solution: use localise sync.Mutex so the Get() is thread safe

bighelmet7 · Jun 24, 2022 · 31fcae5 · 31fcae5
1 parent 0375653
commit 31fcae5
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diff --git a/2-race-in-cache/go.mod b/2-race-in-cache/go.mod
@@ -0,0 +1,3 @@
+module github.com/bighelmet7/go-concurrency-excercises/2-race-in-cache
+
+go 1.18
diff --git a/2-race-in-cache/main.go b/2-race-in-cache/main.go
@@ -8,7 +8,10 @@
 
 package main
 
-import "container/list"
+import (
+	"container/list"
+	"sync"
+)
 
 // CacheSize determines how big the cache can grow
 const CacheSize = 100
@@ -26,6 +29,8 @@ type page struct {
 
 // KeyStoreCache is a LRU cache for string key-value pairs
 type KeyStoreCache struct {
+	mu sync.Mutex
+
 	cache map[string]*list.Element
 	pages list.List
 	load  func(string) string
@@ -41,6 +46,9 @@ func New(load KeyStoreCacheLoader) *KeyStoreCache {
 
 // Get gets the key from cache, loads it from the source if needed
 func (k *KeyStoreCache) Get(key string) string {
+	k.mu.Lock()
+	defer k.mu.Unlock()
+
 	if e, ok := k.cache[key]; ok {
 		k.pages.MoveToFront(e)
 		return e.Value.(page).Value