Simplify Store interface. Remove unused replication placeholder and untangle expiration option.

MemoryStore is refactored into separate file.

store/Memory.go

@@ -0,0 +1,73 @@
+/*
+File Name:  Memory.go
+Copyright:  2021 Peernet s.r.o.
+Author:     Peter Kleissner
+*/
+
+package store
+
+import (
+	"sync"
+	"time"
+)
+
+// MemoryStore is a simple in-memory key/value store for testing purposes.
+type MemoryStore struct {
+	mutex     *sync.Mutex
+	data      map[string][]byte
+	expireMap map[string]time.Time
+}
+
+// NewMemoryStore create a properly initialized memory store.
+func NewMemoryStore() *MemoryStore {
+	return &MemoryStore{
+		data:      make(map[string][]byte),
+		mutex:     &sync.Mutex{},
+		expireMap: make(map[string]time.Time),
+	}
+}
+
+// ExpireKeys is called to delete all keys that are marked for expiration.
+func (ms *MemoryStore) ExpireKeys() {
+	ms.mutex.Lock()
+	defer ms.mutex.Unlock()
+	for k, v := range ms.expireMap {
+		if time.Now().After(v) {
+			delete(ms.expireMap, k)
+			delete(ms.data, k)
+		}
+	}
+}
+
+// Store stores the key/value pair.
+func (ms *MemoryStore) Store(key []byte, data []byte) error {
+	ms.mutex.Lock()
+	ms.data[string(key)] = data
+	ms.mutex.Unlock()
+	return nil
+}
+
+// StoreExpire stores the key/value pair and deletes it after the expiration time.
+func (ms *MemoryStore) StoreExpire(key []byte, data []byte, expiration time.Time) error {
+	ms.mutex.Lock()
+	ms.expireMap[string(key)] = expiration
+	ms.data[string(key)] = data
+	ms.mutex.Unlock()
+	return nil
+}
+
+// Retrieve returns the value for the key if present.
+func (ms *MemoryStore) Retrieve(key []byte) (data []byte, found bool) {
+	ms.mutex.Lock()
+	data, found = ms.data[string(key)]
+	ms.mutex.Unlock()
+	return data, found
+}
+
+// Delete deletes a key/value pair.
+func (ms *MemoryStore) Delete(key []byte) {
+	ms.mutex.Lock()
+	delete(ms.expireMap, string(key))
+	delete(ms.data, string(key))
+	ms.mutex.Unlock()
+}