[ISSUE #1751]Fix bug in MessageClientIDSetter (#1758)

* pid 4bytes

* pid is 4 bytes

* #1751 fix bug and add a unit test

* #1751 short pid

* 保持原来

* #1751 remove repeat code

common/src/main/java/org/apache/rocketmq/common/message/MessageClientIDSetter.java

@@ -39,11 +39,8 @@ public class MessageClientIDSetter {
         }
         LEN = ip.length + 2 + 4 + 4 + 2;
         ByteBuffer tempBuffer = ByteBuffer.allocate(ip.length + 2 + 4);
-        tempBuffer.position(0);
         tempBuffer.put(ip);
-        tempBuffer.position(ip.length);
-        tempBuffer.putInt(UtilAll.getPid());
-        tempBuffer.position(ip.length + 2);
+        tempBuffer.putShort((short) UtilAll.getPid());
         tempBuffer.putInt(MessageClientIDSetter.class.getClassLoader().hashCode());
         FIX_STRING = UtilAll.bytes2string(tempBuffer.array());
         setStartTime(System.currentTimeMillis());
@@ -107,6 +104,13 @@ public class MessageClientIDSetter {
         return result;
     }
 
+    public static short getPidFromID(String msgID) {
+        byte[] bytes = UtilAll.string2bytes(msgID);
+        ByteBuffer wrap = ByteBuffer.wrap(bytes);
+        wrap.position(bytes.length - 2 - 4 - 4 - 2);
+        return wrap.getShort();
+    }
+
     public static String createUniqID() {
         StringBuilder sb = new StringBuilder(LEN * 2);
         sb.append(FIX_STRING);
@@ -120,7 +124,6 @@ public class MessageClientIDSetter {
         if (current >= nextStartTime) {
             setStartTime(current);
         }
-        buffer.position(0);
         buffer.putInt((int) (System.currentTimeMillis() - startTime));
         buffer.putShort((short) COUNTER.getAndIncrement());
         return buffer.array();
@@ -145,4 +148,3 @@ public class MessageClientIDSetter {
         return fakeIP;
     }
 }
-    

common/src/test/java/org/apache/rocketmq/common/message/MessageClientIDSetterTest.java

@@ -17,6 +17,7 @@
 
 package org.apache.rocketmq.common.message;
 
+import org.apache.rocketmq.common.UtilAll;
 import org.junit.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -25,12 +26,22 @@ public class MessageClientIDSetterTest {
 
     @Test
     public void testGetIPStrFromID() {
-        String ipv4HostMsgId = "C0A803CA00002A9F0000000000031367";
-        String ipv6HostMsgId = "24084004018081003FAA1DDE2B3F898A00002A9F0000000000000CA0";
-        String v4Ip = "192.168.3.202";
-        String v6Ip = "2408:4004:0180:8100:3faa:1dde:2b3f:898a";
-        assertThat(MessageClientIDSetter.getIPStrFromID(ipv4HostMsgId)).isEqualTo(v4Ip);
-        assertThat(MessageClientIDSetter.getIPStrFromID(ipv6HostMsgId)).isEqualTo(v6Ip);
+        byte[] ip = UtilAll.getIP();
+        String ipStr = (4 == ip.length) ? UtilAll.ipToIPv4Str(ip) : UtilAll.ipToIPv6Str(ip);
+
+        String uniqID = MessageClientIDSetter.createUniqID();
+        String ipStrFromID = MessageClientIDSetter.getIPStrFromID(uniqID);
+
+        assertThat(ipStr).isEqualTo(ipStrFromID);
     }
 
+    @Test
+    public void testGetPidFromID() {
+        int pid = UtilAll.getPid();
+
+        String uniqID = MessageClientIDSetter.createUniqID();
+        short pidFromID = MessageClientIDSetter.getPidFromID(uniqID);
+
+        assertThat(pid).isEqualTo(pidFromID);
+    }
 }