cache PBKDF2 hash, closes #18

Markdown conversion is not the reason for 2s per 100 comments response,
the hash function is. When using the email/remote_addr from cache, the
response time is pretty fast.

* when uWSGI is available, use their caching framework

* for multi-threaded environment (the default), use a simple cache
  shipped with werkzeug

isso.ini

@@ -2,6 +2,7 @@
 http = :8080
 master = true
 processes = 4
+cache2 = name=hash,items=1024,blocksize=32
 spooler = %v/mail
 module = isso
 virtualenv = .

isso/core.py

@@ -30,6 +30,8 @@ from isso import notify
 from isso.utils import parse
 from isso.compat import text_type as str
 
+from werkzeug.contrib.cache import NullCache, SimpleCache
+
 logger = logging.getLogger("isso")
 
 
@@ -137,10 +139,29 @@ def SMTP(conf):
     return mailer
 
 
+class Cache:
+    """Wrapper around werkzeug's cache class, to make it compatible to
+    uWSGI's cache framework.
+    """
+
+    def __init__(self, cache):
+        self.cache = cache
+
+    def get(self, cache, key):
+        return self.cache.get(key)
+
+    def set(self, cache, key, value):
+        return self.cache.set(key, value)
+
+    def delete(self, cache, key):
+        return self.cache.delete(key)
+
+
 class Mixin(object):
 
     def __init__(self, conf):
         self.lock = threading.Lock()
+        self.cache = Cache(NullCache())
 
     def notify(self, subject, body, retries=5):
         pass
@@ -167,7 +188,7 @@ class ThreadedMixin(Mixin):
             self.purge(conf.getint("moderation", "purge-after"))
 
         self.mailer = SMTP(conf)
-
+        self.cache = Cache(SimpleCache(threshold=1024, default_timeout=3600))
 
     @threaded
     def notify(self, subject, body, retries=5):
@@ -188,6 +209,28 @@ class ThreadedMixin(Mixin):
             time.sleep(delta)
 
 
+class uWSGICache(object):
+    """Uses uWSGI Caching Framework. INI configuration:
+
+    .. code-block:: ini
+
+        cache2 = name=hash,items=1024,blocksize=32
+
+    """
+
+    @classmethod
+    def get(self, cache, key):
+        return uwsgi.cache_get(key, cache)
+
+    @classmethod
+    def set(self, cache, key, value):
+        uwsgi.cache_set(key, value, 3600, cache)
+
+    @classmethod
+    def delete(self, cache, key):
+        uwsgi.cache_del(key, cache)
+
+
 class uWSGIMixin(Mixin):
 
     def __init__(self, conf):
@@ -210,9 +253,11 @@ class uWSGIMixin(Mixin):
             else:
                 return uwsgi.SPOOL_OK
 
+        uwsgi.spooler = spooler
+
         self.lock = Lock()
         self.mailer = SMTP(conf)
-        uwsgi.spooler = spooler
+        self.cache = uWSGICache
 
         timedelta = conf.getint("moderation", "purge-after")
         purge = lambda signum: self.db.comments.purge(timedelta)

isso/views/comment.py

@@ -166,6 +166,7 @@ def single(app, environ, request, id):
         for key in set(rv.keys()) - FIELDS:
             rv.pop(key)
 
+        app.cache.delete('hash', id)
         logger.info('comment %i edited: %s', id, json.dumps(rv))
 
         checksum = hashlib.md5(rv["text"].encode('utf-8')).hexdigest()
@@ -182,6 +183,7 @@ def single(app, environ, request, id):
             for key in set(rv.keys()) - FIELDS:
                 rv.pop(key)
 
+        app.cache.delete('hash', id)
         logger.info('comment %i deleted', id)
 
         resp = Response(json.dumps(rv), 200, content_type='application/json')
@@ -198,7 +200,14 @@ def fetch(app, environ, request, uri):
 
     for item in rv:
 
-        item['hash'] = str(pbkdf2(item['email'] or item['remote_addr'], app.salt, 1000, 6))
+        key = item['email'] or item['remote_addr']
+        val = app.cache.get('hash', key)
+
+        if val is None:
+            val = str(pbkdf2(key, app.salt, 1000, 6))
+            app.cache.set('hash', key, val)
+
+        item['hash'] = val
 
         for key in set(item.keys()) - FIELDS:
             item.pop(key)