( null , null ) ; } } ) ; } , function parseDb ( data , callback ) { t . __db = data && data . trim ( ) . length ? jsonlint . parse ( data ) : { } ; callback ( null , t . __db ) ; } ] , callback ) ; }
Loads the cached database

@param callback
Loads the cached database