Docs: Use ETags.

BUG=270818
R=jyasskin@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/218363002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261222 0039d316-1c4b-4281-b951-d872f2087c98

9 files changed, 100 insertions, 18 deletions

diff --git a/chrome/common/extensions/docs/server2/app.yaml b/chrome/common/extensions/docs/server2/app.yaml
index c3ddbcc..0df4ad1 100644
--- a/chrome/common/extensions/docs/server2/app.yaml
+++ b/chrome/common/extensions/docs/server2/app.yaml
@@ -1,5 +1,5 @@
 application: chrome-apps-doc
-version: 3-17-1
+version: 3-17-2
 runtime: python27
 api_version: 1
 threadsafe: false
diff --git a/chrome/common/extensions/docs/server2/content_provider.py b/chrome/common/extensions/docs/server2/content_provider.py
index 2a6de2a..8dd963a 100644
--- a/chrome/common/extensions/docs/server2/content_provider.py
+++ b/chrome/common/extensions/docs/server2/content_provider.py
@@ -27,9 +27,10 @@ class ContentAndType(object):
   '''Return value from ContentProvider.GetContentAndType.
   '''
 
-  def __init__(self, content, content_type):
+  def __init__(self, content, content_type, version):
     self.content = content
     self.content_type = content_type
+    self.version = version
 
 
 class ContentProvider(object):
@@ -100,7 +101,9 @@ class ContentProvider(object):
       content = ToUnicode(text)
     else:
       content = text
-    return ContentAndType(content, mimetype)
+    return ContentAndType(content,
+                          mimetype,
+                          self.file_system.Stat(path).version)
 
   def GetCanonicalPath(self, path):
     '''Gets the canonical location of |path|. This class is tolerant of
@@ -133,7 +136,7 @@ class ContentProvider(object):
     if self._directory_zipper and ext == '.zip':
       zip_future = self._directory_zipper.Zip(ToDirectory(base))
       return Future(callback=
-          lambda: ContentAndType(zip_future.Get(), 'application/zip'))
+          lambda: ContentAndType(zip_future.Get(), 'application/zip', None))
 
     # If there is no file extension, look for a file with one of the default
     # extensions.
diff --git a/chrome/common/extensions/docs/server2/cron.yaml b/chrome/common/extensions/docs/server2/cron.yaml
index 85fb013..b503692 100644
--- a/chrome/common/extensions/docs/server2/cron.yaml
+++ b/chrome/common/extensions/docs/server2/cron.yaml
@@ -2,4 +2,4 @@ cron:
 - description: Repopulates all cached data.
   url: /_cron
   schedule: every 5 minutes
-  target: 3-17-1
+  target: 3-17-2
diff --git a/chrome/common/extensions/docs/server2/local_renderer.py b/chrome/common/extensions/docs/server2/local_renderer.py
index 96b15f1..ef43dcd 100644
--- a/chrome/common/extensions/docs/server2/local_renderer.py
+++ b/chrome/common/extensions/docs/server2/local_renderer.py
@@ -14,7 +14,7 @@ class LocalRenderer(object):
   '''Renders pages fetched from the local file system.
   '''
   @staticmethod
-  def Render(path):
+  def Render(path, headers=None):
     assert not '\\' in path
-    return RenderServlet(Request.ForTest(path),
+    return RenderServlet(Request.ForTest(path, headers=headers),
                          _LocalRenderServletDelegate()).Get()
diff --git a/chrome/common/extensions/docs/server2/patch_servlet_test.py b/chrome/common/extensions/docs/server2/patch_servlet_test.py
index 0dcebaa..11d0289 100755
--- a/chrome/common/extensions/docs/server2/patch_servlet_test.py
+++ b/chrome/common/extensions/docs/server2/patch_servlet_test.py
@@ -73,8 +73,9 @@ class PatchServletTest(unittest.TestCase):
     '''
     patched_response = self._RenderWithPatch(path, issue)
     unpatched_response = self._RenderWithoutPatch(path)
-    patched_response.headers.pop('cache-control', None)
-    unpatched_response.headers.pop('cache-control', None)
+    for header in ('Cache-Control', 'ETag'):
+      patched_response.headers.pop(header, None)
+      unpatched_response.headers.pop(header, None)
     unpatched_content = unpatched_response.content.ToString()
 
     # Check that all links in the patched content are qualified with
diff --git a/chrome/common/extensions/docs/server2/preview.py b/chrome/common/extensions/docs/server2/preview.py
index 1d10205..c2c3bfe 100755
--- a/chrome/common/extensions/docs/server2/preview.py
+++ b/chrome/common/extensions/docs/server2/preview.py
@@ -47,7 +47,8 @@ class _RequestHandler(BaseHTTPRequestHandler):
       '/favicon.ico': '../../server2/chrome-32.ico',
       '/apple-touch-icon-precomposed.png': '../../server2/chrome-128.png'
     }.get(self.path, self.path)
-    response = LocalRenderer.Render(self.path)
+    response = LocalRenderer.Render(self.path, headers=dict(self.headers))
+    self.protocol_version = 'HTTP/1.1'
     self.send_response(response.status)
     for k, v in response.headers.iteritems():
       self.send_header(k, v)
diff --git a/chrome/common/extensions/docs/server2/render_servlet.py b/chrome/common/extensions/docs/server2/render_servlet.py
index c714b5d..3c783d4 100644
--- a/chrome/common/extensions/docs/server2/render_servlet.py
+++ b/chrome/common/extensions/docs/server2/render_servlet.py
@@ -2,6 +2,7 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+import hashlib
 import logging
 import posixpath
 import traceback
@@ -15,12 +16,16 @@ from special_paths import SITE_VERIFICATION_FILE
 from third_party.handlebar import Handlebar
 
 
-def _MakeHeaders(content_type):
-  return {
-    'X-Frame-Options': 'sameorigin',
+def _MakeHeaders(content_type, etag=None):
+  headers = {
+    # See http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9.1.
+    'Cache-Control': 'public, max-age=0, no-cache',
     'Content-Type': content_type,
-    'Cache-Control': 'max-age=300',
+    'X-Frame-Options': 'sameorigin',
   }
+  if etag is not None:
+    headers['ETag'] = etag
+  return headers
 
 
 class RenderServlet(Servlet):
@@ -122,10 +127,28 @@ class RenderServlet(Servlet):
       if warnings:
         sep = '\n - '
         logging.warning('Rendering %s:%s%s' % (path, sep, sep.join(warnings)))
+      # Content was dynamic. The new etag is a hash of the content.
+      etag = None
+    elif content_and_type.version is not None:
+      # Content was static. The new etag is the version of the content.
+      etag = '"%s"' % content_and_type.version
+    else:
+      # Sometimes non-dynamic content does not have a version, for example
+      # .zip files. The new etag is a hash of the content.
+      etag = None
 
     content_type = content_and_type.content_type
     if isinstance(content, unicode):
       content = content.encode('utf-8')
       content_type += '; charset=utf-8'
 
-    return Response.Ok(content, headers=_MakeHeaders(content_type))
+    if etag is None:
+      # Note: we're using md5 as a convenient and fast-enough way to identify
+      # content. It's not intended to be cryptographic in any way, and this
+      # is *not* what etags is for. That's what SSL is for, this is unrelated.
+      etag = '"%s"' % hashlib.md5(content).hexdigest()
+
+    headers = _MakeHeaders(content_type, etag=etag)
+    if etag == self._request.headers.get('If-None-Match'):
+      return Response.NotModified('Not Modified', headers=headers)
+    return Response.Ok(content, headers=headers)
diff --git a/chrome/common/extensions/docs/server2/render_servlet_test.py b/chrome/common/extensions/docs/server2/render_servlet_test.py
index 1857028..5ab95a9 100755
--- a/chrome/common/extensions/docs/server2/render_servlet_test.py
+++ b/chrome/common/extensions/docs/server2/render_servlet_test.py
@@ -19,8 +19,8 @@ class _RenderServletDelegate(RenderServlet.Delegate):
 
 
 class RenderServletTest(unittest.TestCase):
-  def _Render(self, path):
-    return RenderServlet(Request.ForTest(path),
+  def _Render(self, path, headers=None):
+    return RenderServlet(Request.ForTest(path, headers=headers),
                          _RenderServletDelegate()).Get()
 
   def testExtensionAppRedirect(self):
@@ -110,6 +110,35 @@ class RenderServletTest(unittest.TestCase):
     # whether or not that exists.
     self.assertEqual(('/dir', False), self._Render('dir/').GetRedirect())
 
+  def testEtags(self):
+    def test_path(path, content_type):
+      # Render without etag.
+      response = self._Render(path)
+      self.assertEqual(200, response.status)
+      etag = response.headers.get('ETag')
+      self.assertTrue(etag is not None)
+
+      # Render with an If-None-Match which doesn't match.
+      response = self._Render(path, headers={
+        'If-None-Match': '"fake etag"',
+      })
+      self.assertEqual(200, response.status)
+      self.assertEqual(content_type, response.headers.get('Content-Type'))
+      self.assertEqual(etag, response.headers.get('ETag'))
+
+      # Render with the correct matching If-None-Match.
+      response = self._Render(path, headers={
+        'If-None-Match': etag,
+      })
+      self.assertEqual(304, response.status)
+      self.assertEqual('Not Modified', response.content.ToString())
+      self.assertEqual(content_type, response.headers.get('Content-Type'))
+      self.assertEqual(etag, response.headers.get('ETag'))
+
+    # Test with a static path and a dynamic path.
+    test_path('static/css/out/site.css', 'text/css; charset=utf-8')
+    test_path('extensions/storage', 'text/html; charset=utf-8')
+
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/chrome/common/extensions/docs/server2/servlet.py b/chrome/common/extensions/docs/server2/servlet.py
index f7c14e7..7672ca5 100644
--- a/chrome/common/extensions/docs/server2/servlet.py
+++ b/chrome/common/extensions/docs/server2/servlet.py
@@ -2,13 +2,34 @@
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
+
+class RequestHeaders(object):
+  '''A custom dictionary impementation for headers which ignores the case
+  of requests, since different HTTP libraries seem to mangle them.
+  '''
+  def __init__(self, dict_):
+    if isinstance(dict_, RequestHeaders):
+      self._dict = dict_
+    else:
+      self._dict = dict((k.lower(), v) for k, v in dict_.iteritems())
+
+  def get(self, key, default=None):
+    return self._dict.get(key.lower(), default)
+
+  def __repr__(self):
+    return repr(self._dict)
+
+  def __str__(self):
+    return repr(self._dict)
+
+
 class Request(object):
   '''Request data.
   '''
   def __init__(self, path, host, headers):
     self.path = path.lstrip('/')
     self.host = host.rstrip('/')
-    self.headers = headers
+    self.headers = RequestHeaders(headers)
 
   @staticmethod
   def ForTest(path, host='http://developer.chrome.com', headers=None):
@@ -77,6 +98,10 @@ class Response(object):
     return Response(content=content, headers=headers, status=404)
 
   @staticmethod
+  def NotModified(content, headers=None):
+    return Response(content=content, headers=headers, status=304)
+
+  @staticmethod
   def InternalError(content, headers=None):
     '''Returns an internal error (500) response.
     '''