From 9b32b8b8f29a4079fcb76554599a79779dd7c191 Mon Sep 17 00:00:00 2001
From: edipretoro <edipretoro@gmail.com>
Date: Tue, 21 Jul 2026 21:36:14 +0200
Subject: [PATCH] Adding the challenge 0103

---
 0103/kv.go       | 21 ++++++++++++++
 0103/kv_entry.go | 51 ++++++++++++++++++++++++++++++++
 0103/kv_test.go  | 75 ++++++++++++++++++++++++++++++++++++++++++++++++
 0103/log.go      | 38 ++++++++++++++++++++++++
 4 files changed, 185 insertions(+)
 create mode 100644 0103/kv.go
 create mode 100644 0103/kv_entry.go
 create mode 100644 0103/kv_test.go
 create mode 100644 0103/log.go

diff --git a/0103/kv.go b/0103/kv.go
new file mode 100644
index 0000000..f4bcdcb
--- /dev/null
+++ b/0103/kv.go
@@ -0,0 +1,21 @@
+package db0103
+
+type KV struct {
+	log Log
+	mem map[string][]byte
+}
+
+func (kv *KV) Open() error
+
+func (kv *KV) Close() error { return kv.log.Close() }
+
+func (kv *KV) Get(key []byte) (val []byte, ok bool, err error) {
+	val, ok = kv.mem[string(key)]
+	return
+}
+
+func (kv *KV) Set(key []byte, val []byte) (updated bool, err error)
+
+func (kv *KV) Del(key []byte) (deleted bool, err error)
+
+// QzBQWVJJOUhU https://trialofcode.org/
diff --git a/0103/kv_entry.go b/0103/kv_entry.go
new file mode 100644
index 0000000..2dbfca0
--- /dev/null
+++ b/0103/kv_entry.go
@@ -0,0 +1,51 @@
+package db0103
+
+import (
+	"encoding/binary"
+	"io"
+)
+
+type Entry struct {
+	key     []byte
+	val     []byte
+	deleted bool
+}
+
+func (ent *Entry) Encode() []byte {
+	data := make([]byte, 4+4+1+len(ent.key)+len(ent.val))
+	binary.LittleEndian.PutUint32(data[0:4], uint32(len(ent.key)))
+	copy(data[9:], ent.key)
+	if ent.deleted {
+		data[8] = 1
+	} else {
+		binary.LittleEndian.PutUint32(data[4:8], uint32(len(ent.val)))
+		copy(data[9+len(ent.key):], ent.val)
+	}
+	return data
+}
+
+func (ent *Entry) Decode(r io.Reader) error {
+	var header [9]byte
+	if _, err := io.ReadFull(r, header[:]); err != nil {
+		return err
+	}
+	klen := int(binary.LittleEndian.Uint32(header[0:4]))
+	vlen := int(binary.LittleEndian.Uint32(header[4:8]))
+	deleted := header[8]
+
+	data := make([]byte, klen+vlen)
+	if _, err := io.ReadFull(r, data); err != nil {
+		return err
+	}
+
+	ent.key = data[:klen]
+	if deleted != 0 {
+		ent.deleted = true
+	} else {
+		ent.deleted = false
+		ent.val = data[klen:]
+	}
+	return nil
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/
diff --git a/0103/kv_test.go b/0103/kv_test.go
new file mode 100644
index 0000000..a1d52eb
--- /dev/null
+++ b/0103/kv_test.go
@@ -0,0 +1,75 @@
+package db0103
+
+import (
+	"bytes"
+	"os"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestKVBasic(t *testing.T) {
+	kv := KV{}
+	kv.log.FileName = ".test_db"
+	defer os.Remove(kv.log.FileName)
+
+	os.Remove(kv.log.FileName)
+	err := kv.Open()
+	assert.Nil(t, err)
+	defer kv.Close()
+
+	updated, err := kv.Set([]byte("k1"), []byte("v1"))
+	assert.True(t, updated && err == nil)
+
+	val, ok, err := kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+
+	_, ok, err = kv.Get([]byte("xxx"))
+	assert.True(t, !ok && err == nil)
+
+	updated, err = kv.Del([]byte("xxx"))
+	assert.True(t, !updated && err == nil)
+
+	updated, err = kv.Del([]byte("k1"))
+	assert.True(t, updated && err == nil)
+
+	_, ok, err = kv.Get([]byte("xxx"))
+	assert.True(t, !ok && err == nil)
+
+	updated, err = kv.Set([]byte("k2"), []byte("v2"))
+	assert.True(t, updated && err == nil)
+
+	// reopen
+	kv.Close()
+	err = kv.Open()
+	assert.Nil(t, err)
+
+	_, ok, err = kv.Get([]byte("k1"))
+	assert.True(t, !ok && err == nil)
+	val, ok, err = kv.Get([]byte("k2"))
+	assert.True(t, string(val) == "v2" && ok && err == nil)
+}
+
+func TestEntryEncode(t *testing.T) {
+	ent := Entry{key: []byte("k1"), val: []byte("xxx")}
+	data := []byte{2, 0, 0, 0, 3, 0, 0, 0, 0, 'k', '1', 'x', 'x', 'x'}
+
+	assert.Equal(t, data, ent.Encode())
+
+	decoded := Entry{}
+	err := decoded.Decode(bytes.NewBuffer(data))
+	assert.Nil(t, err)
+	assert.Equal(t, ent, decoded)
+
+	ent = Entry{key: []byte("k1"), deleted: true}
+	data = []byte{2, 0, 0, 0, 0, 0, 0, 0, 1, 'k', '1'}
+
+	assert.Equal(t, data, ent.Encode())
+
+	decoded = Entry{}
+	err = decoded.Decode(bytes.NewBuffer(data))
+	assert.Nil(t, err)
+	assert.Equal(t, ent, decoded)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/
diff --git a/0103/log.go b/0103/log.go
new file mode 100644
index 0000000..98714de
--- /dev/null
+++ b/0103/log.go
@@ -0,0 +1,38 @@
+package db0103
+
+import (
+	"io"
+	"os"
+)
+
+type Log struct {
+	FileName string
+	fp       *os.File
+}
+
+func (log *Log) Open() (err error) {
+	log.fp, err = os.OpenFile(log.FileName, os.O_RDWR|os.O_CREATE, 0o644)
+	return err
+}
+
+func (log *Log) Close() error {
+	return log.fp.Close()
+}
+
+func (log *Log) Write(ent *Entry) error {
+	_, err := log.fp.Write(ent.Encode())
+	return err
+}
+
+func (log *Log) Read(ent *Entry) (eof bool, err error) {
+	err = ent.Decode(log.fp)
+	if err == io.EOF {
+		return true, nil
+	} else if err != nil {
+		return false, err
+	} else {
+		return false, nil
+	}
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/