log4js-node/lib/appenders/dateFile.js

var semver = require('semver')
, layouts = require('../layouts')
, path = require('path')
, os = require('os')
, eol = os.EOL || '\n'
, openFiles = []
, streams;

//close open files on process exit.
process.on('exit', function() {
    openFiles.forEach(function (file) {
        file.end();
    });
});

/**
 * File appender that rolls files according to a date pattern.
 * @filename base filename.
 * @pattern the format that will be added to the end of filename when rolling,
 *          also used to check when to roll files - defaults to '.yyyy-MM-dd'
 * @layout layout function for log messages - defaults to basicLayout
 */
function appender(filename, pattern, layout) {
  layout = layout || layouts.basicLayout;
  var logFile;

  if (semver.satisfies(process.version, '>=0.10.0')) {
    streams = require('../streams');
    logFile = new streams.DateRollingFileStream(filename, pattern);
  } else {
    streams = require('../old-streams');
    logFile = new streams.BufferedWriteStream(new streams.DateRollingFileStream(filename, pattern));
  }
  openFiles.push(logFile);
  
  return function(logEvent) {
    logFile.write(layout(logEvent) + eol, "utf8");
  };

}

function configure(config, options) {
  var layout;
  
  if (config.layout) {
	  layout = layouts.layout(config.layout.type, config.layout);
  }

  if (options && options.cwd && !config.absolute) {
    config.filename = path.join(options.cwd, config.filename);
  }

  return appender(config.filename, config.pattern, layout);
}

exports.appender = appender;
exports.configure = configure;