fix(api): in-memory refresh, date range bug, and server cleanup

Extract InMemoryHandler.refresh() to deduplicate init and ticker logic;
on error keep the previously-held value instead of zeroing it. Fix
GetVolumeByDate date range check which was computing
StartDate.Sub(EndDate)
instead of EndDate.Sub(StartDate), making the 30-day guard always pass.
Call inMemoryHandler.Stop() on server startup failure so the background
goroutine does not leak.

Author: nman98

api/handlers/in_memory.go

@@ -52,49 +52,40 @@ func NewInMemoryHandler(db InMemoryDbHandler, chainName string) *InMemoryHandler
 // - none
 func (h *InMemoryHandler) Start() {
 	// initialize the data
+	h.refresh()
+
+	go func() {
+		for {
+			select {
+			case <-h.done:
+				return
+			case <-time.After(h.interval):
+				h.refresh()
+			}
+		}
+	}()
+}
+
+// refresh fetches the latest constant data from the database.
+// On error it logs and keeps the previously held value, so a transient
+// failure does not wipe otherwise-good data.
+func (h *InMemoryHandler) refresh() {
 	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(15*time.Second))
 	defer cancel()
+
 	avgBlockProdTime, err := h.db.GetAvgBlockProdTime(ctx, h.chainName)
 	if err != nil {
 		log.Printf("error getting average block production time: %v", err)
-		h.data.AvgBlockProdTime = 0
-		return
+	} else {
+		h.data.AvgBlockProdTime = avgBlockProdTime
 	}
-	h.data.AvgBlockProdTime = avgBlockProdTime
 
 	totalAddressesCount, err := h.db.GetTotalAddressesCount(ctx, h.chainName)
 	if err != nil {
 		log.Printf("error getting total addresses count: %v", err)
-		h.data.TotalAddressesCount = 0
-		return
+	} else {
+		h.data.TotalAddressesCount = totalAddressesCount
 	}
-	h.data.TotalAddressesCount = totalAddressesCount
-
-	go func() {
-		for {
-			select {
-			case <-h.done:
-				return
-			case <-time.After(h.interval):
-				ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(15*time.Second))
-				defer cancel()
-				avgBlockProdTime, err := h.db.GetAvgBlockProdTime(ctx, h.chainName)
-				if err != nil {
-					log.Printf("error getting average block production time: %v", err)
-					h.data.AvgBlockProdTime = 0
-					continue
-				}
-				h.data.AvgBlockProdTime = avgBlockProdTime
-				totalAddressesCount, err := h.db.GetTotalAddressesCount(ctx, h.chainName)
-				if err != nil {
-					log.Printf("error getting total addresses count: %v", err)
-					h.data.TotalAddressesCount = 0
-					continue
-				}
-				h.data.TotalAddressesCount = totalAddressesCount
-			}
-		}
-	}()
 }
 
 func (h *InMemoryHandler) Stop() {

api/handlers/transactions.go

@@ -287,7 +287,7 @@ func (h *TransactionsHandler) GetVolumeByDate(ctx context.Context, input *humaty
 	if !input.StartDate.Before(input.EndDate.Time) {
 		return nil, badRequest("start_date must be before end_date")
 	}
-	if input.StartDate.Sub(input.EndDate.Time) > 24*time.Hour*30 {
+	if input.EndDate.Sub(input.StartDate.Time) > 24*time.Hour*30 {
 		return nil, badRequest("end_date must be within 30 days of start_date")
 	}
 

api/serve.go

@@ -205,12 +205,14 @@ func runServe(cmd *cobra.Command, args []string) {
 		log.Printf("Starting server on %s with HTTPS", addr)
 		err = http.ListenAndServeTLS(addr, certFilePath, keyFilePath, mux)
 		if err != nil {
+			inMemoryHandler.Stop()
 			log.Fatalf("failed to start server: %v", err)
 		}
 	} else {
 		log.Printf("Starting server on %s with HTTP", addr)
 		err = http.ListenAndServe(addr, mux)
 		if err != nil {
+			inMemoryHandler.Stop()
 			log.Fatalf("failed to start server: %v", err)
 		}
 	}