Merge pull request #430 from euanwm/fix/query_race_condition

fix/query race condition

backend/dbtools/cache_handler.go

@@ -1,54 +1,68 @@
 package dbtools
 
 import (
-	"backend/enum"
 	"backend/structs"
+	"sync"
+)
+
+type QueryState int
+
+const (
+	None QueryState = iota
+	Working
+	Completed
 )
 
 type QueryCache struct {
-	Store []Query
+	HashStore sync.Map // [structs.LeaderboardPayload]Query
 }
 
 type Query struct {
-	Filter        structs.LeaderboardPayload
 	DataPositions []int
+	Status        QueryState
 }
 
 // AddQuery - Adds a query to the cache.
 func (q *QueryCache) AddQuery(query structs.LeaderboardPayload, dataPositions []int) {
-	q.Store = append(q.Store, Query{Filter: query, DataPositions: dataPositions})
+	query.Start, query.Stop = 0, 0
+	q.HashStore.Store(query, Query{dataPositions, Completed})
 }
 
-// CheckQuery - Checks if the query has been run before, if so, return the data positions.
-// A true value indicates that the query has been run before.
-// A false value indicates that the query has not been run before.
-// And a false value with a non-nil slice indicates that a similar query has been run before and the data positions are returned that should be used to filer from.
-// Hoping that the last case makes things a bit faster to reduce having to run multiple startup caching queries.
-func (q *QueryCache) CheckQuery(query structs.LeaderboardPayload) (bool, []int) {
-	for _, cacheQuery := range q.Store {
-		if cacheQuery.Filter == query {
-			return true, cacheQuery.DataPositions
-		}
-		// checks for exact match
-		if cacheQuery.Filter.SortBy == query.SortBy && cacheQuery.Filter.Federation == query.Federation && cacheQuery.Filter.WeightClass == query.WeightClass && cacheQuery.Filter.Year == query.Year {
-			return true, cacheQuery.DataPositions
+func (q *QueryCache) InitQuery(query structs.LeaderboardPayload) {
+	q.HashStore.Store(query, Query{
+		DataPositions: nil,
+		Status:        Working,
+	})
+}
+
+func (q *QueryCache) QueryStatus(query structs.LeaderboardPayload) QueryState {
+	query.Start, query.Stop = 0, 0
+	queryStuff, ok := q.HashStore.Load(query)
+	if !ok {
+		return None
+	} else {
+		query, ok := queryStuff.(Query)
+		if !ok {
+			panic("how the fuck did you fuck this up?")
 		}
+		return query.Status
 	}
-	// if we get here, we haven't found a match, so we'll do some partial matching
-	for _, cacheQuery := range q.Store {
-		// all years for the same total/sinclair, federation and weight class
-		if cacheQuery.Filter.SortBy == query.SortBy && cacheQuery.Filter.Federation == query.Federation && cacheQuery.Filter.WeightClass == query.WeightClass && cacheQuery.Filter.Year == enum.AllYearsStr {
-			return false, cacheQuery.DataPositions
-		}
-		// all years for the same total/sinclair, federation, and all gendered weight classes
-		if cacheQuery.Filter.SortBy == query.SortBy && cacheQuery.Filter.Federation == query.Federation && cacheQuery.Filter.Year == enum.AllYearsStr {
-			if query.WeightClass[0] == 'M' && cacheQuery.Filter.WeightClass == "MALL" {
-				return false, cacheQuery.DataPositions
-			}
-			if query.WeightClass[0] == 'F' && cacheQuery.Filter.WeightClass == "FALL" {
-				return false, cacheQuery.DataPositions
-			}
+}
+
+// CheckQuery - Checks if the query has been run before, if so, return the query state and data positions if they exist
+func (q *QueryCache) CheckQuery(query structs.LeaderboardPayload) (state QueryState, positions []int) {
+	query.Start, query.Stop = 0, 0
+	loadedData, ok := q.HashStore.Load(query)
+	if ok {
+		storedQuery, ok := loadedData.(Query)
+		if ok && (storedQuery.Status == Completed) || (storedQuery.Status == Working) {
+			state = storedQuery.Status
+			positions = storedQuery.DataPositions
+			return
 		}
 	}
-	return false, nil
+
+	state = None
+	positions = []int{}
+	return state, positions
 }

backend/dbtools/sortby.go

@@ -10,15 +10,27 @@ import (
 
 // FilterLifts - Returns a slice of structs relating to the selected filter selection
 func FilterLifts(bigData []structs.Entry, filterQuery structs.LeaderboardPayload, weightCat structs.WeightClass, cache *QueryCache) (filteredData structs.LeaderboardResponse) {
-	exists, positions := cache.CheckQuery(filterQuery)
-
-	if exists {
+	queryState, positions := cache.CheckQuery(filterQuery)
+
+	switch queryState {
+	case None:
+		cache.InitQuery(filterQuery)
+	case Working:
+		state := cache.QueryStatus(filterQuery)
+		for state == Working {
+			time.Sleep(100 * time.Millisecond)
+			state = cache.QueryStatus(filterQuery)
+			if state == Completed {
+				filteredData.Data, filteredData.Size = fetchLifts(&bigData, positions, &filterQuery)
+				return
+			}
+		}
+	case Completed:
 		filteredData.Data, filteredData.Size = fetchLifts(&bigData, positions, &filterQuery)
 		return
-	}
-
-	if !exists && positions != nil {
-		bigData = fetchLiftsAll(&bigData, positions)
+	default:
+		// if you hit this, fuck you
+		panic("Invalid query state")
 	}
 
 	var names []string
@@ -50,6 +62,27 @@ func FilterLifts(bigData []structs.Entry, filterQuery structs.LeaderboardPayload
 }
 
 func PreCacheFilter(bigData []structs.Entry, filterQuery structs.LeaderboardPayload, weightCat structs.WeightClass, cache *QueryCache) {
+	queryState, _ := cache.CheckQuery(filterQuery)
+
+	switch queryState {
+	case None:
+		cache.InitQuery(filterQuery)
+	case Working:
+		state := cache.QueryStatus(filterQuery)
+		for state == Working {
+			time.Sleep(100 * time.Millisecond)
+			state = cache.QueryStatus(filterQuery)
+			if state == Completed {
+				return
+			}
+		}
+	case Completed:
+		return
+	default:
+		// if you hit this, fuck you
+		panic("Invalid query state")
+	}
+
 	var names []string
 	var liftPtr *structs.Entry
 	var liftPositions []int
@@ -84,13 +117,6 @@ func fetchLifts(bigData *[]structs.Entry, pos []int, query *structs.LeaderboardP
 	return
 }
 
-func fetchLiftsAll(bigData *[]structs.Entry, pos []int) (lifts []structs.Entry) {
-	for _, p := range pos {
-		lifts = append(lifts, (*bigData)[p])
-	}
-	return
-}
-
 // SortSinclair Descending order by entry sinclair
 func SortSinclair(sliceStructs []structs.Entry) {
 	sort.Slice(sliceStructs, func(i, j int) bool {

backend/endpoints.go

@@ -175,7 +175,7 @@ func LifterHistory(c *gin.Context) {
 //		@Success		200	{object}	structs.LeaderboardResponse
 //		@Router			/leaderboard [post]
 func Leaderboard(c *gin.Context) {
-	sortby, exists := c.GetQuery("sortby")
+	sortby, exists := c.GetQuery("sortBy")
 	if !exists {
 		sortby = "total"
 	}