add paid article cache

1 files changed, 28 insertions, 11 deletions

diff --git a/talerblog/blog/blog.py b/talerblog/blog/blog.py
index 20320f6..c118872 100644
--- a/talerblog/blog/blog.py
+++ b/talerblog/blog/blog.py
@@ -28,6 +28,7 @@ import uuid
 import base64
 import requests
 import flask
+from werkzeug.contrib.cache import SimpleCache
 from talerblog.talerconfig import TalerConfig
 from ..blog.content import ARTICLES, get_article_file, get_image_file
 
@@ -131,6 +132,28 @@ def refund(order_id):
     flask.abort(500)
 
 
+def render_article(article_name):
+    article_info = ARTICLES.get(article_name)
+    if article_info is None:
+        flask.abort(500)
+    if data is not None:
+        if data in article_info.extra_files:
+            return flask.send_file(get_image_file(data))
+        return "permission denied", 403
+    # needed for refunds
+    order_id = flask.request.args.get("order_id")
+    return flask.render_template("templates/article_frame.html",
+                                 article_file=get_article_file(article_info),
+                                 article_name=article_name,
+                                 order_id=order_id)
+
+
+# Cache for paid articles (in the form <session_id>-<article_name>), so we
+# don't always have to ask the backend / DB, and so we don't have to store
+# variable-size cookies on the client.
+paid_articles_cache = SimpleCache()
+
+
 @app.route("/essay/<article_name>")
 @app.route("/essay/<article_name>/data/<data>")
 def article(article_name, data=None):
@@ -145,6 +168,9 @@ def article(article_name, data=None):
     if not session_id:
         session_id = flask.session["uid"] = uuid.uuid4()
 
+    if paid_articles_cache.get(session_id + "-" + article_name):
+        return render_article(article_name)
+
     if order_id and not session_sig:
         # If there was an order_id but no session_sig, either the user played
         # around with the URL or the wallet is old/broken.
@@ -180,17 +206,8 @@ def article(article_name, data=None):
                                      article_name=article_name)
 
     if pay_status.get("paid"):
-        article_info = ARTICLES.get(article_name)
-        if article_info is None:
-            flask.abort(500)
-        if data is not None:
-            if data in article_info.extra_files:
-                return flask.send_file(get_image_file(data))
-            return "permission denied", 403
-        return flask.render_template("templates/article_frame.html",
-                                     article_file=get_article_file(article_info),
-                                     article_name=article_name,
-                                     order_id=order_id)
+        paid_articles_cache.set(session_id + "-" + article_name, True)
+        return render_article(article_name)
 
     # no pay_redirect but article not paid, this should never happen!
     flask.abort(500)