FIX: emoji cache could get corrupt

FEATURE: enforce 1 day expiry by default on discourse cache

remove family expiry concept as the implementation was fragile

lib/cache.rb

@@ -1,9 +1,15 @@
-# Discourse specific cache supports expire by family missing from standard cache
+# Discourse specific cache, enforces 1 day expiry
 
 class Cache < ActiveSupport::Cache::Store
 
+  # nothing is cached for longer than 1 day EVER
+  # there is no reason to have data older than this clogging redis
+  # it is dangerous cause if we rename keys we will be stuck with
+  # pointless data
+  MAX_CACHE_AGE = 1.day unless defined? MAX_CACHE_AGE
+
   def initialize(opts = {})
-    opts[:namespace] ||= "_CACHE_"
+    @namespace = opts[:namespace] || "_CACHE_"
     super(opts)
   end
 
@@ -11,27 +17,18 @@ class Cache < ActiveSupport::Cache::Store
     $redis
   end
 
-  def delete_by_family(key)
-    k = family_key(key, options)
-    redis.smembers(k).each do |member|
-      redis.del(member)
-    end
-    redis.del(k)
-  end
-
   def reconnect
     redis.reconnect
   end
 
   def clear
-    redis.keys.each do |k|
-      redis.del(k) if k =~ /^_CACHE_:/
+    redis.keys("#{@namespace}:*").each do |k|
+      redis.del(k)
     end
   end
 
   def namespaced_key(key, opts=nil)
-    opts ||= options
-    super(key,opts)
+    "#{@namespace}:" << key
   end
 
   protected
@@ -47,17 +44,8 @@ class Cache < ActiveSupport::Cache::Store
 
   def write_entry(key, entry, options)
     dumped = Marshal.dump(entry.value)
-
-    if expiry = options[:expires_in]
-      redis.setex(key, expiry, dumped)
-    else
-      redis.set(key, dumped)
-    end
-
-    if family = family_key(options[:family], options)
-      redis.sadd(family, key)
-    end
-
+    expiry = options[:expires_in] || MAX_CACHE_AGE
+    redis.setex(key, expiry, dumped)
     true
   end
 
@@ -65,13 +53,4 @@ class Cache < ActiveSupport::Cache::Store
     redis.del key
   end
 
-  private
-
-  def family_key(name, options)
-    if name
-      key = namespaced_key(name, options)
-      key << "FAMILY:#{name}"
-    end
-  end
-
 end