improve cache handler, embracing #2210 too

cache/entry/store.go

@@ -0,0 +1,52 @@
+package entry
+
+import (
+	"sync"
+)
+
+// Store is the interface which is responsible to store the cache entries.
+type Store interface {
+	// Get returns an entry based on its key.
+	Get(key string) *Entry
+	// Set sets an entry based on its key.
+	Set(key string, e *Entry)
+	// Delete deletes an entry based on its key.
+	Delete(key string)
+}
+
+// memStore is the default in-memory store for the cache entries.
+type memStore struct {
+	entries map[string]*Entry
+	mu      sync.RWMutex
+}
+
+var _ Store = (*memStore)(nil)
+
+// NewMemStore returns a new in-memory store for the cache entries.
+func NewMemStore() Store {
+	return &memStore{
+		entries: make(map[string]*Entry),
+	}
+}
+
+// Get returns an entry based on its key.
+func (s *memStore) Get(key string) *Entry {
+	s.mu.RLock()
+	e := s.entries[key]
+	s.mu.RUnlock()
+	return e
+}
+
+// Set sets an entry based on its key.
+func (s *memStore) Set(key string, e *Entry) {
+	s.mu.Lock()
+	s.entries[key] = e
+	s.mu.Unlock()
+}
+
+// Delete deletes an entry based on its key.
+func (s *memStore) Delete(key string) {
+	s.mu.Lock()
+	delete(s.entries, key)
+	s.mu.Unlock()
+}