Adding the challenge 0105

0105/kv.go

@@ -0,0 +1,66 @@
+package db0105
+
+import (
+	"bytes"
+)
+
+type KV struct {
+	log Log
+	mem map[string][]byte
+}
+
+func (kv *KV) Open() error {
+	if err := kv.log.Open(); err != nil {
+		return err
+	}
+
+	kv.mem = map[string][]byte{}
+	for {
+		ent := Entry{}
+		eof, err := kv.log.Read(&ent)
+		if err != nil {
+			return err
+		} else if eof {
+			break
+		}
+
+		if ent.deleted {
+			delete(kv.mem, string(ent.key))
+		} else {
+			kv.mem[string(ent.key)] = ent.val
+		}
+	}
+	return nil
+}
+
+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) {
+	prev, exist := kv.mem[string(key)]
+	updated = !exist || !bytes.Equal(prev, val)
+	if updated {
+		if err = kv.log.Write(&Entry{key: key, val: val}); err != nil {
+			return false, err
+		}
+		kv.mem[string(key)] = val
+	}
+	return
+}
+
+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, deleted: true}); err != nil {
+			return false, err
+		}
+		delete(kv.mem, string(key))
+	}
+	return
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0105/kv_entry.go

@@ -0,0 +1,20 @@
+package db0105
+
+import (
+	"errors"
+	"io"
+)
+
+type Entry struct {
+	key     []byte
+	val     []byte
+	deleted bool
+}
+
+func (ent *Entry) Encode() []byte
+
+var ErrBadSum = errors.New("bad checksum")
+
+func (ent *Entry) Decode(r io.Reader) error
+
+// QzBQWVJJOUhU https://trialofcode.org/

0105/kv_test.go

@@ -0,0 +1,126 @@
+package db0105
+
+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 TestKVRecovery(t *testing.T) {
+	kv := KV{}
+	kv.log.FileName = ".test_db"
+	defer os.Remove(kv.log.FileName)
+
+	prepare := func() {
+		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)
+		updated, err = kv.Set([]byte("k2"), []byte("v2"))
+		assert.True(t, updated && err == nil)
+	}
+
+	prepare()
+	// simulate truncated log
+	fp, _ := os.OpenFile(kv.log.FileName, os.O_RDWR, 0o644)
+	st, _ := fp.Stat()
+	fp.Truncate(st.Size() - 1)
+	fp.Close()
+	// reopen
+	err := kv.Open()
+	assert.Nil(t, err)
+	// test
+	val, ok, err := kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+	_, ok, err = kv.Get([]byte("k2")) // bad
+	assert.True(t, !ok && err == nil)
+	kv.Close()
+
+	prepare()
+	// simulate bad checksum
+	fp, _ = os.OpenFile(kv.log.FileName, os.O_RDWR, 0o644)
+	st, _ = fp.Stat()
+	fp.WriteAt([]byte{0}, st.Size()-1)
+	fp.Close()
+	// reopen
+	err = kv.Open()
+	assert.Nil(t, err)
+	// test
+	val, ok, err = kv.Get([]byte("k1"))
+	assert.True(t, string(val) == "v1" && ok && err == nil)
+	_, ok, err = kv.Get([]byte("k2")) // bad
+	assert.True(t, !ok && err == nil)
+	kv.Close()
+}
+
+func TestEntryEncode(t *testing.T) {
+	ent := Entry{key: []byte("k1"), val: []byte("xxx")}
+	data := []byte{0xe9, 0xec, 0x4d, 0x9e, 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{0x4c, 0xd0, 0xfe, 0xe5, 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/

0105/log.go

@@ -0,0 +1,30 @@
+package db0105
+
+import (
+	"os"
+)
+
+type Log struct {
+	FileName string
+	fp       *os.File
+}
+
+func (log *Log) Open() (err error) {
+	log.fp, err = createFileSync(log.FileName)
+	return err
+}
+
+func (log *Log) Close() error {
+	return log.fp.Close()
+}
+
+func (log *Log) Write(ent *Entry) error {
+	if _, err := log.fp.Write(ent.Encode()); err != nil {
+		return err
+	}
+	return log.fp.Sync() // fsync
+}
+
+func (log *Log) Read(ent *Entry) (eof bool, err error)
+
+// QzBQWVJJOUhU https://trialofcode.org/

0105/os_other.go

@@ -0,0 +1,11 @@
+//go:build !unix
+
+package db0105
+
+import "os"
+
+func createFileSync(file string) (*os.File, error) {
+	return os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o644)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/

0105/os_unix.go

@@ -0,0 +1,34 @@
+//go:build unix
+
+package db0105
+
+import (
+	"os"
+	"path"
+	"syscall"
+)
+
+// open or create a file and fsync the directory
+func createFileSync(file string) (*os.File, error) {
+	fp, err := os.OpenFile(file, os.O_RDWR|os.O_CREATE, 0o644)
+	if err != nil {
+		return nil, err
+	}
+	if err = syncDir(path.Base(file)); err != nil {
+		_ = fp.Close()
+		return nil, err
+	}
+	return fp, err
+}
+
+func syncDir(file string) error {
+	flags := os.O_RDONLY | syscall.O_DIRECTORY
+	dirfd, err := syscall.Open(path.Dir(file), flags, 0o644)
+	if err != nil {
+		return err
+	}
+	defer syscall.Close(dirfd)
+	return syscall.Fsync(dirfd)
+}
+
+// QzBQWVJJOUhU https://trialofcode.org/