Twitter Recommendation Algorithm

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graph-feature-service/doc/getintersection.md

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+# GetIntersection
+
+## Request and response syntax
+
+A `GetIntersection` call takes as input a `GfsIntersectionRequest` thrift struct. 
+
+```thrift
+struct GfsIntersectionRequest {
+  1: required i64 userId
+  2: required list<i64> candidateUserIds
+  3: required list<FeatureType> featureTypes
+}
+```
+
+The response is returned in a `GfsIntersectionResponse` thrift struct.
+
+```thrift
+struct GfsIntersectionResponse {
+  1: required i64 userId
+  2: required list<GfsIntersectionResult> results
+}
+
+struct GfsIntersectionResult {
+  1: required i64 candidateUserId
+  2: required list<IntersectionValue> intersectionValues
+}
+
+struct IntersectionValue {
+  1: required FeatureType featureType
+  2: optional i32 count
+  3: optional list<i64> intersectionIds
+  4: optional i32 leftNodeDegree
+  5: optional i32 rightNodeDegree
+}(persisted="true")
+```
+
+## Behavior
+
+The `GfsIntersectionResponse` contains in its `results` field a `GfsIntersectionResult` for every candidate in `candidateIds` which contains an  `IntersectionValue` for every `FeatureType` in the request's `featureTypes` field. 
+
+The `IntersectionValue` contains the size of the intersection between the `leftEdgeType` edges from `userId` and the `rightEdgeType` edges from `candidateId` in the `count` field, as well as their respective degrees in the graphs in `leftNodeDegree` and `rightNodeDegree` respectively.
+
+**Note:** the `intersectionIds` field currently only contains `Nil`.