[ISSUE #8448] commitlog class comment optimize

apache · Jul 29, 2024 · 263f0fb · 263f0fb
1 parent cc484d5
commit 263f0fb
Showing 1 changed file with 10 additions and 5 deletions.
diff --git a/store/src/main/java/org/apache/rocketmq/store/CommitLog.java b/store/src/main/java/org/apache/rocketmq/store/CommitLog.java
@@ -1964,23 +1964,28 @@ public AppendMessageResult doAppend(final long fileFromOffset, final ByteBuffer
                     queueOffset, CommitLog.this.defaultMessageStore.now() - beginTimeMills);
             }
 
-            int pos = 4 + 4 + 4 + 4 + 4;
+            int pos = 4     // 1 TOTALSIZE
+                + 4     // 2 MAGICCODE
+                + 4     // 3 BODYCRC
+                + 4     // 4 QUEUEID
+                + 4;    // 5 FLAG
             // 6 QUEUEOFFSET
             preEncodeBuffer.putLong(pos, queueOffset);
             pos += 8;
             // 7 PHYSICALOFFSET
             preEncodeBuffer.putLong(pos, fileFromOffset + byteBuffer.position());
+            pos += 8;
             int ipLen = (msgInner.getSysFlag() & MessageSysFlag.BORNHOST_V6_FLAG) == 0 ? 4 + 4 : 16 + 4;
-            // 8 SYSFLAG, 9 BORNTIMESTAMP, 10 BORNHOST, 11 STORETIMESTAMP
-            pos += 8 + 4 + 8 + ipLen;
-            // refresh store time stamp in lock
+            // 8 SYSFLAG, 9 BORNTIMESTAMP, 10 BORNHOST
+            pos += 4 + 8 + ipLen;
+            // 11 STORETIMESTAMP refresh store time stamp in lock
             preEncodeBuffer.putLong(pos, msgInner.getStoreTimestamp());
             if (enabledAppendPropCRC) {
                 // 18 CRC32
                 int checkSize = msgLen - crc32ReservedLength;
                 ByteBuffer tmpBuffer = preEncodeBuffer.duplicate();
                 tmpBuffer.limit(tmpBuffer.position() + checkSize);
-                int crc32 = UtilAll.crc32(tmpBuffer);
+                int crc32 = UtilAll.crc32(tmpBuffer);   // UtilAll.crc32 function will change the position to limit of the buffer
                 tmpBuffer.limit(tmpBuffer.position() + crc32ReservedLength);
                 MessageDecoder.createCrc32(tmpBuffer, crc32);
             }