Protect cached vsp stats with mutex.

webapi/admin.go

@@ -10,7 +10,7 @@ import (
 // adminPage is the handler for "GET /admin".
 func adminPage(c *gin.Context) {
 	c.HTML(http.StatusOK, "admin.html", gin.H{
-		"VspStats": stats,
+		"VspStats": getVSPStats(),
 	})
 }
 
@@ -32,7 +32,7 @@ func ticketSearch(c *gin.Context) {
 			"Found":  found,
 			"Ticket": ticket,
 		},
-		"VspStats": stats,
+		"VspStats": getVSPStats(),
 	})
 }
 
@@ -44,7 +44,7 @@ func adminLogin(c *gin.Context) {
 	if password != cfg.AdminPass {
 		log.Warnf("Failed login attempt from %s", c.ClientIP())
 		c.HTML(http.StatusUnauthorized, "login.html", gin.H{
-			"VspStats":          stats,
+			"VspStats":          getVSPStats(),
 			"IncorrectPassword": true,
 		})
 		return

webapi/homepage.go

@@ -2,6 +2,7 @@ package webapi
 
 import (
 	"net/http"
+	"sync"
 	"time"
 
 	"github.com/decred/vspd/database"
@@ -21,14 +22,26 @@ type vspStats struct {
 	Debug               bool
 }
 
+var statsMtx sync.RWMutex
 var stats *vspStats
 
-func updateVSPStats(db *database.VspDatabase, cfg Config) (*vspStats, error) {
+func getVSPStats() *vspStats {
+	statsMtx.RLock()
+	defer statsMtx.RUnlock()
+
+	return stats
+}
+
+func updateVSPStats(db *database.VspDatabase, cfg Config) error {
 	total, feeConfirmed, err := db.CountTickets()
 	if err != nil {
-		return nil, err
+		return err
 	}
-	return &vspStats{
+
+	statsMtx.Lock()
+	defer statsMtx.Unlock()
+
+	stats = &vspStats{
 		PubKey:              signPubKey,
 		TotalTickets:        total,
 		FeeConfirmedTickets: feeConfirmed,
@@ -38,11 +51,13 @@ func updateVSPStats(db *database.VspDatabase, cfg Config) (*vspStats, error) {
 		SupportEmail:        cfg.SupportEmail,
 		VspClosed:           cfg.VspClosed,
 		Debug:               cfg.Debug,
-	}, nil
+	}
+
+	return nil
 }
 
 func homepage(c *gin.Context) {
 	c.HTML(http.StatusOK, "homepage.html", gin.H{
-		"VspStats": stats,
+		"VspStats": getVSPStats(),
 	})
 }

webapi/middleware.go

@@ -57,7 +57,7 @@ func requireAdmin() gin.HandlerFunc {
 
 		if admin == nil {
 			c.HTML(http.StatusUnauthorized, "login.html", gin.H{
-				"VspStats": stats,
+				"VspStats": getVSPStats(),
 			})
 			c.Abort()
 			return

webapi/webapi.go

@@ -59,10 +59,10 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 		return fmt.Errorf("Failed to get keypair: %v", err)
 	}
 
-	// Populate template data before starting webserver.
-	stats, err = updateVSPStats(vdb, config)
+	// Populate cached VSP stats before starting webserver.
+	err = updateVSPStats(vdb, config)
 	if err != nil {
-		return fmt.Errorf("could not initialize homepage data: %v", err)
+		return fmt.Errorf("could not initialize VSP stats cache: %v", err)
 	}
 
 	// Get the last used address index and the feeXpub from the database, and
@@ -147,9 +147,9 @@ func Start(ctx context.Context, requestShutdownChan chan struct{}, shutdownWg *s
 				shutdownWg.Done()
 				return
 			case <-ticker.C:
-				stats, err = updateVSPStats(db, cfg)
+				err = updateVSPStats(db, cfg)
 				if err != nil {
-					log.Errorf("Failed to update homepage data: %v", err)
+					log.Errorf("Failed to update cached VSP stats: %v", err)
 				}
 			}
 		}