implement token bucket rate limiting

db/migrate/20170106012138_create_token_buckets.rb

@@ -0,0 +1,10 @@
+class CreateTokenBuckets < ActiveRecord::Migration
+  def up
+  	execute "create unlogged table token_buckets (user_id integer, last_touched_at timestamp not null, token_count real not null)"
+  	add_index :token_buckets, :user_id, :unique => true
+  end
+
+  def down
+  	raise NotImplementedError
+  end
+end

db/structure.sql

@@ -3054,6 +3054,17 @@ CREATE SEQUENCE tags_id_seq
 ALTER SEQUENCE tags_id_seq OWNED BY tags.id;
 
 
+--
+-- Name: token_buckets; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE UNLOGGED TABLE token_buckets (
+    user_id integer,
+    last_touched_at timestamp without time zone NOT NULL,
+    token_count real NOT NULL
+);
+
+
 --
 -- Name: uploads; Type: TABLE; Schema: public; Owner: -
 --
@@ -6963,6 +6974,13 @@ CREATE UNIQUE INDEX index_tags_on_name ON tags USING btree (name);
 CREATE INDEX index_tags_on_name_pattern ON tags USING btree (name text_pattern_ops);
 
 
+--
+-- Name: index_token_buckets_on_user_id; Type: INDEX; Schema: public; Owner: -
+--
+
+CREATE UNIQUE INDEX index_token_buckets_on_user_id ON token_buckets USING btree (user_id);
+
+
 --
 -- Name: index_uploads_on_uploader_id; Type: INDEX; Schema: public; Owner: -
 --
@@ -7389,3 +7407,5 @@ INSERT INTO schema_migrations (version) VALUES ('20161227003428');
 
 INSERT INTO schema_migrations (version) VALUES ('20161229001201');
 
+INSERT INTO schema_migrations (version) VALUES ('20170106012138');
+