feat: added interval based wal synchronization (#44)

options.go

@@ -1,6 +1,9 @@
 package wal
 
-import "os"
+import (
+	"os"
+	"time"
+)
 
 // Options represents the configuration options for a Write-Ahead Log (WAL).
 type Options struct {
@@ -29,6 +32,10 @@ type Options struct {
 
 	// BytesPerSync specifies the number of bytes to write before calling fsync.
 	BytesPerSync uint32
+
+	// SyncInterval is the time duration in which explicit synchronization is performed.
+	// If SyncInterval is zero, no periodic synchronization is performed.
+	SyncInterval time.Duration
 }
 
 const (
@@ -44,4 +51,5 @@ var DefaultOptions = Options{
 	SegmentFileExt: ".SEG",
 	Sync:           false,
 	BytesPerSync:   0,
+	SyncInterval:   0,
 }

wal.go

@@ -9,6 +9,7 @@ import (
 	"sort"
 	"strings"
 	"sync"
+	"time"
 )
 
 const (
@@ -40,6 +41,8 @@ type WAL struct {
 	pendingWrites     [][]byte
 	pendingSize       int64
 	pendingWritesLock sync.Mutex
+	closeC            chan struct{}
+	syncTicker        *time.Ticker
 }
 
 // Reader represents a reader for the WAL.
@@ -64,6 +67,7 @@ func Open(options Options) (*WAL, error) {
 		options:       options,
 		olderSegments: make(map[SegmentID]*segment),
 		pendingWrites: make([][]byte, 0),
+		closeC:        make(chan struct{}),
 	}
 
 	// create the directory if not exists.
@@ -117,6 +121,22 @@ func Open(options Options) (*WAL, error) {
 		}
 	}
 
+	// only start the sync operation if the SyncInterval is greater than 0.
+	if wal.options.SyncInterval > 0 {
+		wal.syncTicker = time.NewTicker(wal.options.SyncInterval)
+		go func() {
+			for {
+				select {
+				case <-wal.syncTicker.C:
+					_ = wal.Sync()
+				case <-wal.closeC:
+					wal.syncTicker.Stop()
+					return
+				}
+			}
+		}()
+	}
+
 	return wal, nil
 }
 
@@ -428,6 +448,13 @@ func (wal *WAL) Close() error {
 	wal.mu.Lock()
 	defer wal.mu.Unlock()
 
+	select {
+	case <-wal.closeC:
+		// channel is already closed
+	default:
+		close(wal.closeC)
+	}
+
 	// close all segment files.
 	for _, segment := range wal.olderSegments {
 		if err := segment.Close(); err != nil {

wal_test.go

@@ -1,11 +1,12 @@
 package wal
 
 import (
-	"github.com/stretchr/testify/assert"
 	"io"
 	"os"
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func destroyWAL(wal *WAL) {