Improved error messages

README.md

@@ -97,31 +97,33 @@ Benchmarks run on a 11" Macbook with a 1.4Ghz Intel Core i7:
 ```
 $ make bench
 ...
-BenchmarkGet/128B-4         	  200000	      5780 ns/op	     400 B/op	       5 allocs/op
-BenchmarkGet/256B-4         	  200000	      6138 ns/op	     656 B/op	       5 allocs/op
-BenchmarkGet/512B-4         	  200000	      5967 ns/op	    1200 B/op	       5 allocs/op
-BenchmarkGet/1K-4           	  200000	      6290 ns/op	    2288 B/op	       5 allocs/op
-BenchmarkGet/2K-4           	  200000	      6293 ns/op	    4464 B/op	       5 allocs/op
-BenchmarkGet/4K-4           	  200000	      7673 ns/op	    9072 B/op	       5 allocs/op
-BenchmarkGet/8K-4           	  200000	     10373 ns/op	   17776 B/op	       5 allocs/op
-BenchmarkGet/16K-4          	  100000	     14227 ns/op	   34928 B/op	       5 allocs/op
-BenchmarkGet/32K-4          	  100000	     25953 ns/op	   73840 B/op	       5 allocs/op
+BenchmarkGet/128B-4         	  300000	      5178 ns/op	     400 B/op	       5 allocs/op
+BenchmarkGet/256B-4         	  300000	      5273 ns/op	     656 B/op	       5 allocs/op
+BenchmarkGet/512B-4         	  200000	      5368 ns/op	    1200 B/op	       5 allocs/op
+BenchmarkGet/1K-4           	  200000	      5800 ns/op	    2288 B/op	       5 allocs/op
+BenchmarkGet/2K-4           	  200000	      6766 ns/op	    4464 B/op	       5 allocs/op
+BenchmarkGet/4K-4           	  200000	      7857 ns/op	    9072 B/op	       5 allocs/op
+BenchmarkGet/8K-4           	  200000	      9538 ns/op	   17776 B/op	       5 allocs/op
+BenchmarkGet/16K-4          	  100000	     13188 ns/op	   34928 B/op	       5 allocs/op
+BenchmarkGet/32K-4          	  100000	     21620 ns/op	   73840 B/op	       5 allocs/op
 
-BenchmarkPut/128B-4         	  100000	     17353 ns/op	     680 B/op	       5 allocs/op
-BenchmarkPut/256B-4         	  100000	     18620 ns/op	     808 B/op	       5 allocs/op
-BenchmarkPut/512B-4         	  100000	     19068 ns/op	    1096 B/op	       5 allocs/op
-BenchmarkPut/1K-4           	  100000	     23738 ns/op	    1673 B/op	       5 allocs/op
-BenchmarkPut/2K-4           	   50000	     25118 ns/op	    2826 B/op	       5 allocs/op
-BenchmarkPut/4K-4           	   50000	     44605 ns/op	    5389 B/op	       5 allocs/op
-BenchmarkPut/8K-4           	   30000	     55237 ns/op	   10001 B/op	       5 allocs/op
-BenchmarkPut/16K-4          	   20000	     78966 ns/op	   18972 B/op	       5 allocs/op
-BenchmarkPut/32K-4          	   10000	    116253 ns/op	   41520 B/op	       5 allocs/op
+BenchmarkPut/128B-4         	  200000	      7875 ns/op	     409 B/op	       6 allocs/op
+BenchmarkPut/256B-4         	  200000	      8712 ns/op	     538 B/op	       6 allocs/op
+BenchmarkPut/512B-4         	  200000	      9832 ns/op	     829 B/op	       6 allocs/op
+BenchmarkPut/1K-4           	  100000	     13105 ns/op	    1410 B/op	       6 allocs/op
+BenchmarkPut/2K-4           	  100000	     18601 ns/op	    2572 B/op	       6 allocs/op
+BenchmarkPut/4K-4           	   50000	     36631 ns/op	    5151 B/op	       6 allocs/op
+BenchmarkPut/8K-4           	   30000	     56128 ns/op	    9798 B/op	       6 allocs/op
+BenchmarkPut/16K-4          	   20000	     83209 ns/op	   18834 B/op	       6 allocs/op
+BenchmarkPut/32K-4          	   10000	    135899 ns/op	   41517 B/op	       6 allocs/op
+
+BenchmarkScan-4             	 1000000	      1851 ns/op	     493 B/op	      25 allocs/op
 ```
 
 For 128B values:
 
-* ~180,000 reads/sec
-*  ~60,000 writes/sec
+* ~200,000 reads/sec
+* ~130,000 writes/sec
 
 The full benchmark above shows linear performance as you increase key/value sizes.
 

bitcask.go

@@ -1,7 +1,7 @@
 package bitcask
 
 import (
-	"errors"
+	"fmt"
 	"io"
 	"io/ioutil"
 	"os"
@@ -9,15 +9,8 @@ import (
 	"strings"
 	"time"
 
-	"github.com/derekparker/trie"
 	"github.com/gofrs/flock"
-)
-
-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")
+	"github.com/prologic/trie"
 )
 
 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 {
@@ -73,10 +66,10 @@ func (b *Bitcask) Get(key string) ([]byte, error) {
 
 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)
@@ -365,7 +358,7 @@ 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())
 	})
 }
 
@@ -393,7 +389,7 @@ 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

@@ -1,13 +1,14 @@
 package bitcask
 
 import (
-	"errors"
 	"fmt"
 	"os"
 	"path/filepath"
 	"sync"
 	"time"
 
+	"github.com/pkg/errors"
+
 	pb "github.com/prologic/bitcask/proto"
 	"github.com/prologic/bitcask/streampb"
 )
@@ -23,11 +24,12 @@ var (
 type Datafile struct {
 	sync.RWMutex
 
-	id  int
-	r   *os.File
-	w   *os.File
-	dec *streampb.Decoder
-	enc *streampb.Encoder
+	id     int
+	r      *os.File
+	w      *os.File
+	offset int64
+	dec    *streampb.Decoder
+	enc    *streampb.Encoder
 }
 
 func NewDatafile(path string, id int, readonly bool) (*Datafile, error) {
@@ -50,16 +52,23 @@ func NewDatafile(path string, id int, readonly bool) (*Datafile, error) {
 	if err != nil {
 		return nil, err
 	}
+	stat, err := r.Stat()
+	if err != nil {
+		return nil, errors.Wrap(err, "error calling Stat()")
+	}
+
+	offset := stat.Size()
 
 	dec := streampb.NewDecoder(r)
 	enc := streampb.NewEncoder(w)
 
 	return &Datafile{
-		id:  id,
-		r:   r,
-		w:   w,
-		dec: dec,
-		enc: enc,
+		id:     id,
+		r:      r,
+		w:      w,
+		offset: offset,
+		dec:    dec,
+		enc:    enc,
 	}, nil
 }
 
@@ -87,22 +96,9 @@ func (df *Datafile) Sync() error {
 }
 
 func (df *Datafile) Size() (int64, error) {
-	var (
-		stat os.FileInfo
-		err  error
-	)
-
-	if df.w == nil {
-		stat, err = df.r.Stat()
-	} else {
-		stat, err = df.w.Stat()
-	}
-
-	if err != nil {
-		return -1, err
-	}
-
-	return stat.Size(), nil
+	df.RLock()
+	defer df.RUnlock()
+	return df.offset, nil
 }
 
 func (df *Datafile) Read() (e pb.Entry, err error) {
@@ -129,23 +125,17 @@ func (df *Datafile) Write(e pb.Entry) (int64, error) {
 		return -1, ErrReadonly
 	}
 
-	stat, err := df.w.Stat()
-	if err != nil {
-		return -1, err
-	}
+	df.Lock()
+	defer df.Unlock()
 
-	index := stat.Size()
-
-	e.Index = index
+	e.Index = df.offset
 	e.Timestamp = time.Now().Unix()
 
-	df.Lock()
-	err = df.enc.Encode(&e)
-	df.Unlock()
-
+	n, err := df.enc.Encode(&e)
 	if err != nil {
 		return -1, err
 	}
+	df.offset += n
 
-	return index, nil
+	return e.Index, nil
 }

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=

streampb/stream.go

@@ -1,6 +1,7 @@
 package streampb
 
 import (
+	"bufio"
 	"encoding/binary"
 	"io"
 
@@ -16,32 +17,40 @@ const (
 
 // NewEncoder creates a streaming protobuf encoder.
 func NewEncoder(w io.Writer) *Encoder {
-	return &Encoder{w}
+	return &Encoder{w: bufio.NewWriter(w)}
 }
 
 // Encoder wraps an underlying io.Writer and allows you to stream
 // proto encodings on it.
 type Encoder struct {
-	w io.Writer
+	w *bufio.Writer
 }
 
 // Encode takes any proto.Message and streams it to the underlying writer.
 // Messages are framed with a length prefix.
-func (e *Encoder) Encode(msg proto.Message) error {
+func (e *Encoder) Encode(msg proto.Message) (int64, error) {
 	prefixBuf := make([]byte, prefixSize)
 
 	buf, err := proto.Marshal(msg)
 	if err != nil {
-		return err
+		return 0, err
 	}
 	binary.BigEndian.PutUint64(prefixBuf, uint64(len(buf)))
 
 	if _, err := e.w.Write(prefixBuf); err != nil {
-		return errors.Wrap(err, "failed writing length prefix")
+		return 0, errors.Wrap(err, "failed writing length prefix")
 	}
 
-	_, err = e.w.Write(buf)
-	return errors.Wrap(err, "failed writing marshaled data")
+	n, err := e.w.Write(buf)
+	if err != nil {
+		return 0, errors.Wrap(err, "failed writing marshaled data")
+	}
+
+	if err = e.w.Flush(); err != nil {
+		return 0, errors.Wrap(err, "failed flushing data")
+	}
+
+	return int64(n + prefixSize), nil
 }
 
 // NewDecoder creates a streaming protobuf decoder.