Improves performance of file.expand, file.expandMapping, and task.normalizeMultiTaskFiles by caching glob fs results across multiple calls to glob.sync

Author: cspotcode

lib/grunt/file.js

@@ -93,6 +93,8 @@ file.expand = function() {
   // If the first argument is an options object, save those options to pass
   // into the file.glob.sync method.
   var options = grunt.util.kindOf(args[0]) === 'object' ? args.shift() : {};
+  // Cache fs calls across multiple file.glob.sync operations
+  var globOptions = grunt.util._.extend(file._createGlobIoCache(), options);
   // Use the first argument if it's an Array, otherwise convert the arguments
   // object to an array and use that.
   var patterns = Array.isArray(args[0]) ? args[0] : args;
@@ -101,7 +103,7 @@ file.expand = function() {
   // Return all matching filepaths.
   var matches = processPatterns(patterns, function(pattern) {
     // Find all matching files for this pattern.
-    return file.glob.sync(pattern, options);
+    return file.glob.sync(pattern, globOptions);
   });
   // Filter result set?
   if (options.filter) {
@@ -452,3 +454,14 @@ file.isPathInCwd = function() {
     return false;
   }
 };
+
+// Creates all glob options that store cached fs results for the `glob` library.
+// Can be removed when this glob PR is released: https://github.com/isaacs/node-glob/pull/306
+file._createGlobIoCache = function() {
+  return {
+    cache: Object.create(null),
+    statCache: Object.create(null),
+    symlinks: Object.create(null),
+    realpathCache: Object.create(null)
+  };
+};

lib/grunt/task.js

@@ -117,6 +117,7 @@ task.normalizeMultiTaskFiles = function(data, target) {
   }
 
   // Process all normalized file objects.
+  var globIoCache = grunt.file._createGlobIoCache();
   files = grunt.util._(files).chain().forEach(function(obj) {
     if (!('src' in obj) || !obj.src) { return; }
     // Normalize .src properties to flattened array.
@@ -127,7 +128,7 @@ task.normalizeMultiTaskFiles = function(data, target) {
     }
   }).map(function(obj) {
     // Build options object, removing unwanted properties.
-    var expandOptions = grunt.util._.extend({}, obj);
+    var expandOptions = grunt.util._.extend({}, globIoCache, obj);
     delete expandOptions.src;
     delete expandOptions.dest;