mtredisalize: Add infrastructure to send backend store changes to separate daemons.

cmd/mtredisalize/main.go

@@ -16,8 +16,9 @@ import (
 )
 
 const (
-	Version    = "0.3"
-	GCDuration = "24h"
+	Version        = "0.3"
+	GCDuration     = "24h"
+	ChangeDuration = "30s"
 )
 
 func usage() {
@@ -30,13 +31,15 @@ func usage() {
 func main() {
 
 	var (
-		port        int
-		host        string
-		driver      string
-		cacheSize   int
-		version     bool
-		interleaved bool
-		gcDuration  string
+		port           int
+		host           string
+		driver         string
+		cacheSize      int
+		version        bool
+		interleaved    bool
+		changeUrl      string
+		gcDuration     string
+		changeDuration string
 	)
 
 	flag.Usage = usage
@@ -46,8 +49,13 @@ func main() {
 	flag.StringVar(&host, "host", "", "host to bind")
 	flag.IntVar(&cacheSize, "cache", 32, "cache size in MB")
 	flag.BoolVar(&version, "version", false, "Print version and exit.")
-	flag.BoolVar(&interleaved, "interleaved", false, "Backend stores key in interleaved form.")
-	flag.StringVar(&gcDuration, "gc-duration", GCDuration, "Duration between forced GCs.")
+	flag.BoolVar(&interleaved,
+		"interleaved", false, "Backend stores key in interleaved form.")
+	flag.StringVar(&gcDuration,
+		"gc-duration", GCDuration, "Duration between forced GCs.")
+	flag.StringVar(&changeDuration,
+		"change-duration", ChangeDuration, "Duration to aggregate changes.")
+	flag.StringVar(&changeUrl, "change-url", "", "URL to send changes to.")
 	flag.Parse()
 
 	if version {
@@ -60,26 +68,47 @@ func main() {
 	}
 
 	var (
-		err     error
-		backend Backend
-		gcDur   time.Duration
+		err           error
+		backend       Backend
+		gcDur         time.Duration
+		chDur         time.Duration
+		changeTracker *ChangeTracker
 	)
 
 	if gcDur, err = time.ParseDuration(gcDuration); err != nil {
 		log.Fatal(err)
 	}
 
+	// Setup the change listening stuff.
+
+	var changeChan <-chan time.Time
+
+	useChangeNotification := changeUrl != ""
+
+	if useChangeNotification {
+		if chDur, err = time.ParseDuration(changeDuration); err != nil {
+			log.Fatal(err)
+		}
+		changeChan = time.Tick(chDur)
+		changeTracker = NewChangeTracker()
+	} else {
+		// We will never receive ticks on this.
+		changeChan = make(<-chan time.Time)
+	}
+
 	path := flag.Arg(0)
 
 	if driver == "sqlite" {
-		if backend, err = NewSqliteBackend(path, interleaved); err != nil {
+		if backend, err = NewSqliteBackend(path, changeTracker, interleaved); err != nil {
 			log.Fatal(err)
 		}
 	} else {
-		if backend, err = NewLeveDBBackend(path, interleaved, cacheSize); err != nil {
+		if backend, err = NewLeveDBBackend(
+			path, changeTracker, interleaved, cacheSize); err != nil {
 			log.Fatal(err)
 		}
 	}
+
 	defer backend.Shutdown()
 
 	var listener net.Listener
@@ -127,6 +156,10 @@ func main() {
 			log.Println("Starting garbage collection.")
 			runtime.GC()
 			log.Println("Garbage collection done.")
+		case <-changeChan:
+			if changeTracker != nil {
+				changeTracker.FlushChanges(changeUrl)
+			}
 		}
 	}
 }