implement token bucket rate limiting

app/logical/anonymous_user.rb

@@ -180,13 +180,13 @@ class AnonymousUser
   def enable_sequential_post_navigation
     true
   end
+
+  def api_regen_multiplier
+    1
+  end
   
-  def api_hourly_limit(idempotent = false)
-    if idempotent
-      500
-    else
-      5
-    end
+  def api_burst_limit
+    5
   end
   
   def statement_timeout

app/logical/api_limiter.rb

@@ -1,26 +0,0 @@
-module ApiLimiter
-  def self.idempotent?(method)
-    case method
-    when "POST", "PUT", "DELETE", "PATCH"
-      false
-
-    else
-      true
-    end
-  end
-
-  def throttled?(user_key, http_method = "GET")
-    idempotent = ApiLimiter.idempotent?(http_method)
-    key = "api/#{user_key}/#{Time.now.hour}/#{idempotent}"
-    MEMCACHE.fetch(key, 1.hour, :raw => true) {0}
-    MEMCACHE.incr(key).to_i > CurrentUser.user.api_hourly_limit(idempotent)
-  end
-
-  def remaining_hourly_limit(user_key, idempotent = true)
-    key = "api/#{user_key}/#{Time.now.hour}/#{idempotent}"
-    requests = MEMCACHE.fetch(key, 1.hour, :raw => true) {0}.to_i
-    CurrentUser.user.api_hourly_limit(idempotent) - requests
-  end
-  
-  module_function :throttled?, :remaining_hourly_limit
-end

app/logical/daily_maintenance.rb

@@ -17,5 +17,6 @@ class DailyMaintenance
     Tag.clean_up_negative_post_counts!
     PostApproval.prune!
     SuperVoter.init!
+    TokenBucket.prune!
   end
 end