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From a.@apache.org
Subject [26/29] hadoop git commit: HDFS-8709. Clarify automatic sync in FSEditLog#logEdit.
Date Fri, 03 Jul 2015 14:16:29 GMT
HDFS-8709. Clarify automatic sync in FSEditLog#logEdit.


Project: http://git-wip-us.apache.org/repos/asf/hadoop/repo
Commit: http://git-wip-us.apache.org/repos/asf/hadoop/commit/5fddc517
Tree: http://git-wip-us.apache.org/repos/asf/hadoop/tree/5fddc517
Diff: http://git-wip-us.apache.org/repos/asf/hadoop/diff/5fddc517

Branch: refs/heads/HADOOP-12111
Commit: 5fddc5177ddad07a735d49c15a63cfc5f74d0891
Parents: bff5999
Author: Andrew Wang <wang@apache.org>
Authored: Thu Jul 2 10:26:40 2015 -0700
Committer: Andrew Wang <wang@apache.org>
Committed: Thu Jul 2 10:26:40 2015 -0700

----------------------------------------------------------------------
 hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt     |  2 ++
 .../hadoop/hdfs/server/namenode/FSEditLog.java  | 28 +++++++++++++-------
 2 files changed, 20 insertions(+), 10 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/hadoop/blob/5fddc517/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
index 7b96c56..6678a3e 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
+++ b/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
@@ -699,6 +699,8 @@ Release 2.8.0 - UNRELEASED
     HDFS-8703. Merge refactor of DFSInputStream from ErasureCoding branch
     (vinayakumarb)
 
+    HDFS-8709. Clarify automatic sync in FSEditLog#logEdit. (wang)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

http://git-wip-us.apache.org/repos/asf/hadoop/blob/5fddc517/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
----------------------------------------------------------------------
diff --git a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
index 1b0b572..939e841 100644
--- a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
+++ b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLog.java
@@ -409,10 +409,14 @@ public class FSEditLog implements LogsPurgeable {
   }
 
   /**
-   * Write an operation to the edit log. Do not sync to persistent
-   * store yet.
+   * Write an operation to the edit log.
+   * <p/>
+   * Additionally, this will sync the edit log if required by the underlying
+   * edit stream's automatic sync policy (e.g. when the buffer is full, or
+   * if a time interval has elapsed).
    */
   void logEdit(final FSEditLogOp op) {
+    boolean needsSync = false;
     synchronized (this) {
       assert isOpenForWrite() :
         "bad state: " + state;
@@ -434,14 +438,16 @@ public class FSEditLog implements LogsPurgeable {
       endTransaction(start);
       
       // check if it is time to schedule an automatic sync
-      if (!shouldForceSync()) {
-        return;
+      needsSync = shouldForceSync();
+      if (needsSync) {
+        isAutoSyncScheduled = true;
       }
-      isAutoSyncScheduled = true;
     }
     
-    // sync buffered edit log entries to persistent store
-    logSync();
+    // Sync the log if an automatic sync is required.
+    if (needsSync) {
+      logSync();
+    }
   }
 
   /**
@@ -1191,11 +1197,13 @@ public class FSEditLog implements LogsPurgeable {
       throws IOException {
     return journalSet.getEditLogManifest(fromTxId);
   }
- 
+
   /**
    * Finalizes the current edit log and opens a new log segment.
-   * @return the transaction id of the BEGIN_LOG_SEGMENT transaction
-   * in the new log.
+   *
+   * @param layoutVersion The layout version of the new edit log segment.
+   * @return the transaction id of the BEGIN_LOG_SEGMENT transaction in the new
+   * log.
    */
   synchronized long rollEditLog(int layoutVersion) throws IOException {
     LOG.info("Rolling edit logs");


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