Add Redis cache backend

README.md

@@ -60,8 +60,8 @@ Full installation (including optional dependencies)
 pip install git+https://git.pictuga.com/pictuga/morss.git#[full]
 ```
 
-The full install includes mysql (possible cache backend). Otherwise, only
-in-memory and sqlite3 caches are available.
+The full install includes mysql and redis (possible cache backends). Otherwise,
+only in-memory and sqlite3 caches are available.
 
 The dependency `lxml` is fairly long to install (especially on Raspberry Pi, as
 C code needs to be compiled). If possible on your distribution, try installing
@@ -372,6 +372,8 @@ will be cleared every time the program is run). Path can be defined with
 `SQLITE_PATH`.
 - `CACHE=mysql`: MySQL cache. Connection can be defined with the following
 environment variables: `MYSQL_USER`, `MYSQL_PWD`, `MYSQL_DB`, `MYSQL_HOST`
+- `CACHE=redis`: Redis cache. Connection can be defined with the following
+environment variables: `REDIS_HOST`, `REDIS_PORT`, `REDIS_DB`, `REDIS_PWD`
 
 To limit the size of the cache:
 

morss/cache.py

@@ -141,6 +141,23 @@ class CappedDict(OrderedDict, BaseCache):
         OrderedDict.__setitem__(self, key, data)
 
 
+try:
+    import redis # isort:skip
+except ImportError:
+    pass
+
+
+class RedisCacheHandler(BaseCache):
+    def __init__(self, host='localhost', port=6379, db=0, password=None):
+        self.r = redis.Redis(host=host, port=port, db=db, password=password)
+
+    def __getitem__(self, key):
+        return self.r.get(key)
+
+    def __setitem__(self, key, data):
+        self.r.set(key, data)
+
+
 if 'CACHE' in os.environ:
     if os.environ['CACHE'] == 'mysql':
         default_cache = MySQLCacheHandler(
@@ -159,5 +176,13 @@ if 'CACHE' in os.environ:
 
         default_cache = SQLiteCache(path)
 
+    elif os.environ['CACHE'] == 'redis':
+        default_cache = RedisCacheHandler(
+            host = os.getenv('REDIS_HOST', 'localhost'),
+            port = int(os.getenv('REDIS_PORT', 6379)),
+            db = int(os.getenv('REDIS_DB', 0)),
+            password = os.getenv('REDIS_PWD', None)
+        )
+
 else:
         default_cache = CappedDict()

setup.py

@@ -14,7 +14,7 @@ setup(
     license = 'AGPL v3',
     packages = [package_name],
     install_requires = ['lxml', 'bs4', 'python-dateutil', 'chardet'],
-    extras_require = {'full': ['pymysql']},
+    extras_require = {'full': ['pymysql', 'redis']},
     package_data = {package_name: ['feedify.ini']},
     data_files = [
         ('share/' + package_name, ['README.md', 'LICENSE']),