Talking to a Redis server

mutalyzer/config/default_settings.py

@@ -26,7 +26,12 @@ MAX_CACHE_SIZE = 50 * 1048576 # 50 MB
 # Maximum size for uploaded and downloaded files (in bytes).
 MAX_FILE_SIZE = 10 * 1048576 # 10 MB
 
-# Database connection URL (can be any SQLAlchemy connection URI).
+# Redis connection URI (can be any redis-py connection URI). Redis is used
+# for keeping statistics counters. Setting this to `None`, will silently
+# yield a mock Redis.
+REDIS_URI = None
+
+# Database connection URI (can be any SQLAlchemy connection URI).
 DATABASE_URI = 'sqlite://'
 
 # Host name for local MySQL databases.

mutalyzer/redisclient.py

+"""
+Lazy global interface to Redis.
+
+Redis connections can safely be shared among threads, so we can keep this very
+simple and just use one global connection pool as created by `StrictRedis`.
+
+.. note:: Redis is only used for non-essential features in Mutalyzer and
+    therefore a Redis server is not a hard requirement to run Mutalyzer.
+
+    If the `REDIS_URI` configuration setting is `None`, we silently
+    instantiate a mock interface to Redis.
+"""
+
+
+import redis
+
+from mutalyzer import settings
+from mutalyzer import util
+
+
+class LazyClient(util.LazyObject):
+    """
+    A lazy proxy for a `StrictRedis` object.
+    """
+    def _setup(self):
+        """
+        Instantiate the Redis interface. This called the first time Redis is
+        used.
+        """
+        if settings.REDIS_URI is None:
+            import mockredis
+            self._wrapped = mockredis.MockRedis(strict=True)
+        else:
+            self._wrapped = redis.StrictRedis.from_url(settings.REDIS_URI)
+
+
+client = LazyCLient()

requirements.txt

@@ -18,3 +18,5 @@ Jinja2==2.7.1
 -e git+https://github.com/mammadori/magic-python.git#egg=Magic_file_extensions
 Flask==0.10.1
 https://bitbucket.org/zzzeek/sqlalchemy/downloads/SQLAlchemy-0.9.0b1.tar.gz
+redis==2.8.0
+mockredispy==2.8.0.2