From eb5bd53ff0b6dc01e247fce9af01d0ed97d8c9ba Mon Sep 17 00:00:00 2001
From: Vojta Jina <vojta.jina@gmail.com>
Date: Tue, 5 Aug 2014 13:19:47 -0700
Subject: [PATCH] fix(web-server): cache static files
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Files in `karma/static/*` were always read from file system.
These files typically don’t change (except when developing Karma itself)
and so it makes sense to cache them in memory.
Especially `./static/context.html`, which is read for every test run.

The main reason for this change is that when using native events
(non-polling), watching can easily hit the EMFILE limit and then this
`fs.readFile()` can be super delayed. This was easily reproducible
problem in AngularJS test suite.
---
 lib/middleware/common.js               | 8 ++++++++
 test/unit/middleware/karma.spec.coffee | 5 +++--
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/lib/middleware/common.js b/lib/middleware/common.js
index 6376dface..979efafee 100644
--- a/lib/middleware/common.js
+++ b/lib/middleware/common.js
@@ -26,6 +26,8 @@ var serve404 = function(response, path) {
 
 
 var createServeFile = function(fs, directory) {
+  var cache = Object.create(null);
+
   return function(filepath, response, transform, content) {
     var responseData;
 
@@ -33,6 +35,10 @@ var createServeFile = function(fs, directory) {
       filepath = directory + filepath;
     }
 
+    if (!content && cache[filepath]) {
+      content = cache[filepath];
+    }
+
     // serve from cache
     if (content) {
       response.setHeader('Content-Type', mime.lookup(filepath, 'text/plain'));
@@ -51,6 +57,8 @@ var createServeFile = function(fs, directory) {
         return serve404(response, filepath);
       }
 
+      cache[filepath] = data.toString();
+
       response.setHeader('Content-Type', mime.lookup(filepath, 'text/plain'));
 
       // call custom transform fn to transform the data
diff --git a/test/unit/middleware/karma.spec.coffee b/test/unit/middleware/karma.spec.coffee
index d806e7130..dbb58c59f 100644
--- a/test/unit/middleware/karma.spec.coffee
+++ b/test/unit/middleware/karma.spec.coffee
@@ -21,16 +21,17 @@ describe 'middleware.karma', ->
         'debug.html': mocks.fs.file(0, 'DEBUG\n%SCRIPTS%\n%X_UA_COMPATIBLE%')
         'karma.js': mocks.fs.file(0, 'root: %KARMA_URL_ROOT%, v: %KARMA_VERSION%')
 
-  serveFile = require('../../../lib/middleware/common').createServeFile fsMock, '/karma/static'
+  createServeFile = require('../../../lib/middleware/common').createServeFile
   createKarmaMiddleware = require('../../../lib/middleware/karma').create
 
-  handler = filesDeferred = nextSpy = response = null
+  handler = serveFile = filesDeferred = nextSpy = response = null
 
   beforeEach ->
     clientConfig = foo: 'bar'
     nextSpy = sinon.spy()
     response = new HttpResponseMock
     filesDeferred = q.defer()
+    serveFile = createServeFile fsMock, '/karma/static'
     handler = createKarmaMiddleware filesDeferred.promise, serveFile,
       '/base/path', '/__karma__/', clientConfig