Solving the challenge 0103

0103/kv.go

@@ -1,11 +1,34 @@
 package db0103
 
+import "bytes"
+
 type KV struct {
 	log Log
 	mem map[string][]byte
 }
 
-func (kv *KV) Open() error
+func (kv *KV) Open() error {
+    if err := kv.log.Open(); err != nil {
+        return err
+    }
+    kv.mem = map[string][]byte{}
+    for {
+        entry := Entry{}
+        eof, err := kv.log.Read(&entry)
+        if err != nil {
+            return err
+        } else if eof {
+            break
+        }
+
+        if entry.deleted {
+            delete(kv.mem, string(entry.key))
+        } else {
+            kv.mem[string(entry.key)] = entry.val
+        }
+    }
+    return nil
+}
 
 func (kv *KV) Close() error { return kv.log.Close() }
 
@@ -14,8 +37,27 @@ func (kv *KV) Get(key []byte) (val []byte, ok bool, err error) {
 	return
 }
 
-func (kv *KV) Set(key []byte, val []byte) (updated bool, err error)
+func (kv *KV) Set(key []byte, val []byte) (updated bool, err error) {
+	prev, exist := kv.mem[string(key)]
+	updated = !exist || !bytes.Equal(prev, val)
+    if updated {
+        if err = kv.log.Write(&Entry{key: key, val: val, deleted: false}); err != nil {
+            return false, err
+        }
+        kv.mem[string(key)] = val
+    }
+	return
+}
 
-func (kv *KV) Del(key []byte) (deleted bool, err error)
+func (kv *KV) Del(key []byte) (deleted bool, err error) {
+	_, deleted = kv.mem[string(key)]
+    if deleted {
+        if err = kv.log.Write(&Entry{key: key, val: nil, deleted: true}); err != nil {
+            return false, err
+        }
+        delete(kv.mem, string(key))
+    }
+	return
+}
 
 // QzBQWVJJOUhU https://trialofcode.org/