Common thrift types

GFS uses several thrift datastructures which are common to multiple queries. They are listed below.

EdgeType

EdgeType is a thrift enum which specifies which edge types to query for the graph.

enum EdgeType {
  FOLLOWING,
  FOLLOWED_BY,
  FAVORITE,
  FAVORITED_BY,
  RETWEET,
  RETWEETED_BY,
  REPLY,
  REPLYED_BY,
  MENTION,
  MENTIONED_BY,
  MUTUAL_FOLLOW,
  SIMILAR_TO, // more edge types (like block, report, etc.) can be supported later.
  RESERVED_12,
  RESERVED_13,
  RESERVED_14,
  RESERVED_15,
  RESERVED_16,
  RESERVED_17,
  RESERVED_18,
  RESERVED_19,
  RESERVED_20
}

For an example of how this is used, consider the GetNeighbors query. If we set the edgeType field of the GfsNeighborsRequest, the response will contain all the users that the specified user follows. If, on the other hand, we set edgeType to be FollowedBy it will return all the users who are followed by the specified user.

FeatureType

FeatureType is a thrift struct which is used in queries which require two edge types.

struct FeatureType {
  1: required EdgeType leftEdgeType // edge type from source user
  2: required EdgeType rightEdgeType // edge type from candidate user
}(persisted="true")

UserWithScore

The candidate generation queries return lists of candidates together with a computed score for the relevant feature. UserWithScore is a thrift struct which bundles together a candidate's ID with the score.

struct UserWithScore {
  1: required i64 userId
  2: required double score
}