Adds WithSync(...) option to turn on sync after write durability (#63)

* Added WithSync(...) option to turn  on sync after write durability

* Add Sync/NoSync benchmark variants for Put()

bitcask.go

@@ -155,6 +155,12 @@ func (b *Bitcask) Put(key, value []byte) error {
 		return err
 	}
 
+	if b.config.sync {
+		if err := b.curr.Sync(); err != nil {
+			return err
+		}
+	}
+
 	item := b.keydir.Add(key, b.curr.FileID(), offset, n)
 	b.trie.Add(string(key), item)
 

bitcask_test.go

@@ -566,18 +566,6 @@ func BenchmarkPut(b *testing.B) {
 		b.Fatal(err)
 	}
 
-	testdir, err := ioutil.TempDir(currentDir, "bitcask_bench")
-	if err != nil {
-		b.Fatal(err)
-	}
-	defer os.RemoveAll(testdir)
-
-	db, err := Open(testdir)
-	if err != nil {
-		b.Fatal(err)
-	}
-	defer db.Close()
-
 	tests := []benchmarkTestCase{
 		{"128B", 128},
 		{"256B", 256},
@@ -589,8 +577,30 @@ func BenchmarkPut(b *testing.B) {
 		{"32K", 32768},
 	}
 
+	variants := map[string][]Option{
+		"NoSync": []Option{
+			WithSync(false),
+		},
+		"Sync": []Option{
+			WithSync(true),
+		},
+	}
+
+	for name, options := range variants {
+		testdir, err := ioutil.TempDir(currentDir, "bitcask_bench")
+		if err != nil {
+			b.Fatal(err)
+		}
+		defer os.RemoveAll(testdir)
+
+		db, err := Open(testdir, options...)
+		if err != nil {
+			b.Fatal(err)
+		}
+		defer db.Close()
+
 		for _, tt := range tests {
-		b.Run(tt.name, func(b *testing.B) {
+			b.Run(tt.name+name, func(b *testing.B) {
 				b.SetBytes(int64(tt.size))
 
 				key := []byte("foo")
@@ -605,6 +615,7 @@ func BenchmarkPut(b *testing.B) {
 			})
 		}
 	}
+}
 
 func BenchmarkScan(b *testing.B) {
 	currentDir, err := os.Getwd()

options.go

@@ -24,6 +24,7 @@ type config struct {
 	maxDatafileSize int
 	maxKeySize      int
 	maxValueSize    int
+	sync            bool
 }
 
 func (c *config) MarshalJSON() ([]byte, error) {
@@ -31,10 +32,12 @@ func (c *config) MarshalJSON() ([]byte, error) {
 		MaxDatafileSize int  `json:"max_datafile_size"`
 		MaxKeySize      int  `json:"max_key_size"`
 		MaxValueSize    int  `json:"max_value_size"`
+		Sync            bool `json:"sync"`
 	}{
 		MaxDatafileSize: c.maxDatafileSize,
 		MaxKeySize:      c.maxKeySize,
 		MaxValueSize:    c.maxValueSize,
+		Sync:            c.sync,
 	})
 }
 
@@ -43,6 +46,7 @@ func getConfig(path string) (*config, error) {
 		MaxDatafileSize int  `json:"max_datafile_size"`
 		MaxKeySize      int  `json:"max_key_size"`
 		MaxValueSize    int  `json:"max_value_size"`
+		Sync            bool `json:"sync"`
 	}
 
 	var cfg Config
@@ -60,6 +64,7 @@ func getConfig(path string) (*config, error) {
 		maxDatafileSize: cfg.MaxDatafileSize,
 		maxKeySize:      cfg.MaxKeySize,
 		maxValueSize:    cfg.MaxValueSize,
+		sync:            cfg.Sync,
 	}, nil
 }
 
@@ -94,3 +99,12 @@ func WithMaxValueSize(size int) Option {
 		return nil
 	}
 }
+
+// WithSync causes Sync() to be called on every key/value written increasing
+// durability and saftey at the expense of performance
+func WithSync(sync bool) Option {
+	return func(cfg *config) error {
+		cfg.sync = sync
+		return nil
+	}
+}