add '?v=<date>' to require URLs

- resets cache on server restart
- don't cache requests on master (rely on 304 for content caching)

IPython/html/base/handlers.py

@@ -130,6 +130,11 class IPythonHandler(AuthenticatedHandler):
     #---------------------------------------------------------------
     
     @property
+    def version_hash(self):
+        """The version hash to use for cache hints for static files"""
+        return self.settings.get('version_hash', '')
+    
+    @property
     def mathjax_url(self):
         return self.settings.get('mathjax_url', '')
     
@@ -240,6 +245,7 class IPythonHandler(AuthenticatedHandler):
             static_url=self.static_url,
             sys_info=sys_info,
             contents_js_source=self.contents_js_source,
+            version_hash=self.version_hash,
         )
     
     def get_json_body(self):

IPython/html/notebookapp.py

@@ -7,6 +7,7
 from __future__ import print_function
 
 import base64
+import datetime
 import errno
 import io
 import json
@@ -84,6 +85,7 from IPython.utils.traitlets import (
 )
 from IPython.utils import py3compat
 from IPython.utils.path import filefind, get_ipython_dir
+from IPython.utils.sysinfo import get_sys_info
 
 from .utils import url_path_join
 
@@ -151,6 +153,15 class NotebookWebApplication(web.Application):
 
         jenv_opt = jinja_env_options if jinja_env_options else {}
         env = Environment(loader=FileSystemLoader(template_path), **jenv_opt)
+        
+        sys_info = get_sys_info()
+        if sys_info['commit_source'] == 'repository':
+            # don't cache (rely on 304) when working from master
+            version_hash = ''
+        else:
+            # reset the cache on server restart
+            version_hash = datetime.datetime.now().strftime("%Y%m%d%H%M%S")
+
         settings = dict(
             # basics
             log_function=log_request,
@@ -160,6 +171,7 class NotebookWebApplication(web.Application):
             static_path=ipython_app.static_file_path,
             static_handler_class = FileFindHandler,
             static_url_prefix = url_path_join(base_url,'/static/'),
+            version_hash=version_hash,
             
             # authentication
             cookie_secret=ipython_app.cookie_secret,

IPython/html/templates/page.html

@@ -18,6 +18,9
     <script src="{{static_url("components/requirejs/require.js") }}" type="text/javascript" charset="utf-8"></script>
     <script>
       require.config({
+          {% if version_hash %}
+          urlArgs: "v={{version_hash}}",
+          {% endif %}
           baseUrl: '{{static_url("", include_version=False)}}',
           paths: {
             nbextensions : '{{ base_url }}nbextensions',