Refactored some internals and removed timestamp field (unsure why it was needed in the original paper)

bitcask.go

@@ -1,23 +1,16 @@
 package bitcask
 
 import (
-	"errors"
+	"fmt"
+	"hash/crc32"
 	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"strings"
-	"time"
 
-	"github.com/derekparker/trie"
 	"github.com/gofrs/flock"
-)
+	"github.com/prologic/trie"
-
-var (
-	ErrKeyNotFound    = errors.New("error: key not found")
-	ErrKeyTooLarge    = errors.New("error: key too large")
-	ErrValueTooLarge  = errors.New("error: value too large")
-	ErrDatabaseLocked = errors.New("error: database locked")
 )
 
 type Bitcask struct {
@@ -54,7 +47,7 @@ func (b *Bitcask) Get(key string) ([]byte, error) {
 
 	item, ok := b.keydir.Get(key)
 	if !ok {
-		return nil, ErrKeyNotFound
+		return nil, fmt.Errorf("error: key not found %s", key)
 	}
 
 	if item.FileID == b.curr.id {
@@ -63,28 +56,33 @@ func (b *Bitcask) Get(key string) ([]byte, error) {
 		df = b.datafiles[item.FileID]
 	}
 
-	e, err := df.ReadAt(item.Index)
+	e, err := df.ReadAt(item.Offset)
 	if err != nil {
 		return nil, err
 	}
 
+	checksum := crc32.ChecksumIEEE(e.Value)
+	if checksum != e.Checksum {
+		return nil, fmt.Errorf("error: checksum falied %s %d != %d", key, e.Checksum, checksum)
+	}
+
 	return e.Value, nil
 }
 
 func (b *Bitcask) Put(key string, value []byte) error {
 	if len(key) > b.opts.MaxKeySize {
-		return ErrKeyTooLarge
+		return fmt.Errorf("error: key too large %d > %d", len(key), b.opts.MaxKeySize)
 	}
 	if len(value) > b.opts.MaxValueSize {
-		return ErrValueTooLarge
+		return fmt.Errorf("error: value too large %d > %d", len(value), b.opts.MaxValueSize)
 	}
 
-	index, err := b.put(key, value)
+	offset, err := b.put(key, value)
 	if err != nil {
 		return err
 	}
 
-	item := b.keydir.Add(key, b.curr.id, index, time.Now().Unix())
+	item := b.keydir.Add(key, b.curr.id, offset)
 	b.trie.Add(key, item)
 
 	return nil
@@ -212,7 +210,7 @@ func Merge(path string, force bool) error {
 				continue
 			}
 
-			keydir.Add(e.Key, ids[i], e.Index, e.Timestamp)
+			keydir.Add(e.Key, ids[i], e.Offset)
 		}
 
 		tempdf, err := NewDatafile(temp, id, false)
@@ -223,7 +221,7 @@ func Merge(path string, force bool) error {
 
 		for key := range keydir.Keys() {
 			item, _ := keydir.Get(key)
-			e, err := df.ReadAt(item.Index)
+			e, err := df.ReadAt(item.Offset)
 			if err != nil {
 				return err
 			}
@@ -305,7 +303,7 @@ func Open(path string, options ...func(*Bitcask) error) (*Bitcask, error) {
 
 			for key := range hint.Keys() {
 				item, _ := hint.Get(key)
-				_ = keydir.Add(key, item.FileID, item.Index, item.Timestamp)
+				_ = keydir.Add(key, item.FileID, item.Offset)
 				trie.Add(key, item)
 			}
 		} else {
@@ -324,7 +322,7 @@ func Open(path string, options ...func(*Bitcask) error) (*Bitcask, error) {
 					continue
 				}
 
-				item := keydir.Add(e.Key, ids[i], e.Index, e.Timestamp)
+				item := keydir.Add(e.Key, ids[i], e.Offset)
 				trie.Add(e.Key, item)
 			}
 		}
@@ -365,7 +363,7 @@ func Open(path string, options ...func(*Bitcask) error) (*Bitcask, error) {
 	}
 
 	if !locked {
-		return nil, ErrDatabaseLocked
+		return nil, fmt.Errorf("error: database locked %s", path)
 	}
 
 	return bitcask, nil

bitcask_test.go

@@ -45,7 +45,7 @@ func TestAll(t *testing.T) {
 		assert.NoError(err)
 		_, err = db.Get("foo")
 		assert.Error(err)
-		assert.Equal(err.Error(), "error: key not found")
+		assert.Equal("error: key not found foo", err.Error())
 	})
 
 	t.Run("Sync", func(t *testing.T) {
@@ -92,7 +92,7 @@ func TestDeletedKeys(t *testing.T) {
 			assert.NoError(err)
 			_, err = db.Get("foo")
 			assert.Error(err)
-			assert.Equal("error: key not found", err.Error())
+			assert.Equal("error: key not found foo", err.Error())
 		})
 
 		t.Run("Sync", func(t *testing.T) {
@@ -120,7 +120,7 @@ func TestDeletedKeys(t *testing.T) {
 		t.Run("Get", func(t *testing.T) {
 			_, err = db.Get("foo")
 			assert.Error(err)
-			assert.Equal("error: key not found", err.Error())
+			assert.Equal("error: key not found foo", err.Error())
 		})
 
 		t.Run("Close", func(t *testing.T) {
@@ -138,19 +138,17 @@ func TestMaxKeySize(t *testing.T) {
 
 	var db *Bitcask
 
-	size := 16
-
 	t.Run("Open", func(t *testing.T) {
-		db, err = Open(testdir, WithMaxKeySize(size))
+		db, err = Open(testdir, WithMaxKeySize(16))
 		assert.NoError(err)
 	})
 
 	t.Run("Put", func(t *testing.T) {
-		key := strings.Repeat(" ", size+1)
+		key := strings.Repeat(" ", 17)
 		value := []byte("foobar")
 		err = db.Put(key, value)
 		assert.Error(err)
-		assert.Equal("error: key too large", err.Error())
+		assert.Equal("error: key too large 17 > 16", err.Error())
 	})
 }
 
@@ -162,19 +160,17 @@ func TestMaxValueSize(t *testing.T) {
 
 	var db *Bitcask
 
-	size := 16
-
 	t.Run("Open", func(t *testing.T) {
-		db, err = Open(testdir, WithMaxValueSize(size))
+		db, err = Open(testdir, WithMaxValueSize(16))
 		assert.NoError(err)
 	})
 
 	t.Run("Put", func(t *testing.T) {
 		key := "foo"
-		value := []byte(strings.Repeat(" ", size+1))
+		value := []byte(strings.Repeat(" ", 17))
 		err = db.Put(key, value)
 		assert.Error(err)
-		assert.Equal("error: value too large", err.Error())
+		assert.Equal("error: value too large 17 > 16", err.Error())
 	})
 }
 
@@ -291,10 +287,9 @@ func TestConcurrent(t *testing.T) {
 			wg := &sync.WaitGroup{}
 
 			go f(wg, 2)
-			wg.Add(1)
-
 			go f(wg, 3)
-			wg.Add(1)
+			go f(wg, 5)
+			wg.Add(3)
 
 			wg.Wait()
 		})
@@ -314,10 +309,9 @@ func TestConcurrent(t *testing.T) {
 			wg := &sync.WaitGroup{}
 
 			go f(wg, 100)
-			wg.Add(1)
-
 			go f(wg, 100)
-			wg.Add(1)
+			go f(wg, 100)
+			wg.Add(3)
 
 			wg.Wait()
 		})
@@ -393,7 +387,7 @@ func TestLocking(t *testing.T) {
 
 	_, err = Open(testdir)
 	assert.Error(err)
-	assert.Equal("error: database locked", err.Error())
+	assert.Equal(fmt.Sprintf("error: database locked %s", testdir), err.Error())
 }
 
 type benchmarkTestCase struct {

datafile.go

@@ -5,7 +5,6 @@ import (
 	"os"
 	"path/filepath"
 	"sync"
-	"time"
 
 	"github.com/pkg/errors"
 
@@ -96,6 +95,8 @@ func (df *Datafile) Sync() error {
 }
 
 func (df *Datafile) Size() (int64, error) {
+	df.RLock()
+	defer df.RUnlock()
 	return df.offset, nil
 }
 
@@ -123,17 +124,16 @@ func (df *Datafile) Write(e pb.Entry) (int64, error) {
 		return -1, ErrReadonly
 	}
 
-	e.Index = df.offset
-	e.Timestamp = time.Now().Unix()
-
 	df.Lock()
-	n, err := df.enc.Encode(&e)
+	defer df.Unlock()
-	df.Unlock()
 
+	e.Offset = df.offset
+
+	n, err := df.enc.Encode(&e)
 	if err != nil {
 		return -1, err
 	}
 	df.offset += n
 
-	return e.Index, nil
+	return e.Offset, nil
 }

entry.go

@@ -7,11 +7,11 @@ import (
 )
 
 func NewEntry(key string, value []byte) pb.Entry {
-	crc := crc32.ChecksumIEEE(value)
+	checksum := crc32.ChecksumIEEE(value)
 
 	return pb.Entry{
-		CRC:   crc,
+		Checksum: checksum,
-		Key:   key,
+		Key:      key,
-		Value: value,
+		Value:    value,
 	}
 }

go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/pkg/errors v0.8.1
 	github.com/prologic/msgbus v0.1.1
+	github.com/prologic/trie v0.0.0-20190316011403-395e39dac705
 	github.com/prometheus/client_golang v0.9.2 // indirect
 	github.com/sirupsen/logrus v1.3.0
 	github.com/spf13/cobra v0.0.3

go.sum

@@ -42,6 +42,8 @@ github.com/pkg/errors v0.8.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/prologic/msgbus v0.1.1/go.mod h1:B3Qu4/U2FP08x93jUzp9E8bl155+cIgDH2DUGRK6OZk=
+github.com/prologic/trie v0.0.0-20190316011403-395e39dac705 h1:2J+cSlAeECj0lfMKSmM7n5OlIio+yLovaKLZJzwLc6U=
+github.com/prologic/trie v0.0.0-20190316011403-395e39dac705/go.mod h1:LFuDmpHJGmciXd8Rl5YMhVlLMps9gz2GtYLzwxrFhzs=
 github.com/prometheus/client_golang v0.9.2 h1:awm861/B8OKDd2I/6o1dy3ra4BamzKhYOiGItCeZ740=
 github.com/prometheus/client_golang v0.9.2/go.mod h1:OsXs2jCmiKlQ1lTBmv21f2mNfw4xf/QclQDMrYNZzcM=
 github.com/prometheus/client_model v0.0.0-20180712105110-5c3871d89910 h1:idejC8f05m9MGOsuEi1ATq9shN03HrxNkD/luQvxCv8=

keydir.go

@@ -9,9 +9,8 @@ import (
 )
 
 type Item struct {
-	FileID    int
+	FileID int
-	Index     int64
+	Offset int64
-	Timestamp int64
 }
 
 type Keydir struct {
@@ -25,11 +24,10 @@ func NewKeydir() *Keydir {
 	}
 }
 
-func (k *Keydir) Add(key string, fileid int, index, timestamp int64) Item {
+func (k *Keydir) Add(key string, fileid int, offset int64) Item {
 	item := Item{
-		FileID:    fileid,
+		FileID: fileid,
-		Index:     index,
+		Offset: offset,
-		Timestamp: timestamp,
 	}
 
 	k.Lock()

proto/entry.pb.go

@@ -19,11 +19,10 @@ var _ = math.Inf
 const _ = proto.ProtoPackageIsVersion2 // please upgrade the proto package
 
 type Entry struct {
-	CRC                  uint32   `protobuf:"varint,1,opt,name=CRC,proto3" json:"CRC,omitempty"`
+	Checksum             uint32   `protobuf:"varint,1,opt,name=Checksum,proto3" json:"Checksum,omitempty"`
 	Key                  string   `protobuf:"bytes,2,opt,name=Key,proto3" json:"Key,omitempty"`
-	Index                int64    `protobuf:"varint,3,opt,name=Index,proto3" json:"Index,omitempty"`
+	Offset               int64    `protobuf:"varint,3,opt,name=Offset,proto3" json:"Offset,omitempty"`
 	Value                []byte   `protobuf:"bytes,4,opt,name=Value,proto3" json:"Value,omitempty"`
-	Timestamp            int64    `protobuf:"varint,5,opt,name=Timestamp,proto3" json:"Timestamp,omitempty"`
 	XXX_NoUnkeyedLiteral struct{} `json:"-"`
 	XXX_unrecognized     []byte   `json:"-"`
 	XXX_sizecache        int32    `json:"-"`
@@ -33,7 +32,7 @@ func (m *Entry) Reset()         { *m = Entry{} }
 func (m *Entry) String() string { return proto.CompactTextString(m) }
 func (*Entry) ProtoMessage()    {}
 func (*Entry) Descriptor() ([]byte, []int) {
-	return fileDescriptor_entry_4f5906245d08394f, []int{0}
+	return fileDescriptor_entry_3e91842c99935ae2, []int{0}
 }
 func (m *Entry) XXX_Unmarshal(b []byte) error {
 	return xxx_messageInfo_Entry.Unmarshal(m, b)
@@ -53,9 +52,9 @@ func (m *Entry) XXX_DiscardUnknown() {
 
 var xxx_messageInfo_Entry proto.InternalMessageInfo
 
-func (m *Entry) GetCRC() uint32 {
+func (m *Entry) GetChecksum() uint32 {
 	if m != nil {
-		return m.CRC
+		return m.Checksum
 	}
 	return 0
 }
@@ -67,9 +66,9 @@ func (m *Entry) GetKey() string {
 	return ""
 }
 
-func (m *Entry) GetIndex() int64 {
+func (m *Entry) GetOffset() int64 {
 	if m != nil {
-		return m.Index
+		return m.Offset
 	}
 	return 0
 }
@@ -81,28 +80,20 @@ func (m *Entry) GetValue() []byte {
 	return nil
 }
 
-func (m *Entry) GetTimestamp() int64 {
-	if m != nil {
-		return m.Timestamp
-	}
-	return 0
-}
-
 func init() {
 	proto.RegisterType((*Entry)(nil), "proto.Entry")
 }
 
-func init() { proto.RegisterFile("entry.proto", fileDescriptor_entry_4f5906245d08394f) }
+func init() { proto.RegisterFile("entry.proto", fileDescriptor_entry_3e91842c99935ae2) }
 
-var fileDescriptor_entry_4f5906245d08394f = []byte{
+var fileDescriptor_entry_3e91842c99935ae2 = []byte{
-	// 134 bytes of a gzipped FileDescriptorProto
+	// 126 bytes of a gzipped FileDescriptorProto
 	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0x4e, 0xcd, 0x2b, 0x29,
-	0xaa, 0xd4, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0x62, 0x05, 0x53, 0x4a, 0xa5, 0x5c, 0xac, 0xae,
+	0xaa, 0xd4, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0x62, 0x05, 0x53, 0x4a, 0xc9, 0x5c, 0xac, 0xae,
-	0x20, 0x51, 0x21, 0x01, 0x2e, 0x66, 0xe7, 0x20, 0x67, 0x09, 0x46, 0x05, 0x46, 0x0d, 0xde, 0x20,
+	0x20, 0x51, 0x21, 0x29, 0x2e, 0x0e, 0xe7, 0x8c, 0xd4, 0xe4, 0xec, 0xe2, 0xd2, 0x5c, 0x09, 0x46,
-	0x10, 0x13, 0x24, 0xe2, 0x9d, 0x5a, 0x29, 0xc1, 0xa4, 0xc0, 0xa8, 0xc1, 0x19, 0x04, 0x62, 0x0a,
+	0x05, 0x46, 0x0d, 0xde, 0x20, 0x38, 0x5f, 0x48, 0x80, 0x8b, 0xd9, 0x3b, 0xb5, 0x52, 0x82, 0x49,
-	0x89, 0x70, 0xb1, 0x7a, 0xe6, 0xa5, 0xa4, 0x56, 0x48, 0x30, 0x2b, 0x30, 0x6a, 0x30, 0x07, 0x41,
+	0x81, 0x51, 0x83, 0x33, 0x08, 0xc4, 0x14, 0x12, 0xe3, 0x62, 0xf3, 0x4f, 0x4b, 0x2b, 0x4e, 0x2d,
-	0x38, 0x20, 0xd1, 0xb0, 0xc4, 0x9c, 0xd2, 0x54, 0x09, 0x16, 0x05, 0x46, 0x0d, 0x9e, 0x20, 0x08,
+	0x91, 0x60, 0x56, 0x60, 0xd4, 0x60, 0x0e, 0x82, 0xf2, 0x84, 0x44, 0xb8, 0x58, 0xc3, 0x12, 0x73,
-	0x47, 0x48, 0x86, 0x8b, 0x33, 0x24, 0x33, 0x37, 0xb5, 0xb8, 0x24, 0x31, 0xb7, 0x40, 0x82, 0x15,
+	0x4a, 0x53, 0x25, 0x58, 0x14, 0x18, 0x35, 0x78, 0x82, 0x20, 0x9c, 0x24, 0x36, 0xb0, 0x5d, 0xc6,
-	0xac, 0x1e, 0x21, 0x90, 0xc4, 0x06, 0xb6, 0xdd, 0x18, 0x10, 0x00, 0x00, 0xff, 0xff, 0x07, 0x99,
+	0x80, 0x00, 0x00, 0x00, 0xff, 0xff, 0x76, 0xd2, 0x3e, 0x83, 0x81, 0x00, 0x00, 0x00,
-	0x47, 0xb9, 0x93, 0x00, 0x00, 0x00,
 }

proto/entry.proto

@@ -3,9 +3,8 @@ syntax = "proto3";
 package proto;
 
 message Entry {
-	uint32 CRC = 1;
+	uint32 Checksum = 1;
 	string Key = 2;
-	int64 Index = 3;
+	int64 Offset = 3;
 	bytes Value = 4;
-	int64 Timestamp = 5;
 }