可以自动切割的日志stream

logstream.js

/**
 * Log file stream
 */

var fs = require('fs');
var path = require('path');
var Stream = require('stream').Stream;
var util = require('util');

var ONE_MINUTE = 60000;
var ONE_HOUR = 60 * ONE_MINUTE;
var ONE_DAY = 24 * ONE_HOUR;

// format datetime, demo: new Date().format("yyyy-MM-dd hh:mm:ss W");
var WEEK_DAYS = [ '周日', '周一', '周二', '周三', '周四', '周五', '周六' ];
Date.prototype.format = function(format) {
  format = format || "yyyy-MM-dd hh:mm:ss";
  var day = this.getDay();
  var weeken = (day === 0 || day === 6) ? WEEK_DAYS[day] : '';
  var o = {
    "M+" : this.getMonth() + 1, //month
    "d+" : this.getDate(),    //day
    "h+" : this.getHours(),   //hour
    "m+" : this.getMinutes(), //minute
    "s+" : this.getSeconds(), //second
    "q+" : Math.floor((this.getMonth() + 3) / 3), //quarter
    "W" : WEEK_DAYS[day], // weekday
    "E" : weeken, // end of week
    "S" : this.getMilliseconds() //millisecond
  };
  if (/(y+)/.test(format)) {
    format = format.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
  }
  for (var k in o) {
    if (new RegExp("("+ k +")").test(format)) {
      format = format.replace(RegExp.$1, RegExp.$1.length === 1 ? o[k] : ("00"+ o[k]).substr((""+ o[k]).length));
    }
  }
  return format;
};


/**
 * Log stream, auto cut the log file.
 * 
 * @param  {Object} options
 *  - {String} logdir
 *  - {String} filename, if set `filename`, logstream will not auto cut.
 *  - {String} nameformat, default is 'yyyy-MM-dd.hhmmss.{pid}.log'
 *  - {Number} duration, default is one houre(24 * 3600000 ms), must >= 60s.
 * return {LogStream}
 */
exports.createStream = function (options) {
  return new LogStream(options);
};

function LogStream(options) {
  if (!(this instanceof LogStream)) {
    return new LogStream(options);
  }
  options = options || {};
  this.logdir = options.logdir || './logs';
  if (!path.existsSync(this.logdir)) {
    fs.mkdirSync(this.logdir, '0777');
  }
  this.filename = options.filename;
  this.nameformat = options.nameformat;
  if (this.nameformat === null || this.nameformat === undefined) {
    this.nameformat = 'yyyy-MM-dd.hhmmss.{pid}.log';
  }
  this.nameformat = this.nameformat.replace('{pid}', process.pid);
  this.duration = options.duration || ONE_HOUR;
  // must >= one second
  if (this.duration < 60000) {
    this.duration = 60000;
  }
  this.cut();
  this.startTimer(this.firstDuration());
}

util.inherits(LogStream, Stream);

LogStream.prototype.firstDuration = function () {
  var now = new Date();
  var firstDuration = this.duration;
  var end = new Date(now + this.duration);
  if (this.duration > ONE_MINUTE) {
    if (this.duration < ONE_HOUR) { // in minute
      firstDuration = new Date(new Date(now.getTime() + this.duration).format('yyyy-MM-dd hh:mm:00')) - now;
    } else if (this.duration < ONE_DAY) { // in hour
      firstDuration = new Date(new Date(now.getTime() + this.duration).format('yyyy-MM-dd hh:00:00')) - now;
    } else { // in day
      firstDuration = new Date(new Date(now.getTime() + this.duration).format('yyyy-MM-dd 00:00:00')) - now;
    }
  }
  return firstDuration;
};

LogStream.prototype.startTimer = function (duration) {
  if (this._timer) {
    clearTimeout(this._timer);
  }
  this._timer = setTimeout(function (self) {
    this._timer = null;
    self.cut();
    self.startTimer(self.duration);
  }, duration || this.duration, this);
};

LogStream.prototype.cut = function () {
  if (this.stream) {
    this.stream.end();
    this.stream.destroySoon();
    this.stream = null;
  }
  var now = new Date();
  var name = (this.filename || '');
  if (this.nameformat) {
    name += now.format(this.nameformat);
  }
  var logpath = path.join(this.logdir, name);
  this._reopening = true;
  this.stream = fs.createWriteStream(logpath, { flags: 'a', mode: '0666' });
  this.stream
    .on("error", this.emit.bind(this, "error"))
    .on("pipe", this.emit.bind(this, "pipe"))
    .on("drain", this.emit.bind(this, "drain"))
    .on("open", function () {
      this._reopening = false;
    }.bind(this))
    .on("close", function () {
      if (!this._reopening) {
        this.emit("close");
      }
    }.bind(this));
};

LogStream.prototype.write = function (string, encoding) {
  this.stream.write(string, encoding);
};

LogStream.prototype.end = function () {
  if (this._timer) {
    clearTimeout(this._timer);
    this._timer = null;
  }
  if (this.stream) {
    this.stream.end();
    this.stream.destroySoon();
    this.stream = null;
  }
};

exports.LogStream = LogStream;