remove timerwheel mappedbytebuffer

Change-Id: If70c18789843d4fea3e6bd3348972e6896f080e5

Author: guyinyou

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

@@ -45,7 +45,6 @@ public class TimerWheel {
     private String fileName;
     private final RandomAccessFile randomAccessFile;
     private final FileChannel fileChannel;
-    private MappedByteBuffer mappedByteBuffer;
     private final ByteBuffer byteBuffer;
     private final ThreadLocal<ByteBuffer> localBuffer = new ThreadLocal<ByteBuffer>() {
         @Override
@@ -80,10 +79,6 @@ public TimerWheel(String fileName, int slotsTotal, int precisionMs, long snapOff
             }
             randomAccessFile.setLength(wheelLength);
             fileChannel = randomAccessFile.getChannel();
-            if (snapOffset < 0) {
-                mappedByteBuffer = fileChannel.map(FileChannel.MapMode.READ_WRITE, 0, wheelLength);
-                assert wheelLength == mappedByteBuffer.remaining();
-            }
             this.byteBuffer = ByteBuffer.allocateDirect(wheelLength);
             this.byteBuffer.put(Files.readAllBytes(file.toPath()));
         } catch (FileNotFoundException e) {
@@ -100,16 +95,6 @@ public void shutdown() {
     }
 
     public void shutdown(boolean flush) {
-        if (flush) {
-            try {
-                this.flush();
-            } catch (Throwable e) {
-                log.error("flush error when shutdown", e);
-            }
-        }
-
-        // unmap mappedByteBuffer
-        UtilAll.cleanBuffer(this.mappedByteBuffer);
         UtilAll.cleanBuffer(this.byteBuffer);
         localBuffer.remove();
 
@@ -120,20 +105,6 @@ public void shutdown(boolean flush) {
         }
     }
 
-    public void flush() {
-        ByteBuffer bf = localBuffer.get();
-        bf.position(0);
-        bf.limit(wheelLength);
-        mappedByteBuffer.position(0);
-        mappedByteBuffer.limit(wheelLength);
-        for (int i = 0; i < wheelLength; i++) {
-            if (bf.get(i) != mappedByteBuffer.get(i)) {
-                mappedByteBuffer.put(i, bf.get(i));
-            }
-        }
-        this.mappedByteBuffer.force();
-    }
-
     /**
      * Perform backup operation.
      * <p>