add top n recommenders to candidates

config/config.go

@@ -25,6 +25,7 @@ import (
 	"sync"
 	"time"
 
+	"github.com/antonmedv/expr"
 	"github.com/go-playground/locales/en"
 	ut "github.com/go-playground/universal-translator"
 	"github.com/go-playground/validator/v10"
@@ -109,6 +110,7 @@ type RecommendConfig struct {
 	Replacement   ReplacementConfig   `mapstructure:"replacement"`
 	Offline       OfflineConfig       `mapstructure:"offline"`
 	Online        OnlineConfig        `mapstructure:"online"`
+	Candidate     CandidateConfig     `mapstructure:"candidate"`
 }
 
 type DataSourceConfig struct {
@@ -164,6 +166,20 @@ type OnlineConfig struct {
 	NumFeedbackFallbackItemBased int      `mapstructure:"num_feedback_fallback_item_based" validate:"gt=0"`
 }
 
+type CandidateConfig struct {
+	Top []TopConfig `mapstructure:"top"`
+}
+
+type TopConfig struct {
+	Name  string `mapstructure:"name" validate:"required"`
+	Score string `mapstructure:"score" validate:"required"`
+}
+
+func (top *TopConfig) Validate() error {
+	_, err := expr.Compile(top.Score)
+	return err
+}
+
 type TracingConfig struct {
 	EnableTracing     bool    `mapstructure:"enable_tracing"`
 	Exporter          string  `mapstructure:"exporter" validate:"oneof=jaeger zipkin otlp otlphttp"`

config/config_test.go

@@ -450,3 +450,10 @@ func TestConfig_OfflineRecommendDigest(t *testing.T) {
 	cfg2.Recommend.Replacement.PositiveReplacementDecay = 0.2
 	assert.Equal(t, cfg1.OfflineRecommendDigest(), cfg2.OfflineRecommendDigest())
 }
+
+func TestTopConfig(t *testing.T) {
+	top := TopConfig{Score: "a+b"}
+	assert.NoError(t, top.Validate())
+	top = TopConfig{Score: "%%"}
+	assert.Error(t, top.Validate())
+}

go.mod

@@ -5,6 +5,7 @@ go 1.18
 require (
 	github.com/ReneKroon/ttlcache/v2 v2.11.0
 	github.com/XSAM/otelsql v0.17.0
+	github.com/antonmedv/expr v1.12.5
 	github.com/araddon/dateparse v0.0.0-20210429162001-6b43995a97de
 	github.com/benhoyt/goawk v1.20.0
 	github.com/bits-and-blooms/bitset v1.2.1

go.sum

@@ -53,6 +53,8 @@ github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRF
 github.com/alecthomas/units v0.0.0-20190717042225-c3de453c63f4/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/alecthomas/units v0.0.0-20190924025748-f65c72e2690d/go.mod h1:rBZYJk541a8SKzHPHnH3zbiI+7dagKZ0cgpgrD7Fyho=
 github.com/antihax/optional v1.0.0/go.mod h1:uupD/76wgC+ih3iEmQUL+0Ugr19nfwCT1kdvxnR2qWY=
+github.com/antonmedv/expr v1.12.5 h1:Fq4okale9swwL3OeLLs9WD9H6GbgBLJyN/NUHRv+n0E=
+github.com/antonmedv/expr v1.12.5/go.mod h1:FPC8iWArxls7axbVLsW+kpg1mz29A1b2M6jt+hZfDkU=
 github.com/araddon/dateparse v0.0.0-20210429162001-6b43995a97de h1:FxWPpzIjnTlhPwqqXc4/vE0f7GvRjuAsbW+HOIe8KnA=
 github.com/araddon/dateparse v0.0.0-20210429162001-6b43995a97de/go.mod h1:DCaWoUhZrYW9p1lxo/cm8EmUOOzAPSEZNGF2DK1dJgw=
 github.com/benbjohnson/clock v1.1.0 h1:Q92kusRqC1XV2MjkWETPvjJVqKetz1OzxZB7mHJLju8=

server/rest.go

@@ -418,6 +418,26 @@ func (s *RestServer) CreateWebService() {
 		Returns(http.StatusOK, "OK", []cache.Document{}).
 		Writes([]cache.Document{}))
 
+	// Get top items
+	ws.Route(ws.GET("/top/{name}").To(s.getTopItem).
+		Doc("Get top items.").
+		Metadata(restfulspec.KeyOpenAPITags, []string{RecommendationAPITag}).
+		Param(ws.HeaderParameter("X-API-Key", "API key").DataType("string")).
+		Param(ws.PathParameter("name", "Name of the top item recommender.").DataType("string")).
+		Param(ws.QueryParameter("n", "Number of returned items").DataType("integer")).
+		Param(ws.QueryParameter("offset", "Offset of returned items").DataType("integer")).
+		Returns(http.StatusOK, "OK", []cache.Document{}).
+		Writes([]cache.Document{}))
+	ws.Route(ws.GET("/top/{name}/{category}").To(s.getTopItem).
+		Doc("Get top items in category.").
+		Metadata(restfulspec.KeyOpenAPITags, []string{RecommendationAPITag}).
+		Param(ws.HeaderParameter("X-API-Key", "API key").DataType("string")).
+		Param(ws.PathParameter("name", "Name of the top item recommender.").DataType("string")).
+		Param(ws.PathParameter("category", "Category of returned items.").DataType("string")).
+		Param(ws.QueryParameter("n", "Number of returned items").DataType("integer")).
+		Param(ws.QueryParameter("offset", "Offset of returned items").DataType("integer")).
+		Returns(http.StatusOK, "OK", []cache.Document{}).
+		Writes([]cache.Document{}))
 	// Get popular items
 	ws.Route(ws.GET("/popular").To(s.getPopular).
 		Doc("Get popular items.").
@@ -614,6 +634,13 @@ func (s *RestServer) searchDocuments(collection, subset, category string, isItem
 	Ok(response, items)
 }
 
+func (s *RestServer) getTopItem(request *restful.Request, response *restful.Response) {
+	name := request.PathParameter("name")
+	category := request.PathParameter("category")
+	log.ResponseLogger(response).Debug("get top items", zap.String("name", name), zap.String("category", category))
+	s.searchDocuments(cache.TopItems, name, category, true, request, response)
+}
+
 func (s *RestServer) getPopular(request *restful.Request, response *restful.Response) {
 	category := request.PathParameter("category")
 	log.ResponseLogger(response).Debug("get category popular items in category", zap.String("category", category))

storage/cache/database.go

@@ -85,6 +85,8 @@ const (
 	//  Categorized the latest items - latest_items/{category}
 	LatestItems = "latest_items"
 
+	TopItems = "top_items"
+
 	// ItemCategories is the set of item categories. The format of key:
 	//	Global item categories - item_categories
 	ItemCategories = "item_categories"