[ISSUE #9412] Flush bak metrics file before deleting the original file (#9413)

* flush bak file before delete original file.

* timer metrics.

* english comment.

Author: GenerousMan

broker/src/main/java/org/apache/rocketmq/broker/transaction/TransactionMetrics.java

@@ -25,7 +25,11 @@
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
+import java.nio.channels.FileChannel;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
@@ -209,6 +213,10 @@ public synchronized void persist() {
             File configFile = new File(config);
             if (configFile.exists()) {
                 Files.copy(configFile, new File(backup));
+                Path backupPath = Paths.get(backup);
+                try (FileChannel channel = FileChannel.open(backupPath, StandardOpenOption.WRITE)) {
+                    channel.force(true); // force flush before deleting original file.
+                }
                 configFile.delete();
             }
 

common/src/main/java/org/apache/rocketmq/common/BrokerConfig.java

@@ -287,7 +287,7 @@ public class BrokerConfig extends BrokerIdentity {
     @ImportantField
     private long transactionCheckInterval = 30 * 1000;
 
-    private long transactionMetricFlushInterval = 3 * 1000;
+    private long transactionMetricFlushInterval = 10 * 1000;
 
     /**
      * transaction batch op message

store/src/main/java/org/apache/rocketmq/store/timer/TimerMetrics.java

@@ -25,7 +25,11 @@
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.Writer;
+import java.nio.channels.FileChannel;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.StandardOpenOption;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
@@ -263,6 +267,10 @@ public synchronized void persist() {
             File configFile = new File(config);
             if (configFile.exists()) {
                 Files.copy(configFile, new File(backup));
+                Path backupPath = Paths.get(backup);
+                try (FileChannel channel = FileChannel.open(backupPath, StandardOpenOption.WRITE)) {
+                    channel.force(true); // force flush before deleting original file.
+                }
                 configFile.delete();
             }