Add a little delay to the database call.

This additional slowdown offers the change to optimizing the locking code.

2-race-in-cache/mockdb.go

@@ -6,11 +6,15 @@
 
 package main
 
+import "time"
+
 // MockDB used to simulate a database model
 type MockDB struct{}
 
 // Get only returns an empty string, as this is only for demonstration purposes
 func (*MockDB) Get(key string) (string, error) {
+	d, _ := time.ParseDuration("20ms")
+	time.Sleep(d)
 	return "", nil
 }
 

2-race-in-cache/mockserver.go

@@ -12,7 +12,7 @@ import (
 )
 
 const (
-	cycles        = 3
+	cycles        = 15
 	callsPerCycle = 100
 )