From 40ad5aeafe5019abf59c3d149df42d5f4afcc1a2 Mon Sep 17 00:00:00 2001
From: zhangduo <zhangduo@apache.org>
Date: Thu, 22 Mar 2018 08:31:20 +0800
Subject: [PATCH] HBASE-20116 addendum fix javadoc and also a simple
 optimization

---
 .../ZKReplicationQueueStorage.java            | 22 +++++++++++--------
 .../TestZKReplicationQueueStorage.java        |  2 +-
 2 files changed, 14 insertions(+), 10 deletions(-)

diff --git a/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java b/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java
index 6c9752a9f70..1a5749eadb8 100644
--- a/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java
+++ b/hbase-replication/src/main/java/org/apache/hadoop/hbase/replication/ZKReplicationQueueStorage.java
@@ -133,26 +133,30 @@ class ZKReplicationQueueStorage extends ZKReplicationStorageBase
   }
 
   /**
+   * <p>
    * Put all regions under /hbase/replication/regions znode will lead to too many children because
-   * of the huge number of regions in real production environment. So here we use hash of encoded
-   * region name to distribute the znode into multiple znodes. <br>
+   * of the huge number of regions in real production environment. So here we will distribute the
+   * znodes to multiple directories.
+   * </p>
+   * <p>
    * So the final znode path will be format like this:
    *
    * <pre>
-   * /hbase/replication/regions/e1/ff/dd04e76a6966d4ffa908ed0586764767-100
+   * /hbase/replication/regions/dd/04/e76a6966d4ffa908ed0586764767-100
    * </pre>
    *
-   * The e1 indicate the first level hash of encoded region name, and the ff indicate the second
-   * level hash of encoded region name, the 100 indicate the peer id. <br>
-   * Note that here we use two-level hash because if only one-level hash (such as mod 65535), it
-   * will still lead to too many children under the /hbase/replication/regions znode.
+   * Here the full encoded region name is dd04e76a6966d4ffa908ed0586764767, and we use the first two
+   * characters 'dd' as the first level directory name, and use the next two characters '04' as the
+   * second level directory name, and the rest part as the prefix of the znode, and the suffix '100'
+   * is the peer id.
+   * </p>
    * @param encodedRegionName the encoded region name.
    * @param peerId peer id for replication.
    * @return ZNode path to persist the max sequence id that we've pushed for the given region and
    *         peer.
    */
   @VisibleForTesting
-  public String getSerialReplicationRegionPeerNode(String encodedRegionName, String peerId) {
+  String getSerialReplicationRegionPeerNode(String encodedRegionName, String peerId) {
     if (encodedRegionName == null || encodedRegionName.length() != RegionInfo.MD5_HEX_LENGTH) {
       throw new IllegalArgumentException(
           "Invalid encoded region name: " + encodedRegionName + ", length should be 32.");
@@ -160,7 +164,7 @@ class ZKReplicationQueueStorage extends ZKReplicationStorageBase
     return new StringBuilder(regionsZNode).append(ZNodePaths.ZNODE_PATH_SEPARATOR)
         .append(encodedRegionName.substring(0, 2)).append(ZNodePaths.ZNODE_PATH_SEPARATOR)
         .append(encodedRegionName.substring(2, 4)).append(ZNodePaths.ZNODE_PATH_SEPARATOR)
-        .append(encodedRegionName).append("-").append(peerId).toString();
+        .append(encodedRegionName.substring(4)).append("-").append(peerId).toString();
   }
 
   @Override
diff --git a/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestZKReplicationQueueStorage.java b/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestZKReplicationQueueStorage.java
index 28cdff17f44..ca86a05d456 100644
--- a/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestZKReplicationQueueStorage.java
+++ b/hbase-replication/src/test/java/org/apache/hadoop/hbase/replication/TestZKReplicationQueueStorage.java
@@ -257,7 +257,7 @@ public class TestZKReplicationQueueStorage {
   public void testRegionsZNodeLayout() throws Exception {
     String peerId = "1";
     String encodedRegionName = "31d9792f4435b99d9fb1016f6fbc8dc7";
-    String expectedPath = "/hbase/replication/regions/31/d9/" + encodedRegionName + "-" + peerId;
+    String expectedPath = "/hbase/replication/regions/31/d9/792f4435b99d9fb1016f6fbc8dc7-" + peerId;
     String path = STORAGE.getSerialReplicationRegionPeerNode(encodedRegionName, peerId);
     Assert.assertEquals(expectedPath, path);
   }