fix: make sure manifest writes don't overlap (#56)

* fix: make sure manifest writes don't overlap

* fix: make sure absolute file path is respected

lib/plugin.js

@@ -1,6 +1,9 @@
 var path = require('path');
 var fse = require('fs-extra');
 var _ = require('lodash');
+var mutexify = require('mutexify');
+
+var lock = mutexify();
 
 function ManifestPlugin(opts) {
   this.opts = _.assign({
@@ -142,23 +145,23 @@ ManifestPlugin.prototype.apply = function(compiler) {
 
     var json = JSON.stringify(manifest, null, 2);
 
-    compilation.assets[outputName] = {
-      source: function() {
-        return json;
-      },
-      size: function() {
-        return json.length;
-      }
-    };
+    var outputFolder = compilation.options.output.path;
+    var outputFile = path.resolve(compilation.options.output.path, this.opts.fileName);
 
     if (this.opts.writeToFileEmit) {
-      var outputFolder = compilation.options.output.path;
-      var outputFile = path.join(outputFolder, this.opts.fileName);
-
       fse.outputFileSync(outputFile, json);
     }
 
-    compileCallback();
+    compiler.outputFileSystem.mkdirp(path.dirname(outputFile), function(err) {
+      if (err) return compileCallback(err);
+
+      lock(function(release) {
+        compiler.outputFileSystem.writeFile(outputFile, json, function(err) {
+          release();
+          compileCallback(err);
+        });
+      });
+    });
   }.bind(this));
 };
 

package.json

@@ -40,7 +40,8 @@
   "homepage": "https://github.com/danethurber/webpack-manifest-plugin",
   "dependencies": {
     "fs-extra": "^0.30.0",
-    "lodash": ">=3.5 <5"
+    "lodash": ">=3.5 <5",
+    "mutexify": "^1.1.0"
   },
   "nyc": {
     "reporter": [