handle simultaneous change of LastAccessTime and ModifiedTime (#793)

lib/nodefs-handler.js

@@ -11,6 +11,11 @@ var isBinaryPath = require('is-binary-path');
 // (may be shared across chokidar FSWatcher instances)
 var FsWatchInstances = Object.create(null);
 
+// atime and mtime are changing simultaneously by OS
+// so we need threshold (in ms) to understand when file is changed
+// or when only atime is updated (which we want to ignore)
+var accessTimeDelayThreshold = 1000;
+
 // Private function: Instantiates the fs.watch interface
 
 // * path       - string, path to be watched
@@ -266,7 +271,8 @@ function(file, stats, initialAdd, callback) {
         } else {
           // Check that change event was not fired because of changed accessTime.
           var at = newStats.atime.getTime();
-          if (!at || at <= newStats.mtime.getTime()) {
+          var mt = newStats.mtime.getTime();
+          if (!at || at <= mt || (at - mt) <= accessTimeDelayThreshold) {
             this._emit('change', file, newStats);
           }
         }
@@ -275,7 +281,8 @@ function(file, stats, initialAdd, callback) {
     } else if (parent.has(basename)) {
       // Check that change event was not fired because of changed accessTime.
       var at = newStats.atime.getTime();
-      if (!at || at <= newStats.mtime.getTime()) {
+      var mt = newStats.mtime.getTime();
+      if (!at || at <= mt || (at - mt) <= accessTimeDelayThreshold) {
         this._emit('change', file, newStats);
       }
     }