Initial commit

lib/carto/user_db_size_cache.rb

@@ -0,0 +1,55 @@
+module Carto
+  class UserDbSizeCache
+
+    DB_SIZE_IN_BYTES_EXPIRATION = 2.days
+
+    UPDATE_PROPAGATION_THRESHOLD = 8.hours
+
+    BATCH_SIZE = 100
+
+    def initialize(redis_cache = $users_metadata)
+      @redis = redis_cache
+    end
+
+    def update_if_old(user)
+      if last_updated(user) > UPDATE_PROPAGATION_THRESHOLD
+        set_db_size_in_bytes(user)
+      end
+    end
+
+    def db_size_in_bytes(user)
+      @redis.get(db_size_in_bytes_key(user.username)).to_i
+    end
+
+    def db_size_in_bytes_change_users
+      keys = @redis.scan_each(match: db_size_in_bytes_key('*')).to_a.uniq
+
+      db_size_in_bytes_change_users = {}
+
+      keys.each_slice(BATCH_SIZE) do |key_batch|
+        usernames = key_batch.map { |key| extract_username_from_key(key) }
+        db_size_in_bytes_change_users.merge!(Hash[usernames.zip(@redis.mget(key_batch).map(&:to_i))])
+      end
+
+      db_size_in_bytes_change_users
+    end
+
+    private
+
+    def last_updated(user)
+      DB_SIZE_IN_BYTES_EXPIRATION - @redis.ttl(db_size_in_bytes_key(user.username))
+    end
+
+    def set_db_size_in_bytes(user)
+      @redis.setex(db_size_in_bytes_key(user.username), DB_SIZE_IN_BYTES_EXPIRATION.to_i, user.db_size_in_bytes)
+    end
+
+    def db_size_in_bytes_key(username)
+      "rails:users:#{username}:db_size_in_bytes"
+    end
+
+    def extract_username_from_key(key)
+      /#{db_size_in_bytes_key('(.*)')}/.match(key)[1]
+    end
+  end
+end