BUGFIX: redis-rails has always been a problem child

implemented an ActiveSupport::Cache::Store for our internal use.
* allows for expire by family
* works correctly in multisite
* namespaced correctly

Removed redis-rails from the project, no longer needed

lib/cache.rb

@@ -1,55 +1,72 @@
-# Standard Rails.cache is lacking support for this interface, possibly yank all in from redis:cache and start using this instead
-#
+# Discourse specific cache supports expire by family missing from standard cache
 
-class Cache
-  def initialize(redis=nil)
-    @redis = redis
+class Cache < ActiveSupport::Cache::Store
+
+  def initialize(opts = {})
+    opts[:namespace] ||= "_CACHE_"
+    super(opts)
   end
 
   def redis
-    @redis || $redis
-  end
-
-  def fetch(key, options={})
-    result = redis.get key
-    if result.nil?
-      if expiry = options[:expires_in]
-        if block_given?
-          result = yield
-          redis.setex(key, expiry, result)
-        end
-      else
-        if block_given?
-          result = yield
-          redis.set(key, result)
-        end
-      end
-    end
-
-    if family = family_key(options[:family])
-      redis.sadd(family, key)
-    end
-
-    result
-  end
-
-  def delete(key)
-    redis.del(key)
+    $redis
   end
 
   def delete_by_family(key)
-    k = family_key(key)
+    k = family_key(key, options)
     redis.smembers(k).each do |member|
-      delete(member)
+      redis.del(member)
     end
     redis.del(k)
   end
 
-  private
+  def reconnect
+    redis.reconnect
+  end
 
-  def family_key(name)
-    if name
-      "FAMILY_#{name}"
+  def clear
+    redis.keys.each do |k|
+      redis.del(k) if k =~ /^_CACHE_:/
     end
   end
+
+  def namespaced_key(key, opts=nil)
+    opts ||= options
+    super(key,opts)
+  end
+
+  protected
+
+  def read_entry(key, options)
+    if data = redis.get(key)
+      ActiveSupport::Cache::Entry.new data
+    end
+  end
+
+  def write_entry(key, entry, options)
+    if expiry = options[:expires_in]
+      redis.setex(key, expiry, entry.value)
+    else
+      redis.set(key, entry.value)
+    end
+
+    if family = family_key(options[:family], options)
+      redis.sadd(family, key)
+    end
+
+    true
+  end
+
+  def delete_entry(key, options)
+    redis.del key
+  end
+
+  private
+
+  def family_key(name, options)
+    if name
+      key = namespaced_key(name, options)
+      key << "FAMILY:#{name}"
+    end
+  end
+
 end