Add tentatively cockroachdb/pebble as initial database! This can be changed/replaced easily. Unfortunately it adds 7 MB to the binary and tons of dependencies :(

store/Pebble.go

@@ -0,0 +1,68 @@
+/*
+File Name:  Pebble.go
+Copyright:  2021 Peernet s.r.o.
+Author:     Peter Kleissner
+*/
+
+package store
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/cockroachdb/pebble"
+)
+
+// PebbleStore is a key/value store using Pebble from CockroachDB.
+// Expiration is currently not supported.
+type PebbleStore struct {
+	mutex    *sync.Mutex
+	filename string
+	db       *pebble.DB
+}
+
+// NewPebbleStore create a properly initialized pebble store.
+func NewPebbleStore(filename string) (store *PebbleStore, err error) {
+	// if the database does not exist, it will be created
+	db, err := pebble.Open(filename, &pebble.Options{})
+	if err != nil {
+		return nil, err
+	}
+
+	return &PebbleStore{
+		mutex:    &sync.Mutex{},
+		filename: filename,
+		db:       db,
+	}, nil
+}
+
+func (store *PebbleStore) ExpireKeys() {
+	// Not yet implemented
+}
+
+// Store stores the key/value pair.
+func (store *PebbleStore) Set(key []byte, data []byte) error {
+	return store.db.Set(key, data, pebble.Sync)
+}
+
+// StoreExpire stores the key/value pair and deletes it after the expiration time.
+func (store *PebbleStore) StoreExpire(key []byte, data []byte, expiration time.Time) error {
+	// Not yet implemented
+	return errors.New("not yet implemented")
+}
+
+// Get returns the value for the key if present.
+func (store *PebbleStore) Get(key []byte) (data []byte, found bool) {
+	value, closer, err := store.db.Get(key)
+	if err != nil {
+		return nil, false
+	}
+	closer.Close()
+	return value, true
+}
+
+// Delete deletes a key/value pair.
+func (store *PebbleStore) Delete(key []byte) {
+	store.db.Delete(key, pebble.Sync)
+}