From 02c22a449f527d4e24e7b03053efd55037a5229e Mon Sep 17 00:00:00 2001
From: larsh <larsh@unknown>
Date: Sat, 6 Apr 2013 03:18:27 +0000
Subject: [PATCH] HBASE-8208 In some situations data is not replicated to
 slaves when deferredLogSync is enabled (Jeffrey Zhong)

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1465176 13f79535-47bb-0310-9956-ffa450edef68
---
 .../hadoop/hbase/regionserver/HRegion.java       | 16 ++++++++++++++--
 .../hadoop/hbase/regionserver/wal/FSHLog.java    | 10 +++++-----
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
index 843f69a9b6e..99d1dad9e69 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
@@ -1447,6 +1447,12 @@ public class HRegion implements HeapSize { // , Writable{
     status.setStatus(s);
     LOG.debug(s);
 
+    // sync unflushed WAL changes when deferred log sync is enabled
+    // see HBASE-8208 for details
+    if (wal != null && isDeferredLogSyncEnabled()) {
+      wal.sync();
+    }
+
     // wait for all in-progress transactions to commit to HLog before
     // we can start the flush. This prevents
     // uncommitted transactions from being written into HFiles.
@@ -5333,12 +5339,18 @@ public class HRegion implements HeapSize { // , Writable{
    * @throws IOException If anything goes wrong with DFS
    */
   private void syncOrDefer(long txid) throws IOException {
-    if (this.getRegionInfo().isMetaRegion() ||
-      !this.htableDescriptor.isDeferredLogFlush() || this.deferredLogSyncDisabled) {
+    if (this.getRegionInfo().isMetaRegion() || !isDeferredLogSyncEnabled()) {
       this.log.sync(txid);
     }
   }
 
+  /**
+   * check if current region is deferred sync enabled.
+   */
+  private boolean isDeferredLogSyncEnabled() {
+    return (this.htableDescriptor.isDeferredLogFlush() && !this.deferredLogSyncDisabled);
+  }
+
   /**
    * A mocked list implementaion - discards all updates.
    */
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
index dd7d37dcba7..a375c8b8a0b 100644
--- a/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
+++ b/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/wal/FSHLog.java
@@ -1071,6 +1071,11 @@ class FSHLog implements HLog, Syncable {
 
   // sync all transactions upto the specified txid
   private void syncer(long txid) throws IOException {
+    // if the transaction that we are interested in is already
+    // synced, then return immediately.
+    if (txid <= this.syncedTillHere) {
+      return;
+    }
     Writer tempWriter;
     synchronized (this.updateLock) {
       if (this.closed) return;
@@ -1080,11 +1085,6 @@ class FSHLog implements HLog, Syncable {
       // See HBASE-4387, HBASE-5623, HBASE-7329.
       tempWriter = this.writer;
     }
-    // if the transaction that we are interested in is already 
-    // synced, then return immediately.
-    if (txid <= this.syncedTillHere) {
-      return;
-    }
     try {
       long doneUpto;
       long now = EnvironmentEdgeManager.currentTimeMillis();