Enable the deletion of old log files after X log files have been created. (#50)

* Enable deletion of old files when maxsize option is not set

This change enables the transport to delete old files when maxsize has not been configured.

This functionality uses the maxfiles property to determine how many files are kept and will delete files that exceed this limit beginning with the oldest.  During start up the transport will check the log directory for any files that contain the the _basename used by it and will save these filenames to an internal variable.  These files will count towards the maxfiles limit.

Example.

The daily rotating file transport for the error level uses a MM-dd date pattern, prepends this pattern to the file name and has maxfiles set to 3.  On the  2nd of Jan the transport starts and discovers a file already exists in the log directory for the 1st of Jan and proceeds to create a file for the 2nd of Jan e.g.

01-01.error.log
01-02.error.log

While creating the log file for the 4th of Jan the transport realizes it has hit its max file limit and so deletes the 01-01.error.log file leaving the log directory with the following contents.

01-02.error.log
01-03.error.log
01-04.error.log

This functionality will not be enabled if the maxsize property has been configured for the transport.

* Update _currentFiles initialization function

Update the function that initializes the internal _currentFiles variable to ensure the filenames are returned in chronological order.

* fixing linting issues

* Adding tests for new functionality

Tests added to ensure file rotation and file deletion behaves as expected when maxsize is not set but maxfiles is.

* Remove use of fs.accessSync

Removed the uses of fs.accessSync as they are not available in older versions of Node and were breaking the Travis Integration tests.

Author: markjbyrne81

index.js

@@ -93,6 +93,34 @@ var DailyRotateFile = module.exports = function (options) {
   this._draining = false;
   this._failures = 0;
 
+  // Internal variable which will hold a record of all files
+  // belonging to this transport which are currently in the
+  // log directory in chronological order.
+  //
+  this._currentFiles = function () {
+    //
+    // Only proceed if maxsize is not configured for this transport.
+    if (!this.maxsize) {
+      try {
+        return fs.readdirSync(this.dirname).filter(function (file) {
+          return file.includes(this._basename);
+        }.bind(this)).map(function (file) {
+          return {
+            name: file,
+            time: fs.statSync(path.join(this.dirname, file)).mtime.getTime()
+          };
+        }.bind(this)).sort(function (a, b) {
+          return a.time - b.time;
+        }).map(function (v) {
+          return v.name;
+        });
+      } catch (e) {
+        // directory doesnt exist so there are no files. Do nothing.
+      }
+    }
+    return [];
+  }.bind(this)();
+
   var now = new Date();
   this._year = now.getUTCFullYear();
   this._month = now.getUTCMonth();
@@ -598,6 +626,26 @@ DailyRotateFile.prototype._getFile = function (inc) {
     }
 
     this._created += 1;
+  } else if (!this.maxsize) {
+    //
+    // If the filename does not exist in the _currentFiles array then add it.
+    if (this._currentFiles.indexOf(filename) === -1) {
+      this._currentFiles.push(filename);
+    }
+
+    // While the _currentFiles array contains more file names than is configured
+    // in maxFiles loop the _currentFiles array and delete the file found at el
+    // 0.
+    while (this.maxFiles && (this._currentFiles.length > this.maxFiles)) {
+      try {
+        fs.unlinkSync(path.join(this.dirname, this._currentFiles[0]));
+      } catch (e) {
+        // File isn't accessible, do nothing.
+      }
+
+      // Remove the filename that was just deleted from the _currentFiles array.
+      this._currentFiles = this._currentFiles.slice(1);
+    }
   }
 
   return this._created ? filename + '.' + this._created : filename;

test/simple.tests.js

@@ -401,5 +401,85 @@ describe('winston/transports/daily-rotate-file', function () {
         });
       });
     });
+
+    describe('when passed with maxfiles set and maxsize not set', function () {
+      var dailyRotationPattern = {
+        pattern: '.yyyy-MM-dd',
+        jan1: 1861947160000, // GMT: Mon, 01 Jan 2029 07:32:40 GMT
+        jan2: 1862033560000, // GMT: Mon, 02 Jan 2029 07:32:40 GMT
+        jan3: 1862119960000, // GMT: Mon, 03 Jan 2029 07:32:40 GMT
+        file1: 'test-rotation-no-maxsize.log.2029-01-01',
+        file2: 'test-rotation-no-maxsize.log.2029-01-02',
+        file3: 'test-rotation-no-maxsize.log.2029-01-03'
+      };
+
+      describe('when passed the pattern ' + dailyRotationPattern.pattern + ' and no maxsize', function () {
+        var transport;
+        var rotationLogPath = path.join(fixturesDir, 'rotations_no_maxsize');
+
+        beforeEach(function (done) {
+          rimraf.sync(rotationLogPath);
+          mkdirp.sync(rotationLogPath);
+          transport = new DailyRotateFile({
+            filename: path.join(rotationLogPath, 'test-rotation-no-maxsize.log'),
+            datePattern: dailyRotationPattern.pattern,
+            maxFiles: 2
+          });
+
+          done();
+        });
+
+        afterEach(function () {
+          tk.reset();
+        });
+
+        it('should properly rotate log without maxzsize set and with old files getting deleted', function (done) {
+          var self = this;
+          self.time = new Date(dailyRotationPattern.jan1);
+          tk.travel(self.time);
+
+          transport.log('error', 'test message on Jan 1st', {}, function (err) {
+            if (err) {
+              done(err);
+            }
+
+            self.time = new Date(dailyRotationPattern.jan2);
+            tk.travel(self.time);
+
+            transport.log('error', 'test message on Jan 2nd', {}, function (err) {
+              if (err) {
+                done(err);
+              }
+
+              self.time = new Date(dailyRotationPattern.jan3);
+              tk.travel(self.time);
+
+              transport.log('error', 'test message on Jan 3rd', {}, function (err) {
+                if (err) {
+                  done(err);
+                }
+
+                self.time = new Date(dailyRotationPattern.jan3);
+                tk.travel(self.time);
+
+                transport.log('error', 'second test message on Jan 3rd', {}, function (err) {
+                  if (err) {
+                    done(err);
+                  }
+
+                  var filesCreated = fs.readdirSync(rotationLogPath);
+                  console.log('files : ' + filesCreated);
+                  expect(filesCreated.length).to.eql(2);
+                  expect(filesCreated).not.to.include(dailyRotationPattern.file1);
+                  expect(filesCreated).to.include(dailyRotationPattern.file2);
+                  expect(filesCreated).to.include(dailyRotationPattern.file3);
+                  done();
+                });
+              });
+            });
+          });
+        });
+      });
+    });
   });
 });