Merge branch '11-static-cache' into 'master'

Resolve "Caching of Static Resources"

Closes #11

See merge request s3lph/matemat!13

matemat/webserver/httpd.py

@@ -323,7 +323,7 @@ class HttpHandler(BaseHTTPRequestHandler):
             # Send the HTTP status code
             self.send_response(hsc)
             # Format the session cookie timeout string and send the session cookie header
-            expires = timeout.strftime("%a, %d %b %Y %H:%M:%S GMT")
+            expires = timeout.strftime('%a, %d %b %Y %H:%M:%S GMT')
             self.send_header('Set-Cookie',
                              f'matemat_session_id={session_id}; expires={expires}')
             # Compute the body length and add the appropriate header
@@ -345,6 +345,21 @@ class HttpHandler(BaseHTTPRequestHandler):
             filepath: str = os.path.abspath(os.path.join(self.server.webroot, path[1:]))
             # Make sure the file is actually inside the webroot directory and that it exists
             if os.path.commonpath([filepath, self.server.webroot]) == self.server.webroot and os.path.exists(filepath):
+                # Parse the If-Modified-Since header to check whether the browser can reuse cached content
+                datestr: str = self.headers.get('If-Modified-Since', 'Thu, 01 Jan 1970 00:00:00 GMT')
+                maxage: datetime = datetime.strptime(datestr, '%a, %d %b %Y %H:%M:%S %Z')
+                # Get file modification time
+                filestat: int = int(os.path.getmtime(filepath))
+                # Create UTC datetime object from mtime
+                fileage: datetime = datetime.utcfromtimestamp(filestat)
+
+                # If the file has not been replaced by a newer version than requested by the client, send a 304 response
+                if fileage <= maxage:
+                    self.send_response(304, 'Not Modified')
+                    self.send_header('Content-Length', '0')
+                    self.end_headers()
+                    return
+
                 # Open and read the file
                 with open(filepath, 'rb') as f:
                     data = f.read()
@@ -358,6 +373,8 @@ class HttpHandler(BaseHTTPRequestHandler):
                 # Send content type and length header
                 self.send_header('Content-Type', mimetype)
                 self.send_header('Content-Length', str(len(data)))
+                self.send_header('Last-Modified', fileage.strftime('%a, %d %b %Y %H:%M:%S GMT'))
+                self.send_header('Cache-Control', 'max-age=1')
                 self.end_headers()
                 # Send the requested resource as response body
                 self.wfile.write(data)

matemat/webserver/test/abstract_httpd_test.py

@@ -118,7 +118,7 @@ class MockServer:
         )
         # Set up logger
         self.logger: logging.Logger = logging.getLogger('matemat unit test')
-        self.logger.setLevel(0)
+        self.logger.setLevel(logging.DEBUG)
         # Initalize a log handler to stderr and set the log format
         sh: logging.StreamHandler = logging.StreamHandler()
         sh.setFormatter(logging.Formatter('%(asctime)s %(name)s [%(levelname)s]: %(message)s'))

matemat/webserver/test/test_serve.py

@@ -3,6 +3,8 @@ from typing import Any, Dict, Union
 
 import os
 import os.path
+from datetime import datetime, timedelta
+
 from matemat.exceptions import HttpException
 from matemat.webserver import HttpHandler, RequestArguments, PageletResponse, RedirectResponse, TemplateResponse
 from matemat.webserver.test.abstract_httpd_test import AbstractHttpdTest, test_pagelet
@@ -163,6 +165,34 @@ class TestServe(AbstractHttpdTest):
         self.assertEqual(403, packet.statuscode)
         self.assertNotEqual(b'This should not be readable', packet.body)
 
+    def test_serve_static_cache(self):
+        # Request a static resource
+        timeout: datetime = datetime.utcnow() + timedelta(hours=1)
+        timeoutstr = timeout.strftime('%a, %d %b %Y %H:%M:%S GMT')
+        self.client_sock.set_request(
+            f'GET /static_resource.txt HTTP/1.1\r\nIf-Modified-Since: {timeoutstr}\r\n\r\n'.encode('utf-8'))
+        HttpHandler(self.client_sock, ('::1', 45678), self.server)
+        packet = self.client_sock.get_response()
+
+        # Make sure that no pagelet was called
+        self.assertIsNone(packet.pagelet)
+        # Make sure a 304 Not Modified is sent and the body is empty
+        self.assertEqual(304, packet.statuscode)
+        self.assertEqual(0, len(packet.body))
+
+    def test_serve_static_cache_renew(self):
+        # Request a static resource
+        self.client_sock.set_request(
+            b'GET /static_resource.txt HTTP/1.1\r\nIf-Modified-Since: Mon, 01 Jan 2018 13:37:42 GMT\r\n\r\n')
+        HttpHandler(self.client_sock, ('::1', 45678), self.server)
+        packet = self.client_sock.get_response()
+
+        # Make sure that no pagelet was called
+        self.assertIsNone(packet.pagelet)
+        # Make sure the expected content is served
+        self.assertEqual(200, packet.statuscode)
+        self.assertEqual(b'static resource test', packet.body)
+
     def test_serve_not_found(self):
         # Request a nonexistent resource
         self.client_sock.set_request(b'GET /nonexistent HTTP/1.1\r\n\r\n')