use proper transactions

isso/__init__.py

@@ -180,7 +180,7 @@ def make_app(conf):
     if uwsgi is not None:
         cacheobj = cache.uWSGICache(timeout=3600)
     else:
-        cacheobj = cache.SACache(dbobj, threshold=2048)
+        cacheobj = cache.SACache(conf.get("general", "dbpath"), threshold=2048)
 
     jobs = tasks.Jobs()
     jobs.register("db-purge", dbobj, conf.getint("moderation", "purge-after"))

isso/cache/sa.py

@@ -4,64 +4,79 @@ from __future__ import absolute_import, unicode_literals
 
 import time
 
+from sqlalchemy import Table, Column, MetaData, create_engine
+from sqlalchemy import Float, String, LargeBinary
 from sqlalchemy.sql import select, func
 
 from . import Base
 
 
-class SACache(Base):
-    """Implements cache using SQLAlchemy Core.
-
-    JSON is used for safe serialization of python primitives.
-    """
-
-    serialize = True
-
-    def __init__(self, db, threshold=1024, timeout=-1):
-        super(SACache, self).__init__(threshold, timeout)
-        self.db = db
-
-    def _get(self, ns, key):
-        rv = self.db.engine.execute(
-            select([self.db.cache.c.value]).where(
-                self.db.cache.c.key == ns + b'-' + key)).fetchone()
+def get(con, cache, key):
+    rv = con.execute(
+        select([cache.c.value]).where(
+            cache.c.key == key)).fetchone()
 
     if rv is None:
         raise KeyError
 
     return rv[0]
 
-    def _set(self, ns, key, value):
-        with self.db.transaction:
-            cnt = self.db.engine.execute(
-                select([func.count(self.db.cache)])).fetchone()[0]
 
-            if cnt + 1 > self.threshold:
-                self.db.engine.execute(
-                    self.db.cache.delete().where(
-                        self.db.cache.c.key.in_(select(
-                            [self.db.cache.c.key])
-                            .order_by(self.db.cache.c.time)
+def set(con, cache, key, value, threshold):
+    cnt = con.execute(
+        select([func.count(cache)])).fetchone()[0]
+
+    if cnt + 1 > threshold:
+        con.execute(
+            cache.delete().where(
+                cache.c.key.in_(select(
+                    [cache.c.key])
+                    .order_by(cache.c.time)
                     .limit(1))))
 
     try:
-                self._get(ns, key)
+        get(con, cache, key)
     except KeyError:
         insert = True
     else:
         insert = False
 
     if insert:
-                stmt = self.db.cache.insert().values(
-                    key=ns + b'-' + key, value=value, time=time.time())
+        stmt = cache.insert().values(key=key, value=value, time=time.time())
     else:
-                stmt = self.db.cache.update().values(
-                    value=value, time=time.time()).where(
-                        self.db.cache.c.key == ns + b'-' + key)
+        stmt = cache.update().values(value=value, time=time.time()) \
+                             .where(cache.c.key == key)
 
-            self.db.engine.execute(stmt)
+    con.execute(stmt)
+
+
+def delete(con, cache, key):
+    con.execute(cache.delete(cache.c.key == key))
+
+
+class SACache(Base):
+    """Implements cache using SQLAlchemy Core.
+    """
+
+    serialize = True
+
+    def __init__(self, db, threshold=1024, timeout=-1):
+        super(SACache, self).__init__(threshold, timeout)
+        self.metadata = MetaData()
+        self.engine = create_engine(db)
+
+        self.cache = Table("cache", self.metadata,
+            Column("key", String(255), primary_key=True),
+            Column("value", LargeBinary(65535)),
+            Column("time", Float))
+
+        self.metadata.create_all(self.engine)
+
+    def _get(self, ns, key):
+        return get(self.engine.connect(), self.cache, ns + b'-' + key)
+
+    def _set(self, ns, key, value):
+        set(self.engine.connect(), self.cache, ns + b'-' + key, value, self.threshold)
 
     def _delete(self, ns, key):
-        with self.db.transaction:
-            self.db.engine.execute(
-                self.db.cache.delete(self.db.cache.c.key == ns + b'-' + key))
+        delete(self.engine.connect(), self.cache, ns + b'-' + key)

isso/db.py

@@ -52,10 +52,6 @@ class Adapter(object):
             Column("key", String(255), primary_key=True),
             Column("value", String(255)))
 
-        self.cache = Table("cache", self.metadata,
-            Column("key", String(255), primary_key=True),
-            Column("value", LargeBinary(65535)),
-            Column("time", Float))
 
         self.metadata.create_all(self.engine)
         self.preferences = Preferences(self.engine, preferences)