Tail mysqlbinlog in row mode with Node JS

binlog.js

#!/usr/bin/env node

var determineDb = function(lines, startIndex){
  // Look backward from statement at startIndex to find database name used
  var result;
  for(var i = startIndex; i >= 0; i--){
    result = lines[i].match(/^use (`([^\.]+)`|[^\.\/]+)?/i);
    if(result === null) continue;
    if(result[2] === undefined){
      return result[1];
    }else{
      return result[2];
    }
  }
};

var tableModEvents = [
  {
    type: 'alterTable',
    match: /^ALTER TABLE/i
  },
  {
    type: 'dropTable',
    match: /^DROP TABLE/i
  },
  {
    type: 'createTable',
    match: /^CREATE TABLE( IF NOT EXISTS)?/i
  },
  {
    type: 'truncateTable',
    match: /^TRUNCATE/i
  },
  {
    type: 'insert',
    match: /^### INSERT INTO/
  },
  {
    type: 'update',
    match: /^### UPDATE/
  },
  {
    type: 'delete',
    match: /^### DELETE FROM/
  }
];

var checkTableMod = function(lines, index){
  for(var m = 0; m < tableModEvents.length; m++){
    var result = lines[index].match(tableModEvents[m].match);
    var table, db;
    if(!result) continue;
    var target = lines[index].substr(result[0].length)
                  .match(/^ (`([^\.]+)`|[^\.]+)?(\.`(.+)`|\..+)?/);
    // Map possible regex results to data
    // x: value must not be undefined but discard
    // t: table name
    // d: database name
    // -: undefined
    var checkRes = ['xt---', 'xxt--', 'xd-xt', 'xd-t-', 'xxdt-', 'xxdxt' ];
    var expect;
    for(var p = 0; p < checkRes.length; p++){
      table = undefined;
      db = undefined;
      for(var i = 0; i < checkRes[p].length; i++){
        expect = checkRes[p][i];
        if((expect === '-' && target[i] !== undefined) ||
           ((expect === 'x' || expect === 't') && target[i] === undefined)){
          break;
        }
        if(expect === 't') table = target[i];
        else if(expect === 'd') db = target[i];
      }
      if(i === checkRes[p].length) break;
    }
    if(!db) db = determineDb(lines, index);
    if(table.substr(0, 1) === '.') table = table.substr(1);
    return {
      type: tableModEvents[m].type,
      table: table,
      db: db
    };
  }
};

// include db in cmd params
var binlog  = '/usr/bin/mysqlbinlog -v --base64-output=DECODE-ROWS --start-position=%d %s',
    exec    = require('child_process').exec,
    fs      = require('fs'),
    output  = function (e, out, err) {
      console.log(out);
      // event emitters
      var lines = out.split("\n");
      for (var i=0; i < lines.length; i++) {
        var tableMod = checkTableMod(lines, i);
        tableMod && console.log(tableMod);
      }
    },
    util    = require('util'),
    tail    = function (e, out, err) {
      var logfile = out.replace(/(\n|\r)+$/, '');
      var prev = fs.statSync(logfile);
      console.log('tailing ' + logfile + '...');
      fs.watch(logfile , function (evt, filename) {
        console.log(arguments, prev);
        var cmd = util.format(binlog, prev.size, logfile);
        console.log(cmd);
        exec(cmd, output);
        prev = fs.statSync(logfile);
      });
    };
exec('ls -t /var/log/mysql/mysql-bin* | head -n1', tail );

I began working on this as an update to https://gist.github.com/petethomas/1572119 but am not going to use this approach. Instead, the zongji NPM module seems like a better way to accomplish this task.