Log compression.

lib/appenders/file.js

@@ -27,7 +27,7 @@ process.on('exit', function() {
  * @param numBackups - the number of log files to keep after logSize 
  *   has been reached (default 5)
  */
-function fileAppender (file, layout, logSize, numBackups, level) {
+function fileAppender (file, layout, logSize, numBackups, level, compress) {
   var bytesWritten = 0;
   file = path.normalize(file);
   layout = layout || layouts.basicLayout;
@@ -41,7 +41,8 @@ function fileAppender (file, layout, logSize, numBackups, level) {
       stream = new streams.RollingFileStream(
         file,
         fileSize,
-        numFiles
+        numFiles,
+        { "compress": compress }
       );
     } else {
       stream = fs.createWriteStream(
@@ -90,7 +91,7 @@ function configure(config, options) {
     config.filename = path.join(options.cwd, config.filename);
   }
 
-  return fileAppender(config.filename, layout, config.maxLogSize, config.backups, config.level);
+  return fileAppender(config.filename, layout, config.maxLogSize, config.backups, config.level, config.compress);
 }
 
 function shutdown(cb) {

lib/streams/BaseRollingFileStream.js

@@ -16,7 +16,11 @@ module.exports = BaseRollingFileStream;
 function BaseRollingFileStream(filename, options) {
   debug("In BaseRollingFileStream");
   this.filename = filename;
-  this.options = options || { encoding: 'utf8', mode: parseInt('0644', 8), flags: 'a' };
+  this.options = options || {};
+  this.options.encoding = this.options.encoding || 'utf8';
+  this.options.mode = this.options.mode || parseInt('0644', 8);
+  this.options.flags = this.options.flags || 'a';
+
   this.currentSize = 0;
   
   function currentFileSize(file) {

lib/streams/RollingFileStream.js

@@ -3,6 +3,8 @@ var BaseRollingFileStream = require('./BaseRollingFileStream')
 , debug = require('../debug')('RollingFileStream')
 , util = require('util')
 , path = require('path')
+, child_process = require('child_process')
+, zlib = require("zlib")
 , fs = require('fs')
 , async = require('async');
 
@@ -25,7 +27,7 @@ function RollingFileStream (filename, size, backups, options) {
 util.inherits(RollingFileStream, BaseRollingFileStream);
 
 RollingFileStream.prototype.shouldRoll = function() {
-  debug("should roll with current size %d, and max size %d", this.currentSize, this.size);
+  debug("should roll with current size " + this.currentSize + " and max size " + this.size);
   return this.currentSize >= this.size;
 };
 
@@ -38,6 +40,7 @@ RollingFileStream.prototype.roll = function(filename, callback) {
   }
   
   function index(filename_) {
+    debug('Calculating index of '+filename_);
     return parseInt(filename_.substring((path.basename(filename) + '.').length), 10) || 0;
   }
   
@@ -51,16 +54,42 @@ RollingFileStream.prototype.roll = function(filename, callback) {
     }
   }
 
+  function compress (filename, cb) {
+
+    var gzip = zlib.createGzip();
+    var inp = fs.createReadStream(filename);
+    var out = fs.createWriteStream(filename+".gz");
+    inp.pipe(gzip).pipe(out);
+    fs.unlink(filename, cb);
+
+  }
+
   function increaseFileIndex (fileToRename, cb) {
     var idx = index(fileToRename);
     debug('Index of ' + fileToRename + ' is ' + idx);
     if (idx < that.backups) {
+
+      var ext = path.extname(fileToRename);
+      var destination = filename + '.' + (idx+1);
+      if (that.options.compress && /^gz$/.test(ext.substring(1))) {
+        destination+=ext;
+      }
       //on windows, you can get a EEXIST error if you rename a file to an existing file
       //so, we'll try to delete the file we're renaming to first
-      fs.unlink(filename + '.' + (idx+1), function (err) {
+      fs.unlink(destination, function (err) {
         //ignore err: if we could not delete, it's most likely that it doesn't exist
-        debug('Renaming ' + fileToRename + ' -> ' + filename + '.' + (idx+1));
-        fs.rename(path.join(path.dirname(filename), fileToRename), filename + '.' + (idx + 1), cb);
+        debug('Renaming ' + fileToRename + ' -> ' + destination);
+        fs.rename(path.join(path.dirname(filename), fileToRename), destination, function(err) {
+          if (err) {
+            cb(err);
+          } else {
+            if (that.options.compress && ext!=".gz") {
+              compress(destination, cb);
+            } else {
+              cb();
+            }
+          }
+        });
       });
     } else {
       cb();