move md5 into writer thread

pmtiles/makesync.go

@@ -111,21 +111,6 @@ func Makesync(logger *log.Logger, cli_version string, file string, block_size_kb
 	defer output.Close()
 	output.Write([]byte(fmt.Sprintf("version=%s\n", cli_version)))
 
-	if checksum == "md5" {
-		localfile, err := os.Open(file)
-		if err != nil {
-			panic(err)
-		}
-		defer localfile.Close()
-		reader := bufio.NewReaderSize(localfile, 64*1024*1024)
-		md5hasher := md5.New()
-		if _, err := io.Copy(md5hasher, reader); err != nil {
-			panic(err)
-		}
-		md5checksum := md5hasher.Sum(nil)
-		fmt.Printf("Completed md5 in %v.\n", time.Since(start))
-		output.Write([]byte(fmt.Sprintf("md5=%x\n", md5checksum)))
-	}
 
 	output.Write([]byte("hash=fnv1a\n"))
 	output.Write([]byte(fmt.Sprintf("blocksize=%d\n", block_size_bytes)))
@@ -169,6 +154,8 @@ func Makesync(logger *log.Logger, cli_version string, file string, block_size_kb
 
 	synclines := make([][]uint64, 0)
 
+	md5hasher := md5.New()
+
 	go func() {
 		buffer := make(map[uint64]Result)
 		nextIndex := uint64(0)
@@ -180,6 +167,9 @@ func Makesync(logger *log.Logger, cli_version string, file string, block_size_kb
 				if next, ok := buffer[nextIndex]; ok {
 
 					synclines = append(synclines, []uint64{next.Block.Start, next.Block.Offset, next.Block.Length, next.Hash})
+					if _, err := io.Copy(md5hasher, bytes.NewReader(next.Data)); err != nil {
+						panic(err)
+					}
 
 					delete(buffer, nextIndex)
 					nextIndex++
@@ -233,6 +223,9 @@ func Makesync(logger *log.Logger, cli_version string, file string, block_size_kb
 
 	<-done
 
+	md5checksum := md5hasher.Sum(nil)
+	output.Write([]byte(fmt.Sprintf("md5=%x\n", md5checksum)))
+
 	for _, s := range synclines {
 		output.Write([]byte(fmt.Sprintf("%d\t%d\t%d\t%x\n", s[0], s[1], s[2], s[3])))
 	}